Table of contents

Buildings and structures of a nuclear facility, 15.11.2013YVL E.6


With regard to new nuclear facilities, this Guide shall apply as of 1 December 2013 until further notice. With regard to operating nuclear facilities and those under construction, this Guide shall be enforced through a separate decision to be taken by STUK. This Guide replaces Guides YVL 4.1 and YVL 4.2.

First edition
Helsinki 2014
ISBN 978-952-309-133-7 (print) Kopijyvä Oy 2014
ISBN 978-952-309-134-4 ( pdf)
ISBN 978-952-309-135-1 (html)


Authorisation

According to Section 7 r of the Nuclear Energy Act (990/1987), the Radiation and Nuclear Safety Authority (STUK) shall specify detailed safety requirements for the implementation of the safety level in accordance with the Nuclear Energy Act.

Rules for application

The publication of a YVL Guide shall not, as such, alter any previous decisions made by STUK. After having heard the parties concerned STUK will issue a separate decision as to how a new or revised YVL Guide is to be applied to operating nuclear facilities or those under construction, and to licensees’ operational activities. The Guide shall apply as it stands to new nuclear facilities.

When considering how the new safety requirements presented in the YVL Guides shall be applied to the operating nuclear facilities, or to those under construction, STUK will take due account of the principles laid down in Section 7 a of the Nuclear Energy Act (990/1987): The safety of nuclear energy use shall be maintained at as high a level as practically possible. For the further development of safety, measures shall be implemented that can be considered justified considering operating experience, safety research and advances in science and technology.

In accordance with Section 7 r(3) of the Nuclear Energy Act, the safety requirements of the Radiation and Nuclear Safety Authority (STUK) are binding on the licensee, while preserving the licensee’s right to propose an alternative procedure or solution to that provided for in the regulations. If the licensee can convincingly demonstrate that the proposed procedure or solution will implement safety standards in accordance with this Act, the Radiation and Nuclear Safety Authority (STUK) may approve a procedure or solution by which the safety level set forth is achieved.

Translation. Original text in Finnish.


1 Introduction

101. In Finland, the authority that oversees the safety of the use of nuclear energy is the Radiation and Nuclear Safety Authority (STUK). Safety regulation by STUK covers the control of the service life of the buildings and structures of nuclear facilities insofar as they have a bearing on the facilities’ nuclear and radiation safety.

102. By virtue of Section 63(1)(3) of the Nuclear Energy Act (990/1987), the Radiation and Nuclear Safety Authority (STUK) is authorised to require require that structures and components intended as parts of the nuclear facility be manufactured in a manner approved of by the Radiation and Nuclear Safety Authority. STUK is authorised to oblige the licensee or licence applicant to arrange for STUK an opportunity sufficiently to control manufacture of the fuel or such structures and components.

103. According to the Nuclear Energy Act (990/1987) [ 1], the use of nuclear energy must be safe; it shall not cause injury to people, or damage to the environment or property. The safety of a nuclear facility is a result of the design, manufacture, construction, operation and maintenance of the facility, its systems and structures in a manner that is compliant with the safety and quality requirements.

104. Government Decree (717/2013) [ 2] presents the general regulations for the safety of nuclear power plants. The requirements for the safety of the plant’s structures, construction and operation are presented in Sections 3–27 of the Decree.

105. Government Decree (736/2008) [ 4] presents the general regulations for the safety of nuclear waste facilities. The requirements for the design of a nuclear waste facility are presented in Sections 6–9 of the Decree, and the requirements for its construction and operation are presented in Sections 17–18 of the Decree.

106. This Guide sets forth requirements and instructions for the design and execution of safety-classified concrete, steel and composite structures of nuclear facilities, and for the inspections performed during operation.

107. In addition to the requirements set forth in this Guide, the design and manufacture of safety-classified buildings and steel, concrete and composite structures shall also adhere to the laws, regulations, building codes and guidelines that are in force in Finland. These include the Land Use and Building Act (132/1999) [ 6] and Decree (895/1999) [ 7], and the regulations and guidelines issued by virtue of the said Act and Decree.

108. The construction regulations, building codes and guidelines that are in force in Finland shall be followed in the design and execution of structures in class EYT (non-nuclear).

109. A Decree by the Ministry of the Environment may issue more detailed construction requirements concerning structural strength, stability, and fire safety. The Ministry of the Environment maintains the Finnish Building Code, into which the building regulations, orders and Ministry guidelines that have been issued by virtue of the Land Use and Building Act and Decree have been compiled. In each municipality the building supervision authorities supervise that the decrees, regulations and orders given by the Ministry of the Environment are followed in all construction activities.

110. The structures, materials and tests performed on them shall meet the valid requirements of the Finnish building legislation, regulations and building codes.

111. If the Finnish construction regulations, codes and standards are insufficient, foreign regulations, guidelines and standards from the field may be applied. It shall then be ensured, however, that the regulations, codes and standards used form an applicable entity.

112. Within the EU, building products are to be introduced onto the market as laid down in Construction Products Regulation 305/2011 [ 5]. If a construction product is not within the scope of the harmonised product standard, and the manufacturer has not acquired a European Technical Assessment for the product, the construction product may be approved applying the approval procedures described in the Act on the Approval of Certain Construction Products (954/2012) [ 8].


 

2 Scope of application

201. In accordance with this Guide, STUK supervises the design, manufacture and use of the steel, concrete and composite structures of nuclear facilities that are important in terms of nuclear and radiation safety. STUK’s regulation has no bearing on any regulatory measures required under the Land Use and Building Act (132/1999) [ 6] and Decree (895/1999) [ 7], unless authorities agree otherwise.

202. The Guide shall apply to nuclear facilities, unless it is expressly stated that a requirement only applies to nuclear power plants.

203. Pursuant to Guide YVL B.2, a nuclear facility’s structures, systems and components shall be assigned to safety classes 1, 2 and 3, and to class EYT (non-nuclear) on the basis of their safety significance. The systems, structures and components of nuclear facilities shall be assigned to three categories, S1, S2A and S2B, based on the seismic resistance requirements imposed on them. The requirements to be followed in the design, manufacturing, operation and supervision of structures shall be determined on the basis of their safety classification and seismic classification.

204. The steel components of composite structures are governed by the requirements for steel structures laid down in this Guide; correspondingly, their concrete components are governed by the requirements for concrete structures listed in this Guide. If the composite structures or steel structures form assemblies that also include system components, such as piping or valves, the appropriate E series YVL Guides shall be applied to the approval of the system components

205. Steel modular structures shall be processed as either composite structures or steel structures, depending on the design method of the load-bearing structures.

206. If metallic materials other than steel are used in metal structures or composite structures, the guidelines for steel structures or composite structures laid down in this Guide shall be applied in their design, manufacture and approval. The guidelines for steel structures laid down in this Guide shall be applied to the design, manufacture and approval of those structures in safety classes 2 and 3 that are not made of concrete or steel.

207. The requirements set forth in the Guide shall apply to the licensee and, where applicable, the licence applicant, plant suppliers and equipment suppliers, manufacturers of steel structures, and those performing construction work at a nuclear facility: building contractors and subcontractors.

208. The structural requirements set forth in this Guide also involve the requirements presented in the Guides below; these shall be taken into consideration in the design and execution of structures of a nuclear facility:

  1. Guide YVL A.1, Regulatory oversight of safety in the use of nuclear energy, sets forth requirements concerning the safety principles for the design and control of nuclear facilities.
  2. Guide YVL A.3, Management system for a nuclear facility, sets forth the detailed requirements concerning the management system and quality management. These requirements also apply to the design, execution and in-service supervision of steel, concrete and composite structures. Insofar as a Guide mentioned above does not cover the specific features of the quality control of steel, concrete or composite structures, more detailed quality control instructions are provided in this Guide.
  3. Guide YVL A.4, Organisation and personnel of a nuclear facility, sets forth the requirements concerning the organisation, personnel, competence and leadership required for the use of nuclear energy. The Guide also defines the competence requirements and approval procedures for the tasks that require separate approval from STUK.
  4. Guide YVL A.5, Construction and commissioning of a nuclear facility, sets forth requirements for the management and control of the construction project of a nuclear facility during the various phases of construction.
  5. Guide YVL A.7, Probabilistic risk assessment and risk management of a nuclear power plant, sets forth requirements for probabilistic fire risk assessments.
  6. Guide YVL A.8, Ageing management of a nuclear facility, sets forth the requirements for the licensee’s design, operation and maintenance activities concerning ageing management in the systems, structures and equipment of a nuclear power plant.
  7. Guide YVL A.11, Security of a nuclear facility, sets forth the requirements concerning the physical protection at nuclear facilities and their design. The Guide also provides the design requirements for the dimensioning of structures to withstand design basis threats, such as aircraft crashes and explosions.
  8. Guide YVL B.1, Safety design of a nuclear power plant, sets forth requirements for the safety planning of a nuclear power plant and the design of safety-classified systems. This Guide YVL E.6 provides more detailed requirements and guidelines for the design of buildings and structures.
  9. Guide YVL B.2, Classification of systems, structures and components of a nuclear facility, presents the safety classifications and seismic classifications and the principles for following them. When classifying structures for safety, it shall also be ensured that functional entities of structures are classified into the same safety class.
  10. Guide YVL B.6, Containment of a nuclear power plant, provides the guidelines for the design and control of the containment.
  11. Guide YVL B.7, Provisions for internal and external hazards at a nuclear facility, sets forth requirements for room and lay-out design at nuclear facilities, and design against internal and external threats.
  12. Guide YVL B.8, Fire protection at a nuclear facility, sets forth the requirements and guidelines concerning fire protection at a nuclear power plant and presents the requirements for separating and load-bearing structures.
  13. Guide YVL E.1, Authorised inspection body and the licensee’s in-house inspection organisation, sets forth the requirements concerning the authority, tasks, and reporting of inspection organisations. The Guide presents the procedure for approving an organisation as an authorised inspection body or the licensee’s in-house inspection organisation.
  14. Guide YVL E.3, Pressure vessels and piping of a nuclear facility, sets forth the guidelines concerning pressure vessels and piping at a nuclear facility, and the materials and test specimens required for their manufacture and qualification.
  15. Guide YVL E.4, Strength analyses of nuclear power plant pressure equipment, sets forth requirements for the loads and strength analyses of a nuclear power plant’s primary circuit and other nuclear pressure equipment important to safety.
  16. Guide YVL E.12, Testing organisations for mechanical components and structures of a nuclear facility, sets forth requirements for testing organisations.

 

3 Structural requirement specification

301. Before the design of structures is started, a structural requirement specification that includes the requirements for design and quality shall be drawn up for concrete, steel and composite structures in safety classes 2 and 3. Component specific requirement specifications shall also be presented where necessary. The design requirements shall present the following:

  1. The regulations, guidelines and standards applied, the limits of their scope of application with justifications, and the basis of the earthquake resistant design and applicable standards.
  2. Initial data used for the design of structures: The initial data to be presented shall include the purpose of the structure as a part of a nuclear facility, a general description of the construction methods, and references to the room and layout plans.
  3. The load combinations and, when the partial safety factor method is used, the partial combination and safety factors for loads, and the partial safety factors for the material properties.
  4. Loads for which reference is made to regulations, guidelines and standards used and to the information provided by manufacturers, or to descriptions of loads transmitted to structures by components, pipings and radiation under operational and accident conditions. Loads (such as design pressure and design temperature, test pressure) shall be defined by taking into account the requirements of Guides YVL B.6 and YVL B.7 and standard ASME III Div.2 [ 29].
  5. Properties of construction materials and their applicability for the intended purpose of use. The acceptance criteria shall be unambiguously defined.
  6. The calculation methods and test methods used for the structural fire design, and their acceptability.
  7. The coatings and coating combinations used, and the test results for the coating combinations (see chapter 5.4).

302. The licensee shall have in place structural requirement specifications for a nuclear facility’s containment liner, equipment hatch and personnel and emergency airlocks that cover the design and inspection requirements for these components in each safety class. The requirements set in chapter 3 of Guide YVL E.3 shall be followed for these structural requirement specifications.

303. As part of the structural requirement specification, the licensee shall draw up a general inspection plan presenting the inspections and control of manufacturing that are performed on the concrete structures, steel structures and composite structures of a nuclear facility and separate structural parts thereof, such as the equipment hatch and personnel and emergency airlocks. The general inspection plan shall define the inspection and supervision stages in which STUK or an authorised inspection body, a third party, the licensee and other parties shall take part. The inspection programme for the execution stage shall be drawn up on the basis of the general inspection plan (see chapter 7.7).


 

4 Requirements concerning the contractors and the supervision of construction work and of the execution of structures

4.1 Construction supervision by the licensee

401. The licensee may purchase part of the construction functions from an external company through agreements. This does not, however, reduce the licensee’s responsibilities as laid down in the Nuclear Energy Act, or the responsibilities of the party engaging in a building project as laid down in the Land Use and Building Act.

402. If the licensee’s organisation is not responsible for all of the construction functions, the licensee shall present a separate clarification concerning how it has arranged construction supervision.

403. According to the Land Use and Building Act, the licensee shall, as a party engaging in a building project, ensure that the building is designed and constructed in accordance with the regulations and orders governing construction work and pursuant to the building permit granted. With a view to the complexity of the project, the licensee shall have available the necessary prerequisites and a sufficient amount of qualified personnel for the execution of the work. The holder of a construction licence, as referred to in Chapter 5 of the Nuclear Energy Act, shall be responsible for the nuclear facility being constructed to meet all safety requirements.

404. The person in charge of the supervision of a nuclear facility's construction work at the site shall have at least an applicable Bachelor of Science (Civ.) degree from a Department of Construction of a technical institute, university of applied sciences or construction technology training programme, and six years’ work experience, of which no less than three years in constructing demanding structures.

405. The person in charge of the supervision of construction work of structures and buildings in safety class 2 shall have at least an applicable Bachelor of Science (Civ.) degree from a Department of Construction of a technical institute, university of applied sciences or construction technology training programme, and at least three years’ work experience in constructing demanding structures.

406. The person in charge of the supervision of work on safety class 3 structures and buildings shall have at least a Master Builder’s examination at a University of Applied Sciences, a Technician’s degree from a technical institute or a similar qualification, and he or she shall have at least three years’ work experience of constructing demanding structures.

407. Those mentioned under paras 404–406 shall have the qualification of foreperson for concrete structures in execution class 3 as defined in the Finnish Building Code.

408. The person in charge of the installation supervision of steel components of steel and composite structures shall have a qualification of manufacturing foreperson for demanding steel structures as defined in the Finnish Building Code in safety class 2, and a qualification of manufacturing foreperson for regular steel structures in safety class 3.

4.2 Construction work execution organisation

409. The building contractor shall have in place a management system that has been certified in accordance with an applicable standard, such as SFS-EN ISO 9001 [ 36], or otherwise independently audited. Furthermore, the management system of the building contractor executing construction work in safety class 2 shall meet the requirements of Guide YVL A.3, and the management system shall be independently audited.

410. The building contractor shall have in place systematic and documented methods for the assessment, selection and supervision of its subcontractors. The building contractor shall evaluate the effectiveness of the subcontractor’s management system and ascertain that the subcontractor has the prerequisites for delivering products or services that satisfy all requirements. The same regulations and obligations shall apply to both the building contractor and the subcontractors involved in the construction. The building contractor shall be responsible for the operations of the subcontractor.

411. The building contractor shall employ professional, experienced personnel, and appropriately qualified procedures, tools and equipment required in its operations.

412. The building contractor shall employ an individual who is in charge of quality control: this person shall have qualifications at least equal to those of the individual in charge of the supervision implemented by the licensee (see para 404).

413. The supervisors of construction work that are employed by the building contractor shall have at least the same qualifications as the individuals in charge of the licensee’s construction supervision.

414. The person responsible for the production of concrete shall have sufficient knowledge of the proportioning of concrete and the properties of hardened concrete, and the necessary practical experience. The person responsible for the production of concrete shall have the documented qualifications of a person responsible for the production of concrete in the relevant execution class. During the production of concrete, a process controller with sufficient knowledge of the process and properties of concrete shall be present at the batching plant. The person in charge of the concrete laboratory shall be a concrete laboratory technician with sufficient knowledge of concrete technology.

415. The foreperson heading the manufacture of concrete elements at the factory shall have sufficient knowledge of the manufacturing of concrete and concrete elements, and sufficient practical experience. The foreperson heading the manufacture of precast concrete products that are not CE marked shall have documented qualifications.

416. The manufacture of the concrete structures at the construction site shall be headed by a concrete foreperson with execution class 3 qualifications. The concrete foreperson shall be present during the important work phases, especially during concreting. If there are compelling reasons for the concrete foreperson to leave the site temporarily during the concreting of structures in execution class 3, he or she must be substituted on the site by a concrete foreperson with execution class 2 qualifications, at a minimum.

417. The reinforcement steel welding coordinator and welders shall have qualifications meeting the requirements of the standards applied (see Annex A).

418. The qualification information for the persons listed in paras 412–417 shall be submitted to STUK together with the organisation description.

419. The qualifications required in paras 412–417 may be demonstrated by means of training and work experience that has been acquired outside Finland.

4.3 Execution organisation of steel and composite structures

420. The manufacturer of steel structures and composite structures shall have in place a management system that is certified in accordance with an applicable standard, such as SFS-EN ISO 9001 [ 36], or otherwise independently audited. Furthermore, the management system of the manufacturer of steel structures and composite structures in safety class 2 shall meet the requirements of Guide YVL A.3, and the management system shall be independently audited. The management system of a manufacturer employing special processes shall also meet the applicable requirements of Guide YVL A.3 in safety class 3.

421. The management system of a manufacturer performing welding in safety classes 2 and 3 shall meet the requirements of standards SFS EN1090-2 [ 16] and SFS-EN ISO 3834-2 [ 35]. The management system of a manufacturer performing heat treatment in connection with welding and closely related processes shall meet the requirements of standard SFS-EN ISO 17663 [ 37].

422. The manufacturer of steel structures and of steel components of composite structures shall have in place systematic and documented methods for the assessment, selection and supervision of its subcontractors. The manufacturer shall evaluate the effectiveness of the subcontractor’s management system and ascertain that the subcontractor has the prerequisites to deliver products or services that satisfy all requirements. The same regulations and obligations shall apply to both the proper manufacturer and the subcontractors involved in manufacture. The manufacturer shall be responsible for the operations of the subcontractor.

423. The manufacturer of steel structures and of steel components of composite structures shall employ professional, experienced personnel, and appropriately qualified procedures, tools and equipment required in its operations.

424. If the building contains steel structures or composite structures, the person in charge of the supervision of installation or manufacture of steel components shall have the qualifications of manufacture foreperson for demanding steel structures laid down in the Finnish Building Code.

425. The manufacturer of steel structures and of the steel components of composite structures shall have available a sufficient number of competent welding coordinators who plan, draw up and qualify the necessary welding and work procedures defined in the standard applied (for qualification requirements, see Annex B).

426. The manufacturer of steel structures and of the steel components of composite structures shall have in place qualified manufacturing procedures for the manufacture of the structure, or the preparedness to qualify the procedures before manufacture is started.

427. The steel structure and the steel components of composite structures shall be manufactured under the supervision of a person with documented qualifications. The foreperson heading the manufacture process shall have the qualification of manufacturing foreperson for demanding steel structures laid down in the Finnish Building Code in safety class 2, and the qualification of manufacturing foreperson for regular steel structures in safety class 3.

428. Persons making permanent weld joints on steel structures and the steel components of composite structures shall have the welder qualifications defined in standard SFS-EN 287-1 at a minimum.

429. The qualifications of testing organisations shall be presented in a separate description. Guide YVL E.12 deals with the requirements, acceptance procedures and supervision of the operations of the testing organisations and personnel that carry out non-destructive and destructive testing.

430. The testing organisations and personnel that perform destructive testing on steel structures and the steel components of composite structures in safety class 2 shall be approved by STUK under Guide YVL E.12. No approval from STUK is required for an NDT testing organisation of steel and composite structures in safety class 3, but the organisation shall be accredited. The accreditation certificate of an NDT testing organisation shall be delivered together with the manufacturer’s organisation description.

431. The description concerning the manufacturer of steel structures and the steel components of composite structures including the subcontractors shall present the qualifications of the person responsible for installation supervision according to requirement 427.


 

5 Materials and products to be used in concrete and steel structures

5.1 Construction materials and products

501. The construction materials and products shall meet all Finnish requirements. If the Finnish regulations, codes and standards are insufficient, foreign regulations, guidelines and standards from the field may be applied. It shall then be ensured, however, that the regulations, codes and standards used form an applicable entity.

502. The acceptability of construction materials and products shall be demonstrated as follows:

  1. The properties of construction materials and products are demonstrated with the CE marking. If the construction product is not within the field of application of a harmonised product standard, or if the manufacturer does not hold a European Technical Assessment (ETA) for the product, the properties may be demonstrated by means of a type approval or verification certificate under the Act on the Approval of Certain Construction Products (954/2012) [ 8]. A Declaration of Performance (DoP) or an ETA is required for CE marked products. Declarations of Performance, European Technical Assessments, type approval decisions and verification certificates that demonstrate acceptability shall be submitted to STUK for information.
  2. The acceptability of products that are CE marked or that have an ETA, type approval or verification certificate needs to be verified at the construction site if there is reason to assume that a product is not in conformity with the certificate.
  3. In case installation of the product is not covered by the approval certificate, an installation procedure shall be drawn up that covers installation quality control.
  4. The qualification of coatings used in the inner containment shall be demonstrated in the manner presented in chapter 5.4.

5.2 Materials and products for concrete structures

503. As regards the definition, properties, manufacture and conformity of concrete, standard SFS-EN 206-1 [ 17] and its national application standard SFS-7022 [ 18] shall be applied. More detailed instructions concerning nuclear facilities are presented in Annex A to this Guide.

504. The following materials, constituents, supplies and methods shall have a valid verification certificate from a body approved by the Ministry of the Environment, unless they have a CE-marking or a European Technical Assessment:

  1. Concrete admixtures
  2. Special mortars and concretes
  3. Prestressing tendons
  4. Prestressing systems
  5. Load-transferring metal parts and lifting anchors
  6. Joint sealing composites and strips for concrete facades
  7. Special splices for reinforcing steel bars
  8. Special anchorage for reinforcing steel bars
  9. Bearings used in support joints

505. The acceptability of special mortars and concretes shall be demonstrated as follows:

  1. Special mortars and concretes refer to ready-mixed mortars and concretes that are intended for load-bearing structures or structures requiring weather resistance, and that are delivered to the construction site as dry bagged products. Special mortars and concretes also include sealing and repair mortars that are required to be weather-resistant.
  2. If the special mortars and concretes are not CE marked, a verification certificate from a body approved by the Ministry of the Environment is required.

506. The following requirements shall apply to reinforcement steels:

  1. The reinforcement elements shall be manufactured using reinforcement steels and weld joints the characteristics of which match the values used in the design of the structures.
  2. The technical classes of reinforcement steels are defined in the valid Finnish standards. Other steel types may be used on the basis of a statement based on tests at a testing organisation approved by the Ministry of the Environment.

507. The acceptability of the prestressing tendon and the prestressing system shall be demonstrated as follows:

  1. Sufficient preliminary descriptions shall exist of the properties of a prestressing system and of matters relating to its execution, such as bendings, anchors and splices. These descriptions shall be in the form of a European Technical Assessment. If no European Technical Assessment exists for the product, the properties may be demonstrated with a verification certificate issued by a body approved by the Ministry of the Environment.
  2. The prestressing tendons and prestressing system shall follow the requirements of standard SFS EN 13670 [ 20] and the European Technical Approval Guideline ETAG 013 [ 25].

5.3 Materials and products for steel structures and composite structures

508. Steel structures and the steel parts of composite structures shall employ materials, supplies, products or systems that satisfy the requirements of standards SFS-EN 1993 [ 13] and SFS-EN 1090-2 [ 16] and the valid CE marking, type approvals, European Technical Assessments or verification certificates.

509. The materials shall be unambiguously defined using the additional attributes (options) specified in standards SFS-EN 1993 and SFS-EN 1090-2. The additional attributes selected shall be presented in the execution specification and, whenever necessary, in drawings.

510. The material for the steel containment, concrete containment liner, and the penetrations, equipment hatches and personnel and emergency airlocks of the containment shall be selected satisfying the requirements of the standard applied (ASME III Div. 2, ASME III Div. 1 NE, KTA KTA 3401).

511. Steel structures may be attached to concrete structures using load-transferring steel parts installed in the cast concrete, or by using post-installed anchors in line with Annex A. Separate guidelines shall be drafted for the installation and inspection of post-installed anchors to be appended to the construction plan. The qualifications of the installers shall also be defined. A report of the use, installation and quality inspection of any other types of steel parts or anchors shall be provided as an attachment to the construction plan.

512. The properties of structural components in composite structures that create the composite effect, such as the characteristics of shear studs and composite plate profiles, shall be demonstrated with a CE marking. If no harmonised product standards or European Technical Assessments (ETA) exist for the product, its characteristics may be demonstrated by means of a type approval or verification certificate from a body authorised by the Ministry of the Environment.

513. As regards the structural components creating the composite effect in composite structures, the containment liner and pool lining plates, sufficient statistical test results concerning the strength and deformation characteristics shall be submitted to STUK for approval, unless these characteristics are evident from the product’s Declaration of Performance, European Technical Assessment, type approval or verification certificate.

5.4 Coatings for concrete structures, steel structures and composite structures

514. Under accident conditions, the coatings of the containment’s internal structures will be subjected to loads which essentially deviate from those encountered during normal operation. The coatings used shall be such that they will not have an unfavourable effect on accident management. It shall be demonstrated, therefore, that coatings will not come off to an extent which would block flow paths and endanger core cooling or removal of residual heat. Furthermore, it shall be demonstrated that under accident conditions the chemical changes, if any, in the coating material do not create new risks.

  1. The design data shall present the requirements for the coatings inside the containment in terms of radiation tolerance, decontaminability, chemical resistance, durability under operating conditions, durability under postulated accident conditions, fire resistance properties, and in-service inspection principles.
  2. The design data shall also present the methods used to ensure the meeting of requirements set for coating materials, coating treatment combinations and the application of coatings.
  3. Only coatings which have passed tests demonstrating the meeting of these requirements are allowable in structures inside the containment.
  4. The tests shall be repeated in case a different coating material is used for repairs and/or recoating, or in case coating consistency has essentially changed compared with the original.
  5. Corresponding reports shall be presented of the containment's external coatings for which requirements relating to decontaminability or radiation tolerance are set in the room classification of the safety analysis report.
  6. The summary of justifications shall present the meeting of the design requirements: how the testing parameters, such as radiation dose rates, set in the standards applied correspond to the assumptions concerning accident conditions.

515. A plan shall be drawn up covering the quality control of the application of paint and coatings. The plan shall describe the quality control measures taken by the various parties and the recording of the results.

  1. The coatings used inside the containment shall meet the requirements presented in report STUK-YTO TR 210 [ 43]. The requirements shall also be applied to coatings outside the containment for which requirements relating to decontaminability or radiation tolerance are set. Approval from STUK shall be applied for when applying some other requirements or a different testing arrangement.
  2. The intumescent painting of steel structures outside the containment shall adhere to the guidelines on the execution and quality control of intumescent painting provided by a body approved by the Ministry of the Environment. The properties of intumescent paint shall be demonstrated with a verification certificate. The persons applying the intumescent paint and the inspectors of the intumescent painting shall have valid qualification certificates issued by a body.
  3. The coating plan shall describe the methods by means of which the fulfilment of the requirements set for coating materials and surface finishing systems and work is verified.

 

6 Design

6.1 Design and execution process and organisations

601. The licensee shall define in its management system the procedures whereby it assesses and selects a nuclear facility’s structural designers, building contractors, and manufacturers of structures. Management system requirements are set forth in Guide YVL A.3.

602. Concerning the design and execution processes and quality assurance of buildings and structures, descriptions of the organisation shall be presented to STUK for approval; they shall describe how quality assurance related to the design and execution of structures has been arranged in the organisations of the licence applicant, plant supplier, structural designer and building contractor. The descriptions shall demonstrate how the correctness and correct application of the initial data is ensured, and how the design practices, functions of all parties and quality management are verified. Chapter 3 of Guide YVL B.1 presents the general requirements related to the design of nuclear power plants and its verification.

603. The licensee shall have a sufficient, competent organisation in place to ensure the conformity of the nuclear facility during the design, execution and operation of the buildings and structures. The organisation description shall be submitted to STUK for approval.

604. The organisation performing structural design shall have in place a management system that has been certified in accordance with an applicable standard, such as SFS-EN ISO 9001 [ 36], or otherwise independently audited. The licensee shall apply the requirements of chapter 8 of Guide YVL E.4 in the assessment and control of the organisation performing structural design as well as in the quality management of structural analyses.

605. Where operation is concerned, the organisation shall employ a sufficient number of qualified personnel, and the lines of responsibility shall be clear. The organisation descriptions shall present the responsibilities and qualifications of the personnel.

6.2 Qualifications of the structural designer

606. The qualification requirements for structural designers that depend on the competence class of the design task are presented in the Land Use and Building Act and the decree issued by virtue of the Act. For each building or structure of a nuclear facility, a structural designer in charge shall be appointed; he or she shall have the qualifications of a structural designer for competence class AA structures. Depending on the load-bearing structure of the building, the required qualifications may be those for a structural designer of class AA concrete or steel structures.

607. The structural designer in charge shall approve the plans falling under his or her field of responsibility.

608. The structural designer shall have the qualifications of a structural designer for the competence class (AA or A) of the concrete or steel structure designed, and sufficient experience in the design of structures that are similar to those used in a nuclear facility. The designer of composite structures shall have the qualifications of a concrete or steel structure designer according to the competence class of the composite structure.

609. In addition to the class AA concrete structure designer qualifications, the designer of prestressed concrete structures shall have sufficient experience in the design of prestressed structures similar to those used in a nuclear facility.

610. The meeting of the training and experience requirements for competence classes AA and A presented in paras 606, 608 and 609 may be demonstrated with a clarification submitted to STUK; studies and qualifications completed abroad are also acceptable.

611. During the construction of structural frames of buildings in safety classes 2 and 3, a representative of the structural designer shall be present at the construction site or promptly available if required. The designer’s representative shall have the same qualifications as the structural designer (paras. 608 and 609).

6.3 Plan review and reviewer qualifications

612. The licensee shall review and approve the documents submitted to STUK for approval and information. In order to ensure correctness and acceptability, comparison analyses or mock-up tests shall be used when necessary. As regards construction plans, the results from document inspections shall be enclosed with the summary of justifications submitted, see chapter 7.11.

613. The person responsible for the plan review shall have the qualifications required in para. 606 from a responsible structural designer.

614. The plan reviewer shall have the qualifications required in para. 608 from a structural designer; the reviewer of plans for prestressed structures shall have the qualifications required in para 609.

6.4 Design methods

615. Design shall be founded on generally accepted, experimentally verified standards and calculation methods. The version of the calculation software shall be verified in the calculation environment that is used. Significant design parameters that are not based on standards shall be verified by means of experiments. In the design of load-bearing and bracing structures, essential technical requirements are considered fulfilled when the structures are designed and implemented in accordance with the Eurocodes [ 1014] and their national annexes that have been issued as decrees by the Ministry of the Environment.

616. The design and analysis applications of numerical methods, such as the finite element method (FEM), shall be ensured by using a validation method that is sufficient for the intended purpose. The results from the validation method shall be presented in the management system documentation of the designing organisation (see para. 604 and Guide YVL E.4, chapter 8).

617. When using demanding design methods and computer software, the individual performing the calculation shall have the necessary training and experience to use the calculation method or software in question.

618. The results from numerical calculation methods shall be verified using simpler analyses. The realisation of the equilibrium and compatibility conditions in numerical calculations shall be verified. Equilibrium conditions shall be verified by comparing loads and support reactions. The results shall be inspected for satisfying boundary conditions and how realistic the structural deformations are.

6.5 General design requirements

619. When selecting the structure types and materials for the concrete and steel structures, the operating and environmental conditions of the structure as well as requirements and restrictions resulting from manufacturing and testing shall be considered.

620. The life cycle of the nuclear facility shall be taken into consideration when designing the service life of buildings and structures. The structure shall be designed and implemented in a manner that allows it to maintain sufficient operability throughout the planned service life of the structure. The structures that have a shorter service life than the planned service life of the facility shall be replaceable. Essential operability requirements are presented in chapter 4 of Guide YVL A.8.

621. The service life dimensioning of a concrete structure shall be performed according to Concrete Code BY50 [ 39]. The exposure classes of concrete structures shall be selected according to standard SFS-EN 206-1 [ 17], and the corrosivity categories of the areas surrounding steel components shall be selected according to standard SFS-EN 12944.

622. Structures shall be designed and designed in a manner that provides them with sufficient reliability in the ultimate limit state. During service, the structure shall also be sufficiently resistant to the generation of deformations, cracks, vibrations, compressions or other effects that may be detrimental to the intended purpose and location of use of the structure.

623. In addition to strength analysis, stability, deformation, fatigue, creep, relaxation and progressive collapse of the structure shall be assessed, if necessary, to verify its durability and reliability under operational and accident conditions.

624. During the fire exposure, the capacity (R) of the load-bearing structure, and the integrity (E) and insulation capacity (I) of the separating structure, shall remain at a sufficient level for the time period required. Guide YVL B.8 presents the fire resistance requirements for buildings and their load-bearing and separating structures. The design and testing of fire resistance shall be based on methods that are pursuant to the EN or ISO standards. When using other methods, their validity shall be demonstrated.

625. Based on the failure consequences of possible damage, the buildings are divided into three consequence classes: CC3, CC2, and CC1. The consequence classes are presented in the Ministry of the Environment Decree concerning the national choices of standard SFS-EN 1990.

626. Structures in safety class 2 belong to consequence class CC3, which means that their design shall take place according to competence class AA (see chapter 8).

627. Structures in safety class 3 belong to consequence class CC3. Their design shall take place according to competence class AA. Consequence class CC2 may be approved for justified reasons; in this case, the design shall take place according to competence class A, at a minimum.

628. The assumptions of the structural analyses and the structural systems, structures and boundary conditions shall be uniform with regard to the behaviour of loads and structures. This shall apply to the operation of the load-bearing and bracing structures, structural continuity characteristics and vibration characteristics.

629. For structural complexes, the aim shall be to achieve structures with sufficient toughness and uniform strength. If the brittle failure mechanism is dimensioning by nature, the level of certainty shall be justified.

630. The structural requirement specification shall present how the cracking of concrete structures and its effects are taken into account in the design of the structures, and what measures are taken to limit cracking.

6.6 Dynamic analysis of structures

631. The seismic design of structures and components assigned to seismic category S1, as defined in Guide YVL B.2, shall consider loads generated by a design basis earthquake. To determine the loads, dynamic analyses shall be used to derive the floor response spectra or acceleration-time diagrams of those building levels that house the structures and components under examination using the ground response spectrum as initial data.

632. The eigenvalues of vibration, accelerations and displacements of the structure shall be defined by means of structural analyses that consider inertial forces (dynamic structural analyses). Guide YVL B.7 provides more detailed instructions on performing dynamic analyses and earthquake analyses. Guide A.11 provides the design requirements for designing structures to withstand certain dynamic design basis threats, such as aircraft crashes.

633. The objectives of the vibration resistance, structural damping and assumptions of the energy dissipation shall be in balance. The damping ratio values chosen shall be justified, taking into consideration the utilisation rate of the structural capacity and the cracking of the concrete and composite structure.

6.7 Containment

634. The leak-tightness of a concrete containment building shall be ensured by using a steel liner. The dimensioning of the liner and penetrations of the concrete containment’s protective shell shall follow standard ASME III Div. 2 [ 29]. The design, manufacture and quality control of steel structures for equipment hatches and personnel airlocks in concrete containment shall follow the guidelines of ASME III Div.1 Subsection NE [ 30]. The requirements set for pressure vessels in Guide YVL E.3 shall be applied to the design, manufacture and quality control of the pressure resisting shell’s penetrations, equipment hatches and personnel airlocks. A strength analysis report shall be drawn up according to Guide YVL E.4.

635. The design, manufacture and quality control of a steel containment and it’s penetrations, equipment hatches and personnel airlocks shall follow the guidelines of ASME III Div.1 Subsection NE. The requirements set for pressure vessels in Guide YVL E.3 shall be applied to the design, manufacture and quality control of the steel containment. A strength analysis report pursuant to Guide YVL E.4 shall be drawn up for the steel containment.

636. The licensee may present alternative standards to ASME III for the design of the containment and its penetrations, hatches and airlocks that meet the design requirements set forth in Guides YVL B.1 and YVL B.6. One of the prerequisites for approval is that the standard in question (for example, SFS-EN 13445-3, KTA3401.1, KTA3401.2 and KTA3401.3) has been followed earlier in the construction of similar nuclear power plants.

637. The concrete containment may be be designed in accordance with Eurocode EN 1992 [ 12] and its national choices that are provided as a Ministry of the Environment decree. The reliability of concrete structures of the containment in ultimate limit state shall be as high as when designed according to standard ASME III Div. 2, at a minimum.

  1. In the structural requirement specification of the containment, the licensee shall present the loads and load combinations, with their partial safety factors and combination factors, used in the design. The partial safety factors and possible limits for stresses shall also be presented.
  2. When load combinations are calculated, care shall be taken not to overestimate loads reducing maximum stress.
  3. The loads and load combinations shall take into account the general design criteria given in Guides YVL B.1 and YVL B.6.
  4. The partial safety factors for load combinations and loads as well as partial safety factors for material properties shall be presented for the loads during construction, operation and accident conditions (earthquake, external and internal events, postulated and severe accident).
  5. The leak-tightness and other operability characteristics for the structures shall be demonstrated by using service limit state dimensioning, and structural strength shall be demonstrated by means of ultimate limit state design.

638. As set forth in Guide YVL A.7, containment leak mechanisms and failure shall be analysed in conjunction with a Level 2 probabilistic risk assessment (PRA); at the same time, probabilistic assessments shall also be made to assess the structural reliability of the containment. When assessing containment reliability, use shall be made of the probability distributions of loads and material properties. The reliability levels of material properties shall be based on quality control documentation from the construction period.

6.8 Leaktightness and leak monitoring of pools containing radioactive substances

639. The concrete structures, liner structure and leak collection systems of pools that contain radioactive substances shall be designed and implemented in a manner that prevents severe damage to spent fuel as laid down in para. 424 of Guide YVL B.1.

640. The concrete structures of pools and tunnels that are filled with water or solutions containing radioactive substances shall be designed to be watertight by using materials meeting all water-tightness requirements and reinforcement that limits the cracking of concrete.

641. The water-tightness of pools containing radioactive substances shall be ensured by using a stainless steel liner. Weld seams in the pools shall be equipped with a leak drainage system that can identify liner leaks and the area of the leak. The design shall take account of the requirement that the weld seams of the liner shall be testable using non-destructive methods (NDT).

642. The liner structure of pools containing radioactive substances shall remain watertight in all design conditions. The design conditions shall be presented in the structural requirement specification, and they shall be based on a generally accepted standard, such as KTA 2502.

6.9 Verification of the design solution

643. Where necessary, design solutions shall be verified using independent comparative analyses and mock-up tests.

644. The design of the containment’s pressure resistant shell against accident conditions (earthquake, external and internal events, postulated and severe accident) shall be verified using comprehensive analyses by an independent third party. The verification shall be performed by means of global and local non-linear analyses. Guide YVL B.6 sets forth requirements concerning the durability of the containment under transients and accident conditions.

645. If necessary, the durability and tightness of the structures shall be verified using test loads, pressure tests, water filling etc. Guide YVL B.6 sets forth the essential requirements concerning the experimental verification of the operation of the containment.


 

7 Construction plan

701. The construction plan for safety class 2 and 3 steel structures and the design documents of concrete structures shall include the following documents, and as a rule they shall be specific to each building or type of structure:

  1. Organisation description
  2. The regulations, codes and standards applied
  3. Design bases
  4. Structural calculations
  5. Structural drawings
  6. Execution specification
  7. Quality control plan
  8. Installation construction plan
  9. In-service structural inspection plan
  10. Plan for containment pressure and leakage tests
  11. The licensee’s summary of justifications

702. The installation construction plan shall be submitted for approval under Annex C to STUK or an authorised inspection body.

703. The construction plans for steel structures shall also include the following documents:

  1. Manufacturing plan for consequence classes CC3 and CC2
  2. Manufacturing plan for structures subjected to fatigue loads

7.1 Organisation description

704. The organisation description shall describe how the quality assurance of the design and execution of structures has been arranged in the organisations of the various parties. The setting up of quality assurance in other organisations whose activities have a bearing on the quality of structures shall also be accounted for. The quality assurance function shall be sufficiently independent of design and execution.

705. The organisation description shall include a description of the management system of the building contractor or steel structure manufacturer and assessments of the said system, including a report on the following:

  1. Management system certification
  2. The assessment, selection, familiarisation and supervision processes of subcontractors
  3. Delivery references of similar locations
  4. Qualifications of the forepersons and employees (for requirements, see chapter 4.2)

706. In addition to the above, the following requirements shall apply to the manufacturers of steel structures.

  1. If the manufacturer of the steel structure or the manufacturer’s important subcontractor is a manufacturer approved by STUK, the construction plan shall include references to STUK’s decisions of approval and the periods of validity of these decisions.
  2. As regards testing organisations, a reference shall be made to STUK’s decisions on approval of the testing organisation, including the periods of validity.
  3. If the testing organisation has been accredited, a reference shall be added to the construction plan.

7.2 Applicable regulations, guidelines and standards

707. The official regulations, guidelines and standards applied shall be presented. Any deviations from the design requirements of the structural requirement specification approved by STUK shall be justified.

7.3 Design bases

708. At least the following initial data employed in the design of structures shall be given:

  1. Room and layout drawings
  2. A building’s purpose as part of the nuclear facility
  3. A structure’s purpose as part of the building
  4. Loads and load combinations
  5. Materials, construction supplies and construction products used
  6. A general description of construction methods
  7. Classification of coatings of structure surfaces
  8. In-service inspection rules

709. The justifications for the loads and load combinations selected shall be presented by referring to the applied standard and to the design requirements of the structural requirement specification approved by STUK.

710. The acceptability of the concrete types and constituents of the concrete structure shall be demonstrated by means of a report, and the composition of the fresh concrete shall be ensured by means of preliminary test results (see Annex A).

711. An analysis shall be presented regarding the properties of reinforcement steels, prestressing tendons and prestressing systems, and their applicability for the intended purpose.

712. In the material report and drawings, the following shall be presented for the different parts of the steel structure:

  1. Standard marking and type of material and welding consumables used in accordance with the applicable standard
  2. Method of manufacture, delivery status and type of material certificate of the material as laid down in standard SFS EN 10204 [ 41] (for requirements, see Annexes B and D).
  3. Grounds for the choice of construction material made, where necessary

713. The design information shall present the coatings of the structures and the requirements and classification defined for them. The requirements for coatings are presented in chapter 5.4.

7.4 Structural calculations and analyses

714. The structural calculation shall describe how the dimensioning presented has been derived from the structural system, structures, boundary conditions, load combinations and material properties. The document shall be detailed enough that the reliability of the analysis method used and the fulfilment of the design requirements can be assessed based on it. The document shall allow for the replication of the essential parts of the calculation. The structural calculation shall assess at least the following points:

  1. The analyses concerning the stability, deformation, fatigue, creep, relaxation and progressive collapse of the structure shall be presented when necessary.
  2. The results of non-linear analyses shall also be presented for the functionality of the containment under accident conditions.
  3. Initial data, assumptions and simplifications, calculation methods, illustrated results, the acceptability of results and conclusions shall be presented for the structural calculations included in the construction plan. A free body diagram or structural model shall be presented for the structure dimensioned.
  4. Verification results shall be presented for the computer software used for structural calculations as laid down in the requirements of para 616.
  5. The structural models for the static functionality and bracing of the structural system shall be presented. When the finite element method is used, the input data, the element mesh chosen, information of element types, boundary conditions, assumptions made and an interpretation of the results shall be presented in a summary report. Furthermore, the independence of the solution from the element mesh density shall be demonstrated when necessary.
  6. The realisation and verification of the equilibrium and compatibility conditions shall be presented in the outputs (see para 618).
  7. The outputs shall present the essential forces and deformations of the structures. The outputs shall allow for the assessment of the effects of different design parameters and loads on the behaviour of the structure. The forces and deformations caused by the dominating design load combinations shall be presented as regards the structural elements and details.
  8. The ultimate limit state and service limit state analyses, applicable accident analyses, and the structural fire design shall be presented.
  9. The references to source literature and the applied points of the source literature shall be presented.
  10. The source literature shall be presented to the inspector of the construction plan upon request.
  11. The calculated deformations of structural elements subjected to test loads during the various phases of test loading shall be presented.
  12. The structural calculations shall be clearly presented and the necessary references to other documents, source literature and drawings shall be made.

7.5 Drawings

715. The drawings shall describe the structure, structural components and details such that the size, geometry, manufacture, and installation of the structure and their allowable tolerances are given in adequate detail. The drawings shall be explicit and clear.

  1. The drawings shall present the necessary further instructions concerning execution of the work, quality control and the requirements set for structures during construction.
  2. In addition to the information required by the regulations and guidelines of the Finnish Building Code, the drawings shall present the safety classes and seismic classes of the structures and their boundaries if the drawings present structures which have various classifications.

7.6 Execution specification

716. An execution specification shall be drawn up for the load-bearing and bracing structures. The execution specification shall be drawn up for steel structures according to standard SFS-EN 1090-2, and for concrete structures according to standard SFS-EN 13670, as well as their national application standards SFS 5975 [ 21] and SFS 5976 [ 44]. The execution specifications for composite structures shall apply both of the above standards.

717. The execution specification shall set forth the requirements and instructions for the execution of a structure. The requirements concerning execution are based on the execution classes. The execution specification shall be detailed enough so that, with the help of it and structural drawings, structures can be constructed to meet all requirements. The execution classes for safety-classified structures are presented in chapters 8.1 and 8.3 that discuss execution.

7.7 Quality plan

718. An execution quality plan shall always be required for the execution of construction work at nuclear facilities. The quality plan is a building project quality control document that includes a description of the constructor’s performance in view of the requirements imposed, a description of the organisation and the responsible in charge, the principles and responsibilities of quality control, and a plan concerning quality control (quality control plan) and quality control records (see the Ministry of the Environment’s decree on load-bearing structures [ 42]).

719. The quality control plan shall present items subject to quality control, and the quality control measures, inspections and tests to be performed. Corresponding instructions shall be prepared for each quality control procedure or inspection, including the recording of quality control results. The instructions shall present, among other matters, the item inspected, the inspection method, scope and requirements, and the performer of the procedure, the drawing up of records, and reporting. As regards detailed information, standards may be referred to.

720. For concrete structures, the quality control plan shall include the readiness inspection for concreting as one phase; for steel structures, it shall include a construction inspection.

721. The responsible organisation/persons and the date of execution shall also be given of measures and inspections conducted under the quality control plan.

722. The quality control plan for structures may be divided into an inspection plan and inspection procedures, describing in detail the methods, reporting and supervision.

723. For mock-up and procedure tests of the various manufacturing procedures performed and their related supervision, the licensee’s statement on their acceptability and suitability for the manufacture in question shall be available.

724. Annex A presents more detailed requirements concerning the quality control plan and inspection plan of concrete structures.

725. Annex B presents more detailed requirements concerning the inspection plan of steel structures.

7.8 Installation construction plan

726. The licensee shall draw up a construction plan for the installation of safety-classified steel structures, steel components of composite structures, and concrete elements. It may be submitted separately or included in the manufacturing construction plan. Where applicable, the requirements for the manufacturing construction plan shall also apply to the installation construction plan.

727. The installation construction plan shall be submitted for approval under Annex C to STUK or an authorised inspection body.

728. The installation construction plan (installation plan) for concrete elements and precast concrete products shall include the information and stability analyses presented in standards SFS-EN 13670 [ 20] and BY50 Concrete Code 2012 [ 39].

729. The installation construction plan (installation plan) for steel structures and steel assemblies of composite structures shall be drawn up according to the requirements of standard SFS-EN 1090-2.

7.9 In-service structural inspection plan

730. The in-service structural inspection plan shall present the inspections to be conducted on structures at specified intervals during plant operation, the manner of performance of the inspections, and the criteria for assessment and recording of the inspection results. The plan for the in-service inspection of reactor containment concrete structures shall include the following information:

  1. Inspection of displacements, strains and leak-tightness of structures at specified intervals and in conjunction with leakage and pressure tests.
  2. Inspection of the condition of post-tensioned containment tendons and anchorages at specified intervals.
  3. Inspection of structures essential for the containment’s function by test loading or other reliable methods, if necessary.

731. The containment shall feature measurement instrumentation that allows for the acquisition of sufficient information on the displacements and strains of the containment’s base slab and pressure resistant shell, as well as temperature and humidity, during the leak-tightness and pressure tests. The prestressing force in the tendons of a post-tensioned pressure resistant shell shall be measurable for at least some of the tendons.

7.10 Plan for containment pressure and leakage tests

732. The plan for the pressure and leakage tests of the reactor containment shall present unambiguous acceptance criteria for at least the below items:

  1. Containment displacements and strains under different pressure levels
  2. Recovery of displacements and strains
  3. Cracks and their mapping
  4. Temperatures, leak volumes

733. Guidelines that are useful for the preparation of the plan are presented in standard ASME III Div.2 [ 29] and USNRC Regulatory Guide 1.90 [ 31]. The plan for containment pressure and leakage tests may also be part of the in-service inspection plan.

7.11 Summary of justifications

734. The licensee shall draw up a summary of justifications presenting how the structure meets the requirements set for it, and how the licensee has established its conformity to requirements. The summary of justifications shall also present the changes made to the approved documents, any non-conformances that occurred during manufacture, and their impact on the suitability and acceptability of the structure.

735. If the construction plan does not entirely meet the requirements of the YVL Guides, the safety analysis report or STUK’s decisions, the summary of justifications shall present how the requirements have been deviated from and how the safety level required by the YVL Guides can be achieved in this case.


 

8 Execution

8.1 Execution of concrete structures

801. The execution of concrete structures shall follow the requirements set forth in this Guide and standard SFS-EN 13670 and its national application standard SFS 5975.

802. The quality assurance of load-bearing welds and fixing joints of reinforcement steels of structures in safety classes 2 and 3 shall be made in accordance with standard SFS-EN 13670 and its national application standard SFS 5975, pursuant to the requirements of execution class 3. The welding procedure specifications for load-bearing welding joints of reinforcement shall be submitted to STUK for approval together with the design documentation of the concrete structures.

803. Detailed requirements for the execution of concrete structures are presented in Annex A to this Guide.

804. The definition, properties, manufacturing and conformity of concrete shall follow standard SFS-EN 206-1 and its national application standard SFS 7022, which details the preservation guidelines and allowed cement types.

805. The safety class for concrete structures shall be presented in the plans. Concrete structures in safety class 2 and 3 shall be manufactured as execution class 3 structures under standard SFS-EN 13670. Structures made of high strength concrete and prestressed structures belong to execution class 3.

806. The exposure classes of the concrete structure under standard SFS-EN 206-1 shall be defined according to the prevailing environmental conditions.

8.2 Precast concrete products and concrete elements

807. The requirements of this Guide shall be applied to the design, manufacture and supervision of concrete elements cast at the construction site and CE marked, product standards compliant precast concrete products.

808. Concrete element construction shall follow the requirements of standard EN 13670 and its national application standard SFS 5975. These requirements shall also apply to concrete elements manufactured at the construction site and the factory-fabricated concrete elements that are not manufactured under a European product standard. The requirements shall also apply to the installation of precast concrete products and elements.

809. The manufacture of precast concrete products shall follow the requirements of this Guide, those laid down in standard EN 13369 and the harmonised product standards leading to the CE marking of precast concrete products.

810. The following information shall be submitted to STUK for approval concerning factories that manufacture safety-classified concrete elements or precast concrete products:

  1. Organisation description
  2. The regulations, codes and standards applied
  3. Quality control plan

811. Quality control documentation shall be submitted for approval concerning the scope of inspection of concrete elements and precast concrete products; it shall define the inspection scope per element type.

812. Before casting the precast element, the manufacturer of the concrete element or product shall perform an inspection to verify conformity to the construction plan. After an approving inspection by the manufacturer, the licensee’s representative shall perform a concreting readiness inspection on safety class 3 concrete elements or precast concrete products, inspecting the first element or precast concrete product and at least 10% of the total number of concrete elements or precast concrete products of the lot. The concreting readiness inspection of concrete elements or precast concrete products in safety class 2 shall be performed by STUK.

8.3 Execution of steel structures and composite structures

813. The licensee shall describe the detailed requirements and procedures concerning the qualification of the manufacturing procedures of steel structures and the steel components of composite structures in its management system and related instructions. The instructions shall take into consideration the manufacture of the structures and installation performed at the construction site; therefore, the requirements apply to the equipment suppliers and their subcontractors, the welding contractors and the licensee’s manufacture activities.

814. The execution of steel structures and the steel components of composite structures shall follow the requirements set forth in this Guide, standard SFS-EN 1090-2, and its national application standard SFS 5976.

815. Detailed requirements for the execution of steel structures and the steel components of composite structures are presented in Annex B to this Guide.

816. Steel structures in safety class 2 shall be manufactured as execution class EXC4 structures under standard SFS-EN 1090-2. Steel structures in safety class 3 shall be manufactured as execution class EXC3 structures, at a minimum.

817. Composite structures do not have a specific execution class; the execution class of a concrete and steel composite structure is defined separately for the concrete and steel under paras 805 and 816 and standards SFS-EN 1090-2 and SFS-EN-13670.


 

9 Inspections of civil structures

9.1 Readiness inspections for concreting, injection and prestressing work

901. The manufacturing of concrete structures and composite structures in safety classes 2 and 3 is based on STUK-approved design documents of structures and on plans for individual work phases or work assignments.

902. The installation of formwork and reinforcement for concrete structures in safety classes 2 and 3 may begin once the design documents have been submitted to STUK and the licensee has authorised that this work may be started.

903. The installation of reinforcement for composite structures in safety classes 2 and 3 may begin once STUK or an authorised inspection body has performed the installation inspection of the steel components of the composite structure.

904. The design documents of a structure in safety class 2 or 3 to be inspected shall be approved by STUK before concreting begins.

905. The concreting, injection or prestressing of structures in safety class 2 may be started after STUK has approved the design documents and the detailed work plans, and inspected that concreting readiness exists on the site.

906. The concreting work plan shall be submitted to STUK for approval no later than two weeks before concreting is started. However, if the concreting process in question is very extensive or demanding, the plan shall be submitted no later than four weeks before concreting is commenced.

907. For prestressing and injection work, detailed plans concerning work performance and quality control shall be submitted to STUK no later than four weeks before the work in question is started.

908. The prerequisite for the readiness inspection performed by STUK on concrete and composite structures in safety class 2 is that the licensee has inspected and approved the quality control documents concerning the concrete structure or concreting part of the composite structure, and has for its part determined that there is sufficient readiness to start work.

909. The licensee shall request a concreting readiness inspection from STUK about one week before the planned inspection date. The protocol from the licensee’s readiness inspection shall be submitted to STUK for information before the readiness inspection carried out by STUK.

910. The concreting and injection of concrete structures or composite structures in safety class 3 may be started after STUK or an authorised inspection body has approved the design documents pertaining to the structures. The licensee shall inspect and approve the quality control protocols concerning the concrete structure, concreting part of the composite structure, or injection work, and determine that sufficient readiness exists for starting the work.

911. In its decision, STUK or an authorised inspection body will separately list those structures whose concreting, injection or prestressing may be started only after an inspector from STUK or an inspection organisation has approved the detailed work plans and ascertained on the site that there is sufficient readiness to start work.

912. Application of coatings on safety class 2 and 3 concrete structures may be started after STUK has approved the documents concerning them, and once all of the structural inspections and reviews that are required before the coating work are complete.

9.2 Construction inspection and installation construction inspection of steel structures and the steel assemblies of composite structures

913. The construction inspection of a steel structure or the steel components of a composite structure consists of the following:

  1. A review of construction plan execution
  2. A review of the manufacturing documents
  3. A visual inspection of the structure
  4. Potentially, a functional test and leak-tightness test

914. The licensee shall request STUK or an authorised inspection body to conduct a construction inspection approximately two weeks before the planned inspection date.

915. Welds shall be inspected before the application of coating on a steel structure or composite structure.

916. The construction inspection is usually performed on the completed steel structure (components to be embedded in concrete, for example) or on steel components of steel or composite structures on the manufacturer’s premises before delivery or installation. If the construction inspection is conducted at the plant site, the licensee shall, during the acceptance inspection, ensure that the requirements for conducting a construction inspection have been fulfilled.

917. The licensee, plant and equipment supplier and manufacturer shall ensure that staff with the necessary expertise are available during the construction inspection.

918. The licensee shall agree on the essential construction inspection dates with the manufacturer, plant supplier or importer.

919. When agreeing on a date for the construction inspection, attention shall be given to the approval procedures related to the various manufacturing phases and any necessary intermediate construction inspections in accordance with the construction plan. The manufacturer shall ensure that construction inspections and intermediate inspections are conducted during the work phase for which they were planned.

920. It shall be a prerequisite for the construction inspection conducted by STUK or an authorised inspection body that the construction plan for the item inspected has been approved in accordance with the decisions on the inspection area boundaries either by STUK or an authorised inspection body.

921. A construction inspection shall not be performed on serially manufactured standard structures, if their properties have been demonstrated by means of a CE marking, a European Technical Assessment, a type approval or a verification certificate.

922. The construction inspection shall be performed if the CE marked, ETA approved or type approved product is a safety class 2 or 3 steel structure or component, the construction plans of which have been approved by STUK or an authorised inspection body.

923. The licensee shall be obliged to ensure that all plans concerning the manufacture of the steel or composite structure as well as the approvals and conditions pertaining to them are taken into account in the construction inspection.

924. The licensee, manufacturer and plant supplier shall assess and approve the manufacture result documentation of the equipment or structure prior to submitting it to STUK or an authorised inspection body.

925. The licensee, manufacturer and plant supplier shall ensure beforehand, by conducting their own inspections, that the requirements for starting the construction inspection are met and that the steel structures or their components to be inspected can be inspected and approved in the construction inspection.

926. The licensee shall request STUK or an authorised inspection body to conduct an installation construction inspection of steel structures or the steel components of composite structures about two weeks before the planned date. The installation construction inspection and intermediate inspections shall ensure the acceptability of the installation of the steel structure or the steel component of a composite structure, and the result documentation of the installation quality inspection.

9.3 Execution audits

927. The licensee shall supervise the implementation of quality assurance in various organisations to the extent deemed necessary and in accordance with Guide YVL A.3. Audits are particularly important if deviations from approved documents and plans have been observed.

928. Independently of the licensee’s follow-up inspections, STUK carries out audits at various sites before the commencement of and during construction work in a scope it considers necessary; these visits are made, in particular, to the production plants which supply materials listed below: steel factories (reinforcement steels and prestressing tendons), plants manufacturing components for prestressing systems, plants manufacturing anchor plates, concrete batching plants and concrete element factories.

9.4 Reporting on inspections and testing

929. Reporting aims to provide STUK with the prerequisites for the monitoring of work progress and of the control actions taken, and for the rapid assessment of test results.

930. The licensee shall draw up a plan concerning reporting to STUK and the inspection organisations before the construction work for the plant is started, and it shall be submitted to STUK for approval. In the plan, the licensee shall present a proposal for the key schedules and testing results related to the construction of structural elements to be submitted for information.

931. The reporting plan shall include the following schedules and results:

Work schedules: general schedules, monthly schedules, weekly schedules of concreting work; work schedules for the next two weeks shall be submitted on a weekly basis.

  1. Weekly schedules for the inspections of steel structures and steel components of composite structures.
  2. Summaries of the key results related to concreting work: test results for cement, results from tests at construction site and batching plant, grading strengths for structures in safety class 2 by concreting part, rolling average and grading strengths for nine test specimens from the construction site results, test results for reinforcement steel and prestressing tendons, and other necessary results.

932. The results concerning concreting work in safety classes 2 and 3 shall be submitted to STUK for information every month.

933. STUK shall be notified without delay, and a deviation report drawn up when necessary, if any part of the concrete test results deviates from the acceptable range of fluctuation. The same shall apply if any unexpected matters which may affect the acceptability of the structures arise at the construction site.

934. Upon completion of a nuclear facility’s concrete structures, a concrete work report shall be drawn up by the licensee for all concrete structures (safety class 2, 3 and EYT (non-nuclear)), which shall be submitted to STUK for information before any buildings are commissioned. The concrete work report shall contain at least the following information:

  1. Contractor’s work arrangements, quality assurance and control, quality control of materials, work quality control
  2. Concreted structures, acceptability of hardened concrete, acceptance tests for concrete at the batching plant, acceptance tests for concrete at the construction site, special concreting, post-concreting
  3. Prestressing work
  4. Non-conformancies and how they are addressed
  5. Summary of how the design criteria for concrete structures have been met

9.5 Commissioning inspections and test programmes

935. Buildings and structures in safety classes 2 and 3 may be commissioned after they have been accepted by STUK or an authorised inspection body in a commissioning inspection. STUK does not perform commissioning inspections on buildings and structures in class EYT.

936. The licensee shall present to STUK the procedures whereby it approves the completed buildings and structures in safety classes 2, 3 and EYT for commissioning.

937. The licensee shall perform the commissioning inspections on buildings and structures. After this, the licensee may present a written request for a commissioning inspection to STUK, and it shall be submitted to STUK no later than two weeks before the time of the inspection.

938. Pursuant to Guide YVL B.6, a pressure test shall be performed on the containment before commissioning the plant to ensure the structural durability of the containment. The test programme of the containment pressure tests and leak-tightness tests shall be prepared and delivered to STUK for approval in accordance with Guide YVL A.5. The containment commissioning inspection shall be conducted in two phases:

  1. the readiness of the containment for the pressure test, and non-conformancies from the state required for commissioning,
  2. the results from the pressure test, and the readiness of the containment for commissioning.

939. The commissioning inspections of the containment material and personnel airlocks shall be performed in two phases, following chapters “The first phase of the commissioning inspection” and “The second phase of the commissioning inspection” of Guide YVL E.3.

940. The commissioning programmes for the equipment hatch and personnel airlocks shall be prepared and delivered to STUK for approval in accordance with Guide YVL A.5. The approval status will be examined by STUK during the first phase of the commissioning inspection.

941. The commissioning inspections of the facility’s buildings and structures shall have been acceptably performed before the facility or parts thereof are taken into use.

942. The commissioning inspections may be performed in stages, so that the buildings and structures that must be operable before fuel is introduced into the facility are inspected first. Once the loading of nuclear fuel begins, STUK’s commissioning inspection shall have been acceptably completed on all safety related buildings and structures.

9.6 In-service inspections

943. During the operation of a nuclear facility, the licensee shall conduct in-service inspections of buildings and structures according to a separate programme. The inspection programme shall take account of the requirements for in-service inspections established in the design data. The in-service inspection programme shall be submitted to STUK for approval before the commercial operation of the facility is started.

944. Detailed inspection procedures may be sent to STUK for approval at a later date, however no later than one month prior to the first planned inspection date.

9.7 Repairs and modifications

945. Pursuant to Guide YVL B.1, conceptual design plans and system-specific pre-inspection documents shall be submitted to STUK for approval for all safety class 1, 2 and 3 systems prior to the commencement of the detailed design of components and structures. The content of a system’s conceptual design plan shall correspond to that of the preliminary safety analysis report. Additionally, the conceptual design plan shall contain a report on the quality management principles, including design reviews and the qualification of the design organisation.

946. This Guide shall be applied, to the extent appropriate, when repairing or modifying concrete and steel structures during the operation of nuclear facilities. Repair and modification plans for safety class 2 and 3 concrete structures and steel structures shall be approved by STUK or an authorised inspection body before work is started.


 

10 Documents to be submitted to STUK

10.1 Phases of a nuclear facility's regulatory control

1001. The regulatory control of a nuclear facility contains five phases: the decision-in-principle phase, the construction licence phase, the construction phase, the operating licence phase, and in-service condition monitoring. This chapter presents the documents to be submitted to STUK in the phases listed above, and the key contentual requirements.

1002. Source literature not easily available, or copies thereof, relating to the documents shall be submitted to STUK with the documents in question.

10.2 Documents to be submitted during the decision-in-principle phase

1003. During the decision-in-principle phase, documents shall be submitted whereby the prerequisites for achieving the standards required by Finnish regulations and guidelines in terms of construction technology and structures can be ascertained. The documents to be submitted are presented in Annex A.1 of Guide YVL A.1.

10.3 Documents to be submitted at the construction licence phase

1004. Annex A.2 of Guide YVL A.1 presents the requirements for the documents to be submitted during the construction licence phase. For construction technology, the preliminary safety analysis report, the topical reports supplementing it, the classification document, and the preliminary plans for construction quality assurance (see para 602) shall be submitted. A topical report shall be submitted concerning, in particular, the preparations made for earthquakes and aircraft crashes. The descriptions concerning the organisation and the design process quality assurance presented in chapters 6.1 and 6.2 shall be presented.

1005. The following shall also be presented for structures in safety classes 2 and 3:

  1. System description of the buildings and the functions of their structures as part of a nuclear facility
  2. Preliminary structural requirement specifications for steel, concrete and composite structures, including the regulations, guidelines and standards applied and their areas of application pursuant to chapter 3
  3. Structure and building specific general requirement specifications and general inspection plans
  4. Test results that are important in terms of design, such as the effects of molten core material on concrete structures
  5. Preliminary materials report
  6. Preliminary dimensioning, applicable calculation models and computer software
  7. Criteria for the in-service structural supervision of the containment
  8. Principles of leak monitoring and structural supervision of the fuel pools

10.4 Design documents to be submitted during construction

1006. The delivery plan for the design documents shall be submitted to STUK for information. In the delivery plan, the licensee shall present a proposal for the documents to be delivered and their delivery times.

1007. The construction plans of concrete structures and of the concrete parts of composite structures in safety classes 2 and 3 shall be submitted to STUK for approval two months before concreting is started on the structures or structural components in question. The structural requirement specification with the design requirements shall have been approved by STUK before the construction plans are delivered.

1008. The manufacture of steel structures and the steel components of composite structures in safety class 2 may be started once STUK has approved the construction plans. This requirement shall also apply to the components of composite structures in safety class 2 or 3, in the design of which other E series equipment Guides (known as system modular structures, para. 204) are used.

1009. The construction plans of steel structures and the steel components of composite structures in safety class 3 shall be submitted to STUK or an inspection organisation for approval before manufacture may begin. The structural requirement specification of the steel and composite structures with their design requirements shall have been approved by STUK before the construction plans are delivered. The construction inspections shall be performed in line with the design documents approved by STUK.

1010. The design documents of structures and buildings in class EYT shall be presented to STUK upon request whenever they are relevant in terms of radiation and nuclear safety.

1011. The final in-service structural supervision plan shall be submitted to STUK for approval before the reactor is loaded.

1012. If deviations from approved documents are detected during manufacture, a non-conformance report shall be drawn up in which at least the following information is presented:

  1. The nuclear safety significance of the non-conformance, with justifications
  2. Description of the location, who discovered the non-conformance, who created the report, who processed the matter
  3. Description of the non-conformance, proposal/plan for action
  4. Inspection/approval markings of the report, distribution of the non-conformance report
  5. Inspection markings of actions necessitated by the non-conformance report
  6. Final approval markings of the non-conformance report

1013. If the non-conformancies discovered during manufacture affect the properties of the structure, the summary of justifications delivered together with the construction plans (see section 7.11) shall be updated and delivered to STUK for approval before the commissioning inspection of the structure in question.

10.5 Documents to be submitted during the operating licence phase

1014. The final safety analysis report will be processed in conjunction with the operating licence application. Chapter 8 and Annexes A and B discuss other control procedures relating to buildings and structures.

1015. The as-built documentation shall be submitted to STUK for information. The documents to be submitted are defined in more detail in the delivery plan for the design documents.

10.6 Modifications to structural systems of an operating nuclear facility

1016. The submission of documents related to modifications to the structural systems of an operating nuclear facility shall follow the same principles as those presented above for a nuclear facility under construction.


 

11 Regulatory oversight by the Radiation and Nuclear Safety Authority

11.1 Division of inspection responsibilities

1101. STUK inspects and approves the plans for concrete, steel and composite structures in safety classes 2 and 3, and performs concreting readiness inspections and construction inspections for steel structures and the steel components of composite structures at key locations.

1102. Annex C presents the division of inspection responsibilities between STUK and an authorised inspection body. The division of inspection responsibilities can be supplemented by issuing separate decisions concerning buildings and structures that STUK will inspect (such as structures for physical protection, fuel pools, and pressure tests).

1103. The inspection organisation shall be authorised and approved in accordance with Guide YVL E.1, and it shall have the prerequisites for the inspection.

11.2 Structural requirement specification

1104. STUK shall approve in its decision the structural requirement specifications set by the licensee for the concrete, steel and composite structures.

1105. The meeting of the set requirements shall be verified in connection with document reviews and construction inspections, and as part of the construction and operation inspection programmes.

1106. The specifications based on the licensee’s requirements and drafted by the plant and equipment suppliers shall be approved in STUK’s decisions.

11.3 Approval of inspection and testing organisations

1107. The requirements and approval procedure for inspection organisations are presented in Guide YVL E.1, and the requirements and approval procedure for testing organisations is presented in Guide YVL E.12.

11.4 Regulation of design organisations

1108. The regulation of design organisations is covered in Guides YVL B.1 and YVL E.4.

1109. STUK approves the organisation description of the design organisation and inspects the qualifications of the structural designers according to the requirements set forth in chapter 6.2 of the present Guide.

11.5 Construction plans and design documents

1110. STUK or an authorised inspection body shall process the construction plan for steel structures and the steel components of composite structures and the design documents of concrete structures, which include the documents laid down in chapters 7 and 10 of this Guide.

1111. The first phase of the construction plan and design document review is the assessment of the licensee’s summary of justifications. If the licensee’s own review is deemed insufficient, it shall be supplemented by the licensee.

1112. The result of processing the construction plan shall be presented in a decision by STUK or an authorised inspection body. Minor updates to approved plans may be processed as received for information.

1113. STUK or an authorised inspection body shall issue permission to start manufacture on the basis of construction plans and design documents pursuant to chapter 10.4, and inspections pursuant to chapter 11.

11.6 Control of manufacturing and construction inspection

1114. STUK or an authorised inspection body monitors the manufacture of safety-classified steel structures in connection with intermediate construction inspections or during separate visits. The supervision visit may also be agreed to be included in the monitoring audits carried out during manufacturing.

1115. STUK approves the construction supervision organisation description and inspects the qualifications of the supervisors according to the requirements set forth in chapter 4.1 of the present Guide.

1116. STUK supervises the manufacture of safety-classified concrete structures by means of readiness inspections conducted on concreting, grouting, injection or prestressing work, or during separate visits. Concreting, grouting, injection or prestressing work is also supervised while the work proceeds.

1117. Supervision observations shall be recorded in the construction inspection protocol and/or inspection memoranda of steel structures. Observations made during the supervision of concrete structures shall be recorded in readiness protocols. If any essential defects are discovered, the inspector may discontinue manufacturing.

1118. The construction inspection by STUK or an authorised inspection body of a steel structure or steel component of a composite structure shall comprise verification of the structure’s conformity to requirements against the construction plan, review of the manufacturing or installation result documentation, a construction inspection, checking the results of strength verification tests as well as a review of the necessary pressure and functional tests.

1119. A concreting readiness inspection of a concrete structure or a composite structure performed by STUK consists of the verification of the conformity of the reinforcement and formwork against the construction plan, the review of the result documentation of the installation of embedded steel components and formwork, and the inspection of the readiness for concreting at the site of casting.

1120. The inspector shall draw up a protocol of the construction inspection, intermediate construction inspection or readiness inspection, specifying the item inspected and the inspections made. Any shortcomings detected shall be entered as remarks in an annex to the inspection protocol.

1121. The construction inspection or readiness inspection shall be deemed complete and the inspection protocol shall be signed when the structure inspected has undergone all the inspections and testing required in the construction plan or inspection plan, and when the remarks documented during the construction inspections have been clarified by the licensee.

1122. An approved construction inspection shall be a prerequisite for transporting the steel component to the site of installation. If necessary, the construction inspection may also be performed at the plant site.

1123. An approved readiness inspection shall be a prerequisite for starting concreting, grouting, injection or prestressing work in safety class 2 or, when separately indicated, in safety class 3 (see chapter 9.1).

11.7 Installation control and construction inspection

1124. The control of installation, and the installation construction inspection, shall be performed in a similar manner to the control of manufacturing and the construction inspection.

1125. An approved installation construction inspection of a steel structure is a prerequisite for the commissioning inspection.

1126. An approved installation construction inspection of the steel component of a composite structure is a prerequisite for the concreting readiness inspection of a composite structure, or it may be an intermediate inspection related to the concreting readiness inspection of a composite structure.

11.8 Commissioning inspection

1127. During the commissioning inspection of structures, STUK shall inspect the following:

  1. The structures and buildings have been constructed according to the design documents approved by STUK or an authorised inspection body, and the required concreting readiness inspections, construction inspections of steel structures, and installation construction inspections have been performed (document review and visual inspection).
  2. Non-conformancies have been processed in an acceptable manner.
  3. The quality control records of concrete structures and the concrete parts of composite structures have been approved by the licensee, STUK or an authorised inspection body.
  4. The licensee has performed the commissioning inspections.

1128. The commissioning inspection of structures may be conducted in two phases for buildings and structures on which functional tests are performed. In this case, the first phase of the commissioning inspection of a structure by STUK or an authorised inspection body shall verify the approval status of documents, completion of installation and fulfilment of the safety regulations required by functional tests.

1129. In the second phase of the commissioning inspection, the functional tests to ensure readiness for operation shall be carried out. The functional tests shall be conducted in accordance with an approved pre-operational testing programme.

1130. Based on approved pre-operational testing, the structure shall be granted an operating licence in a commissioning inspection protocol. The operating licence may also be granted for a fixed period. If pre-operational testing is not performed, the operating licence may be granted during the first stage of the commissioning inspection.

11.9 Use, condition monitoring, maintenance, in-service inspections

1131. STUK supervises the use, condition monitoring and maintenance of steel, concrete and composite structures of a nuclear power plant during the inspections that are part of its in-service inspection programme and during other inspections it performs.

1132. The reviews of maintenance and repair work plans, work construction inspection and readiness inspections follow the same process as the approval of the original work.

1133. STUK oversees the licensee’s in-service inspections at its discretion and, in addition to this, also conducts in-service inspections of safety class 2 and 3 buildings and structures according to its own programme.

11.10 Modifications

1134. Inspections and monitoring of modifications are carried out in nearly the same manner as those of the original structure. Repair and modification plans of safety class 2 and 3 concrete structures and steel structures shall be processed at the licensee’s request, and at the level required by the scope and impact of the modification. Upon completion of work, STUK or an authorised inspection body conducts a combined construction and commissioning inspection.

1135. The licensee shall request an inspection from STUK or an authorised inspection body approximately two weeks before the intended date. The manufacturer, the plant supplier (in plant deliveries), a third party, and the licensee shall establish in advance using their own inspections that the conditions for the requested inspections exist.

1136. STUK may grant inspection rights to an authorised inspection body it has approved in accordance with Guide YVL E.1. Annex C defines the principles for the division of inspection responsibilities between STUK and authorised inspection bodies; these principles may be supplemented by issuing separate decisions.

1137. STUK or an authorised inspection body shall draw up an inspection record specifying the item inspected and the inspections made. The protocol shall record any shortcomings that the licensee is to clarify by a set deadline.


 

Definitions

Installation construction plan
Installation construction plan shall (for buildings and structures), refer to a construction plan describing how a steel structure, steel component of a composite structure, or a concrete element or a precast concrete product, including supports, connects to other structures.
Authorised inspection body
Authorised inspection body shall refer to an independent inspection organisation approved by the Radiation and Nuclear Safety Authority under Section 60 a of the Nuclear Energy Act to carry out inspections of the pressure equipment, steel and concrete structures and mechanical components of nuclear facilities in the capacity of an agency performing public administrative duties.
Concrete
Concrete shall refer to material that has been fabricated by mixing cement, coarse and fine aggregate and water, and potentially admixtures and additives, and the properties of material develop as the cement hardens (hydrates) with the help of water.
Concrete element
Concrete element shall refer to a concrete structure that has been cast and cured outside of its final location (either factory-built or fabricated at the construction site).
Fresh concrete
Fresh concrete shall refer to fully mixed concrete that is still in a state where it may be compacted using a method of choice.
Concrete cover
Concrete cover shall refer to the thickness of the concrete layer protecting the reinforcement.
Concrete structure
Concrete structure shall refer to concrete, reinforced concrete and prestressed concrete structures.
Reinforcement steel
Reinforcement steel shall refer to steel used for non-prestressed reinforcement of a concrete structure.
Precast concrete product
Precast concrete product shall refer to a concrete element manufactured under an applicable European product standard.
CE marking
CE marking shall refer to the only label that indicates that a building product complies with the declared performance levels and the applicable requirements of the European Union’s harmonised legislation.
Non-linear structural analysis
Non-linear structural analysis shall refer to solving a partial differential equation group using the finite element method (FEM), for example. The non-linearity of a structure may be geometrical by nature, due to the behaviour of the material, or related to the boundary conditions. A geometrical non-linearity is created when the loads cause large displacements in relation to the dimensions of the structure; in this case, the distribution of stress in the non-deformed and deformed structure will vary greatly. The non-linearity of a material means that the constitutive equations of the material are not linear.
Special process
Special processes shall refer to manufacturing processes, the results of which cannot be directly verified by means of a product inspection or testing after manufacture; instead, any shortcomings in the process may only appear later while the product is in use.
European Technical Assessment (ETA)
European Technical Assessment (ETA) shall refer to an approval that may be granted for building products for which no harmonised product standard exists. ETA is a voluntary technical approval resulting in CE marking.
Eurocodes
Eurocodes shall refer to the pan-European design standards for load-bearing structures published by the European Committee for Standardization.
Prestressing system
Prestressing system shall refer to the complex formed by the prestressing tendons used, the installation, prestressing, locking, and protection of the prestressing tendons , and the related equipment and work methods.
Prestressing tendon
Prestressing tendon shall refer to the base material used for reinforcement of concrete structures subject to prestressing.
Prestressed concrete structure
Prestressed concrete structure shall refer to a reinforced concrete structure with reinforcement that is partially or fully prestressed.
Aggregate
Aggregate shall refer to granular mineral constituent material of concrete, which forms concrete when joined together by cement paste.
Test specimen
Test specimen shall refer to a piece manufactured for testing from a concrete, steel or reinforcement sample.
High strength concrete
High strength concrete shall refer to concrete that has a compression strength class higher than C50/60 pursuant to standard EN 1992-1-1.
Utilisation rate
Utilisation rate shall refer to the ratio between the design load of the structure and the capacity of the structure.
Service life
Service life shall refer to the period of time during which a SSC installed at its service place is estimated to reliably retain its operability.
Service limit state dimensioning
Service limit state dimensioning shall refer to dimensioning at a limit state where a structure no longer meets the requirements set as conditions for its usability (such as maximum crack width or displacement).
Commissioning inspection
Commissioning inspection shall refer to an inspection that ensures the operability of safety class 2 and 3 concrete structures, steel and concrete structures, prestressed concrete structures, or steel and composite structures and buildings and that is performed before the nuclear operation of the facility begins.
Composite structure
Composite structure shall refer to a structural entity formed by a concrete and steel structure where the interoperation of the concrete and the steel components have a substantial role in relation to the load-bearing capacity, leak-tightness and fire protection properties of the structural entity. A composite structure consists of load-bearing structural components where the slip between steel and concrete and the disconnection of the components remains limited. Typical composite structures include composite columns, walls, beams and slabs.
Licensee
Licensee shall refer to the holder of a licence entitling to the use of nuclear energy. The use of nuclear energy refers to the operations laid down in Sections 2(1) and 2(2) of the Nuclear Energy Act.
Modular structure
Modular structure shall refer to an assembly consisting of several structural components and equipment parts. Components of the structure may include steel components, piping and piping supports, valves, cable trays, steel platforms and reinforcement steel. As the load-bearing structure of a modular structure act usually the steel components delivered to the construction site as pre-fabricated parts, or a composite structure consisting of these steel components and concrete.
Ultimate limit state design
Ultimate limit state design shall refer to design at a limit state where the structure is considered to lose its load-bearing capacity in part or entirely.
Summary of justifications
Summary of justifications shall refer to a document that presents how the structure meets the requirements set for it, and how the licensee has established its conformity to requirements. The summary of justifications shall also present the changes made to the approved documents, any non-conformances that occurred during manufacture, and their impact on the suitability and acceptability of the structure.
Damping ratio
Damping ratio shall refer to the ratio of the actual damping coefficient (the ratio of the viscous damping force to velocity) for a single-degree-of-freedom oscillator to the critical damping coefficient (the maximum value of the damping coefficient at which periodically attenuating oscillation is possible). The damping ratio is usually expressed as a percentage.
Inspection organisation
Inspection organisation shall refer to an organisation that performs inspections to examine a product, process, service or installation, or the design thereof, and to verify their conformity to requirements. (EN 17020).
Steel structure
Steel structure shall refer to structural steel components that are delivered as construction products. Typical steel structures of nuclear facilities include: load-bearing structures of buildings, load-bearing steel structures of the concrete reactor containment, vessels subject to hydrostatic pressure, piping break supports, missile protectors, storage racks for fresh and spent fuel, gates and linings of spent fuel pools, crane rail supports, doors and hatches, steel platforms and spent fuel handling equipment and crane rails.
Testing organisation
Testing organisation shall refer to an organisation performing testing activities requiring special competence. (Nuclear Energy Act 990/1987)
Execution (construction)
Execution of construction shall refer to all functions required for the physical creation of a building, including the acquisitions made for the site, the manufacture, transport, storage and installation of building materials and products, and inspection activities and documentation.
Execution class (construction)
Execution class shall refer to a classified collection of requirements set for execution, which may apply to the entire construction work, a single assembly or a detail of a single assembly (SFS-EN 1090-2, SFS-EN 13670).
Execution specification (construction)
Execution specification shall refer to a presentation of the information and requirements that are necessary for the execution of steel structures, including the necessary information and requirements concerning steel structural products and steel structure components. Execution specification for a concrete structure shall refer to a classified collection of requirements set for execution, which may apply to the entire construction work or a single component.
Type approval (building products)
Type approval for building products shall refer to a decision demonstrating that the characteristics of a building product meet the essential technical requirements set forth in the Land Use and Building Act (132/1999) or those decreed by virtue of the Act. Type approval is granted by a type approval organisation or the Ministry of the Environment for a particular reason (Act on the type approval of certain construction products [ 954/ 2012]). If the product belongs to the expanding scope of the CE marking, the validity of the type approval ends.
Manufacturing (building products)
Manufacturing shall, in the context of Guide YVL E.6, refer to all the measures that are required to produce and deliver a steel assembly. Depending on the case, this may include procurement, pre-fabrication and assembly, welding, mechanical attachment, transport, surface treatment, inspection, and documentation. Manufacturing shall refer to the manufacture of a steel assembly, building product, building part or building element when it takes place elsewhere than at the site of construction.
Verification certificate
Verification certificate shall refer to a certificate verifying that the characteristics of a building product are in line with the Land Use and Building Act (132/1999) or the provisions issued by virtue of the Act for the intended purpose of use defined by the manufacturer. The verification certificate is granted by a body approved by the Ministry of the Environment (Act on the Approval of Certain Construction Products [ 954/ 2012]).
Harmonised product standard
Harmonised product standard shall refer to a product standard drawn up by the European Committee for Standardization (CEN) that results in CE marking and of which an announcement has been published in the Official Journal of the European Union. For each product group, it defines the properties that are determined for the products, the manufacture quality control requirements, and the information to be reported in the CE marking.

References

  1. Nuclear Energy Act (990/1987).
  2. Government Decree on the Safety of Nuclear Power Plants (717/2013).
  3. Nuclear Energy Decree (161/1988).
  4. Government Decree on the Safety of Disposal of Nuclear Waste (736/2008).
  5. Regulation (EU) No 305/2011 of the European Parliament and of the Council.
  6. Land Use and Building Act (132/1999).
  7. Land Use and Building Decree (895/1999).
  8. Act on the Approval of Certain Construction Products (954/2012).
  9. The National Building Code of Finland (RakMK), Ministry of the Environment
  10. SFS-EN 1990 Eurocode. Basis of structural design (all parts)
  11. SFS-EN 1991 Eurocode 1: Actions on structures (all parts).
  12. SFS-EN 1992 Eurocode 2: Design of concrete structures (all parts).
  13. SFS-EN 1993 Eurocode 3: Design of steel structures (all parts).
  14. SFS-EN 1994 Eurocode 4: Design of composite steel and concrete structures (all parts).
  15. SFS-EN ISO 1090-1, Execution of steel structures and aluminium structures. Part 1: Requirements for conformity assessment of structural components.
  16. SFS-EN ISO 1090-2, Execution of steel structures and aluminium structures. Part 2: Technical requirements for steel structures.
  17. SFS-EN 206-1 Concrete. Part 1: Specification, performance, manufacturing and conformity .
  18. SFS 7022 Concrete. Application of standard SFS-EN 206-1 in Finland.
  19. SFS-EN 197-1. Cement. Part 1: Composition, specifications and conformity criteria for common cements.
  20. SFS-EN 13670 Execution of concrete structures.
  21. SFS 5975 Execution of concrete structures. Application of standard SFS-EN 13670 in Finland.
  22. SFS-EN ISO 17660-1 Welding. Welding of reinforcement steel. Part 1: Load-bearing welded joints.
  23. SFS-EN ISO 17660-2 Welding. Welding of reinforcement steel. Part 2: Non load-bearing welded joints.
  24. ETAG 001, Guideline for European Technical Approval of Metal Anchors for Use in Concrete. EOTA
  25. ETAG 013, Guideline for European Technical Approval of Post-Tensioning Kits for Prestressing of Structures. EOTA
  26. SFS-EN 1998 Eurocode 8: Design of structures for earthquake resistance.
  27. ASCE 4-98 Seismic Analysis of Safety-Related Nuclear Structures and Commentary.
  28. ASCE 43-05 Seismic Design Criteria for Structures, Systems, and Components in Nuclear Facilities.
  29. ASME Boiler and Pressure Vessel Code III Division 2, Code for Concrete Reactor Vessels and Containments.
  30. ASME Boiler and Pressure Vessel Code III Division 1, Subsection NE, Class MC Components
  31. USNRC Regulatory Guide 1.90, Inservice inspection of prestressed concrete containment structures with grouted tendons.
  32. KTA 3401.1 Reaktorsicherheitsbehälter aus Stahl, Teil 1 (Steel Containment Vessels, Part 1 ) Werkstoffe und Erzeugnisformen (Materials).
  33. KTA 3401.2 Reaktorsicherheitsbehälter aus Stahl, Teil 2: (Steel Containment Vessels, Part 2: ) Auslegung, Konstruktion und Berechnung (Analysis and Design).
  34. KTA 3401.3 Reaktorsicherheitsbehälter aus Stahl, Teil 3 : (Steel Containment Vessels, Part 3: ) Herstellung (Manufacture).
  35. SFS-EN ISO 3834 Quality requirements for fusion welding of metallic materials. Part 2: Comprehensive quality requirements.
  36. SFS-EN ISO 9001, Quality management systems. Requirements.
  37. SFS-EN ISO 17663 Welding. Quality requirements for heat treatment in connection with welding and allied processes.
  38. SFS-EN 287-1 Qualification test of welders. Fusion welding. Part 1: Steels.
  39. BY50, Concrete Code 2012, Concrete Association of Finland.
  40. SFS-EN ISO 12944-1 Paints and varnishes. Corrosion protection of steel structures by protective paint systems. Part 1: General introduction.
  41. SFS-EN 10204 Metallic materials. Types of inspection documents.
  42. Ministry of the Environment’s Decree on load-bearing structures, decree draft 17 April 2013.
  43. STUK-YTO-TR 210, Requirements for coatings of nuclear power plant containments, August 2004.
  44. SFS 5976 Execution of steel structures and aluminium structures. Application of standard SFS-EN 1090-2 in Finland.
  45. EN 13369 Common rules for precast concrete products

ANNEX A Detailed instructions for the execution of concrete structures

A.1 Quality control of the manufacture of concrete structures

A101. The requirements and instructions set forth in standard SFS-EN 206-1 [ 1], its national application standard SFS-7022 [ 4], and the Concrete Code BY50 apply to the quality control of fresh concrete and hardened concrete.

A102. Quality control measures and inspections of concrete structures are required at least for the items listed below:

  1. batching plant and laboratory
  2. concrete constituents
  3. fresh concrete (proportioning)
  4. hardening and hardened concrete
  5. reinforcement steels
  6. reinforcement steel splicing sleeves and end anchorage
  7. prestressing systems
  8. load-transferring metal components and lifting anchors
  9. special mortars and concretes
  10. application of paints and coatings
  11. CE marked products, products in accordance with verification certificates, and type approved products

A103. Batching plant and laboratory:

  1. The manufacturing and testing of concrete shall be subject to inspection by an organisation approved by the Finnish Safety and Chemicals Agency (TUKES, body approved by the Ministry of the Environment). The concrete manufacturer's quality manual shall be sent to STUK for information.

A104. Concrete constituents:

  1. Cement shall be CE-marked under standard SFS-EN 197-1. The allowed types of cement are listed in national application standard SFS-7022 for standard SFS-EN 206-1 [ 1]. The qualification of the mineral additions shall be established in accordance with Concrete Code 2012 BY 50. However, samples shall always be taken of cement if there is any reason to doubt its acceptability. This shall also apply to mineral additions, such as ground blast furnace slag, if they are used as binding agents in the concrete. The tests shall be conducted at an approved testing laboratory. If the additions are not CE-marked, the results of their quality inspections shall be submitted to STUK for information.
  2. Aggregate: aggregate pursuant to standard SFS EN 12620 and its national application standard SFS 7003 shall be used in the mixing of concrete. The aggregate shall be CE marked and inspected. If the aggregate is not CE marked, the concrete mixing company shall ensure, under the supervision of an inspector approved by the Ministry of the Environment, that the manufacturer’s quality control testing required by the above standards has been completed.
  3. Water: Potable water can be used for manufacturing concrete without a separate analysis. If the water used for manufacturing is not taken from the water supply network, it shall be tested for concentration of chlorides, sulphates, and humus before construction is started. The water shall be subjected to tests during the construction phase if there is any reason to doubt its acceptability. Standard SFS-EN 1008 discusses the testing of water.
  4. Admixtures: the use of concrete admixtures shall adhere to standard SFS-EN 934-2. A verification certificate from an organisation approved by the Ministry of the Environment shall be available for admixtures without a CE marking. The verification certificates of admixtures shall be submitted to STUK for information with the submission of the preliminary test programme for concrete.

A105. Properties of fresh concrete:

  1. The properties of fresh concrete shall be determined under the instructions laid down in Concrete Code 2012 BY 50.
  2. Site: The consistency of fresh concrete shall always be determined in connection with the making of test specimens. Other properties of fresh concrete shall be monitored, where necessary.

A106. Preliminary testing of concrete:

  1. Preliminary tests shall be undertaken to determine the correct composition of fresh concrete and to test the fulfilment of the properties laid down in plans, such as compressive strength, resistance to water penetration, gas permeability, pumpability, frost-resistance, and shrinkage/creep.
  2. The preliminary test programme shall be sent to STUK for information before testing is started. Test results shall be sent to STUK for information before concreting work is started. In the tests, the same concrete constituents shall be used as in actual work. The preliminary tests shall determine the limit values for concrete composition; these values define a range for variation in the concrete constituents, admixtures, and other composition in actual work. Preliminary tests shall be repeated if essential changes take place in the constituents, admixture or composition of concrete, or in other conditions in the area covered by the preliminary tests.

A107. Concrete acceptance tests during construction at the batching plant:

  1. Certified manufacturing at a batching plant: Concrete acceptance tests shall be performed under the guidelines of Concrete Code 2012 BY 50 and the instructions from a certification body supervised by the Ministry of the Environment.
  2. Certified manufacturing of concrete elements: Concrete acceptance tests shall be performed under the guidelines of Concrete Code 2012 BY 50 and the instructions from a certification body supervised by the Ministry of the Environment.

A108. Concrete acceptance tests during construction on the site or at the element factory regarding concrete structures in safety class 2:

  1. For determining the compressive strength of the concrete, at least one test specimen shall be made for each beginning 25 cubic metres of concrete and for each strength class; however, at least three test specimens shall be made for each concreting section (small concreting sections will be assessed on a case-by-case basis). Some test specimens may be tested before or after the actual quality assessment age.
  2. For determining the depth of penetration of water, at least three test specimens shall be made for each beginning 250 cubic metres of concrete if water penetration resistance requirement has been set for the concrete.
  3. For controlling tensile and bond strength, gas permeability and other properties of the concrete, a separate written plan shall be drafted, where necessary.
  4. Cored specimens shall be taken of the finished structure or reliable tests performed by NDT methods to determine the compressive strength and any other properties of the concrete in accordance with a separately approved programme. Tests shall be repeated a sufficient number of times so that they or the standard test specimens give a reliable idea of the properties of the concrete used for the structural element in question.

A109. Concrete acceptance tests during construction on the site or at the element factory regarding concrete structures in safety class 3:

  1. For determining compressive strength, at least one test specimen shall be taken for each beginning 50 cubic metres and for each strength class.
  2. If a water penetration resistance requirement has been set for the concrete, at least one test specimen shall be made for each beginning 250 cubic metres of the concrete to determine conformity with this requirement.
  3. For controlling tensile and bond strength, permeability to gas and other properties of the concrete, a separate written plan shall be drafted, where necessary.

A110. Grading strength shall be calculated under the guidelines of Concrete Code 2012 BY 50. If the test specimens are intended to be tested before or after the actual quality evaluation date, extra test specimens shall be made for these tests.

A111. The quality control of reinforcement steels shall meet the requirements of Concrete Code 2012 BY 50. Furthermore, the following measures shall be included in the quality control plan:

  1. Three specimens identical in size shall be taken of each batch of reinforcement steel used for safety class 2 concrete structures; the test specimens shall undergo both tensile and bending tests.
  2. Specimens shall be taken of reinforcement steels used for safety class 3 structures if there is any reason to doubt their acceptability.
  3. The tensile and bending tests of reinforcement steels shall be conducted at an approved testing laboratory.
  4. The results of the reinforcement steel tests shall be available before the structures from the reinforcement steels of which the samples have been taken are concreted.

A112. Mechanical splices of reinforcement steel bars:

  1. Reinforcement steel bars may be spliced by means of mechanical splices whose characteristics can be found in a verification certificate issued by a body approved by the Ministry of the Environment. Special mechanical splices of reinforcement steel bars such as sleeves are considered acceptable if the quality control of the splice manufacturer is subject to supervision by a body approved by the Ministry of the Environment.
  2. The quality control of mechanical splices of reinforcement steel bars shall meet the requirements given in the guidelines of Concrete Code 2012 BY 50. Furthermore, the following measures shall be included in the quality control plan:
    i. For the verification of the validity of splicing sleeves used for safety class 2 concrete structures, one sample for each beginning 200 splices shall undergo a tensile test.
    ii. Tensile tests of splicing sleeves shall be carried out at an approved testing laboratory.
  3. The results of the tests of the mechanical splices of reinforcement steels shall be available before the structures from which the reinforcement steel samples were taken are concreted.

A113. Reinforcement steel welded joints made at the construction site

  1. The welds and welding quality control performed at the construction site on reinforcement steels for structures in safety classes 2 and 3 shall adhere to the requirements for execution class 3 laid down in standards SFS-EN 13670 and SFS 5975.
  2. Execution class 3 requires that load-bearing welded joints shall be inspected under standard SFS-EN ISO 17660-1 and that non load-bearing tack weld joints shall be inspected under standard SFS-EN ISO 17660-2.
  3. The qualification requirements for welders and welding coordinators are presented in standards SFS-EN ISO 17660-1 and SFS-EN ISO 17660-2.

A114. Prestressing systems

The quality control of prestressing tendons shall meet the requirements of the guidelines of Concrete Code 2012 BY 50. Furthermore, the following measures shall be included in the quality control plan:

  1. Lists specifying the prestressing steel grades, nominal diameters and volumes as well as batch numbers and factory material testing results of various prestressing tendon delivery lots shall be presented.
  2. For prestressing tendons used for safety class 2 structures, one specimen shall be taken of every beginning fifty tonnes/batch/nominal diameter for both tensile testing and deflected tensile testing; however, at least three specimens shall be taken of each batch for tensile testing and deflected tensile testing.
  3. Prestressing tendons used for safety class 2 structures shall be subjected to a stress corrosion cracking resistance test programme, if necessary.
  4. Specimens shall always be taken of prestressing tendons intended for use in safety class 3 structures if there is any reason to doubt their acceptability.
  5. The tensile tests, deflected tensile tests , relaxation tests, and stress corrosion cracking tests shall be performed at an approved testing organisation.
  6. The results of prestressing tendon tensile test and deflected tensile tests shall be available before prestressing work is started on the tendons manufactured of the batch under examination.
  7. The results of the 1,000-hour relaxation test for tendons shall be available before the grouting of prestressing tendons manufactured from the batch under examination is started.

A115. Work related to the prestressing system and the installation and prestressing of tendons. For the installation of the prestressing system and for the prestressing and grouting of tendons, a separate quality control plan shall be drawn up presenting the following items:

  1. Corrosion protection of components of the prestressing system during transport, and during storage at the factory and at the construction site
  2. Installation of prestressing system components (ducts, tendons and anchorages)
  3. Condition monitoring of prestressing system components during various work phases
  4. Prestressing
  5. Grouting

A116. Load-transferring metal components and lifting anchors

  1. The acceptability of continuously manufactured metal components transferring loads in concrete structures (anchor plates, anchor bolts) and lifting anchors shall be established with the CE marking. If there are no harmonised product standards or Guidelines for European Technical Assessment for the product, its characteristics can be demonstrated by means of type approval, a verification certificate, or by means of calculations and experiments performed at accepted testing organisations.
  2. The characteristics of non-continuously manufactured metal components transferring loads shall be established either by means of calculations based on the design principles of the materials, or tests. The instructions issued for the design and supervision of steel structures shall be followed in the manufacture of these metal components.
  3. Post-installed anchor plates:
    1. The acceptability of the post-installed anchor plate used shall be established according to the requirements for load-transferring steel components stated above.
    2. Post-installed anchors must not be used without a justified reason:
      1. in fastenings that may be subject to dynamic reversed stresses
      2. to fasten steel structures, equipment and piping in safety classes 1 and 2
    3. iii. A separate procedure shall be prepared for the installation and installation quality control of post-installed anchors and plates; the procedure shall also determine the qualifications of the staff installing the post-installed anchors and plates.
  4. A description shall be drawn up on the use and installation of other fastenings, such as grouted bolts and chemical anchors, covering the quality control measures concerning the fastenings in question and their installation.

A117. Special mortars and concretes

  1. The quality control of special mortars and concretes shall conform to the requirements of the Ministry of the Environment decrees and directions laid down in the Finnish Building Code.
  2. There shall be a quality control plan for injection work carried out on repair cracks in concrete and for grouting work to protect post-tensioned tendons against corrosion; the plan shall satisfy the requirements of the Finnish Building Code or Guidelines for the European Technical Approval (ETAG). Furthermore, the following requirements shall be included in the quality control plan for grout used filling the prestressing tendon ducts:
    1. For compressive strength tests, at least three 7-day and three 28-day specimens/per work shift per item shall be made; however, at least one 7-day and one 28-day specimen shall be fabricated per each beginning cubic metre of grout.
    2. 7-day and 28-day specimens shall be made of one batch of grout manufactured.
    3. Specimens for the determination of grout bleeding and volume change shall always be made at the same time as the compressive strength specimens.
    4. The consistency of grout shall always be determined during the fabrication of the compressive strength test specimens.
  3. Before the grouting work phase is started, preliminary tests on the grout shall be conducted to verify compliance with the requirements.

A.2 Detailed requirements for concreting and other work plans

A201. A concreting work plan shall be drawn up for every concreting section to provide additional information on details regarding the manufacture and quality control of structures.

A202. Description of the concrete manufacturer shall be submitted together with the concreting work plan.

A203. The concreting work plan consists of a description for the concreting section and work, and a quality plan for the concreting section.

  1. The concreting work plan shall be drawn up by the contractor, and it shall be reviewed by the building owner and licensee, who will then add to it their own quality control plans, if necessary. In the concreting work plan, it is not necessary to repeat items which have been brought up in the design documentation, unless this is necessary to emphasise some measure related to quality control or work performance. A common concreting work plan may be drawn up for small concreting sections for which similar concreting methods are used.

A204. The information presented in the description of the concreting plan and work shall be sufficiently detailed pursuant to the guidelines set for a detailed concreting work plan of structures in execution class 3 in the Finnish Building Code.

A205. The quality plan for a concreting section shall contain a detailed description of all the inspection and quality control measures related to the manufacture of the section. The inspection and quality control items relating to the manufacture of a concreting section are as follows:

  1. Requirements which the concreting of a section places on other structures
  2. Preliminary testing related to the concreting
  3. Tests to be conducted on concrete constituents
  4. Tests to be conducted on fresh concrete
  5. Concrete test specimen plan
  6. Tests to be conducted on hardened concrete
  7. Tests to be conducted on reinforcement steels and prestressing tendons and their splices
  8. Concrete transportation equipment
  9. Concrete target temperatures
  10. Provisions made for excavation and other vibrations
  11. Monitoring of the strength development of hardened concrete
  12. Action plan in case concreting work is discontinued
  13. Dimensions of structure
  14. Curing of concrete
  15. Inspection of the concreting section after the disassembly of formwork.

A206. Detailed plans concerning work performance and quality control shall be prepared for other work, such as prestressing and grouting. When drawing up the work plans, the procedures issued for concreting work shall be applied.

A.3 Mock-up tests of concrete structures

A301. A mock-up test shall be completed for the manufacture of complex structures. A plan shall be drawn up in advance for the mock-up test, the performance of the test shall be documented, and the final report shall establish the usability of the materials and methods when manufacturing the actual structures.

A302. In at least the following cases, mock-up tests are required to demonstrate the validity of a work method:

  1. The work method, such as a demanding injection or grouting work, is used for the first time.
  2. It is difficult to ascertain the results and validity of accomplished work.
  3. Accomplished work is difficult to repair.

A303. Plans and justifications for the mock-up tests shall be presented for the purpose of assessing the test results.

A304. The mock-up tests may also be needed to demonstrate the qualifications of the staff.

A.4 References

  1. SFS-EN 206-1 Concrete. Part 1: Specification, performance, manufacturing and conformity .
  2. Finnish Building Code (RakMK), Ministry of the Environment
  3. BY 50, Concrete Code 2012, Concrete Association of Finland.
  4. SFS-7022 , Concrete. Application of standard SFS-EN 206-1 in Finland.

ANNEX B Detailed instructions for the execution of steel structures and steel components of composite structures

B.1 Quality control of steel component manufacturing

B101. A nuclear facility’s safety class 2 and 3 steel structures shall be manufactured according to an approved construction plan.

B102. The approved manufacture-related construction plan, procedures and standards shall be available at the place of manufacture.

B103. The manufacturer shall oversee all demanding work phases. Inspection and testing phases specified in the SFS-EN ISO 3834-2 [ 1] standard shall be applied in welding supervision.

B104. Personnel engaged in the heat treatment of a steel structure shall have the proper training and instructions for the task. Requirements for heat treatment equipment and the performance of heat treatment have been presented in standard SFS-EN ISO 17663 [ 2], among others.

B105. If the construction plan states that a steel structure shall be heat treated after welding, post-heat treatment repair welding requires a repair plan approved by STUK or an inspection organisation approved by STUK.

B106. When manufacturing has been completed, the manufacturer shall inspect the equipment or structure's surface quality and cleanliness in accordance with the construction plan, as well as ensure that product quality is preserved during storage and transport. Records on the control of manufacturing conducted by various parties shall be kept, describing the manufacturing, inspection or test phase supervised.

B107. The manufacturer shall use non-conformity reports to determine the cause of any errors and non-conformities discovered during manufacturing, assess their significance, and issue a repair recommendation as well as a plan on how to prevent a given non-conformity from recurring.

B108. Non-conformities shall be approved in accordance with the procurement agreement and the manufacturer’s management system. If a non-conformity remains in a product, approval for this shall be explained in the non-conformity report.

B.2 Manufacturing procedures

B201. Manufacturing shall be based on manufacturing procedures approved under the management system.

B202. In safety class 2, the manufacturing procedures shall be submitted to STUK for approval. In safety class 3, the manufacturing procedures shall be submitted where applicable.

B203. The manufacturing procedures and persons involved in manufacturing shall be qualified in accordance with the procedures described in the management system.

B204. With regard to welding, the welding procedure specifications qualified by welding procedure tests in accordance with standard SFS-EN ISO 15614-1 [ 3] or corresponding procedures may be considered acceptable as far as the most demanding load-bearing welded joints are concerned.

B205. The welders and welding operators shall have been qualified. The documents that are required for demonstrating the quality requirements are provided in standard SFS-EN ISO 3834-5. Welder qualification is demonstrated in accordance with SFS-EN 287-1; welding operator qualification is demonstrated in accordance with SFS-EN 1418.

B206. The manufacturer shall have available a sufficient number of personnel to coordinate welding. Persons who are in charge of quality operations shall have sufficient authority to perform all the necessary actions. The tasks and responsibility limits of such persons shall be clearly defined. The qualification of the welding coordinator shall be demonstrated under standard SFS-EN ISO 14731. Standard SFS EN ISO 1090-2 presents the welding coordinator’s level of technical knowledge by execution class.

B.3.1 Quality control and inspection plan of steel assemblies

B301. The inspection plan for steel structures shall present the methods for inspecting and testing base materials, welding filler materials, welded joints and completed structures during the various manufacturing phases. The plan shall be drawn up such that it shows the following:

  1. Component or weld-specific identification data and references to steel structure drawings;
  2. Markings in accordance with the standard applied in the manufacturing of materials and welding filler materials as well as the necessary references to material specifications;
  3. Weld-specific references to the welding procedures and, where necessary, to the procedure and production tests conducted to qualify these procedures;
  4. The detailed tests and inspections to be conducted on a steel structure as well as its components and welds; and a reference to the testing or inspection procedures

B302. If inspections and tests of a component or welded joint are carried out during more than one manufacturing phase, whether repeated in part or in full, they shall be presented as separate inspections (such as a description of the weld root, or ultrasonic testing of a weld prior to and after heat treatment).

B303. If procedure or pre-production tests are needed to qualify the manufacturing procedures, a separate inspection plan shall be presented for them, the contents of which are determined by the above principles. Furthermore, a separate plan is needed if properties of the materials or welded joints are altered during manufacture such that the information provided in the materials report is no longer valid.

B304. The following shall be evident from the inspections and tests marked in the inspection plan of procedure and pre-production tests: on whose premises they take place and who (manufacturer, subcontractor, approved testing or inspection organisation, installer) carries them out. The inspection plan shall present the reports to be drawn up and the supervision of inspection and testing.

B305. The licensee shall list the testing procedures that apply to the material tests of steel structures. In addition, the testing procedures that apply to the manufacturing and installation of steel structures shall be identified. The instructions shall include the method, scope, acceptance criteria and reporting of the inspection or testing. As to details, a reference to applicable standards can be made.

B306. The procedures shall cover the destructive testing of materials with relevant material certificate and control requirements, the methods of manufacture, non-destructive testing as well as the testing (such as leakage and functional tests) and inspection of the final product.

B.3.2 Material certificates

B307. The information required from material certificates is defined in the material certificate, material, and welding consumable standards. If necessary, the licensee shall supplement the requirements in other documents.

B308. The material certificate or other document shall include a confirmation from the manufacturer of the material or welding consumable that the delivered products are compliant with the requirements of the order and the product specification to which reference is made.

B309. The material certificate of a material or a welding filler material shall clearly indicate the certificate type under standard SFS-EN 10204 [ 7] or a corresponding standard.

B310. The material certificate requirements set for construction materials and welding consumables are presented in Annex D of this Guide.

B.4 Procedure tests pre-production tests and production tests

B401. Procedures with essential parameters shall be drawn up for demanding work processes such as welding, forming and heat treatment, which affect material strength and properties. Other manufacturing procedures shall also have the necessary procedures to ensure the quality of work.

B402. Manufacturer-specific welding procedures, heat treatment procedures and hot and cold-forming procedures to be used in manufacturing and installation shall be qualified by means of procedure tests before beginning any manufacturing work. The procedure test shall demonstrate that the material properties approved as the basis for design are retained during manufacture and that the manufacturer is qualified to use the manufacturing procedure.

B403. The procedure test for steel and composite structures in safety class 2 shall be conducted under the supervision of an authorised third party. The procedure tests for structures in safety class 3 may be supervised in accordance with standard EN 1090-2. Procedure tests carried out for each place of manufacture shall remain valid indefinitely insofar as the manufacturing based on them takes place within the range of essential parameters defined in the applicable standard.

B404. When an item is significant in terms of nuclear safety or when the procedure test does not reflect the actual working conditions, a review shall be made of the suitability of the manufacturing procedures with pre-production tests carried out prior to the commencement of manufacture or production tests as part of manufacture.

B405. A pre-production test shall refer to a test performed in advance by the persons participating in the manufacture, taking into account the limitations set by the working environment. A production test refers to a test specimen manufactured using actual manufacturing parameters that allows for testing its metallurgic and strength properties using destructive methods.

B.5 References

  1. SFS-EN ISO 3834 Quality requirements for fusion welding of metallic materials.
  2. SFS-EN ISO 17663 Welding. Quality requirements for heat treatment in connection with welding and allied processes.
  3. SFS-EN ISO 15614 Specification and qualification of welding procedures for metallic materials. Welding procedure test.
  4. SFS-EN 287-1 Qualification test of welders. Fusion welding.
  5. SFS-EN 1478 Tapping screws thread.
  6. SFS-EN ISO 14731 Welding coordination. Tasks and responsibilities.
  7. SFS-EN 10204 Metallic products. Types of inspection documents.

ANNEX C Division of inspection responsibilities

Building structures and structural fire protection (E.6 and B.8) Safety class 1)
1 2 3
Licensing, planning, and other advance approvals
Analysis of the planning process and quality assurance of buildings and structures STUK STUK
Approval of the responsible structural designers of the buildings (E.6), the designer responsible for fire protection planning (B.8), and the design organisation STUK STUK
Manufacturer approval (part of construction plan) STUK IO 2)
Approval of inspection organisation STUK STUK
Approval of testing organisation STUK STUK
Structural and fire technical requirement specifications and quality control guidelines under YVL B.8 and YVL E.6, delivery plan of design documents STUK STUK
Approval of system data STUK STUK
Approval of product approval documentation (CE marking, ETA approval, type approval or verification certificate) STUK IO 2)
Approval of coatings that tolerate radiation and accident conditions and coatings that can be decontaminated (E.6) STUK STUK
Approval of aircraft crash analyses (A.11), earthquake analyses (B.7), fire analyses, fire compartment and exit route drawings (B.8), and structural containment analyses (E.6) STUK STUK
Approval of construction plan STUK IO 2)
Manufacturing and construction inspection
Approval of licensee’s supervision organisation STUK STUK
Plans for concreting, injection, and prestressing work STUK IO 2)
Readiness inspections and on-site supervision for concreting, injection and prestressing work STUK IO 2)
Construction inspection, pressure test, leakage test and factory tests for steel structures and composite structures STUK IO 2)
Installation and commissioning
Installation construction plan STUK IO 2)
Installation construction inspection STUK IO 2)
Pre-operational testing plan STUK STUK
Commissioning inspections, concrete structures, steel structures and composite structures and buildings (E.6), and fire protection systems and arrangements for the commissioning of the building (B.8) STUK STUK/IO
In-service supervision and inspections
Repair and modification plans, building structures (E.6) and structural fire protection (B.8) STUK IO2
Inspections of repairs and modifications STUK IO2
Ageing management (A.8) STUK STUK
Plan for in-service inspection (ISI) (E.6) STUK STUK
Performance of in-service inspections, such as containment pressure and leakage tests LH 4) LH 4)
Results of in-service inspections, such as containment pressure and leakage tests STUK STUK

1) Class EYT to be defined separately.
2) See para. 1102.
3) Pressure tests and leakage tests and combinations thereof will be performed in accordance with a plan approved by STUK.
4) LH = licensee.


ANNEX D Material certificate requirements for materials and welding filler materials, SFS-EN 10204

Component Safety class
2 3
Structural steels 3.1 1) 3.1
Stainless steels 3.1 1) 3.1
Welding consumables 3.1 2.2
Structural bolting assemblies 2.2 2.2
Self-tapping and self-drilling screws and blind rivets 2.1 2.1
Studs for arc studs welding 3.1 3.1

1) Certificate 3.2i is required for the carbon steels and stainless steels of the containment’s material and personnel airlocks.

A material certificate of a higher level shall be approved in all cases.