Our codes

AFCEN’s design and construction codes are generally prefixed with RCC-, while the in-service code is prefixed with RSE-.

In some cases, codes can only be used on the EPR design, in which case the code is prefixed with ETC-. This prefix is likely to be superseded by RCC-.

AFCEN currently publishes seven codes, including 6 RCC- codes and one RSE- code.

Nos codes

Codes updates

There are several reasons for updating AFCEN codes: the need to incorporate feedback, R&D work, changes to legislation and standards, and extension of the subject matter covered by the codes.

Incorporation of feedback

Incorporating feedback is a major reason for updating codes. Several examples will be provided in the following sections which describe each of the codes, but one notable example is the change to the “Liner” chapter in the RCC-CW code to reflect feedback from the Flamanville 3 plant.

New developments, scientific breakthroughs and R&D work

These also represent major reasons for updating the codes.

For example, the 2016 edition of the RSE-M code has been updated to describe the loading history effect on the resistance to the cleavage brittle fracture of RPV steel by taking account of the warm pre-stressing phenomenon (WPS) as well as the associated criteria that were proposed and which are currently being defined within a probationary phase rule (RPP).

To drive the continual improvement process, AFCEN is involved in a R&D focus group on a European level for three codes (RCC-M, RCC-CW and RCC-MRx), with the aim of producing proposals for Gen II-III mechanical engineering, Gen IV mechanical engineering and civil engineering works.

Regulatory changes

Changes to regulations in the various countries in which the codes are used constitute a major reason for updating the codes.

For example, efforts are being made to ensure that the mechanical codes can be applied to guarantee compatibility with the essential safety requirements of French regulations governing nuclear pressure equipment (ESPN Regulation).

Depending on the type of change, regulatory-related modifications are either introduced into the body of the text or as an appendix specific to the country in question.

For instance, AFCEN’s work on France’s Nuclear Pressure Equipment Regulation will either lead to modifications to the body of the code (such as the toughness of low-thickness materials), or the creation of a French appendix.

Changes in standards

AFCEN codes are updated to reflect changes to the standards on which they are based. ISO international standards are the first to be called when available. Otherwise, European EN standards are used.

AFCEN regularly analyzes the standards to determine whether any revisions have been made and updates the codes accordingly (see Section 3.1).

For example, RCC-M was updated in 2014 to introduce the new ISO 9712 standard for the qualification of non-destructive testing personnel, while the 2016 edition of RCC-CW incorporates the recent changes to EN 1992-4.

Extensions of the subject matter

AFCEN codes may be revised if the subject matter is extended.

One example is the future inclusion of a new chapter in the 2017 edition of RCC-M to cover the qualification of mechanical components under accidental conditions.



RCC-M : Design and construction rules for mechanical components of PWR nuclear islands

Purpose and scope

AFCEN’s RCC-M code concerns the mechanical components designed and manufactured for pressurized water reactors (PWR).

It applies to pressure equipment in nuclear islands in safety classes 1, 2 and 3, and certain non-pressure components, such as vessel internals, supporting structures for safety class components, storage tanks and containment penetrations.

RCC-M covers the following technical subjects:

  • sizing and design rating,
  • choice of materials and procurement.
  • fabrication and control, including:
    • associated qualification requirements (procedures, welders and operators, etc.),
    • control methods to be implemented,
    • acceptance criteria for detected defects,
    • documentation associated with the different activities covered, and quality assurance.

The design, manufacture and inspection rules defined in RCC-M leverage the results of the research and development work pioneered in France, Europe and worldwide, and which have been successfully used by industry to design and build PWR nuclear islands. AFCEN’s rules incorporate the resulting feedback.

Use and background


The RCC-M code has been used or served as a baseline for the design and/or fabrication of some Class 1 components (vessels, internals, steam generators, primary motor pump units, pressurizers, primary valves and fittings, etc.), as well as Class 2 and 3 components for:

  • France’s last 16 nuclear units (P’4 and N4).
  • 4 CP1 reactors in South Africa (2) and Korea (2).
  • 44 M310 (4), CPR-1000 (28), CPR-600 (6), HPR-1000 (4) and EPR (2) reactors in service or undergoing construction in China.
  • 4 EPR reactors in Europe: Finland (1), France (1) and UK (2).


AFCEN drafted the first edition of the code in January 1980 for application to France’s second set of four-loop reactors with a power rating of 1,300 MWe (P’4).

Export requirements (Korea, China and South Africa) and the need to simplify contractual relations between operators and building contractors quickly prompted the code to be translated and used in English, followed by Chinese and Russian.

Subsequently, the code was thoroughly updated and modified to reflect the feedback from France’s nuclear industry, as well as through regular interactions with international stakeholders. Six editions ensued (1981, 1983, 1985, 1988, 1993 and 2000) with a number of addenda between each edition.

The 2007 edition took account of changes to European and French regulations (Pressure Equipment Directive 97/23/EC and France’s Nuclear Pressure Equipment Regulation), with the harmonized European standards that were subsequently released.

To date, the 2007 edition is widely used in France and China for EPR projects and replacement steam generators.

The 2012 edition, with three addenda in 2013, 2014 and 2015, incorporated initial feedback from EPR projects. The 2013 addendum also included Probationary Phase Rules (RPP) as a way of providing an alternative set of rules in cases where industry feedback has not been sufficiently consolidated for permanent inclusion in the code.

The new information incorporated into the 2016 edition includes the first series of changes resulting from the commissioned studies into the ESPN Regulation (see Section 2.2.5).

The 2017 edition introduced the Q subsection as Probationary Phase Rules to cover the qualification of active mechanical components (pumps and valves) and the new non-mandatory Appendix Z C to guide users in carrying out non-linear finite element analyses.

Edition available as of early 2019

The 2018 edition is the most recent version of the code. It integrates 176 modification files, mainly relating to the commissioned studies into the ESPN Regulation. This edition is supplemented by the different guides released as PTAN publications and addresses the essential safety requirements of the ESPN Regulation of December 30, 2015, as amended by the Regulation of September 3, 2018. AFCEN has provided an extensive set of documentation to justify how the requirements in the RCC-M code are compliant for N1, N2 and N3 nuclear pressure equipment. Despite being unable to finish examining the safety factors and uncertainties during AFCEN’s demonstrations, ASN and GSEN nevertheless endorsed this edition.

More specifically, the changes implemented in the 2018 edition relate to the following provisions:

  • Incorporation of the work involved in testing the code for conformity with the essential requirements of French regulations (Annex I of Directive 2014/68/EU and Appendices I to IV of the French Nuclear Pressure Equipment Regulation of December 30, 2015, as amended by the “ESPN” Regulation of September 3, 2018), including an update to Appendices ZY and ZZ relating to the French and European regulations respectively, which contain all the work from the commissioned studies:
    • The technical qualification methodology and applicable requirements for materials used in the pressure parts of N1 equipment.
    • The “unacceptable defects” methodology relating to Section 3.4 (Essential Safety Requirements) in Appendix I of the ESPN Regulation (an application guide is available in ZY 360).
  • References to AFCEN’s different technical publications (PTAN), which provide support in the form of solutions for achieving the objectives laid down in the regulation. Introduction of two new Probationary Phase Rules (RPP no. 5 and 6) concerning N1 and N2/N3 assemblies respectively.
  • Introduction of a new appendix to Section III describing the procedure for preparing an equivalence report as defined in MC 2900, which describes the methodology for advanced ultrasound inspections.
  • Lowering of the evaluation threshold for ultrasound inspections of Class 1 and 2 welds to -12 dB.
  • Introduction of eddy current examinations for steam generator tubes after bending.
  • Introduction of reduction factors for effective fatigue resistance for welded joints in N2 or N3 equipment.
  • Clarification of the thicknesses to be used for analysis dossiers.
  • Revision of the terms for carrying out tensile testing.
  • Introduction of two new STRs:
    • M 1161 N1, N2 and N3 bars made from rolled non-alloy steel
    • M 2331 Valve forged from steel with a nickel, chrome and molybdenum alloy for primary pumps in pressurized water reactors
  • Alignment of Chapters B C D 6000 with 4126 and 764-7.
  • Update to Chapter A 5000 introducing the 2015 edition of the ISO 9001 Quality standard.

RCC-M 2017


Next editions

In accordance with the new sales model, AFCEN will now publish editions instead of addenda.

In addition to pursuing its activities relating to the ESPN Regulation, AFCEN is also producing an editorial program for the RCC-M Subcommittee to cover the 2019-2022 period and define the key improvements that need to be made to the RCC-M code to reflect project requirements and industrial practices.

The next edition of RCC-M is scheduled for 2020 to leverage initial feedback on the use of the 2018 edition. This edition will incorporate the modifications relating to the follow-up work on the ESPN Regulation.

The new 2020 edition of the code will also incorporate the feedback on the code’s use in current projects (EPR UK, TSN, FA3, replacement steam generators, etc.) and on the results of the development or assessment work carried out in AFCEN’s working groups (France, China Users Groups, UK, etc.) by ASN or in international groups (Europe and MDEP).

RCC-M Technical Publications


In 2015, AFCEN published a radiation protection guide for the design of nuclear pressure components in PWR plants in France. In 2018, the guide was updated to take account of the latest feedback.

To view the RCC-M Technical Publications

Commissioned studies into the ESPN Regulation led to a series of guides, some of which were published in 2016 and 2017, and subsequently updated and supplemented in 2018.

RCC-M criteria:

The RCC-M code criteria were published late 2014. This 550-page document, produced in both English and French, takes a look back at the code’s background since the decision was taken for its creation.

The technical origins of the code and the changes made to the recommendations until publication of the 2007 edition are explained from the point of view of an engineer who was required to draft a design specification in alignment with the RCC-M code.

A PTAN was also published in 2016 to justify the absence of any requirements for measuring resilience in ustenitic stainless steels and nickel-based alloys, and their welds as defined in RCC-M for products less than 5 mm thick.

Work relating to France’s Nuclear Pressure Equipment Regulation (ESPN)

The Editorial Committee has launched 19 working groups to demonstrate how the RCC-M code can be used to meet the essential safety and radiation protection requirements stipulated in France’s Nuclear Pressure Equipment Regulation and the European PED Directive for N1, N2 and N3 equipment.

These groups have the following missions:

  • hazard analyses,
  • Inspectability.
  • uncertainties and safety factors,
  • the dimensions required to ensure conformity with requirements,
  • fatigue damage,
  • specific evaluations for nuclear components,
  • toughness of low-thickness materials,
  • unacceptable defects (including defects beneath the cladding and sequential penetration),
  • visual inspections during fabrication,
  • proof of compliance with essential safety and radiation protection requirements for fabrication,
  • definition of a component’s admissible limits,
  • instructions manuals,
  • fabrication of assemblies,
  • developments in technologies and practices,
  • safety devices and pressure accessories,
  • technical qualification,
  • SRMCR systems,

The groups’ findings were published in 2016 as:

  • generic modifications introduced into the body of the code,
  • modifications specific to French and European regulations and introduced in non-generic appendices ZY and ZZ exclusively for France,
  • technical publications in the form of guides and criteria.

The working groups produced all the requested changes and evidence to ensure that the 2018 edition of RCC-M conforms to the requirements of France’s Nuclear Pressure Equipment Regulation (“three-year program”).

The results of the group’s work on N1 equipment were submitted to ASN. The results of the group’s work on N2 and N3 equipment were submitted to GSEN (Group for Nuclear Equipment Safety). Aside from the commissioned study on Safety Factors and Uncertainties, whose results will be assessed in 2019, ASN and GSEN examined the proof of compliance submitted by AFCEN and subsequently endorsed the 2018 edition as fulfilling the essential safety requirements of the ESPN Regulation.

In 2018, new commissioned studies were launched to address other regulatory requirements that are not considered to be essential safety requirements:

  • A material storage guide aimed at specifying the rules for identifying and reserving the materials that will be supplied to the operator in accordance with Section 8.1 in the Regulation of December 30, 2015 as amended.
  • A methodological guide for overseeing the fabrication of components that are not subject to specific technical qualification. This guide aims to provide guarantees relating to the conditions for manufacturing certain components that are not subject to specific technical qualification. The main objective is to ensure that suppliers consistently enforce the provisions stipulated by the STR.
  • Work focusing on testing in response to Section 8.2 of the Regulation of December 30, 2015 as amended.
  • A definition of what constitutes “situations” and “loads”.

In addition to the three-year program, AFCEN is also looking into the prospect of:

  • Creating an oversight group to update the standard following changes to the regulation over time and thereby maintain official endorsement; as such, AFCEN proposed a new work program to ASN and GSEN for 2019-2022,
  • Ensuring that the standard is sufficiently stable for implementation in projects; Section 6 of the amended ESPN Regulation gives manufacturers the possibility of submitting a safety options dossier for N1 equipment to ASN for review and subsequent advisory; the principle for this facility will be extended to N2/N3 equipment.
  • International challenges

    The RCC-M Subcommittee is continuing to scale up its activities on an international level by arranging events, carrying out communication initiatives and taking part in technical work sessions within the different organizations influencing the standardization process.

    Events in 2018:

    • AFCEN Day was held on June 25, 2018, under the headline “AFCEN present and future”, which enabled the association to provide members with a review of its RCC-M activities. This event took place ahead of the World Nuclear Exhibition, which AFCEN also attended. To coincide with both events, AFCEN also received a delegation from China. Delegation members were treated to an overview of the Subcommittee’s activities, including detailed presentations on the major updates to the 2017 edition of the RCC-M code.
    • Experts from the RCC-M Subcommittee traveled to China in May (three experts) and November 2018 (four experts) to answer questions from the Chinese Specialized Users Groups (CSUGs). The two-day meetings each attracted over 70 Chinese members from various local companies and allowed the experts to answer several dozens of questions which, where applicable, resulted in code interpretation or modification requests.

    In 2018, the RCC-M Subcommittee also took part in several international working groups and participated in the associated events:

    • RCC-M experts play an active role in the Convergence Board of Mechanical Standards Developing Organizations (SDO Convergence Board) during the ASME Code Week. Members are currently taking an in-depth look at several topics for harmonization.
    • At the European level, the organizations taking part in the GEN II/III Prospective Group (PG1) of CEN Workshop WS 64 - Phase 2 issued several modification requests for the RCC-M code. Phase 2 ended in 2018. Phase 3 will be launched in 2019.

    In 2018, there are plans to maintain international initiatives:

    • focusing on international comparisons by publishing the studies launched by CORDEL and the SDO Convergence Board in line with the expectations of the other SDOs,
    • furthering the aims of OECD/NEA by continuing relevant work on equivalent codes and regulations alongside the Safety Authorities in the CSWG,
    • by leading AFCEN’s Chinese and UK Users Groups, and the corresponding international training courses.
    • at the European level as part of the CEN/WS 64 workshop.


    RSE-M : In-Service Inspection Rules for Mechanical Components of PWR Nuclear Islands.

    Purpose and scope

    The RSE-M code defines in-service inspection operations. It applies to pressure equipment used in PWR plants, as well as spare parts for such equipment.

    The RSE-M code does not apply to equipment made from materials other than metal. It is based on the RCC-M code for requirements relating to the design and fabrication of mechanical components.

    Use and background


    The inspection rules specified in the RSE-M code describe the standard requirements of best practice within the French nuclear industry, based on its own feedback from operating several nuclear units and partly supplemented with requirements stipulated by French regulations.

    To date:

    • The 58 units in France’s nuclear infrastructure enforce the in-service inspection rules of the RSE-M code.
    • Operation of 34 commissioned units in China’s nuclear infrastructure, corresponding to the M310, CPR-1000, ACPR-1000, CPR600 and EPR2 reactors, is based on the RSE-M code (since 2007, use of AFCEN codes has been required by NNSA for Generation II+ reactors).


    AFCEN drafted and published the first edition in July 1990.

    This initial edition served as a draft for preparing the 1997 edition, which extended the code’s scope to encompass elementary systems and supporting structures for the mechanical components concerned.

    This edition was updated on a number of occasions (in 2000 and 2005) before undergoing a complete overhaul in 2010.

    The 2010 edition is supplemented by addenda in 2012, 2013, 2014 and 2015.

    The 2016 edition is in keeping with the work that has been pursued since the 2010 edition by continuing to update the existing version and incorporating EPR aspects (FLA3). The changes made to this new edition mainly involve:

    1. Restructuring Sections A/B/C/D: Section A still contains the rules that apply to all pressure equipment, while Sections B, C and D describe the specific rules for components depending on their class.
    2. Changes to make the text easier to understand:
      • difference between "maintenance operations" and "inspection operations",
      • set of rules relating to cleanliness,
      • procedure for performing hydraulic tests,
      • surveillance of main primary system leaktightness,
      • recommendations for maintenance operations,
      • new chapters on spare parts,
      • quality system requirements,
      • requalification hydraulic test methods,
      • classification method for maintenance operations,
      • inspection of safety devices,
      • classification of maintenance operations.
    3. Enhancement of the code for simplified implementation with EPR projects (FLA3).

      AFCEN is aiming to prioritize development of the RSE-M code in the following directions:

      • incorporate developments in technology and legislation,
      • factor in the constraints facing operators-partners,
      • deliver support for all international practices.

    AFCEN is aiming to prioritize development of the RSE-M code in the following directions:

    • Incorporate developments in technology and legislation,
    • factor in the constraints facing operators-partners,
    • deliver support for all international practices.

    The 2017 edition builds on the technological, legislative and international developments that occurred in 2016. The changes made to this new edition mainly involve the following points:

    • further clarification regarding the limits of main secondary systems,
    • creation of a chapter on the extended shutdown of equipment in the main secondary system (especially steam generators), including the chemical specifications for extended shutdowns,
    • alignment of the paragraphs in B 4000 that describe a manual penetrant testing technique for defence-in-depth examinations (hypothetical defects) with MC 4000 in RCC-M,
    • creation of two chapters: B 4800 (inspection of piping in the main primary and secondary systems) and B 4900 (global inspection of the main primary system) to ensure consistency with current practices,
    • creation of a specific chapter on pre-service inspections, which is neither a periodic requalification nor a periodic inspection, and an update to the text,
    • clarification of the existing definition for an essential parameter: removal of the reference to the primary parameter and addition of further information to improve on-site monitoring of these parameters,
    • complete update to Chapters II and III in Appendix 4.4 relating to the eddy current examination of steam generator tubes to take account of the new transversal rotating probes and offer a clearer description of the operating modes and the examination by acoustic emission method,
    • creation of a new section to introduce Appendix 5 (Appendix 5.0) and provide a detailed explanation of how Appendices 5.1 to 5.8 link together,
    • alignment of Appendices 5.3 and 5.4 for calculating Keq according to the cumulative theta method, clarification when |KII| < 0.02 |KI|,
    • integration of the kth2 method in RCC-MRx 2016 (for aligning Appendix 5.4 of RSE-M with Appendix A16 of RCC-MRx),
    • update of the inspection tables (complete, partial and EPR pre-service inspection) with references to the examination methods for alignment with new sections B4800 and B4900.

    Editions available as of early 2019

    The 2018 edition is the most recent version of the RSE-M code.

    It builds on the technological and legislative developments that occurred in 2017. The changes made to this new edition mainly involve:

    • update of the references specified in the list of applicable standards and codes (Appendix 1.3), especially by analyzing any impacts from the changes made to RCC-M,
    • introduction of an appendix with a safety rating for the modification files in RCC-M and an explanation about its use,
    • inclusion of changes to the conventional qualification of NDT tests,
    • incorporation of regulatory changes as applicable to repairs / modifications (§ 8000 and Appendix 1.6 concerning the associated documents),
    • development of the section covering spare parts,

    Work relating to France’s nuclear pressure equipment regulation (ESPN)

    As part of its involvement in France’s ESPN Regulation, the RSE-M Subcommittee has commissioned studies on the following topics:

    • guide to classifying repairs / modifications / installations on nuclear pressure equipment (not including Class 1 equipment),
    • guide to the documentation associated with repaired / modified N2/3 nuclear pressure equipment,
    • guide to the methodology for verifying the measures taken to protect against admissible limits being exceeded for circuits manufactured according to the old regulations,
    • guide to the procurement of the main pressure parts for main primary / secondary systems,
    • guide to the methodology for the periodic requalification of N2 or N3 piping,
    • guide for equipment not subject to in-service inspections,
    • modifications to the code for the constitution of nuclear facilities.

    Contents of the 2018 edition of RSE-M code

    Outlook and next edition

    The 2020 edition has the objective to consolidate and build on technological, legislative and international developments. With this aim in mind, special attention will be paid to the following points:

    • extension of the scope to encompass all basic nuclear facility equipment (not only pressure equipment),
    • monitoring of changes to the French Regulation of November 10, 1999 (in-service inspection of main primary and secondary systems) and incorporation of those changes into the code,
    • inclusion of feedback on the ESPN guides,
    • examination of the prospect of creating an RSE-M PTAN containing a thesaurus and definitions,
    • use of a requirement engineering process to define the tests, which will be detailed in a section in 2019,
    • safety devices and pressure accessories: work on the requirements in Section B: alignment with nuclear industry practices, consistency/level of requirements with those in Sections C and D,
    • inclusion of the specific characteristics of the FA3 EPR (N1 not including main primary and secondary systems) + inclusion of the Taishan / FA3 ERP inspection plan,
    • Appendix 3.1.1: inspection programs for the main primary and secondary systems, as adapted to EPR projects (if available in 2019),
    • Appendix 3.1.2: N2 and N3 inspection programs, as adapted to EPR projects (if available in 2019),
    • clarify the concepts of rating threshold, characterization threshold and significant variation threshold in terms of measuring thicknesses,
    • Appendix 4.3: review and updating of the methodologies for the general and specific qualification of NDTs,
    • Section A4700 - Qualification and certification of testing personnel: to be aligned with Appendix 4.3 – IX, clarify the case of examinations that should not be considered to be NDTs: metrological examinations, cleanliness Video examination, etc.
    • clarification of the terms for performing pre-service inspections of components at the factory (case of replacement steam generators),
    • Appendix 5.4: update to the KCP method in Appendix 5.4,
    • Appendix 5.2: standardization between RCC-M and RSE-M in terms of priming factors,
    • Appendix 5.2: cleansing in the priming and propagation methods (aggregated transients),

    RSE-M technical publications

    “WPS” criteria (relating to Probationary Phase Rule 2 of RSE-M)

    The purpose of this publication is to describe the loading history effect on the resistance to the cleavage brittle fracture of RPV steel by taking account of the warm pre-stressing phenomenon as well as the associated criteria that were proposed and which are currently being defined within a probationary phase rule (RPP2) in RSE-M.

    "Appendix 5.4" criteria

    These criteria were published in 2017.
    AFCEN's members have made major changes to the mechanical fracture methods specified in the appendix. As part of the Hinkley Point C EPR project in the United Kingdom, an Independent Expert Working Group (IEWG) carried out a thorough review and decided that the methods were suitable for use.

    "Appendix 5.5" criteria

    These criteria were finalized in 2018 and published in the first quarter of 2019.

    The criteria for analyzing the impact of planar defects are explained.

    PTANs due for release in 2019

    Other AFCEN technical publications (PTAN) are being prepared:

    • “Appendix 1.4” criteria for helping control the specific provisions for applying RCC-M for modifications / repairs,
    • PTAN “Methodological guide for defining NDT qualifications with ultrasonic processes”,

    Discussions with NNB

    With respect to the use of the RSE-M code for the Hinkley Point C project, a series of meetings was held in 2018 to produce a UK-specific appendix tailored to UK regulations and the operator’s constraints.

    To simplify the process of making the code accessible to a global audience, the Subcommittee analyzed the sections of the code that could be modified by a foreign operator and the parts that are applicable irrespective of the country. NNB will work with this aim in mind while focusing on in-service inspections.



    RCC-E : Design and construction rules for electrical equipment of PWR nuclear islands

    Purpose and scope

    RCC-E describes the rules for designing, building and installing electrical and I&C systems and equipment for pressurized water reactors.

    The code was drafted in partnership with industry, engineering firms, manufacturers, building control firms and operators, and represents a collection of best practices in accordance with IAEA requirements and IEC standards.

    The code’s scope covers:

    • architecture and the associated systems,
    • equipment engineering and environmental qualification for normal and accidental conditions including seismic events,
    • materials engineering and the qualification procedure for normal and accidental environmental conditions,
    • facility engineering and management of common cause failures (electrical and I&C) and electromagnetic interference,
    • testing and inspecting electrical characteristics,
    • quality assurance requirements supplementing ISO 9001 and activity monitoring.

    Use and background


    RCC-E has been used to build the following power plants:

    • France’s last 12 nuclear units (1,300 MWe (8) and 1,450 MWe (4)),
    • 2 CP1 reactors in South Korea (2),
    • 44 M310 (4), CPR-1000 (28), CPR-600 (6), HPR-1000 (4) and EPR (2) reactors in service or undergoing construction in China,
    • 1 EPR reactor in France.

    The RCC-E code is used for maintenance operations in French power plants (58 units) and Chinese M310 and CPR-1000 power plants.

    RCC-E has been chosen for the construction of the two EPR units in Hinkley Point C(UK).

    Users include:

    • equipment suppliers,
    • engineering firms responsible for designing, building and installing equipment and systems,
    • control and inspection organizations,
    • Nuclear Safety Authorities.


    The editions published between 1981 and 2002 address Generation II reactors.

    The 2005 edition incorporated the requirements stipulated in the design codes specific to the EPR project - ETC-I and ETC-E, which focus on I&C and electrical systems respectively (ETC: EPR Technical Code Instrumentation and Electrical).

    The 2005, 2012 and 2016 editions concern Generation II and III reactors. As from the 2005 edition, project specifications must be written to supplement and implement the rules in RCC-E and allow the code to be used in the project.

    The various editions of the code have been published in French and English.

    The 2005 edition was translated into Chinese and published under CGN’s authority in 2009.

    Edition available as of early 2019

    The RCC-E 2016 edition is the most recent version. French and English versions of the code have been available since early 2017.

    The following sources are used when revising the RCC-E codes:

    • feedback from facilities under construction and in operation,
    • the Nuclear Safety Authorities’ investigation process,
    • users inquiries,
    • changes in the standards used and IAEA’s requirements,
    • changes in industry’s maturity.

    The 2016 edition:

    • represents a departure from previous editions, which have been updates instead of overhauls,
    • addresses Generation II, III and IV reactors, research reactors and naval reactors,
    • organizes requirements into four key areas for easier identification and greater clarity: monitoring, systems, equipment, and component and systems installation. Each key area covers all lifecycle activities,
    • takes account of IAEA requirements as applicable to the scope of the code,
    • clearly defines the supplements to the requirements in the chosen IEC standards for I&C systems.

    Reasons for overhauling the code include:

    • changes to IAEA requirements SSR-2/1, GSR Parts 2 and 4, and recommendations for designing and building electrical and I&C systems (SSG 34 and SSG 39), which are used as inputs to the drafting process,
    • the WENRA handbook on the design of new reactors,
    • changes to IEC standards relating to the SC 45 Technical Committee and IEC industry standards.
    • feedback from current projects: EPR, ITER, RJH and ASTRID,
    • lessons learned following the British Safety Authorities’ investigation into the UK’s EPR as part of the generic design assessment into the electrical and I&C systems,
    • feedback following Fukushima.

    Requirements are:

    • adapted so that they can be applied to nuclear projects other than pressurized water reactors,
    • harmonized and coordinated with the requirements of the relevant IEC international standards.



    Technical publication of the RCC-E Subcommittee:

    Contribution to the ESPN program

    In 2018, the RCC-E Subcommittee took part in producing a “Guide to designing SRMCRs installed at PWR plants to protect N2 or N3 nuclear pressure equipment”.

    Editions gap analysis

    AFCEN has produced :

    • a document that compares the 2012 and 2005 editions of the code entitled: “Nuclear Codes & Standards: RCC-E 2012 Gap analysis with the RCC-E 2005”
    • a document that compares the 2016 and 2012 editions of the code entitled "Nuclear Codes & Standards: RCC-E 2016 Gap analysis with the RCC-E 2012".


    The work topics for the next editions will include:

    • feedback from the application of RCC-E 2016,
    • measurement, control and regulation systems,
    • design extension situations,
    • IT security.

    International activities

    The RCC-E Subcommittee took part in meetings with the CSUG (Chinese Specialized Users Group).

    The Chinese working group comprises approximately 30 members. Every year, a meeting is organized in China to improve interaction and help address the interpretation and/or modification requests issued by the CSUG.

    Two meetings were held in 2018: one in France during the AFCEN Day event in June and the other in September in Beijing. A similar meeting has been scheduled for 2019 and for the following years.

    AFCEN is planning to create a Users Group in the United Kingdom in 2019 to address the specific characteristics of the British projects currently undergoing construction (Hinkley Point, Sizewell and Bradwell).



    RCC-CW : Design and construction rules for civil works in PWR nuclear islands

    Purpose and scope

    RCC-CW describes the rules for designing, building and testing civil engineering works in PWR reactors.

    It explains the principles and requirements for the safety, serviceability and durability of concrete and metal frame structures, based on Eurocode design principles (European standards for the structural design of construction works) combined with specific measures for safety-class buildings.

    The code is produced as part of the RCC-CW Subcommittee, which includes all the parties involved in civil engineering works in the nuclear sector: clients, contractors, general and specialized firms, consultancies and inspection offices.

    The code covers the following areas relating to the design and construction of civil engineering works that play an important safety role:

    • local cases and combinations,
    • geotechnical aspects,
    • reinforced concrete structures and galleries,
    • prestressed containments with metal liner,
    • metal containment and pool liners,
    • metal frames,
    • anchors,
    • concrete cylinder pipes,
    • paints and coatings,
    • containment leak tests.

    The RCC-CW code is available as an ETC-C version specific to EPR projects (European pressurized reactor).

    Use and background

    AFCEN published the first civil engineering code (RCC-G) in 1980. This edition included feedback from France’s 900 MWe nuclear reactors and mainly drew inspiration from the French BAEL regulation (limit state design of reinforced concrete) and BPEL regulation (limit state design of prestressed concrete). It has been used for the Ulchin project in Korea and the M310 project in China.

    AFCEN updated the edition in 1985 and again in 1988 to reflect the latest developments in civil engineering technology.

    In particular, the 1988 edition served for France’s 1,450 MWe PWRs. In April 2006 in response to the specific needs of its Flamanville 3 EPR project in France, EDF published a reference document called ETC-C for the design and construction of civil engineering works.

    The EDF document was not published by AFCEN, but acted as a blueprint for a civil engineering code that AFCEN produced in 2009 as part of the RCC-CW Subcommittee, which led to:

    • initially, the publication of a specific code for EPR projects: ETC-C edition 2010, followed by ETC-C edition 2012,
    • subsequently, the publication of a generic civil engineering code, called RCC-CW, that is not specific to any given project. Two successive editions of RCC-CW were published in 2015 and 2016.

    The ETC-C 2010 edition, which was the first version prepared and published by AFCEN, was used for the generic design assessment of the EPR project in the United Kingdom.

    Successive versions of RCC-CW

    Edition available as of 2019

    In 2015, AFCEN prepared and published the first edition of a generic civil engineering code that does not relate to any specific project.

    As from the 2015 edition, this RCC-CW code no longer adheres to the EPR project and can be used for PWR reactors featuring a prestressed containment with a metal liner. This code is being usted for the new EPR project in France.

    RCC-CW 2015 includes all the relevant proposals based on the experience acquired during current projects:

    • technical discussions concerning the licensing process for Flamanville 3 and the generic design assessment of the EPR project in the United Kingdom,
    • the experience acquired by members through their participation in the Olkiluoto, Flamanville and Taishan projects.

    It takes account of the latest changes in European standards. It includes technological openings and improvements:

    • bonded prestressing has been supplemented with unbonded prestressing,
    • the code covers the design and development of seismic isolation devices,
    • the section on external hazards has been updated to include tornadoes.
    • The design approach has been expanded to provide greater focus on design extension situations.

    The 2016 edition of the RCC-CW code implements the following changes:

    • Correction of various editorial mistakes.
    • Thorough revision of the DANCH chapter on anchors and inclusion of the latest changes to EN 1992-4.

    The 2017 edition of the RCC-CW code implements the following changes:

    • rules for anchor channels and active channels have been worked into the DANCH and CANCH chapters,
    • the CCONC chapter has been completely revised to ensure a better fit with EN 13670 and has been based on the latest version of EN 206,
    • a new CCOAT chapter has been created for paints and coatings,
    • the actions to be considered in design extension hazards have been amended (DGENR chapter),
    • requirements for seismic soil column calculations have been included (Appendix DA).

    The 2018 edition of the RCC-CW code includes the following improvements:

    • improved requirements related to the minimum reinforcement rate,
    • introduction of requirements for post-installed anchors and recently updated standards,
    • changes to the contents for reinforcements (CREIN) in alignment with EN 13670,
    • general revision of the requirements relating to tolerances (CA).

    RCC-CW 2018 covers anchor-related topics

    Contents of the 2018 Edition of the RCC-CW code


    The development of the civil engineering code is continuing in the following directions:

    • integrate feedback from projects currently under development or construction,
    • broaden the scope of robust technologies covered by the code (anchors, metal liners, and so on),
    • encourage application of the code in the European and international arena by offering greater coverage of the latest international standards and promote the code as a civil engineering benchmark for the Prospective Groups that CEN set up to prepare the future nuclear codes,
    • according to AFCEN’s requirements and development objectives, develop appendices and addenda specifically addressing how the code can be adapted to the countries targeted by AFCEN.

    The work program includes the following core topics:

    • composite steel and concrete structures,
    • pile foundations,
    • improved reinforcement rates,
    • maintenance,

    Technical publication on seismic isolation and dissipation

    Technical publication “PTAN – French Experience and Practice of Seismically Isolated Nuclear Facilities” was published in 2014.

    It presents the best practices and experience of French industry resulting from the last 30 years in designing and installing seismic isolation systems beneath nuclear facilities.

    This publication enables European industry to:

    • codify the industrial design and construction practices according to AFCEN: in this respect, RCC-CW 2015 includes a section on seismic isolation,
    • showcase its experience within international organizations and bodies (IAEA, OECD, WENRA, etc.).

    A new technical publication entitled “PTAN – Study report on Seismic Dissipative Devices” will be released early 2019. This PTAN compiles the collective experience of AFCEN’s corporate members on seismic dissipative devices.

    International activities

    CEN/WS 64

    The Subcommittee is involved in the activities of CEN Workshop 64.

    The RCC-CW code is being shared with the other European participants.

    During the workshop’s activities, AFCEN will examine all requests to update the code.

    Chinese Users Group (CSUG)

    The RCC-CW codes are being shared within the Chinese Users Group, which has held meetings every year since 2015 and is attended by 20 to 30 Chinese experts.

    Any interpretation requests for AFCEN codes issued during the meetings are examined by the Subcommittee.

    UK Users Group

    The UK Users Group on civil engineering codes includes the main companies involved in the Hinkley Point C project. The Users Group was officially launched during the AFCEN 2017 Conference. Following the kick-off meeting in November 2016, two meetings were held in June and December 2017.

    The group held two meetings in 2017 and one meeting in 2018.



    RCC-C : Design and construction rules for fuel assemblies of PWR nuclear power plants

    Purpose and scope

    The RCC-C code contains all the requirements for the design, fabrication and inspection of nuclear fuel assemblies and the different types of core components (rod cluster control assemblies, burnable poison rod assemblies, primary and secondary source assemblies and thimble plug assemblies).

    The design, fabrication and inspection rules defined in RCC-C leverage the results of the research and development work pioneered in France, Europe and worldwide, and which have been successfully used by industry to design and build nuclear fuel assemblies and incorporate the resulting feedback.

    The code’s scope covers:

    • fuel system design, especially for assemblies, the fuel rod and associated core components,
    • the characteristics to be checked for products and parts,
    • fabrication methods and associated inspection methods.

    Use and background


    The RCC-C code is used by the operator of the PWR nuclear power plants in France as a reference when sourcing fuel from the world’s top two suppliers in the PWR market, given that the French operator is the world’s largest buyer of PWR fuel.

    Fuel for EPR projects is manufactured according to the provisions of the RCC-C code.

    The code is available in French and English. The 2005 edition has been translated into Chinese.


    The first edition of the AFCEN RCC-C code was published in 1981 and mainly covers fabrication requirements. The second edition of the code was released in 1986 and supplemented the first edition by including design requirements in a specific section at the end of the code. This structure remained unchanged and prioritized the fabrication aspects.

    Between 2013 and 2015, the RCC-C Subcommittee was busy overhauling the code to implement a new structure for improved clarity as well as to reflect the requirements of the latest quality assurance standards and describe all technical requirements that have been missing from previous editions. 45 nuclear fuel experts were involved in these activities. The Subcommittee's work culminated in the 2015 French edition, which was translated into English the following year.

    Since the overhaul in 2015, work on modifying the code has mainly focused on reflecting the changes that suppliers have made to the manufacturing aspects, as well as taking account of new products. The code may also be amended as and when requests are issued by ASN following the Permanent Working Groups on fuel, especially product design.

    Edition available as of early 2019

    The RCC-C 2018 edition is the most recent version

    The main changes between the 2017 and 2018 versions are as follows:

    In terms of design:

    No changes have been made to the design chapter, insofar as ASN reviewed the fuel performance criteria in the summer of 2017 (Permanent Working Group).

    The RCC-C code will be modified in 2019 to take account of any changes requested by ASN in the follow-up letter from the Permanent Working Group on fuel performance criteria.

    In terms of manufacturing:

    The modifications examined by the working group are as follows:

    • Modification to the procedure for inspecting grid welds. Addition of a reinforced inspection during qualification and removal of the need to carry out an inspection during manufacture.
    • Consideration of the specific features of resistance welding in terms of inspecting the joint between the guide tube and thimble plug.
    • Clarification of the inspection methods and frequency for UO2 Gd2O3 and MOX pellets.
    • Clarification of certain formulations relating to the obligation whether or not to specify values in the technical documentation.
    • Correction of the unregistered™ / registered® trademark symbols depending on the alloy’s commercial name. Addition of a notice on legal protection.
    • Update to the paragraph concerning metallurgical inspections of alloy 718 by taking account of the specific features of a partially recrystallized product. Clarification of the provisions for the sampling stages. Further details about the metallurgical state of the material on which inspections are performed.
    • Alignment of the paragraph specifying the conditions for chrome-plating using an electrolyte bath (current density and temperature) with industry practices. The requirements in RCC-C whereby the current density and mean temperature parameters must be continuously monitored have been removed, since they do not accurately represent the local conditions of the electrolyte bath, which could affect the quality of the plating. Therefore, manufacturers carry out a full inspection of the plating (thickness and adherence), which provides the necessary and adequate guarantees about the product’s quality.
    • Alignment of the provisions relating to radiographic examinations with the provisions in the 2005 edition of the RCC-C code, which specified the stages in the inspection process that did not require a certified inspector (e.g. development of the film). Change to the list of unconventional NDT methods, with the addition of an automatic ultrasonic inspection for tubes.
    • Harmonization of the provisions for the qualification testing of guide tube expansion with the latest manufacturing processes. The penetrant-based health inspection and metallographic inspection at a sufficiently high magnification are considered to be equivalent in terms of their effectiveness at detecting defects.
    • Clarification of the terms for inspecting the equivalent hydrogen content of fuel rod pellets.
    • Correction of a typographical error in the specified pressure value during the autoclave corrosion test without any impact on the user.
    • Harmonization with industrial processes for welding fuel rod end plugs by introducing the specific characteristics of non-fusion welding processes (RPW and USW).
    • Alignment of the provisions for determining the ferrite content in castings with ASTM A800 and ISO 13520.
    • Harmonization of the tables of inspection requirements with certain types of industrial processes to allow for an in-line coplanar verification of the guide tubes during rigging, which obviates the need for a later sample-based inspection.
    • Alignment of the provisions for pressurizing core component rods with designs for core components requiring an internal pressure greater than atmospheric pressure.
    • Incorporation of core components to reduce fluence (hafnium core components) in RCC-C as a new product.
    • Clarification of the provisions for radiographic examinations of fuel rod welds in the tables of inspection requirements. Harmonization of the provisions for the radiographic inspection of seal weld holes with industry practices.


    The main changes between the 2015 and 2017 versions are as follows:

    In terms of the general requirements and description of the fuel:

    A customer surveillance section has been added to Chapter 1 that specifies the customer's duty to monitor its fuel suppliers. It sets outs out the reasons and principles for implementing customer surveillance measures as well as the associated objectives. It includes the practice suggested in IAEA Guide NF-G-2.1 concerning quality aspects in nuclear power reactor fuel engineering.

    In terms of design:

    No changes have been made to the design chapter, insofar as ASN reviewed the fuel performance criteria in the summer of 2017.

    The RCC-C 2018 edition takes account of any changes requested by ASN.

    In terms of manufacturing:

    The most significant modifications examined by the working group are as follows:

    • Conditions for examining welded joints on core components: feedback from the manufacturing process has been taken into consideration for defining the most appropriate examination conditions in terms of magnification.
    • Heat treatment of alloy 718: the use of specified heat treatment methods representing an alternative to those defined in the code have been introduced if they improve resistance to stress corrosion cracking. Specific measures relating to the partially recrystallized state have also been introduced.
    • Harmonization of provisions relating to heat treatment on nozzles: stress relieving heat treatment is no longer mandatory due to the measures taken during dimensional inspections.
    • Need to qualify laser marking: laser marking must be qualified in case of cladding tubes due to the component's criticality.
    • Harmonization of the cobalt content for small components: the requirements of the RCC-M code have been included to specify the maximum cobalt content for the small stainless steel components in the assembly.
    • Ultrasonic inspection of cladding tubes: the intervals for verifying ultrasonic inspection equipment have been adjusted to allow sufficient time to perform the inspection.
    • Adaptation of the conditions for qualifying skeleton weld joints in terms of corrosion resistance: corrosion testing may be performed during qualification if the supplier continuously monitors the welding parameters during production.
    • Declaration of the heat treatment conditions for debris filter plates: the code's provisions for this component have been harmonized with ASTM A638.
    • Examination conditions for grid weld joints: if weld parameters are monitored in-line, visual inspections of the beads are no longer required. However, the examination conditions during qualification have been reinforced (high-magnification metallographic inspections).
    • Certification of NDT personnel: the US standard SNT-TC-1A used by Westinghouse and AREVA in the United States has been introduced into the code. The list of standard and non-standard processes has been updated.
    • Clarification of the conditions for the radiographic inspection of seal weld.


    Next edition

    The next edition (French and English) is scheduled for 2019.


    The code will be updated in alignment with the requirements of ISO 9001:2015.

    The RCC-C Subcommittee’s work on adapting the design requirements will focus on incorporating the conclusions of the French 2017 Permanent Working Group on fuel performance criteria once ASN has issued its follow-up letter.

    Manufacturing process requirements will be modified according to the proposals and feedback from Subcommittee members. There are also plans to clarify how heat treatment requirements apply to factories.

    Chapter 5 (situations outside the nuclear steam supply system) will be revised to clarify the rules and scope of requirements. The cleanliness requirements in RCC-C will be analyzed and amended if necessary.

    The table of inspection requirements for manufacturing will be analyzed for the purpose of defining writing recommendations aimed to gradually standardize content. This process will not lead to modifications in the 2019 edition.

    PTAN guide on the qualification of scientific computing tools for first barrier safety demonstrations

    In the wake of ASN Guide 28 on the qualification of scientific computing tools for first barrier safety demonstrations (published on July 25, 2017), AFCEN has responded to calls from EDF, Framatome and CEA by preparing a professional guide (AFCEN Technical Publication) on the same subject matter.

    This PTAN guide aims to help industry meet ASN’s stricter set of requirements by presenting best practices and implementation examples with the focus on achieving qualification.

    A preliminary version of the PTAN was available early 2018 and presented to ASN and IRSN during a meeting on March 12, 2018. Participants confirmed the overall level of consistency between Guide 28 and the PTAN, which is exactly the objective that its authors had been striving to reach in order to simplify work for future users.

    As the meeting was brought to a close, industry professionals announced their intention to improve the PTAN by incorporating the feedback and observations made by ASN and IRSN. Modifications were completed late 2018 and a finalized version was sent to ASN for final comments. This PTAN is due to be published in 2019.



    RCC-F : Design and construction rules for PWR fire protection systems

    Purpose and scope

    The RCC-F code defines the rules for designing, building and installing systems used in a PWR nuclear plant for managing the risk of fire outbreak inside the facility in light of the nuclear hazards involved and thereby control the fundamental nuclear functions. The code also defines the rules for analysing and justifying the means used to create the safety demonstration.

    This code’s target readership is therefore:

    • suppliers of fire protection equipment,
    • engineering firms responsible for designing, building and installing the buildings constituting a PWR,
    • engineering firms responsible for analysing fire hazards and establishing the safety demonstration from a fire hazard perspective,
    • engineering firms responsible for designing the means to prevent and protect against fires and mitigate the effects of a fire outbreak,
    • laboratories carrying out qualification testing of fire protection equipment,
    • Nuclear Safety Authorities responsible for approving the safety demonstration.

    The code defines fire protection systems within a finite scope of service buildings in a light water nuclear power plant.

    Design studies can be used to satisfy the code's requirements.

    The code provides recommendations for guaranteeing that fire hazards are under control from a safety perspective during the design phase, while incorporating aspects relating to:

    • the industrial risk (loss of assets and/or operation),
    • personnel safety,
    • the environment.

    The code is divided into five main sections:

    • generalities,
    • design safety principles,
    • fire protection design bases,
    • construction provisions,
    • rules for installing the fire protection components and equipment.

    The RCC-F code is generally suited to light-water reactors, such as PWRs, as well as EPRs.

    Use and background

    In response to the needs of its Flamanville 3 EPR project in France, EDF published a reference document called ETC-F for the design of fire protection systems.

    The EDF document was not published by AFCEN, but acted as a starting point for a fire protection code that AFCEN produced in 2009 as part of the RCC-F Subcommittee, which led to:

    • Initially, the publication of the 2010 edition of the ETC-F code similar to the EPR projects,
    • Subsequently, the drafting of the 2013 edition, which gave less focus to the specifics of EPR projects but which still addresses the safety principles in alignment with existing EPR projects; UK regulations were incorporated into this version of the code,
    • Finally, the publication of the RCC-F 2017 code, which is generally suited to light-water reactors, such as PWRs.

    Edition available as of early 2019

    The RCC-F 2017 edition is the most recent version

    Amendments have been made based on the ETC-F 2013 edition and concern the following key topics:

    1. 1. Removal of the code's adherence to the safety principles for EPR projects
      Safety principles (aggravating events, fire combined with thermal-hydraulic transients, combined stresses, fire outbreaks following an earthquake, and so on) are generally specified for each project according to the national and international context. In a code that covers fire hazards such as RCC-F, a concerted effort must be made to define an approach for adapting fire protection measures according to these principles. However, even if the principles used for this purpose correspond to updated best practices, they are mentioned for guidance only so their implementation can be adapted to suit other options by a project using the code. The code contains practical principles with this goal in mind.
    2. 2. Improved traceability of requirements
      Various improvements have been made to this subject area to satisfy users' need to easily identify the source of the requirements that led to the rules defined within the code.
    3. 3. Improved identification of the code's scope
      The code's scope is defined in the introductory chapters with a clear distinction between the parts of the installation where the code is fully applicable and the parts where national practices and regulations may take precedence.
    4. 4. Update to the appendix on French regulations
      Appendix A incorporates the specific changes to French and English regulations. The French appendix has undergone a significant review to incorporate the latest major changes (regulation on nuclear facilities and the ASN decision on the applicable rules for nuclear facilities). One of the consequences is that the body of the text in the code now features the new presentation of defence-in-depth vs. fire hazards in accordance with WENRA safety levels.
    Finally, the 2017 edition overhauls the RCC-F code to ensure suitability for a wider range of light-water reactors, such as PWRs, while building on feedback from EPR reactors.

    Content of the 2017 edition of the ETC-F code

    International activities

    The RCC-F Subcommittee held a joint meeting with the CSUG (Chinese Specialized Users Group) in Beijing on September 5, 2018. The Chinese working group comprises 19 permanent members and was created during the first meeting in March 2015. Every year, a meeting is organized in China to improve interaction and help address the interpretation and/or modification requests issued by the CSUG.

    The CSUG was represented during AFCEN Day on June 25, 2018.

    The RCC-F Subcommittee was present at the AFCEN stand during the WNE 2018 exhibition (June 26-28, 2018).

    In addition, RCC-F was represented during the AFCEN/NEA “Codes and Standards” seminar in Beijing on September 6 and 7.

    Two publications on the RCC-F code were released in 2018: one at ICONE 26 (July 2018 in London) and the other at TINCE 2018 (August 2018 in Saclay).

    Outlook and preparation of the RCC-F 2020 edition


    AFCEN is aiming to develop the code in the following directions:

    • integrate state of the art and feedback from projects currently under development or construction,
    • drive the code’s application on a European and international level by including international standards and regulations. According to requirements, this will prompt AFCEN to develop appendices and addenda specifically addressing how the code can be adapted to local regulations (refer to the exercise already carried out for the United Kingdom).

    RCC-F 2020 edition

    The next edition of RCC-F is scheduled for 2020. The general spirit behind these changes is to strengthen the sections that detail the code’s application and provide the most extensive coverage possible, including methods, technical solutions and links with operations.

    In France, further changes may be requested during examination of the RCC-F code as part of the EPR2 project and following China’s activities associated with the AFCEN/NEA memorandum of understanding or the GDA for UK Hualong.

    The first set of priority topics was launched in 2018:

    • methods for analyzing fire risks
    • risks associated with fire protection equipment
    • external fires
    • comparison with international codes (WENRA, IAEA, etc.).


    RCC-MRx: Design and construction rules for mechanical components in high-temperature structures, experimental reactors and fusion reactors

    Purpose and scope

    The RCC-MRx code was developed for sodium-cooled fast reactors (SFR), research reactors (RR) and fusion reactors (FR-ITER).

    It provides the rules for designing and building mechanical components involved in areas subject to significant creep and/or significant irradiation. In particular, it incorporates an extensive range of materials (aluminum and zirconium alloys in response to the need for transparency to neutrons, Eurofer, etc), sizing rules for thin shells and box structures, and new modern welding processes: electron beam, laser beam, diffusion and brazing.

    Background and use

    Since 2009, the RCC-MRx code created by AFCEN’s RCC-MRx Subcommittee has been an inclusion of two documents:

    • The RCC-MR code, drafted by AFCEN’s RCC-MR Subcommittee together with the Tripartite Committee formed on March 16, 1978 by the Commissariat à l’Energie Atomique, Electricité de France and Novatome, to establish the applicable rules for designing components working at high temperatures. AFCEN published four editions of RCC-MR in 1985, 1993, 2002 and 2007.
    • The RCC-MX code, drafted by the RCC-MX Approval Committee formed on March 31, 1998 by the Commissariat à l’Energie Atomique, AREVA-TA and AREVA-NP for the specific needs of the RJH project (Jules Horowitz reactor). This code applies to the design and construction of experimental reactors, auxiliary systems and associated experimental devices. It can also be used for the design and construction of components and systems for existing facilities. CEA published two editions of RCC-MX in 2005 and 2008.

    An unpublished preliminary version of RCC-MRx created in 2010 by AFCEN was chosen as the baseline for the CEN CWA European Workshop (entitled “CEN-WS-MRx, Design and Construction Code for mechanical equipment of innovative nuclear installations”), which was intended to familiarize European partners with the RCC-MRx 2010 code and propose modifications to satisfy the needs of their projects. The results of the workshop were incorporated into the 2012 edition of RCC-MRx published by AFCEN.

    The RCC-MRx code is serving as a reference for the design of the ASTRID project (Advanced Sodium Technological Reactor for Industrial Demonstration), for the design of the primary circuit in MYRRHA (Multi-purpose hYbrid Research Reactor for High-tech Applications) and the design of the target station of the ESS project (European Spallation Source).

    edition available as of early 2019

    Content of the 2018 edition of the RCC-MRx code

    The 2018 edition is the most recent version.

    This edition reflects feedback on the use of the previous editions of the code, especially in current projects and mainly the Jules Horowitz reactor and the ASTRID project. Examples include the inspection and welding procedures for aluminum, as well as the code’s improvements and new structure relating to components used at high temperatures (design rules, welded assemblies and material properties), with special focus on the rules for preventing progressive deformation. The 2018 edition also proved to be the ideal opportunity to clarify how to use the code, which involved modifying the code’s structure and incorporating flowcharts to explain how the rules are organized. This initiative was implemented for the design process, the rules for analyzing fast fracture resistance, and the rules for designing bolted assemblies.

    Integration of the Eurofer material used by the fusion community was finalized in the 2018 edition.

    Furthermore, this edition pays special attention to ensuring consistency between RCC-MRx and the other reference documents that interact with the code, including RCC-M, European and international standards (such as incorporation of ISO 3834) and regulations (e.g. updated versions of France’s nuclear regulations). Lastly, the 2018 edition began factoring in feedback from CEN/WS 64 by integrating the workshop’s initial modification that identifies the applicable procedure for using the code in case of an innovative coolant.


    Between 2019 and 2021, efforts will be dedicated at preparing the next edition of the code, which is due to be published in 2021. The aims for the new edition of RCC-MRx are to improve the code’s modularity and clarity, so that it can be adapted to the many projects that are likely to use it as a reference. Specific volumes, such as Volume K (examination, handling or drive mechanisms) and Volume L (irradiation devices) will be updated, while a general discussion will be launched on the topic of small components.

    Another key objective is pursuing and contributing to the success of Phase 3 of CEN/WS 64.

    In 2017, efforts focused centered on preparing the new edition of RCC-MRx, which is scheduled for publication in 2018. This edition will include:

    • the findings of Workshop 64 (CWA),
    • the results of the commissioned study aimed at improving the rules to take account of irradiation: the study led to two modifications relating to an adjustment of the toughness values for 316L(N) and the fields to which the code applies in respect of irradiation,
    • a new organization for the chapters addressing fast fracture,
    • a new organization for the chapters addressing progressive deformation.
    • feedback from the RJH project,

    Technological commissioned studies

    In 2016, work was finalized on the commissioned study entitled "Terms for introducing a new material into RCC-MRx". This study led to the publication of a methodological guide (AFCEN/RX.17.004 "Guide for introducing a new material in RCC-MRx"), which explains, when introducing a non-coded material into RCC-MRx, the definition of the methods for obtaining the characteristics in Appendix A3 (expected / possible tests, meaning of the data).

    The RCC-MRx Subcommittee launched three commissioned studies in 2017:

    • Fast fracture analysis: this commissioned study also involves the RCC-M code. The aim is to standardize practices between the RCC-M and RCC-MRx codes and clarify the approach for identifying areas where fast fracture analyses must be performed. This commissioned study will continue in 2019.
    • Preparation of a document describing the sources and key reasons underlying Appendix A1 (guide for the seismic analysis of equipment): the aim of this commissioned study is to publish the criteria for Appendix A1 in a PTAN. This commissioned study was finalized in 2018, following which these criteria were published.
    • Update of RCC-MRx – Section II – Part REC 3000 (Special instructions for equipment subject to regulations): the purpose of this commissioned study is to update the sections on French regulations in line with the work carried out for RCC-M. This commissioned study will be continued in 2019.

    Use of the RCC-MRx code in high-temperature and fusion reactors