ATMEA1 reactor. Review of Safety Options

Transcription

1 REPUBLIQUE FRANÇAISE NUCLEAR POWER PLANT DEPARTMENT ATMEA1 reactor Review of Safety Options CODEP-DCN Report of 24 January , place du Colonel Bourgoin Paris cedex 12 Téléphone Fax

2 CONTENTS 1. AIM OF THE REPORT CONTEXT OF THE REVIEW OF THE SAFETY OPTIONS FOR THE ATMEA1 REACTOR ATMEA The ATMEA1 reactor Approach initiated by ATMEA The contractual framework, established mid-2010, for the examination of the safety options for the ATMEA1 reactor Why have a contractual framework? Players involved PROCESS FOR THE REVIEW OF THE SAFETY OPTIONS FOR THE ATMEA1 REACTOR Review basis (French requirements and recommendations) Performing the review: 2 phases Phase 1 of the review Phase 2 of the review: review by ASN Advisory Committees Topics reviewed by the Advisory Committees Reports presented to the Advisory Committees in order that they may make known their opinions and recommendations Taking account of the lessons learned from the accident at the Fukushima Daiichi nuclear power plant in Japan Complementary assessment of aircraft crashes Documents submitted by ATMEA Documents provided by ATMEA, constituting the initial framework of the review Documents sent by ATMEA constituting the basis for the ASN opinion DOCUMENTS PRODUCED BY ASN, ITS ADVISORY COMMITTEES AND THE IRSN DURING THE REVIEW Intermediary conclusions of phase 1 of the examination Consultation of ASN Advisory Committees Review by the GPR Review by the GP ESPN CONCLUSIONS OF THE REVIEW Design features of the nuclear pressure equipment (ESPN) of the MPS and the MSSs Steam generator (SG) Reactor pressure vessel and vessel internals Control rod drive mechanisms (CRDM) Reactor coolant pumps (RCP) Main primary and secondary pipes Pressurizer Protection against overpressures in the primary system and the secondary systems Accident studies (PCC and RRC-A operating conditions) /37

3 5.2.1 Accident study criteria and rules List of PCC situations and RRC-A situations Use of the calculations of radiological consequences Hazards Internal hazards External hazards Safety objectives with regard to aircraft crashes Severe accidents and situations to be practically eliminated Use of Probabilistic Safety Assessments (PSA) Classifications of systems, structures and components Design of the SIS, CSS, CHRS and the SSSS SIS CSS CHRS Standstill seal system (SSSS) Heat Sinks and Electric Power Heat sinks Electric power supplies Reactor containment building Conclusions of the analysis (excluding aircraft crash) Taking aircraft crashes into account Confinement of the buildings Annulus closing system Fuel building Safeguard Building Handling and storing nuclear fuel Instrumentation and control Organisational and human factors Radiation protection Nuclear waste and radioactive effluents Ageing/decommissioning Taking operating experience feedback into account Initial operating experience feedback from the accident at the Fukushima Daiichi nuclear power plant in Japan on the ATMEA 1 design SAFETY OBJECTIVES ESTABLISHED BY WENRA FOR NEW REACTORS ASN s OVERALL OPINION REFERENCES GLOSSARY Appendix 1 : Short presentation of the ATMEA1 reactor (not included see French version of the report) Appendix 2 : Opinion of the GP ESPN Appendix 3 : Opinion of the GPR 3/37

4 Appendix 4 : ASN letter DEP-DCN Applicability of the para-regulatory texts to the ATMEA1 reactor (not included see French version of the report) Appendix 5 : ASN letter CODEP-DCN ATMEA1 reactor first phase of the technical review of the safety options This report is a translation into English of the orginal report written in French. In case of any doubt, the reference is the report written in French. 4/37

5 1. AIM OF THE REPORT The aim of this report is to present the review carried out on the safety options ( options de sûreté in French, which can also be understood as safety design basis) for the ATMEA1 reactor. The safety options dossier for a reactor presents the main general design characteristics and choices adopted in terms of safety. This dossier, established during the basic design studies for the reactor, shows in particular: the safety objectives for the reactor; the safety approach used in its design; the general description of the reactor, and the processes and systems implemented; the operating conditions envisaged and the key parameters of the installation; the accidents and hazards considered for the design and the methods used to deal with such situations. It must be remembered that in France, the safety options for a basic nuclear installation (BNI) and their review by ASN are defined well ahead of any creation authorisation application for such a BNI. Eventually, this creation authorisation application is submitted by the future licensee (operator) of this BNI (also designated petitioner throughout the rest of this document) and includes, in particular, the preliminary safety report and the environmental impact assessment of the BNI. The assessment supporting the review of the safety options for the ATMEA1 reactor and the conclusions drawn by ASN also gave rise to questions that go beyond the safety options themselves and which would need to be dealt with in the event of a possible creation authorisation application for an ATMEA1 reactor in France. These questions require in fact, in whole or in part, choices by the reactor operator (licensee) or the equipment manufacturers. The answers to these questions thus require a more detailed definition of the design of the installation and its operating procedures. 2. CONTEXT OF THE REVIEW OF THE SAFETY OPTIONS FOR THE ATMEA1 REACTOR 2.1 ATMEA ATMEA, a company under French law, was created at the end of It is a 50/50 joint venture between French company Areva and Japanese company Mitsubishi Heavy Industries (MHI). Its aim is the development, certification, marketing and sale of the ATMEA1 reactor. This so called generation III reactor is a priori intended for export 1. It combines the technologies of both designers. 2.2 The ATMEA1 reactor The ATMEA1 reactor is a pressurised water reactor with a 3-loop configuration, with a total thermal output of 3150 MWth (i.e. approximately 1100 MWe). The main primary system, the configuration of the loops and the main components are similar to those of the generations of reactors currently in operation in France. It has a design plant life of 60 years. It is equipped with: 3-train safety system (3 x 100%) to which is added a fourth partial train ( train X ) allowing the maintenance of the diesel generators and systems connected to the heat sink; a core catcher; 1 GDF-Suez has nevertheless expressed its interest in building such a reactor in France, in the Rhone valley. In addition, the (French) Nuclear Council Policy meeting in February 2011 decided that In order to boost the French supply and as a complement to the high-power (1650MW) EPR today the French nuclear industry s reference reactor the Nuclear Policy Council requests that AREVA, EDF, GDF SUEZ and other interested players strengthen their industrial cooperation in order to continue optimization and certify the ATMEA1 mid-sized reactor. The plan to build a first ATMEA1 reactor in France will be studied. 5/37

6 a single-wall reactor containment building with a steel liner inside the annulus being limited to the cylindrical part of the reactor building (collecting leaks from penetrations) also designed to protect against airplane crashes; digital instrumentation and control. Additional information is provided in Appendix 1, and in chapter 2 of the IRSN/DAI/DDI nº 52 report. 2.3 Approach initiated by ATMEA In early 2008, ATMEA initiated discussions with ASN on the possibility of reviewing the safety options for the ATMEA1 reactor. After preliminary contacts by letter [4], ATMEA confirmed its willingness to obtain ASN s opinion on the safety options for the ATMEA1 reactor with regard to compliance with: the safety objectives as set out in France for the new generation of pressurised water reactors, as expressed in A.1.1 of the Technical Guidelines for the design and construction of the new generation of pressurised water nuclear reactors (cf. reference[3]); the statutory and para-regulatory 2 texts applicable to basic nuclear installations in France. This approach forms part of a larger certification approach, with different stakeholders, for the ATMEA1 reactor. Thus: ATMEA contacted the International Atomic Energy Agency (IAEA) in November 2007 and obtained its opinion in the summer of 2008; ATMEA contacted the Canadian Nuclear Safety Commission (CNSC) in early IAEA Review ATMEA-1: The IAEA completes reactor safety features review July 07, 2008 ATMEA, an AREVA and Mitsubishi Heavy Industries Ltd. (MHI) joint-venture, announces the completion of IAEA's review of the ATMEA-1 nuclear reactor Conceptual Design Safety Features. Under the auspices of the IAEA, an international team of senior experts reviewed the ATMEA-1 design and evaluated it against current and applicable IAEA Safety Standards. The objective of the review was to assess whether the Conceptual Safety Features address IAEA requirements in a complete and comprehensive manner. The report concluded that the ATMEA1 conceptual design addresses the IAEA s Fundamental Safety Principles as well as key design and safety assessment requirements. These safety features are the basis for the on-going basic design work. The reactor design will be ready for license application by the end of 2009 as planned. Stefan vom Scheidt, CEO of ATMEA said: Completion of this IAEA review is an important step that confirms the relevance of our basic safety options. I would like to express my appreciation to the IAEA staff and external experts engaged in this review program for their great effort. ATMEA Press Releases CNSC Review AREVA and Mitsubishi Heavy Industries Ltd. Submit ATMEA-1 Design for Preliminary Review with Canadian Nuclear Safety Commission February 24, 2011 ATMEA, a joint venture between AREVA and Mitsubishi Heavy Industries, Ltd. (MHI), has submitted, on February 15, 2011, the ATMEA1 reactor for a pre-project design review with the Canadian Nuclear Safety Commission (CNSC). The ATMEA1 reactor is under consideration as part of the proposed Clean Energy Park near the Point Lepreau nuclear station in New Brunswick. The province of New Brunswick, the Utility New Brunswick Power and AREVA, signed a letter of intent last July to develop a Clean Energy Park that would feature a mid-sized reactor and renewable generation built by AREVA. If approved by the CNSC, the ATMEA1 design also could be selected at sites in other Canadian provinces. 2 By letters (references [5] and [6]), the ASN clarified the applicability of the fundamental safety rules to the safety options review process for the ATMEA1 reactor 6/37

7 2.4 The contractual framework, established mid-2010, for the examination of the safety options for the ATMEA1 reactor Why have a contractual framework? A safety options review process is provided for in article 6 of the decree (reference [2]): Any person intending to operate a basic nuclear installation may, prior to initiating the authorisation decree procedure related to the creation stage as specified in article 29 of the Act of 13 June 2006, ask the Nuclear Safety Authority for its opinion concerning all or some of the options it has chosen to ensure the safety of this installation. However, as ATMEA does not intend to operate the ATMEA1 reactor in France, the abovementioned article cannot be strictly applied. Funding the technical review is, therefore, not justifiable from the budget allocated to ASN by the public authorities. ATMEA must, therefore, remunerate ASN and IRSN for this review. For these reasons, it was decided that the safety options review of the ATMEA1 reactor would be carried out on a contractual basis: an agreement was, therefore, drawn up between ATMEA and a consortium comprising ASN and IRSN. This difference in legal aspects has, however, no impact on the technical analysis to be completed: it was carried out under the same conditions as for a basic nuclear installation intended for construction in France Players involved ASN responded favourably to ATMEA s request and, in the summer of 2010, signed an agreement that frames the review of the safety options for the ATMEA1 reactor. The aim of this review, carried out with the Institut de radioprotection et de sûreté nucléaire (IRSN), is to assess whether the safety options comply with the French safety approach. The agreement between ATMEA and the consortium includes, in particular, an appendix describing the expectations and procedures of the technical review. Within ASN, the Nuclear Power Plant Department (ASN/DCN) is responsible for the technical review of this dossier, with the exception of the review of the design options of the main nuclear pressureretaining equipment of the main primary and secondary systems of the ATMEA1 reactor, which is managed by the Nuclear Pressure Equipment Department (ASN/DEP). For the technical review, the ASN involved its relevant standing Advisory Committees: the Advisory Committee for Nuclear Reactors (GPR) and the Advisory Committee for Nuclear Pressure Equipment (GP ESPN). 7/37

8 3. PROCESS FOR THE REVIEW OF THE SAFETY OPTIONS FOR THE ATMEA1 REACTOR 3.1 Review basis (French requirements and recommendations) The review basis comprises: the French regulations in force on the date the agreement is signed; the Technical Guidelines for the design and construction of the next generation of pressurised water reactors (reference [3]); the para-regulatory texts relating to the design of the reactors of this next generation (cf. reference [5]). Finally, if the above mentioned requirements/recommendations do not cover some safety options areas, the review carried out by IRSN used as a basis the codes and requirements/recommendations put forward by ATMEA, as described in the safety options dossier, without making any judgement about this basis. 3.2 Performing the review: 2 phases The technical review of the safety options for the ATMEA1 reactor was carried out in two phases: phase 1: review of the safety options for the reactor in order to draw up the list of the subjects to be examined in greater detail during phase 2; phase 2: continuation of the review of the safety options, focussing on the review of the additional reports into those aspects identified during phase 1 and review of the nuclear pressure-retaining equipment design options. In addition, during phase 2, an analysis was also carried out on how were taken into account: the initial lessons learned from the accident at the Fukushima Daiichi nuclear power plant in Japan in March 2011; an aircraft crash, including an intentional crash Phase 1 of the review The objectives of the phase 1 examination were, in order to determine the themes to be further investigated in phase 2, to assess if the safety options are: either consistent with reactor designs recently accepted in France; or different but considered initially to be satisfactory or liable to become acceptable after further examination; or different and considered, at this initial stage, to be difficult to accept, or even unacceptable Phase 2 of the review: review by ASN Advisory Committees Topics reviewed by the Advisory Committees The objectives of the phase 2 examination were to : further review the subjects identified in phase 1. It comprised, in particular, several meetings of the GPR (Advisory Committee for nuclear reactors) intended to allow it to render the opinion requested by ASN (letter in reference [9]). Five meetings were arranged for this purpose (26 th May 2011, 30 th June 2011, 6 th October 2011, 14 th October 2011, 28 th October 2011). The consultation procedures were presented to the members of the GPR during its internal meeting held on 24 th February 2011; 8/37

9 completing the analysis of the main design features of the main ESPNs (nuclear pressureretaining equipment) of the main primary and secondary systems of the ATMEA1 reactor, as well as protection against overpressure. It included, in particular, a meeting of the Advisory Committee for nuclear pressure equipment (GPESPN), to which it was referred by letter (reference [10]) and which met on 14 th September The conclusions of this review were presented to the GPR at the meeting on 14 th October The conclusions of the review carried out in phase 2 by the Advisory Committees are summarised in chapter Reports presented to the Advisory Committees in order that they may make known their opinions and recommendations The safety design basis dossier sent by ATMEA contains the safety design basis selected by ATMEA and the bases of a detailed design of the reactor. These design options are presented in the ATMEA dossier to give credibility of the associated safety design basis by illustrating the various types of available design. In order to reach its opinion, the GPR studied the reports drawn up by IRSN. On this basis, at each meeting, the GPR first drafted provisional positions and recommendations, i.e. liable to change later, in line with new ATMEA s committements and any updates to the documents used as a basis for the review. The GPR therefore followed an iterative process which was finally concluded by the opinion rendered to ASN after its fifth meeting. The IRSN reports presented to the GPR contain in particular: IRSN positions, combined if applicable with draft recommendations. These draft recommendations are, as the case may be, endorsed as is, amended or rejected by the GPR after discussion between its members; Commitments taken by ATMEA; draft suggestions for the future reactor operator on points to be dealt with in the event of a possible creation authorisation application for an ATMEA1 reactor in France or for the detailed design of the installation. The opinion of the Advisory Committee was requested on the safety options and, if applicable, on some design options of the ATMEA reactor presented by ATMEA. It was suggested to the GPR that it should examine the draft recommendations as a priority, but also that it should look at the suggestions in order to determine if some of them should be transformed into recommendations. The opinion of the GPR is given in appendix 3 to this report. In order to reach its opinion, the GP ESPN studied the report presenting the conclusions of the review, carried out by ASN, into the design options chosen by ATMEA for the main ESPNs and the protection against primary and secondary overpressures. The report presented to the GP ESPN contains: positions put forward by the rapporteur, combined if applicable with draft recommendations. These draft recommendations are either endorsed as is, amended or rejected by the GP ESPN after discussion between its members; Commitments taken by ATMEA; draft suggestions for the future reactor operator and the equipment manufacturers to be considered in the event of a possible creation authorisation application for an ATMEA1 reactor in France or for the detailed design of the installation. 9/37

10 The opinion of the GP ESPN is given in appendix 2 to this report Taking account of the lessons learned from the accident at the Fukushima Daiichi nuclear power plant in Japan Complementary safety assessments (ECS) of the French nuclear installations were initiated by ASN following the accident at the Fukushima Daiichi nuclear power plant in Japan in March This initiative is also a response to the request by the French Prime Minister to carry out an audit into the safety of French nuclear installations and also to the expectations of the European Council, which in March 2011 called for stress tests of European nuclear power plants. In so far as concerns French nuclear power plants, including EPR reactors (Flamanville 3 and, if its construction were to be authorised, Penly 3), the specifications of these ECSs were set out in ASN decision nº 2011-DC-0213 of 5 th May 2011 ( ). The conclusions of the ASN following the ECSs are shown in the ASN opinion and report made public on 3 rd January 2012, which can be consulted on the ASN Internet site: Review carried out by the GPR as part of the reivew of the safety options for the ATMEA1 reactor The safety options review process for the ATMEA1 reactor was initiated before the accident affecting the Fukushima Daiichi nuclear power plant in Japan. ASN therefore requested the review to address how the ATMEA1 reactor design takes into account the initial lessons learned from the accident at Fukushima Daiichi, taking into account the current state of development of the ATMEA1 reactor design: this is the review of safety options and, in particular, the siting of the reactor is unknown. This analysis was submitted to the GPR at its fourth meeting. It should be noted that most of the subjects brought into focus by the Fukushima accident had already been identified in phase 1 of the review. Nevertheless, this report can only take into account the initial lessons learned from the accident at the Fukushima Daiichi nuclear site, as the associated experience feedback process will require several years, if we think back to the accidents at Three Mile Island and Chernobyl. Additional input provided by the review of the ECS reports on reactors under construction or in operation Moreover, after the GPR opinion on the safety options for the ATMEA1 reactor was issued, on 3 rd January 2012, ASN rendered its report and its opinion on the complementary safety assessments (ECS) for reactors in operation or under construction in France. Thus ASN will impose the implementation of a hardened safety core of material and organisational measures designed to control the fundamental safety functions in extreme situations, for all the installations concerned by the ECS report. Before 30 th June 2012 the French operators must submit to ASN the contents and specifications of the hardened safety core specific to each installation. Although the ATMEA1 reactor does not fall within the scope of this 3 rd January 2012 opinion, the conclusions it includes were also taken into consideration by ASN/DCN in preparing the ASN position on the safety options for the ATMEA1 reactor (see chapter 5.18). 10/37

11 3.2.4 Complementary assessment of aircraft crashes Protection against accidental aircraft crashes is a subject dealt within the traditional external hazards liable to affect the safety of the reactor. From the outset therefore, this subject was covered by the examination to be carried out into the safety options for the ATMEA1 reactor. The same did not apply for intentional aircraft crashes, which is dealt with malicious acts and relies on information that is classified for reasons of national defence, in particular those needed to characterise the threat or to determine the protective measures to be put in place. This is nevertheless a key subject for some safety options for the installations, for example the location of buildings or civil engineering characteristics. The review of this subject, limited to the reactor and fuel buildings, is covered by a specific amendment to the agreement between ATMEA and the consortium {ASN + IRSN} signed in the summer of The services of the Senior Official for Defence and Security (HFDS) of the Ministry responsible for the Environment and the Deputy Director General of IRSN, delegated for defence-related missions, were involved in drawing it up. The conclusions of the review are summarised in chapters 5.3.3, and Documents submitted by ATMEA Documents provided by ATMEA, constituting the initial framework of the review The safety options dossier provided by ATMEA was used to: assess the safety objectives adopted in the light of the French requirements, any differences requiring justification; assess the basis of the safety approach for the reactor design; assess the technical options selected for the design and construction of the installation, and to estimate their potential influence on the construction provisions for the installation, as well as the main options concerning the operation of the installation; assess the possibility of achieving the safety objectives adopted; an initial estimate of the radiological impact of the installation under normal operating conditions, on the environment and the people. For the first phase of the examination, ATMEA provided two documents: ATMEA PN 048 C FIN Safety options (safety design basis) for the ATMEA1 reactor, (design of the ATMEA1 reactor equivalent to that presented in the CSFRF 3 revision 4); ATMEA PN 049 C FIN Compliance with the Technical Guidelines for the design and construction of the new generation of pressurised water nuclear reactors. It should be pointed out that the CSFRF (revision 4 of 1 December 2008), initially took into account the US formulation of safety objectives and made numerous references to US regulations. In the same way, the analysis of compliance with the Technical Guidelines referred systematically to US documents (10CFR50 and GDC, SRP, NUREG reports, Reg Guides, codes and standards (ASME, ANSI, IEEE, )). At the request of ASN, ATMEA updated these documents, prior to sending them, in order 3 Conceptual safety features review file 11/37

12 to make them more explicit relative to French regulations and para-regulatory texts. ASN opinion is indeed taken in the frame of the current French regulations and para-regulatory texts. For the second phase, ATMEA sent additional technical reports, in particular in order to provide additional information on those subjects identified in phase 1 as requiring further development. The same applied to the subjects covered in paragraphs and Documents sent by ATMEA constituting the basis for the ASN opinion In the course of the technical assessment, both during meetings organised by the IRSN or the ASN and during meetings of the ASN Advisory Committees, ATMEA had to clarify some positions or amend one aspect or another of the safety options or design bases of the ATMEA1 reactor. Thus the documents provided by ATMEA and in the light of which the ASN s opinion is given, grouped together under the terms safety options dossier are: ATMEA PN 048 F FIN Report - Safety options (safety design basis) for the ATMEA1 reactor ATMEA PN 049 E FIN Report Compliance with the Technical Guidelines for the design and construction of the new generation of pressurised water nuclear reactors ATMEA PN 053 B FIN Report Technical report Safety injection system ATMEA PN 054 B FIN Report Technical report Residual Heat Removal System and Containment Spray System ATMEA PN 055 B FIN Report Technical report Severe Accident Heat Removal System ATMEA PN 058 B FIN Report Technical report Electrical design ATMEA PN 067 B FIN Report Technical report Overpressure protection ATMEA PN 069 C FIN Report Technical report Protection against internal hazards ATMEA PN 070 B FIN Report Technical report Containment Design ATMEA PN 071 C FIN Report Technical report Confinement Functions ATMEA PN 072 B FIN Report Technical report I&C General architecture ATMEA PN 073 B FIN Report Technical report PSA Level 1 ATMEA PN 080 B FIN Report Technical report External hazards ATMEA PN 079 B FIN Report Technical report Large Commercial Airplane crash ATMEA PN 121 A FIN Report Technical report Post Fukushima short-term experience feedback ATMEA PN 060 B FIN Report Technical report Reactor Pressure Vessel Internals ATMEA PN 062 B FIN Report Technical report Steam Generators ATMEA PN 063 B FIN Report Technical report Reactor Coolant Pumps ATMEA PN 068 B FIN Report Technical report Complementary Requirements to the ASME code for ATMEA1 Basic Design ATMEA PN 061 B FIN Report Technical report Control rod drive mechanisms ATMEA PN 059 B FIN Report Technical report Reactor pressure vessel ATMEA PN 065 B FIN Report Technical report Reactor coolant line ATMEA PN 066 B FIN Report Technical report Main steam line and feedwater line ATMEA PN 064 B FIN Report Technical report Pressurizer 12/37

13 These documents, which contain the commitments given during the examination by ATMEA, are listed in ATMEA letter P of 29 th November 2011, which thus fixes the list of documents which constitute the basis on which the ASN renders its opinion. The scope of the review of the safety options for the ATMEA1 reactor is defined in the agreement (more specifically in its appendix 1) established between ATMEA and the consortium {ASN +IRSN} as well as in the amendment relating to aircraft crashes (see 3.2.4). It should be noted that the documents summarized in ATMEA letter P may be slightly different to those mentioned in the IRSN or ASN reports presented to ASN Advisory Committees. Indeed, some were subsequently updated by ATMEA in order to include the commitments taken during the Advisory Committee meetings or to respond to the recommendations envisaged by the Advisory Committees. The list of all the documents provided by ATMEA in connection with the examination by the Advisory Committees is included in the corresponding IRSN or ASN reports. 13/37

14 4. DOCUMENTS PRODUCED BY ASN, ITS ADVISORY COMMITTEES AND THE IRSN DURING THE REVIEW 4.1 Intermediary conclusions of phase 1 of the examination The technical assessment carried out in phase 1 resulted in the IRSN opinion (reference [7]) and the ASN letter (referenced [8]) presented in appendix 5. This showed that : the safety options dossier included relevant information with a satisfactory level of detail ; some subjects, subject to confirmation by the GPR, did not require further review in phase 2 ; the subjects mentioned in the letter referenced [8] did require further development in phase Consultation of ASN Advisory Committees Review by the GPR The GPR met five times, in accordance with the provisional schedule, to review the safety options for the ATMEA1 reactor. This review was carried out based on reports prepared by the IRSN. GPR Meeting Topics reviewed IRSN Reports 26 th May Presentation of the safety options; - Presentation of the design of the ATMEA1 reactor; - Presentation of topics apparently not requiring further analysis in phase 2 but: o which assist with overall understanding; o which may nevertheless result in recommendations by the GPR 30 th June 2011 Meeting devoted mainly to a review of the systems important for safety, i.e.: - the SIS and CSS/RHRS systems (accumulators, CSS/RHRS interleaving, absence of LHSI); - the containment sumps (clogging risk in all accident situations); - the CHRS system; - the cooling systems (heat sink, CCWS, ESWS); - the electrical systems; - the classification of the systems, structures and components; - IRSN/DAI/DDI report nº 58 which compiles the exchanges between ATMEA and IRSN during the examination of the first phase of the review - IRSN/DAI/DDI report nº 52 which presents the results of the review carried out by IRSN on some subjects identified after the completion of the first phase; - IRSN/DAI/DDI report nº 61 which compiles the exchanges between ATMEA and IRSN to support IRSN drafting of IRSN/DAI/DDI report nº 52 - IRSN/DAI/DDI report nº 64 which presents the results of the review carried out by IRSN on the technical topics presented to the GPR on 30 June 2011; - IRSN/DAI/DDI report nº 67 which compiles the exchanges between ATMEA and IRSN to support IRSN drafting of IRSN/DAI/DDDI report nº /37

15 GPR Meeting Topics reviewed IRSN Reports 6 th October Containment building; - Dynamic confinement; - Consideration of external and internal hazards, including fire. 14 th October Presentation of the conclusions of the GP ESPN (main design features of the main ESPNs, break preclusion hypothesis applied to main primary and secondary pipes and protection against overpressure); - Instrumentation and control including the man-machine interface; - Preliminary level 1 PSA provided for the ATMEA1 reactor; - Handling and storage of the spent fuel (FPCPS); - Review of the initial lessons learned from the Fukushima accident for dealing with severe accidents. 28 th October RHRS break outside the reactor building (cont.) - ATMEA response to the conclusions of GPRs 1, 2, 3 and 4; - Overall conclusions - IRSN/DAI/DDI report nº 90 which presents the results of the review carried out by IRSN on the technical topics presented to the GPR on 6 October 2011; - IRSN/DAI/DDI report nº 89 which compiles the exchanges between ATMEA and IRSN to support IRSN drafting of IRSN/DAI/DDDI report nº IRSN/DAI/DDI report nº 91 which presents the results of the review carried out by the IRSN on the technical topics presented to the GPR on 14 October 2011; - IRSN/DAI/DDI report nº 92 which compiles the exchanges between ATMEA and IRSN to support IRSN drafting of IRSN/DAI/DDDI report nº IRSN/DAI/DDI report nº 108 which presents the action taken by ATMEA in light of the intermediary positions and recommendations taken by the GPR during its first four meetings; - IRSN/DAI/DDI report nº 109 which compiles the suggestions presented by IRSN in its reports presented during the first four meetings of the GPR. After its fifth meeting, the GPR issued its opinion and recommendations (reference [13]). This opinion is attached in appendix Review by the GP ESPN The technical review of the main design features of the main ESPNs of the main primary and secondary systems of the ATMEA1 reactor as well as the protection against primary and secondary overpressures took place sequentially and in accordance with the provisional schedule. A meeting of the GP ESPN on this subject took place on 14 September 2011 based on a report (reference [11]) drawn up by the ASN, during which the following were examined: - the general design approach selected by ATMEA and common to all the equipment; 15/37

16 - the mains design options of each of the main components of the main primary and secondary systems of the ATMEA1 reactor, as well as of the protection against primary and secondary overpressures. The opinion of the GP ESPN (reference [11]) is attached in appendix 2. The conclusions of the review carried out by the GP ESPN were also presented for information to the GPR at its meeting of 14 October CONCLUSIONS OF THE REVIEW As was pointed out by the GPR and GP ESPN in their opinion or as can be seen from the reports submitted to these Advisory Committees by ASN or by IRSN, a large majority of the safety options for the ATMEA1 reactor and the main design features for the ESPNs of the MPS and the MSSs are satisfactory (either already in the dossier initially submitted by ATMEA or in its version as revised following the technical assessment). The following paragraphs detail the main conclusions of the technical review focussing on the points which either require improvement as part of the safety options, or require particular care at a later stage of the project (more often than not at the time of a possible creation authorisation application for an ATMEA1 reactor or at the detailed design stage for such or such equipment or system). 5.1 Design features of the nuclear pressure equipment (ESPN) of the MPS and the MSSs To define the main design features of the main ESPNs of the main primary and secondary systems, ATMEA made extensive use of the design experience of AREVA and MHI. As a result, significant similarities were noted between the equipment of the ATMEA1 reactor and that of the latest third generation reactors designed. The design features chosen appear therefore to be satisfactory even if a review and more detailed studies will be needed to ensure, during the later phases of the project, that their detailed design and the procedures envisaged for their manufacture are totally satisfactory. No recommendation was made after the review by the GP ESPN of the main design features of the main ESPNs of the ATMEA1 reactor s main primary and secondary systems. After studying the dossiers, the GP ESPN: considered that the basic design studies and the design features chosen by ATMEA do not reveal any elements liable, at this stage, to call into question the use of such equipment on a nuclear reactor. It considered necessary, however, to complete the studies available and noted that certain sensitive areas have been identified as requiring more detailed studies in order to define appropriate design and monitoring during operation measures; stressed that the use of break preclusion hypothesis for the main primary and secondary system pipes can only be judged based on a description of all the additional measures applied to render any deterioration of this equipment unlikely. It noted that at this stage of the project, it does not have sufficient information to reach a decision on this point; noted the use, as design requirements, of the ASME code and US regulatory texts considered to be recognized texts. It stressed, however, that the provisions of this code need to be analysed in the light of French regulatory requirements and, if applicable, completed by special specifications notably in respect of studying ductile rupture in the event of the construction of this type of reactor in France; noted that the majority of the regulatory requirements relating to nuclear pressurise equipment are applicable to the later phases of the project, notably detailed design and 16/37

17 equipment manufacturing, and that as a result it was not possible to provide the provisions corresponding to these requirements given the state of progress of the project; pointed out that, if an ATMEA1 reactor were to be built in France, it would be necessary for future manufacturers to put in place all the measures needed to ensure compliance with the French regulatory provisions in force Steam generator (SG) The SGs of the ATMEA1 reactor are designed on a model similar to the SG technology used in 3 rd generation AREVA reactors and ATMEA agrees to apply the requirements of the ASME code that correspond to class 1 for both the primary part and the secondary part of the SGs, which constitutes a significant element to ensure the high level of safety expected for this equipment, whose rupture is not taken into account in the safety demonstration. ASN staff considers that the inspectability requirements of the SGs need to be studied specifically, in respect of all operating experience feedback accumulated in the SGs in operation, without limiting such study to the renewal of measures that have already been implemented. It further considers that the question of the internals, in particular the design of the tie beams and that of the conditioning of the secondary part need to be further developed, taking into account in particular the phenomenon of tube support plates clogging Reactor pressure vessel and vessel internals In designing this equipment, ATMEA relied on the vessel model of the AREVA 3 rd generation reactors. However, in the case of vessel internals, there is no significant operating experience feedback regarding some evolutions, in particular the heavy reflector, and therefore require tests that ATMEA has agreed to carry out. ASN staff considers that during the later phases of the project, studies of fast fracture must be carried out, taking into account fragile and ductile rupture, over a time span of 60 years operation. It recommends specifying a RT NDT at 60 years ensuring, in particular, in addition to the approach proposed, sufficient margins for a realistic defect in the core zone. It also considers that the nozzle connection zone, which may be affected by stress concentration phenomena, requires appropriate justifications in the same way as the core zone. ATMEA identified zones in which the preliminary fatigue studies revealed usage factors requiring additional studies. ATMEA shall continue its studies which must, as a priority, result in the definition of appropriate design measures and in service inspection provisions. ASN staff considers that ATMEA shall take into account the operating experience feedback regarding difficulties which occured during welding on several reactor vessel closure heads penetrations, in order to conclude if specific additional measures are necessary with regard to the design, controllability or welding of the welds concerned, as well as in service inspection. Finally, ATMEA has not yet chosen the solution for the stainless steel cladding of the equipment in contact with the primary fluid, in particular the reactor pressure vessel. ASN staff considers that this choice must be justified and the justification should incorporate measures concerning the limitation of the risk of undercladding flaws. 17/37

18 5.1.3 Control rod drive mechanisms (CRDM) The design choices presented by ATMEA are based on the design experience feedback for the CRDM to be installed on the latest AREVA 3 rd generation reactors. This type of design is, however, not the one used in the French nuclear reactor fleet currently in operation: it is in fact still being assessed by ASN. ASN staff considers that the need for an ageing surveillance program must be examined. ASN staff points out that any future manufacturer must demonstrate that the properties of the materials used are able to guarantee the ductility (including the ability to undergo local deformations) and the weldability of the material. It further considers that given the number of dissimilar metal welds, guarantees must be provided regarding the quality of the manufacturing process. ATMEA will also have to ensure the controllability of the CRDMs as designed Reactor coolant pumps (RCP) ATMEA makes use of the operating experience feedback obtained for some RCP models already in service in the French nuclear reactor fleet and updated by incorporating modifications introduced in the latest AREVA 3 rd generation reactors. ASN staff notes that the calculations already carried out show high usage factors in an area of the RCP bowl and considers that they should be updated with a consistent approach and appropriate methods, with a view to justifying the ability of the equipment to function for 60 years. In so far as concerns the French regulatory requirements, any future manufacturers will have to clearly identify the requirements applicable to each of the parts of the RCP. Moreover, ASN points out that the RCP volute is a cast component which must therefore undergo a 100% volumetric inspection Main primary and secondary pipes ATMEA intends to apply the hypothesis that the break of the main primary pipes and of the main steam lines is excluded (also called break preclusion), in the meaning of the Technical Guidelines (referenced [3]). ASN staff considers that, in so far as concerns the pipes, much more information is required from ATMEA in order to enable a decision to be made on the applicability of the break preclusion hypothesis to theses pipes. The application of break preclusion hypothesis requires particularly robust lines of defence concerning the design, manufacture and in service inspection. The associated measures will have to be defined in details in the subsequent stages of the project. ASN staff considers that these additional measures, beyond the use of the class 1 requirements for all the equipment, will have to be defined in details in the subsequent stages of the project and expressed in the form of requirements. ASN staff notes nevertheless, at this stage of the project, that none of the provisions already taken is clearly incompatible with this hypothesis. A preliminary fatigue and fast fracture analysis carried out based on the criteria and methods of the ASME code shows that the tap on the CVCS feed line shows usage factors requiring special studies that ATMEA committed to carry out. This study shall justify that margins are adequate, or, if necessary, result in the definition of suitable design modifications and appropriate in service inspection provisions. 18/37

19 ASN staff considers that the applicability of the break preclusion hypothesis can only be demonstrated after ATMEA and the future manufacturers and reactor operators have defined the measures taken with regard to: quality of design; verification of the design, including the accessibility and inspectability of the equipment; quality of the manufacture, including the qualification of the processes implemented and more detiled materials specifications; manufacturing process inspection, including the controllability of the equipment manufactured; in service inspection; in accordance with the technical requirements of the French ESPN order and the Technical Guidelines (reference [3]). ASN staff considers necessary for ATMEA to define additional in service inspections, using qualified methods, in order to detect any degradation of the pipes concerned. It further considers that, in the case of the secondary pipes, the resilience and tenacity of the material chosen shall be sufficeint. In addition, justification shall be provided with regard to the routing of the pipes considering the requirement to limit the length of the sections under break preclusion hypothesis outside the reactor containment building, to limit the risk of common mode failure, to prevent hydrodynamic phenomena and to ensure inspectability Pressurizer ATMEA relies on a design that is relatively similar to pressurizers currently in use in or being manufactured for the French nuclear fleet. The pressurizer is, however, the equipment that experiences the highest temperatures of the MPS and ASN staff considers that thermal ageing must be taken into account for this equipment. ASN staff also considers that the design measures shall be further justified and stresses that the location of the spray line must be analysed to take account of the risks of thermal shock on the upper shell / top headweld. Moreover, some design choices have not yet been made and require appropriate justifications on the basis of studies and to take account of operating experience feedback. ASN staff considers that, for the pressurizer expansion line, an inverted thermal sleeve, which significantly improves the prevention of fatigue damage, should be preferably used. Finally, ASN staff considers that the manufacturer will have to ensure that the design of the welds with partial penetration into the heating rods enables adequate non destructive testing to be carried out in order to guarantee their quality Protection against overpressures in the primary system and the secondary systems ASN staff considers that the studies carried out so far and the design options chosen by ATMEA do not cast doubt upon the acceptability of the choices made with regard to protection against overpressures, with the following two reservations: 19/37

20 the use of the MSRT system for protection against overpressures means that the application to this system of the French regulatory requirements applicable to security accessories must be verified, in particular in terms of reliability; the choices made for protection against cold overpressures must be justified and the reliability of the chosen systems demonstrated. The design principles of these systems are not in doubt but their compliance with French regulatory requirements would require an in-depth review during the compliance assessment of the assembly concerned. 5.2 Accident studies (PCC and RRC-A operating conditions) Accident study criteria and rules At this stage of the project, ASN staff considers that the safety principles put forward by ATMEA related to the behaviour of the core and the integrity of the containment barriers, as well as the safety requirements related to the limiting physical phenomena resulting therefrom, are broadly acceptable. Nevertheless, some requirements deriving from the implementation of these principles (melting at hot spot in category 3, requirements applicable for LOCA and for reactivity accidents ) would need to be discussed in the frame of the review of a creation authorisation application for an ATMEA1 reactor. Concerning the combination of PCCs with the LOOP (loss of off-site power), the approach adopted by ATMEA, although not adhering strictly to the French practice implemented since the design of the N4 series, appears acceptable. ASN staff notes that ATMEA made the design choice to not provide for any preventive on-power maintenance on the safety systems with the exception of the CCWS, ESWS systems and emergency electric power supplies. ASN staff considers that, beyond the safety options, in connection with a possible creation authorisation application, the petitioner should define the rules governing the possibilities to carry out preventive maintenance which would make, within a redundant support system, one train unavailable over a short period of time in a state in which it is normally required List of PCC situations and RRC-A situations The safety approach presented by ATMEA to draw up the list of Plant Condition Categories (PCC) and identify situations corresponding to multiple failures (RRC-A) does not give rise to any reservations at this stage Use of the calculations of radiological consequences ASN staff considers that, beyond the safety options, in connection with a possible creation authorisation application, the petitioner will have to identify, for the plant condition categories leading to the highest radiological consequences, the preponderant release and exposure pathways and study the possibility of implementing measures that reduce the contribution of these pathways to the overall dose. 20/37