MULTINATIONAL DESIGNEVALUATION PROGRAMME
Phase 1 Summary Report
2006-2021

Multinational Design Evaluation Programme
Phase 1 Summary Report
2006-2021

MULTINATIONAL DESIGN EVALUATION PROGRAMMEThe Multinational Design Evaluation Programme (MDEP) was established in 2006 as amultinational initiative to develop innovative approaches to leverage the resources andknowledge of the national regulatory authorities that are currently or will be tasked with thereview of new nuclear power reactor designs. MDEP members are the regulatory authorities ofArgentina, Canada, China, Finland, France, Hungary, India, Japan, Korea, Russia, South Africa,
Sweden (up to 2019), Türkiye, the United Arab Emirates, the United Kingdom and the UnitedStates. The Nuclear Energy Agency serves as technical secretariat for MDEP. The International
Atomic Energy Agency also takes part in the work of MDEP.

NUCLEAR ENERGY AGENCYThe OECD Nuclear Energy Agency (NEA) was established on 1 February 1958. Current NEA
membership consists of 34 countries: Argentina, Australia, Austria, Belgium, Bulgaria, Canada,
the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland,
Italy, Japan, Luxembourg, Mexico, the Netherlands, Norway, Poland, Portugal, Korea, Romania,
Russia (suspended), the Slovak Republic, Slovenia, Spain, Sweden, Switzerland, Türkiye, theUnited Kingdom and the United States. The European Commission and the International Atomic
Energy Agency also take part in the work of the Agency.
The mission of the NEA is:•

to assist its member countries in maintaining and further developing, throughinternational co-operation, the scientific, technological and legal bases required for a safe,
environmentally sound and economical use of nuclear energy for peaceful purposes;•

to provide authoritative assessments and to forge common understandings on key
issues as input to government decisions on nuclear energy policy and to broader OECD
analyses in areas such as energy and the sustainable development of low-carbon
economies.

Specific areas of competence of the NEA include the safety and regulation of nuclear activities,
radioactive waste management and decommissioning, radiological protection, nuclear science,
economic and technical analyses of the nuclear fuel cycle, nuclear law and liability, and public
information. The NEA Data Bank provides nuclear data and computer program services forparticipating countries.

Cover page photo credits: ShutterStock, vs148.

MDEP PHASE 1 SUMMARY REPORT 2006-2021

Table of contents

List of abbreviations and acronyms .................................................................................................... 5
1. Purpose ................................................................................................................................................. 7
2. MDEP milestones and evolution ...................................................................................................... 7
Creation ................................................................................................................................................ 7
Objectives ............................................................................................................................................. 7
Scope ..................................................................................................................................................... 7
Membership ......................................................................................................................................... 7
Organisational structure .................................................................................................................... 8
Key decisions leading to close-out of the framework in 2021 ....................................................... 8
3. Successes of MDEP ............................................................................................................................. 9
MDEP products ..................................................................................................................................... 9
Increased co-operation in design evaluations............................................................................... 10
Increased communications.............................................................................................................. 10
Greater quality of national safety assessments ............................................................................ 10
Greater harmonisation of regulatory reviews ............................................................................... 10
Effective engagement with stakeholders ....................................................................................... 11
4. Working group summaries ............................................................................................................. 11
EPRWG ................................................................................................................................................ 11
AP1000WG .......................................................................................................................................... 12
APR1400WG ........................................................................................................................................ 12
ABWRWG ............................................................................................................................................ 12
VVERWG ............................................................................................................................................. 13
HPR1000WG ........................................................................................................................................ 13
CSWG .................................................................................................................................................. 13
DICWG ................................................................................................................................................ 13
VICWG................................................................................................................................................. 14
5. Lessons learnt ................................................................................................................................... 14
Maintaining active involvement of members and participants.................................................. 14
Information sharing .......................................................................................................................... 14
Communication ................................................................................................................................. 15
Realisation of benefits ...................................................................................................................... 15
6. MDEP Library ..................................................................................................................................... 15
7. Conclusion ......................................................................................................................................... 16
8. MDEP future framework .................................................................................................................. 16
Appendix A: MDEP common positions (2006-2021) ....................................................................... 17
Appendix B: MDEP technical reports (2006-2021) ........................................................................... 233

MDEP PHASE 1 SUMMARY REPORT 2006-2021

List of abbreviations and acronyms

ABWR

Advanced boiling water reactor

ABWRWG

Advanced Boiling Water Reactor Working Group

CNRA

Committee on Nuclear Regulatory Activities (NEA)

CSWG

Codes and Standards Working Group

DI&C

Digital instrumentation and controls

DICWG

Digital Instrumentation and Controls Working Group

FANR

Federal Authority for Nuclear Regulation (United Arab Emirates)

FPOT

First-Plant-Only-Tests

I&C

Instrumentation and controls

IAEA

International Atomic Energy Agency

IRWSTIn-containment refuelling water storage tank

KINS

Korea Institute of Nuclear Safety

LOCA

Loss of coolant accident

MBManagement Board

MCCI

Molten Core Concrete Interaction

MDEP

Multinational Design Evaluation Programme

NEA

Nuclear Energy Agency

NNSA

National Nuclear Safety Administration (China)

NRC

Nuclear Regulatory Commission (United States)

ONR

Office for Nuclear Regulation (United Kingdom)PAR

Passive autocatalytic recombiners

PG

Policy Group

PSA

Probabilistic safety assessment

QA/QM

Quality assurance and quality management

SDO

Standards development organisations

STC

Steering Technical Committee

TESG

Technical expert subgroups

ToR

Terms of reference

UAE

United Arab Emirates

VICWG

Vendor Inspection Co-operation Working GroupVVER

Water-water energetic reactor

WG

Working group5

MDEP PHASE 1 SUMMARY REPORT 2006-2021

Multinational Design Evaluation Programme
MDEP Phase 1 summary report for the period 2006-2021

1. Purpose
This report presents a summary of the Multinational Design Evaluation Programme (MDEP),
undertaken between 2006 and 2021, with the intent to ensure an appropriate transition to a new
MDEP framework beyond 2021. This report highlights the key milestones, successes and lessons
learnt from the first 15-year period of MDEP, explains the documentation produced during thisperiod and its future storage, and introduces the new MDEP framework from 2022 onwards.

2. MDEP milestones and evolution
Creation
The idea for the programme originated in 2005 when the United States Nuclear Regulatory
Commission (NRC), the French Nuclear Safety Authority (ASN) and the Finnish Radiation and
Nuclear Safety Authority (STUK) were co-operating on the licensing of the EPR design. In 2006,
the initiative was designated as MDEP, a multinational effort to develop innovative approaches
to leverage the resources and knowledge of the national regulatory authorities involved in thereview of new reactor designs.

Objectives
The main objectives of MDEP have been to enable increased co-operation within existing
regulatory frameworks and establish mutually agreed positions, enhancing the safety of newreactor designs. This strengthened co-operation among regulators focused on improving theeffectiveness and efficiency of the regulatory design reviews, which are part of each country’s
licensing process. The programme focused on co-operation on regulatory practices that aim at
harmonising regulatory requirements. The International Atomic Energy Agency (IAEA) Safety
Standards, which provide a general level of harmonisation, provide input to the work and havebeen able to benefit from the results.

Scope
MDEP is primarily focused on design evaluation but also includes inspection activities and genericissues. As the designs moved into the construction, commissioning and eventually the operational
phases, the scope was expanded to continue co-operation on oversight of construction andcommissioning, and to incorporate feedback from operating experience during the initial twoyear period of operations. A key concept throughout the programme is that MDEP will better
inform the decisions of regulatory authorities through multinational co-operation, while eachregulator retains sovereign authority to make licensing and regulatory decisions.

Membership
Since MDEP’s inception in 2006, regulators from Canada, the People’s Republic of China(hereinafter referred to as China), Finland, France, Japan, Korea, Russia, South Africa, the United
Kingdom, and the United States are involved in MDEP activities as members. The membershiphad grown to 16 national regulators by 2017, with India and the United Arab Emirates joining in

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2012, Sweden and Türkiye joining in 2013 (Sweden withdrew in 2019), Hungary joining in 2015,
and Argentina joining in 2017. The IAEA also takes part in the work of MDEP, to maximise thebenefit of the harmonisation work carried out.

Organisational structure
The programme is governed by a Policy Group (PG), which provides guidance to the Steering
Technical Committee (STC) on the overall focus of MDEP, monitors the progress of the programme,
and determines participation in the programme. The STC provides oversight of working group
activities to ensure consistency in MDEP work and products and to co-ordinate, based on guidancefrom the PG, communications with external stakeholders. The OECD Nuclear Energy Agency (NEA)
performs the technical secretariat function in support of MDEP.
Two streams of activity were established to carry out work under MDEP, covering design-specificactivities and issue-specific activities.
The design-specific activities went from strength to strength under the PG and STC guidance,with the portfolio of reactor designs under evaluation reaching six by 2018:•

EPR Working Group (EPRWG) – operating since MDEP’s creation in 2006;•

AP1000 Working Group (AP1000WG) – established in 2008;•

APR1400 Working Group (APR1400WG) – established in 2012;•

VVER Working Group (VVERWG) – established in 2013;•

Advanced Boiling Water Reactor Working Group (ABWRWG) – established in 2013;•

HPR1000 Working Group (HPR1000WG) – established in 2017.

Under each of the design-specific working groups, technical expert subgroups (TESG) were formed
to address specific technical issues.
For issue-specific activities, three working groups, namely the Codes and Standards Working
Group (CSWG), Digital Instrumentation and Controls Working Group (DICWG) and Vendor
Inspection Co-operation Working Group (VICWG), were created in 2008. In 2015, the PG
determined that MDEP should focus on design-specific activities going forward and the issuespecific working groups should be closed or transferred to another organisation over the next
few years.
Between 2017 and 2018, the PG implemented the transfer of two of the issue-specific working
groups (CSWG and DICWG) and one design-specific working group (ABWRWG) to the NEA
Committee on Nuclear Regulatory Activities (CNRA).

Key decisions leading to close-out of the framework in 2021
MDEP was established as a multinational initiative for a five-year period. It was extended foranother five-year period in 2012 by the PG based on the value gained by the members. In 2015,
the PG determined that MDEP should continue in its current form for at least five more years
beyond 2017.
In 2019, the PG decided to sunset MDEP in its current form by 2022 – the end of the existing termsof reference of MDEP. The decision was taken as the EPRWG, AP1000WG, and APR1400WG were
expected to complete all planned activities specified in the programme plan by 2022. However,the PG affirmed that for the MDEP designs that will continue to be active after 2022 (VVER andHPR1000), the work should continue to enable these technologies to gain the full benefit of the
MDEP approach. In 2020, the PG formally approved implementing plans for closure of the EPRWG,
AP1000WG, and APR1400WG by the end of 2021, as well as agreeing that a new MDEP governancestructure should be implemented in 2022 for the two remaining reactor technologies.

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MDEP PHASE 1 SUMMARY REPORT 2006-2021

The PG also decided to propose transferring the VICWG to the CNRA. VICWG activities will close
under the MDEP framework at the end of 2021. During 2022, the VICWG will be working with the
CNRA, under the auspices of the NEA, on the process of transition. The official transition is
expected in 2023 when CNRA implements a new working group structure.
It has also been confirmed that the EPRWG activities will transfer into the CNRA for 2022, as the
EPRWG members have identified additional work related to operating reactors that is beyond
the MDEP framework. The status of the outstanding activities will be discussed during thecurrent process of CNRA review.

3. Successes of MDEPMDEP products
One of the aims of MDEP is to work towards greater harmonisation of regulatory requirements. To
achieve this aim, it was necessary to establish a degree of convergence on the safety goals thatare required to be met by designers and operators. Consequently, the MDEP STC set up a subcommittee on safety goals to address this and subsequently issued the MDEP Steering TechnicalCommittee Position Paper on Safety Goals. This position paper proposed a hierarchical structure
for developing safety goals and targets, that can be applied to different technologies in a consistentand coherent manner. The hierarchical structure for safety goals encompasses the basic defencein-depth approach, with a top-level safety goal and a set of high-level safety goals, that can beused to integrate the elements of safety desired to protect health and safety during normal
operation and accident conditions for the whole plant lifecycle.
Co-operation among national regulators under MDEP has led to harmonisation of regulatory
positions and practices through the establishment of common positions, achieved through theactivities of different design and issue-specific working groups as well as the STC.
Design-specific common positions document common conclusions that the working groupmembers reached during the design review. Discussions among the members and the sharing
of information in these areas helped to strengthen the individual conclusions reached.
Between 2006 and 2021, MDEP published 39 common positions (see Appendix A). The areas
addressed in common positions reflect a variety of technical topics that were identified during
the design reviews and often required a considered approach to resolution.
Generic common positions apply generically rather than to one specific design. They are intended
to provide guidance to the regulators in reviewing new or unique areas, and have been sharedwith the IAEA and other standards organisations for consideration in standards development
programmes.
Issues related to the Fukushima Daiichi Nuclear Power Plant accident and the impact of
emerging learning on new reactors, such as hydrogen management systems and the Vienna
Declaration on Nuclear Safety, were thoroughly discussed. As a result, a generic Common
Position on Fukushima Daiichi Nuclear Power Plant accident lessons learnt was developed, as
well as six design-specific working group common positions.
MDEP produced 43 technical reports (see Appendix B) that enable member countries to better
appreciate similarities and understand the differences in national requirements and practices.
The topics for technical reports were selected based on the issues arising from regulatory activities
in member countries, safety implications, or the general need to have a better understanding of
the topic. This facilitated sharing experiences and is considered to be the basis of work on
harmonisation.

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Increased co-operation in design evaluations
The most effective aspect of MDEP is the co-operation and exchange of information it facilitatedduring design reviews. While the IAEA provides high-level guidance, MDEP addressed more
specific issues for new reactors for practical use in licensing considerations and provided
opportunities for early dialogue with the industry.
The working groups highlighted areas of difficulty and challenges and allowed participants to
explore these in a co-operative and neutral environment, offering insight into how others had
worked to resolve specific issues. This was facilitated by sharing advanced copies of review
findings, responding to requests for additional information and monitoring the progress of thedesign reviews within member countries.

Increased communications
National regulatory bodies worked closely together through MDEP. Effective communication paths
were established as a result of MDEP activities and it became quick and easy to communicate withcolleagues from other countries when issues arose. In addition to organising working groups,
MDEP provided the regulators with peer contacts to allow them to share information, discuss
issues informally, and disseminate information rapidly. For example, the design-specific working
group members have benefitted significantly from the sharing of questions among the regulators,
resulting in more informed and harmonised regulatory decisions.
When a regulator hosted a working group meeting in a country where a plant was underconstruction, a tour was arranged of the site and a meeting held with the licensee. This allowed
the working group members to see the status of construction first-hand and discuss issues withthe licensees. Working group members were able to see the parts of the plants where issues had
been raised that had been discussed during meetings, helping all to better visualise andunderstand the issues.

Greater quality of national safety assessments
MDEP interactions were useful in aligning views across national regulators on the significanceof specific issues. This improved the focus of the design reviews and also helped discover safetyissues or expand the scope of a review.
Common position papers have meant that additional assessment work can be avoided andprovide additional leverage for safety improvements. Having a harmonised position significantly
improves the credibility of national regulatory positions. Moreover, regulatory bodies havecontributed to and benefitted enormously from interactions with each other in terms ofunderstanding different approaches and different regulatory systems, and this has helped eachregulator look at its approach critically. Some countries considered the interest of updating theirown regulation implicitly taking into account the lessons learnt from the design evaluation.

Greater harmonisation of regulatory reviews
MDEP recognised that achieving harmonisation in specific areas was a valuable but challenging
long-term activity. It found that to make progress, the goal should not be to make all
requirements and practices identical or to produce a single code or standard that would be usedby all countries, but increasing harmonisation incrementally in specific areas would be
beneficial and achievable.
Consequently, MDEP has facilitated the comparison of regulatory requirements and practices,helped regulators understand the differences, and provided an opportunity to understand theirbasis and application, as well as reducing the differences in technical requirements, so far as isreasonably practicable.

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Effective engagement with stakeholders
Successful interactions with stakeholders via MDEP have built links with regulators, industry,
standards development organisations (SDOs) and other international organisations, and havebeen beneficial in aiding the review of different reactor designs. For example, MDEP has brought
together regulators, SDOs and industry, through the World Nuclear Association Co-operation in
Reactor Design Evaluation and Licensing (WNA CORDEL) Working Group, to discuss issues andclarify regulatory positions that have significant impacts.
MDEP is recognised as a unique multinational framework where new reactor vendors canparticipate on a regular basis. Furthermore, MDEP used the opportunities provided by workshops
and conferences. Four MDEP conferences were held under the leadership of the STC, with a totalof about 600 participants. The topics addressed in the conferences included important common
issues at the time, such as new reactor activities related to the Fukushima Daiichi Nuclear Power
Plant accident, with more specific technical discussions around:•common cause failures reassessment;•

multiple units on the same site;•

technical challenges in DI&C;•

commercial off the shelf software;•

nuclear safety culture in the supply chain;•commissioning activities (first-plant-only-test and construction inspection test plan).

Those activities provided a forum for MDEP stakeholders to share the results of their engagementwith the programme, deliver presentations on going activities related to new reactor licensing,and explore options to resolve common issues.

4. Working group summaries
EPRWG
From 2008 to 2021, the EPRWG was a forum of discussion focused on EPR reactor design safetyissues between the nuclear safety authorities of Canada (Canadian Nuclear Safety Commission,
CNSC), China (National Nuclear Safety Administration, NNSA), Finland (STUK), France (Nuclear
Safety Authority, ASN), India (Atomic Energy Regulatory Board, AERB) (from 2012), Sweden(Swedish Radiation Safety Authority, SSM) (from 2013 to 2019), the United Kingdom (Office for
Nuclear Regulation, ONR) and the United States (NRC).
The first long-term objective of the EPRWG was to leverage national regulatory resources by
sharing information and experience on the regulatory safety design reviews and commissioningof the EPR with the purpose of enhancing the safety of the design and enabling regulators tomake timely licensing decisions to ensure safe designs. The second main objective was topromote safety and standardisation of designs through MDEP co-operation (consideration wasgiven to promoting harmonisation of regulatory practices where there may be a safety benefit).
The EPRWG and its TESGs issued many written outcomes, including eight common positions
and seven technical reports. In addition to providing a structured information sharing platform,
the EPRWG also succeeded in engaging valuable technical exchanges with the licensees andvendors in different countries. The working group provided a means for the regulators toleverage resources and to focus design reviews on safety issues in areas that were critical tomaking licensing decisions in member countries.

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AP1000WG
The AP1000WG includes the regulatory authorities of Canada (CNSC), China (NNSA), India(AERB), the United Kingdom (ONR) and the United States (NRC). The working group developed
three common positions and six technical reports addressing some of the more important
discussion topics from the AP1000WG meetings. Further, the working group identified a numberof recommendations and inputs to other issue-specific working groups and MDEP DSWGs
regarding potential generic issues and harmonisation opportunities (including the “Technical
Report on Lessons Learnt from Implementation of the Common Position on First-Plant-OnlyTests (FPOT) for AP1000”).
Between 2009 and 2021, the NRC, ONR, and NNSA finished their safety assessments for the
AP1000 design and drew the conclusion that the AP1000 design was acceptable according to theregulations of the United States, the United Kingdom and China. Sharing the assessments andtheir outcomes improved understanding between the member regulators and provided
significant grounding for AP1000WG discussion and co-operation.

APR1400WG
The APR1400WG was established in August 2012 with four countries, although Finland later
opted to leave following the cancellation of the Olkiluoto 4 project in 2015. In 2021, the final
participants were the regulatory authorities of Korea, the United Arab Emirates (UAE), and theUnited States. The UAE was leading the working group.
From 2012 to 2021, the APR1400WG and its TESGs issued many written outcomes, including fourcommon positions and eight technical reports.
The nuclear safety authorities of Korea (Korea Institute of Nuclear Safety, KINS), United ArabEmirates (Federal Authority for Nuclear Regulation, FANR), and the United States (NRC) publishedtheir APR1400 safety evaluation reports. They granted construction and operating licences for
Shin-Kori Units 3 and 4 and Shin-Hanul Unit 1 in Korea and Barakah Units 1 and 2 in the UAE, as
well as the Design Certification Rule for the APR1400 Design (10CFR52 Appendix F) in the UnitedStates.
The APR1400WG successfully achieved its main goal of developing co-operation between
member regulators on topics of interest and value within the scope of MDEP.

ABWRWGThe ABWRWG was established in January 2014 and included the regulatory authorities ofFinland, Japan, Sweden, the United Kingdom and the United States, although Finland later opted
to leave following the cancellation of the Olkiluoto 4 project in 2015. The ABWRWG achieved
the task of compiling a vendor-informed comparison table of design features between the eight
existing and proposed designs for an advanced boiling water reactor (ABWR).
The ABWRWG and its TESGs issued many written outcomes, including one common position
and three technical reports.
Seven noteworthy differences were highlighted as relating to the severe accident design features
and, as a consequence, the ABWRWG recognised that it is important to document the regulatory
basis for severe accident design differences. The basis was developed by the Severe Accident
Technical Sub-group and was collated in a technical report. Other achievements include thesharing of the United Kingdom’s analysis of the outcomes from the ABWR Generic Design
Assessment (GDA), which resulted in the award of a Design Acceptance Certificate for that design,and the outcomes of the Japanese regulator’s review of the KK6/KK7 reactor site.
The ABWRWG closed its activities under MDEP in May 2018 and is now operating under the
CNRA.

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VVERWGThe VVERWG includes the regulatory authorities of China, Finland, Hungary, India, Russia andTürkiye. The working group members are reviewing plants at various stages of design andconstruction. The VVERWG currently includes four technical expert subgroups that are addressing
specific technical issues: Severe Accidents (SA TESG), Fukushima Accident Lessons Learnt (FUKU
TESG), Reactor Pressure Vessel and Primary Circuit Components (RPV&PC TESG) and Accidents
and Transients (T&A TESG). The members meet regularly to exchange information and experiencein their countries’ regulatory activities, approaches and legal framework related to new designs.
The VVERWG provided many common positions and technical reports and will continue todocument lessons learnt from design reviews and design issues faced during construction andcommissioning and the early phases of operation.

HPR1000WG
The HPR1000WG includes the regulatory authorities of Argentina (ARN), China (NNSA), South
Africa (National Nuclear Regulator, NNR), and the United Kingdom (ONR). The HPR1000WG
completed a common position on Fukushima Daiichi lessons learnt as well as two technicalreports on hydrogen control during severe accidents and regulatory requirements and practices
for severe accidents.
In light of its discussions on Fukushima Daiichi and severe accidents, FPOTs, unique design
features affecting safety, and the treatment of external and internal events, the HPR1000WG
has opted to establish two TESGs to further scrutinise the issues: the Severe Accidents (SA) TESG
and the Internal and External Hazards TESG. The WG together with TESGs has established anumber of objectives to be completed and will continue its efforts on developing common
positions on sump strainer performance, the Vienna Declaration on Nuclear Safety, in-vessel
retention strategy, etc.

CSWG
The primary goal of the CSWG has been to promote international harmonisation of codes andstandards, with an initial focus on pressure boundary components in nuclear power plants thatare important to safety. In working towards this goal, the CSWG collaborated with SDOs fromvarious countries to perform comparisons of several pressure boundary codes and standards
and collaborated with the WNA CORDEL group to converge selected code requirements. These
activities helped some countries consider the interest of updating their own regulation andcontributed to the convergence of regulatory requirements. In addition, the CSWG publishedseveral documents reporting the results of their efforts. These products and the continuing
collaboration with industry organisations span a wide variety of technical topics withapplications for both operating and new reactors.
The CSWG fulfilled its original goals and has been transferred to the CNRA.

DICWG
The DICWG worked under MDEP from 2008 to 2018 to facilitate timely and efficient mechanisms
for sharing of knowledge and experience among members, thus allowing more effective safety
reviews. The second main objective of the DICWG was to work jointly to develop common
positions among members on issues of significance, which may be based on a review of theexisting standards, national regulatory guidance, best practices and group inputs.
As a key accomplishment, the DICWG identified topics for generic common positions, selectedon the basis of their safety implications, and the need to develop a common understanding fromthe perspectives of regulatory authorities. The DICWG generic common positions are notintended to cover all issues associated with the digital instrumentation and controls (I&C)
technical disciplines, but only those of most value to the members.

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Under MDEP, the DICWG published 13 common positions that describe the methods and evidence
that the DICWG member states find acceptable to support safety justification for digital I&C
systems.
The DICWG shared information with key stakeholders such as IAEA, the Institute of Electricaland Electronics Engineers (IEEE) and the International Electrotechnical Commission (IEC). In
2018, the activities led by the DICWG under MDEP were transferred to the CNRA in the Working
Group on Digital Instrumentation and Control (WGDIC).

VICWG
The main goals of the VICWG were to maximise use of the results obtained from regulators’
work in inspecting vendors and understand the similarities and differences between national
regulatory bodies’ quality assurance and quality management (QA/QM) requirements within
MDEP. The information was then used to improve the regulators’ own requirements andapproaches.
The VICWG enhanced the understanding of regulatory inspection procedures and practices byco­ordinating witnessed and multinational inspections of QA arrangements of safety related
components. Multinational inspections consisted of one regulator conducting an inspection
according to its own regulatory framework with the active participation of one or more othernational regulators. This allowed the participating members to use the results of the inspectionthat were applicable to their regulations. Multinational inspections are a tool to gain vendor
performance insight with minimal inspection resources from the participating regulators.
As the VICWG matured, the opportunities it provided expanded from co-operation on vendor
inspection activities to sharing the outcomes of national vendor inspection programmes. The
VICWG programme plan was extended to integrate supply chain nuclear safety culture, enhanced
stakeholder engagement and commercial grade dedication & equipment qualification. In 2020,
the MDEP PG decided to propose transferring the VICWG to the CNRA and the VICWG activities
closed under the MDEP current framework at the end of 2021.

5. Lessons learnt
Maintaining active involvement of members and participants
Good preparation was essential to ensure effective engagement; it was important for participants
to take time to understand the aims and objectives of the working groups to maximise theireffectiveness in realising benefits. This was done in the first instance by reviewing previous
minutes and documents for discussion at forthcoming meetings. In addition, preparation
included consideration of the agenda and discussion of the relevant items internally prior toattendance. It has been suggested that in future, new members may benefit from an inductionnote communicating the scope and aims of each of the working groups and TESGs.
It was observed that the majority of national regulators are content to engage with otherparticipants and provide access to their independent confirmatory analysis, and are willing toshare their assessment in a transparent manner. Active participation has been excellent inbuilding relationships between regulators, bringing greater benefits both within and potentiallyoutside of MDEP activities.
By far the biggest impediment to participation in MDEP meetings and to MDEP-related functions
has been “other regulatory work of higher priority”. This was heightened during the COVID-19
pandemic.

Information sharing
MDEP has made improvements in communicating information regarding member regulatory
practices. The development of an MDEP Library has been a major step forward, serving as acentral repository for all documents associated with the programme. This library is essential to14

MDEP PHASE 1 SUMMARY REPORT 2006-2021

the sharing of research and confirmatory analysis. It has facilitated access to information andthe development of credible common positions.
It was recognised that information sharing may give rise to concern from licensees and vendorsof reactor technologies, as the library can be accessed by many members. Access has been
restricted to only MDEP participating regulatory bodies and it is important that this beunderstood by all members and their associated vendors, plant designers, requesting parties
and licensees. This should avoid situations in which regulators and owners and operator groupmembers are reluctant to provide sensitive documents.
In addition, it has been observed that the terms and conditions of information sharing are notstandard across member countries, and that export licences and commercial issues need to begiven due consideration when sharing information with other members.

Communication
It is clear that the various regulatory regimes do not operate in the same environments or withthe same legal and regulatory frameworks. It has therefore been important to understand thecontext within which regulatory regimes operate. This can only be done through honest andtransparent communication. Experience has shown that the MDEP working groups provided asafe, secure, and neutral environment for participating members to develop ideas and challenge
assumptions in an open, honest and respectful manner.
The adoption of English at the MDEP meetings allowed members and stakeholders tocommunicate, but did understandably create a limitation for some. When members
experienced communication challenges, this resulted in detailed conversations to allow all tounderstand the issues of concern, making sure all in the group had an opportunity to ask
questions and understand.

Realisation of benefits
Effective engagement depended on the level to which the individual member countries
contributed. Participation via timely and relevant input to working group planning activities
enabled members to realise the greatest benefit from the interactions.
The chair of each working group has a key role in ensuring the effectiveness of co-operation.
The chair needs to have knowledge of the reactor technology, the technical issues and theircomplexities/subtleties. The experience and effectiveness of working group chairs has been
variable; in the next phase of MDEP it may be useful to provide guidance for the participants
who take on this role.
Careful consideration needs to be given to how industry representatives become involved inworking group discussions, as their presence changes the dynamic and environment in which thetechnical issues are explored and has the potential to stifle discussion between regulators,
becoming counter-productive. But involving industry representatives is crucial for the working
group to address specific issues and their contribution should be seen as important and beneficial.

6. MDEP Library
MDEP WGs have documented their work and results, including with individual close-out reports
for the design-specific working groups that are now closed. All these materials are archived in
the MDEP Library for future use. This electronic library is password protected and is restricted
to the national regulatory agencies of the member countries that have been or currently areparticipating in MDEP.
The library is managed by the NEA Secretariat. According to the MDEP Terms of Reference,
permission to access the information should be sought through the NEA Secretariat, whichhandles requests according to an agreed protocol.

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MDEP PHASE 1 SUMMARY REPORT 2006-2021

In its final meeting, on 14 December 2021, the MDEP PG agreed that the NEA will manage accessto the MDEP Library by non-MDEP countries. For requests for access to non-proprietary
information held in the library, it was agreed that the NEA Secretariat can use its discretion. For
requests for access to proprietary information received from non-MDEP countries, the NEA
Secretariat must either request permission from the originating country to allow access or direct
the requestor to the originating country. In all instances, the NEA Secretariat will advise the
CNRA of requests from non-MDEP members for access to the library and the subsequent
provision of information. This will ensure that the benefits of MDEP can be realised by a muchwider group of national regulators.
The MDEP Library will continue to be a central repository for MDEP.

7. Conclusion
The MDEP has been and will continue to be a unique multinational initiative leveraging theresources and knowledge of national regulators to review new reactor designs. The programme
has successfully operated for 15 years and is recognised as an effective framework for regulatory
co-operation and harmonisation.
By November 2021, the EPRWG, AP1000WG, APR1400WG, as well as the STC closed their activities
under the current MDEP framework. All relevant documentation – minutes of meetings, common
positions, technical reports, etc., have been archived in the MDEP Library, administered by the
NEA Secretariat, and are available for future reference. For this reason, the MDEP Policy Group
concludes that the MDEP framework 2006-2021 can be closed.

8. MDEP future framework
The regulatory authorities that are members of the VVER and HPR1000 design-specific working
groups, as existing MDEP members, have stated their shared desire to continue the successful
and mutually beneficial collaboration under a new streamlined MDEP framework.
A special session of the MDEP Policy Group involving members of the future framework, namely
Argentina, China, Finland, Hungary, Russia, South Africa, Türkiye, and the United Kingdom, washeld in March 2021. The general consensus from the special session is that:•

The programme of MDEP work will be governed and implemented by a new MDEPManagement Board (MB), with the NEA serving as the technical secretariat.

•

The first priority is to deliver a successful transition to the new MDEP framework.

•

Harmonising regulatory practices should be a greater focus of working groups in the future.

•

Work on cross-cutting issues could still be part of MDEP but awareness of co-operation inexisting NEA working groups on generic topics is necessary.

•

The organisation of events and conversations with a broader group of regulators is still ofgreat interest for the members of the new MDEP framework.

Following the successful transition to the revised framework, the MDEP MB will consider options
for wider international co-operation as national regulators consider new reactor technologies
for assessment.
A transition team that consists of the member countries of the future framework was
established to consider the roles and responsibilities of the PG and the STC and to define theroles and responsibilities of the new Management Board of the future framework. The transitionteam re-structured the MDEP terms of reference (ToR) for the new framework, with the aim ofpresenting the final proposal during the first meeting of the MB.
The transition team also revised the Design-Specific Working Group’s ToR and Issue-SpecificGroups ToR, discussed the transition process, and made preparations for the first MB meeting
following the last PG meeting.

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MDEP PHASE 1 SUMMARY REPORT 2006-2021

Appendix A: MDEP common positions (2006-2021)•

CP-STC-01, “Common Position Addressing FPOT”, provides high-level guidance forapplicants/licensees wishing to take credit for a test performed during the commissioningof the first unit of a similar type, www.oecd-nea.org/mdep/documents/CP-STC-01-FPOTrev1_April_2018.pdf.

•

CP-STC-02, “Common Position Addressing Fukushima Daiichi Nuclear Power Accident”,
identifies approaches to address potential safety improvements for several designs as
related to lesson learnt from the Fukushima Daiichi nuclear accident or related issues,
to ensure adequate safety of new reactor design activities being undertaken pursuant to
the MDEP programme of work. This Common Position also includes a statement
regarding the Vienna Declaration on Nuclear Safety, www.oecd-nea.org/mdep/commonpositions/cp-stc-02-common_position_addressing_fukushima.pdf.

•

CP-EPRWG-01, “Common Positions on the EPR Instrumentation and Controls Design”,
identifies the areas of common agreement between regulatory bodies regarding the EPR
I&C design that were identified during digital instrumentation and controls (DI&C) TESG
interactions, www.oecd-nea.org/mdep/documents/CPEPRWG01_I&C_2020.pdf.

•

CP-EPRWG-02, “Common Position Addressing Fukushima Daiichi-Related Issues”,
identifies common preliminary approaches to address potential safety improvements for
EPR plants, as well as common general expectations for new nuclear power plants, as
related to lessons learnt from the Fukushima Daiichi accident or Fukushima
Daiichi-related issues, www.oecd-nea.org/mdep/documents/CP-EPRWG-02-addressingfukushima-related-issues-v6-September2015.pdf.

•

CP-EPRWG-03, “Common Position on EPR Containment Mixing”, examines the two-room
concept in the containment of the EPR, which differs from many typical pressurised
water reactor containments, and in particular the use of the CONVECT system in the EPR
to promote heat transfer and mixing in accident conditions. The EPR two-room concept
allows personal access to the outer room while the reactor is at power, www.oecdnea.org/mdep/documents/2015-03-16_CP-EPRWG-03-common-position-containmentmixing-March2015.pdf.

•

CP-EPRWG-04, “Common Position on EPR Containment Heat Removal System in Accident
Conditions”, compares and discusses the containment heat removal system across thedifferent EPR reactors, including the regulatory requirements, EPR design andcompliance with the regulatory requirements and the safety authorities’ positions. It
outlines the general expectations regarding containment integrity, and summarises themain EPR design characteristics regarding containment integrity to prevent and mitigate
the consequences of severe accidents, www.oecd-nea.org/mdep/documents/2015-0316_CP-EPRWG-04-common-position-CHRS-SAHRS_March2015.pdf.

•

CP-EPRWG-05, “Common Position on In-containment Refuelling Water Storage Tank
(IRWST) pH Control in Accident Conditions”, compares and discusses the different
approaches to control IRWST pH in the EPR plants, and notes the importance of pH control,
www.oecd-nea.org/mdep/documents/2015-03-16_CP-EPRWG-05-common-positionIRWST-ph-Control-March2015.pdf.

•

CP-EPRWG-06, “Common Position on EPR Boron Dilution During a Small Break Loss of
Coolant Accident (SBLOCA)”, presents the common position developed by theparticipating regulators to ensure consistency in the assessment of the relevant aspectof the design, considering that the potential for rapid reactivity insertion due to inherent
boron dilution resulting from a SBLOCA is of significant safety importance, www.oecdnea.org/mdep/documents/CP-EPRWG-06_Boron_dilution.pdf.

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MDEP PHASE 1 SUMMARY REPORT 2006-2021

18•

CP-EPRWG-07, “Common Position Addressing the Vienna Declaration on Nuclear Safety”,
summaries the regulators’ views on how the EPR design complies with the Vienna
Declaration, www.oecd-nea.org/mdep/documents/CP-EPRWG-07%20Vienna%20Declara
tion%20on%20Nuclear%20Safety.pdf.

•

CP-AP1000WG-01, “Common Position on the Design and Use of Explosive-Actuated(SQUIB) Valves in Nuclear Power Plants”, was developed to communicate a common
position among regulators reviewing squib valve designs in order to promote andunderstand each country’s regulatory decision and basis and to aid in the assessment of
explosive-actuated valves (squib) valves that are used to perform a safety function within
a nuclear power plant, www.oecd-nea.org/mdep/common-positions/PUBLIC%20USE%
20DCP-AP1000-01-%20Squib%20valves.pdf.

•

CP-AP1000WG-02, “Common Position Addressing Fukushima Daiichi NPP Accident-Related
Issues”, identifies common preliminary approaches to address potential safety
improvements for AP1000 plants as related to lessons learnt from the Fukushima Daiichi
accident or Fukushima Daiichi-related issues. In seeking a common position, regulators
provided input to this paper to reflect their safety conclusions regarding the AP1000 designand how the design could be enhanced to address Fukushima Daiichi issues, www.oecdnea.org/mdep/common-positions/cp-ap1000wg-02-common_position_fukushima.pdf.

•

CP-AP1000WG-03, “Common Position on AP1000 IRWST Condensate Return Modelling”,
explains how the members of AP1000WG with active regulatory assessments of theAP1000 reactor co-operated and shared information on issues associated with the returnof condensate to the IRWST in postulated fault conditions. It also captures common
positions reached by the regulators on work done by the Westinghouse Electric Company(Westinghouse or the designer) to address the identified issues that were equallyapplicable to the AP1000 designs proposed for each country, www.oecd-nea.org/mdep/
common-positions/cp-ap1000wg-03.pdf.

•

CP-APR1400WG-01, “Common Position Addressing Fukushima-Related Issues”, wasdeveloped to identify the characteristics of post-Fukushima enhancements put in place byeach country and set a common position to achieve balanced and harmonised APR1400
design. The common preliminary approaches are organised into five sections, namely
external hazards, reliability of safety functions, accidents with core melt, spent fuel pools,
and emergency preparedness in design, supplemented by appendices, www.oecdnea.org/mdep/common-positions/cp-apr1400wg-01-common_position_fukushima.pdf.

•

CP-APR1400WG-02, “Common Positions on the APR1400 Post Loss of Coolant Accident(LOCA) Strainer Performance and Debris In-Vessel Downstream Effects”, was developed
to promote and understand each country’s regulatory decision and basis and to aid in
the assessment of ECCS performance considering debris effect and sump strainer, Also,
the Common Position discussed the common regulatory position on the Sump Strainer
Debris Bypass Testing, Fuel Assembly Head Loss Testing, Reactor Core Long-Term
Cooling Thermal-Hydraulic Analysis, and Risk Informed Approach and Margin
Assessment Approach, www.oecd-nea.org/mdep/common-positions/cp-apr1400wg-02debris-common-position.pdf.

•

CP-APR1400WG-03, “Common Position on the Fuel Thermal Conductivity Degradation”,
has a general position that the degradation of the thermal conductivity with fuel burnup
should be taken into account in an appropriate manner and the compliance with theacceptance criteria based on the evaluation should be confirmed. A specific position wasprovided such as that a replacement of old fuel performance code with new codes having
a capability to account the burnup effect. As an interim approach, penalty to PeakCladding Temperature (PCT) and Peak Local Oxidation (PLO) due to the absence ofconsideration of TCD in the old fuel analysis codes was also discussed, www.oecdnea.org/mdep/documents/DCP-APR1400-Fuel_Thermal_Conductivity_Degradation.pdf.

MDEP PHASE 1 SUMMARY REPORT 2006-2021•

CP-APR1400WG-04, “Common Position on Irradiation Effect on the APR1400 Fuel Bundle
Spacer Grid Strength”, specifies that an evaluation of the spacer grid strength shallappropriately address the potential degradation of the spacer grid crush strength due toirradiation throughout the lifetime of a fuel bundle. In the common position, themethodology of demonstration approved by regulators in Korea, the United States andthe United Arab Emirates was described, including a series of tests on spacer grid andfuel assembly together with a re-analysis of the seismic/LOCA response of the PLUS7 fuelin APR1400 design, www.oecd-nea.org/mdep/common-positions/cp_apr1400wg_01_fuel%20seismic.pdf.

•

CP-ABWRWG-01, “Common Position Addressing Issues Related to the Fukushima Daiichi
Nuclear Power Plant Accident”, identifies common preliminary approaches to address
potential safety improvements for ABWR plants, as well as common general expectations
for new nuclear power plants, as related to lessons learnt from the Fukushima Daiichi
Nuclear Power Plant accident or Fukushima-related issues, www.oecd-nea.org/mdep/
common-positions/cp-abwrwg-01-fukushima_daiichi_accident.pdf.

•

CP-VVERWG-01, “Common Position Addressing Fukushima-Related Issues”, identifies
common preliminary approaches to address potential safety improvements for VVER
plants, as well as common general expectations for new nuclear power plants. The
common preliminary approaches are organised into four sections, namely accounting
for external events in the design, reliability of safety functions implementation, design
solutions to cover specific beyond design basis accident or design extension conditions
or loss of heat removal to ultimate heat sink, emergency preparedness and response,
www.oecd-nea.org/mdep/documents/CP-VVERWG-01-fukushima.pdf.

•

CP-VVERWG-02, “Common Position Addressing Ex-Vessel Corium Stabilisation in Core
Catcher”, identifies common positions regarding the criteria/conditions for reliable exvessel corium stabilisation in the core catcher of VVER designs. These criteria could berecommendatory in addition to the existing requirements of national regulators. It covers
only those issues (phenomena) that can affect corium stabilisation and those that require
some specific properties of the corium and corium stabilisation process, www.oecdnea.org/mdep/documents/CP-VVERWG-02_CoriumStabilization_CoreCatcher_FINAL.pdf.

•

CP-VVERWG-03, “Common Position on Reactor Pressure Vessel and Primary Components
Reliability for AES-2006 Designs”, represents common positions developed by the VVERWG
participating regulators to ensure consistency in the assessment of the reactor pressure
vessel (including vessel, reactor head, internals and bolt connections) and primary
components (main coolant pipelines, reactor coolant pump, pressuriser, pressuriser safetyvalve, pressurised surge line, steam generator primary side) of the VVER design,
www.oecd-nea.org/mdep/documents/CPVVERWG_RPVPC_Final.pdf.

•

CP-HPR1000WG-01, “Common Position Addressing Fukushima Daiichi NPP AccidentRelated Issues”, identifies common preliminary approaches and regulatory expectations
to address potential safety improvements for HPR1000 plants, as related to lessons learnt
from the Fukushima Daiichi accident or Fukushima Daiichi-related issues. In seeking acommon position, regulators provided input to this paper to reflect their regulatory
expectations regarding the HPR1000 design and how the design could be enhanced toaddress Fukushima Daiichi issues. This common position supplements CP-STC-02 andshould be read in conjunction with that document, www.oecd-nea.org/mdep/documents/CP-HPR1000WG-01_CP_AddressingFukushimaDaiichiNPPAccident-RelatedIssues.pdf.

•

CP-VICWG-01, “Common Position: Establishment of Common QA/QM Criteria for theMultinational Vendor Inspection”, provides a set of common positions for harmonisinginspection criteria called “Common QA/QM Criteria” which will be used in Multinational
Vendor Inspection. The Common QA/QM Criteria provides the basic areas forconsideration when performing vendor inspections. The Criteria have been developed inconformity with International Codes and Standards such as IAEA, ISO, etc. that MDEP
member countries have adopted, www.oecd-nea.org/mdep/common-positions/cp-vicwg01.pdf.

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20•

CP-VICWG-02, “Common Position: Witnessed, Joint, and Multinational Vendor Inspection
Protocol”, provides guidance to regulators that wish to carry out witness, joint, andmultinational vendor inspections or participate in other regulators’ vendor inspections. It
also provides guidance for the sponsoring regulator with regard to its interactions withinspecting, witnessing or participating regulators, www.oecd-nea.org/mdep/documents/
CP-VICWG-02_RevApproved_28Jan2021_FINAL.pdf.

•

CP-VICWG-03, “Common Position: Preparation and Performance of Vendor Inspections”,
lists commendable practices in the preparation and performance of vendor inspections
and in addressing any findings, www.oecd-nea.org/mdep/common-positions/cp-vicwg03.pdf.

•

CP-VICWG-04, “Common Position on Mitigating the Risks of Counterfeit, Fraudulent, andSuspect Items”, provides high-level guidance for regulators interested in developing amore robust reporting and information sharing system to minimise the threats posed bycounterfeit, fraudulent, and suspect items (CFSI) in their country. It also offers guidanceon how regulators may reinforce their oversight of nuclear power plant supply chains,www.oecd-nea.org/mdep/documents/VICWG_CFSI_CommonPositions09Jun2021_
approved_FINAL.pdf.

•

CP-DICWG-01, “Common Position on the Treatment of Common Cause Failure Caused by
Software within Digital Safety Systems”, addresses the topic of common cause failures ofsoftware-based, safety DI&C systems. The common position directs readers to consider theeffects of software common cause failures of plant components within the safety analysis
and that diversity can be an effective means to reduce the potential effects of softwarecommon cause failure, www.oecd-nea.org/mdep/common-positions/dicwg-01.pdf.

•

CP-DICWG-02, “Common Position on Software Tools for the Development of Software for
Safety Systems”, addresses software tools used to design and develop DI&C systems
based on the ability of software tools to affect the integrity and reliability of DI&C
products. The common position establishes guidelines for the usage and limitations ofsoftware tools and the applicability of software tools to the overall DI&C system life cycle,
www.oecd-nea.org/mdep/common-positions/gcp-dicwg-02-Software_Tools_Ver_C.pdf.

•

CP-DICWG-03, “Common Position on Verification and Validation Throughout the Life
Cycle of Digital Safety Systems”, sets forth basic guidelines regarding verification andvalidation (V&V) activities for DI&C safety systems throughout the system’s lifecycle. It
addresses a plant’s overall V&V approach, as well as concerns that are specific to digitalcomputers such as pre-developed software V&V, www.oecd-nea.org/mdep/commonpositions/gcp-dicwg-03_VV_Ver_H.pdf.

•

CP-DICWG-04, “Common Position on Principle on Data Communication Independence”,
focuses on data communications independence between safety systems and between
systems of differing safety classification. This common position provides guidelines for
specific areas of interest such as communications between safety divisions, between
systems of differing safety classification and command prioritisation, www.oecdnea.org/mdep/common-positions/dicwg_4_ver_b.pdf.

•

CP-DICWG-05, “Common Position on the Treatment of Hardware Description Language(HDL) Programmed Devices for Use in Nuclear Safety Systems”, focuses on thedevelopment life cycle of HDL-based programmable devices (e.g. FPGAs) and comes as aresult of the proliferation of HDL-based devices in the nuclear industry and theirsimilarity to traditional software, www.oecd-nea.org/mdep/common-positions/gcpdicwg-05_hdl_Pro_Dev_Ver_A.pdf.

•

CP-DICWG-06, “Common Position on Principle on Simplicity in Design”, addresses theconcerns that complexity in DI&C design can lead to more faults in the design, difficulty indetecting and correcting faults, as well as increased licensing uncertainty. This common
position outlines how simplicity in DI&C design is defined and alleviates these concerns
while making designs more straightforward and easier to understand, www.oecdnea.org/mdep/common-positions/gcp-dicwg-06_Simplicity_in_Design_Ver_C.pdf.

MDEP PHASE 1 SUMMARY REPORT 2006-2021•

CP-DICWG-07, “Common Position on Selection and Use of Industrial Digital Device ofLimited Functionality”, addresses digital devices of limited functionality that can befound embedded in plant components such as pumps and breaker. These devices are
not necessarily designed for use in nuclear applications and this common position
provides criteria for their selection and usage, www.oecd-nea.org/mdep/commonpositions/DICWG_GCP-DICWG-07.pdf.

•

CP-DICWG-08, “Common Position on the Impact of Cyber Security Features on Digital
I&C Safety Systems”, provides guidelines on aligning cybersecurity measures with DI&C
systems of the highest safety classification. The goal of the common position is to ensurethat safety measures and cybersecurity measures do not adversely impact each other,
www.oecd-nea.org/mdep/common-positions/dicwg_8_rev_f.pdf.

•

CP-DICWG-09, “Common Position on Safety Design Principles and Supporting Information
for the Overall I&C Architecture”, sets guidelines for safety design principles andsupporting information that should be demonstrated for the entire DI&C architecture of aplant, as modern DI&C systems become more integrated and perform more functions, and
it is critical to implement safety design principles and documentation to ensure safe
operation, www.oecd-nea.org/mdep/common-positions/GCP-09_Overall_IC_Architecture_
final.pdf.

•

CP-DICWG-10, “Common Position on Hazard Identification and Controls for Digital
Instrumentation and Control Systems”, lays the foundation for addressing hazards bothinternal and external to DI&C systems. The common position outlines a systematic
approach for determining the hazards associated with DI&C system and the controls to
address those hazards, www.oecd-nea.org/mdep/common-positions/MDEP_GCP-DICWG10_HazardIDandControl.pdf.
CP-DICWG-11, “Common Position on Digital I&C system Pre-Installation and Initial OnSite Testing”, sets forth guidelines regarding pre-installation and initial on-site testingfor DI&C systems. These types of testing can confirm that DI&C systems comply with
their requirements at different phases of a system’s life cycle, www.oecd-nea.org/mdep/
common-positions/gcp-dicwg-11-ver-e.pdf.

•

CP-DICWG-12, “Common Position on the Use of Automatic Testing in Digital I&C Systems
as Part of Surveillance Testing”, addresses automated testing feature alignment with
DI&C system implementation and performance, in consideration of the fact that
automated fault detection features are a common aspect of modern DI&C systems andcan provide early detection of system issues in advance of surveillance testing, therefore
allowing for a reduction in the need for some manual surveillance activities while
maintaining safe operation, www.oecd-nea.org/mdep/common-positions/Public_Use_
MDEP_GCP-DICWG-12_Ver_A.pdf.

•

CP-DICWG-13, “Common Position on Spurious Actuation”, continues DICWG’s focus on
hazard assessment and controls, focusing on a specific hazard referred to as spurious
actuation. Spurious actuation of plant equipment (regardless of safety class) canpotentially place a plant in an unanalysed state and this common position explores
controlling for this hazard from a DI&C perspective, www.oecd-nea.org/mdep/commonpositions/cp-dicwg-13.pdf.

•

CP-CSWG-01, “Common Position on Findings from Code Comparisons and Establishmentof a Global Framework towards Pressure Boundary Code Harmonisation”, contains acompilation of common positions identified by the CSWG in its pursuit of harmonising
the requirements in codes and standards governing the design, materials, fabrication,
examination, testing and over-pressure protection requirements of presser-boundary
components such as vessels, piping, pumps and valves typically found in large, watercooled reactor nuclear power plants, www.oecd-nea.org/mdep/documents/CP-CSWG01-common-position.pdf.

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Appendix B: MDEP technical reports (2006-2021)•

TR-EPRWG-01, “Regulatory Approaches and Criteria Used in the Analysis of Accidents
and Transients in MDEP EPRWG Member Countries”, summarises key aspects ofpractices used by the regulatory agencies in evaluation of safety analyses in support oflicensing (or certification) of the EPR, www.oecd-nea.org/mdep/documents/EPR-SurveyRegulatory-Approaches.pdf.

•

TR-EPRWG-02, “Insights from PSA Comparison in Evaluation of EPR Designs”, describes
the outcome of a limited probabilistic safety assessment (PSA) comparison on the EPR
designs. It was presented by the chairman of the EPR technical experts’ subgroup on
probabilistic safety assessment at the PSAM 12 meeting in June 2014, www.oecdnea.org/mdep/documents/PSAM-12-PSA.pdf.

•

TR-EPRWG-03, “Technical Report on the Definition of Primary Coolant Source Terms
Used in the Different EPR Designs for Shielding, Radiation Zoning, DBA Consequences”,
considers the way the EPR primary coolant source term was elaborated and used in the
different countries at the design stage. It identifies the main discrepancies and their
origins. Discrepancies are not really linked to the EPR design but to historical practices,available feedback and the different methods used, www.oecd-nea.org/mdep/
documents/TR-EPRWG-03-Source-term-survey_May2015.pdf.

•

TR-EPRWG-04, “Limited Comparison of EPRTM PSA”, describes the outcome of a limited
PSA comparison on the following EPR designs: the Olkiluoto 3 Nuclear Power Plant in
Finland, the Flamanville 3 Nuclear Power Plant in France, the United Kingdom’s EPR
design, and the United States EPR design. The objective of this comparison was to
identify differences in the modelling aspects and results of EPR PSAs, as well as to assess
the rationale for these differences, www.oecd-nea.org/mdep/documents/2017-11-30%
20TR-EPRWG-04%20Limited%20Comparison%20of%20EPR%20PSA.PDF.

•

TR-EPRWG-05, “Technical Report on FPOT Considered for EPR”, provides background to
FPOTs and the development of the generic FPOT common position, and the planned EPR
FPOTs. It also describes the Commissioning Activities TESG observation of the Taishan
Unit 1 special vibration measurements on the reactor pressure vessel internals (RPVI)FPOTs and the lessons learnt associated with the practical arrangements that should beconsidered when preparing to observe any future FPOTs, www.oecd-nea.org/mdep/
documents/EPRWG-EPR05-EPR-for-FPOT.pdf.

•

TR-EPRWG-06, “Technical Report on Hydrogen Management for EPR”, identifies what iscommon and what is different between the EPR designs related to hydrogen management,
focusing mainly on hydrogen passive autocatalytic recombiners (PARs), www.oecdnea.org/mdep/documents/EPRWG06_TechnicalReport_Hydrogen_Management.pdf.

•

TR-EPRWG-07, “Technical Report on EPR Assessment of 2A Large Break Loss of Coolant
Accident (2A-LOCA) Analysis”, presents the work carried out by regulators todemonstrate a common understanding of the response of a generic EPR plant following
a double-ended Large Break LOCA referred to as “2A-LOCA” and how this has beenaddressed within the safety submissions supporting the EPR reactor design, www.oecdnea.org/mdep/documents/EPRWG07_TechnicalReport_2A%20LOCA_public.pdf.

•

TR-EPRWG-08, “Technical Report on EPR I&C”, introduces both the general common
design features and specific features of the five EPR I&C design variants. The report also
discusses the major technical issues or concerns. Finally, it provides recommendations
and lessons learnt to support ongoing MDEP activities and future reviews of new reactors.

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24•

TR-EPRWG-09, “Technical Report on EPR Break Preclusion Approach on the Secondary
System”, provides a comparison of the technical references used for each EPR project
regarding the break preclusion approach on the secondary system.

•

TR-AP1000WG-01, “Technical Report on Lessons Learnt with AP1000 Reactor Coolant
Pumps”, describes the design, manufacturing and testing of the reactor coolant pump(RCP) used in the AP1000 nuclear power plants. The testing includes prototype andcommissioning test. This report focuses on the regulatory practices, co-operative
regulatory experiences, and lessons learnt related to the RCPs, www.oecd-nea.org/mdep/
common-positions/tr-ap1000wg-01.pdf.

•

TR-AP1000WG-02, “Technical Report on AP1000 Squib Valves Design, Construction,
Qualification, and Testing Experience”, describes the design, qualification, andapplication of pyrotechnic-actuated (squib) valves used in the AP1000 nuclear power
plant. The objectives of this report are to describe lessons learnt from these activities forconsideration in future design, construction, qualification, and testing of AP1000 squib
valves, www.oecd-nea.org/mdep/common-positions/tr-ap1000wg-02.pdf.

•

TR-AP1000WG-03, “Technical Exchanges between US NRC and NNSA during the Design,
Construction, and Commissioning of AP1000 Reactors”, provides a compilation of thequestion and answer exchanges between the US NRC and NNSA. The informationexchanges include several documents that are publicly available in the US NRC’s Agency
wide Documents Access and Management System (ADAMS), as well as other documents
provided or exchange during the AP1000WG meetings. It is restricted to AP1000WG
members at the request of the members.

•

TR-AP1000WG-04, “Technical Report on Common Understanding of the Hydrogen Control
System for the AP1000 Design”, identifies a common understanding of the regulatory
requirements for the AP1000 design. This report also identifies differences between the
AP1000 design proposed in China, India, and the United States as it relates to hydrogen
management, the rationale for the Hydrogen Recombiner Subsystem, and the use of
Hydrogen PARs and any related regulatory differences, www.oecd-nea.org/mdep/
documents/Technical_Report_AP1000_Hydrogen_Control_System_Approved_Sept2020_FI
NAL.pdf.

•

TR-AP1000WG-05, “Technical Report on Lessons Learnt from Implementation of theCommon Position on FPOT for AP1000”, evaluates the implementation of the MDEP
Common Position Addressing First-Plant-Only-Tests (FPOT), Version 1, dated April 2018,
CP-STC-01, in the crediting of FPOT and First-Three Plant Only Test (F3POT) for the
AP1000 design. As described in the common position, a FPOT or F3POT performed at one
reactor can be credited to another reactor as long as appropriate preconditions are met,
and the common position identifies a series of such preconditions. This report describes
how each of the preconditions was considered in crediting FPOTs and F3POTs in
implementing the AP1000 design across multiple reactors, www.oecd-nea.org/mdep/
documents/AP1000_TR_LessonsLearnt_ImplementationCP_FPOT_FINAL.pdf.

•

TR-AP1000WG-06, “Technical Report on Hot Functional and Startup Testing Lessons
Learnt”, discusses lessons learnt from the AP1000 Hot Functional Testing (HFT) andStartup testing performed at Sanmen Unit 1 and Haiyang Unit 1 in China, www.oecdnea.org/mdep/documents/AP1000_TR_hotfunctionaltesting_startuplessonslearnt_FINAL
.pdf.

•

TR-APR1400WG-01, “Technical Report on Design Description and Comparison of Design
Differences Between APR1400 Plants”, documents differences in the design of APR1400s
submitted for licensing applications. With APR1400s in different licensing stages among
member countries, APR1400WG members identified design differences in order to better
understand the associated rationale, such as design improvements or regulatory
requirements which are different for each member countries, www.oecd-nea.org/mdep/
documents/TR-APR1400-01%20Design%20Description%20and%20Comparison%20of%20
Design%20Differences.pdf.

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TR-APR1400WG-02, “Technical Report on Background Information Relevant to Addressing
Severe Accidents in the APR1400 Design”, was developed in recognition of differences in thegoverning legislative requirements of the country in which the APR1400 is to be constructed
and operated, that largely influence the design and implementation of measures provided
to prevent and/or mitigate the effects of Severe Accidents in nuclear power plants. The
report compiled regulatory requirements applicable to Severe Accidents in APR1400WG
member countries, Severe Accident prevention and mitigation features of the APR1400
designs, and the summary of codes, methodologies and countermeasures for severe
accident analysis adopted for each APR1400WG member country, www.oecdnea.org/mdep/documents/2017-11-30%20TR-APR1400-02%20on%20the%20comparison%20of%20the%20prevention%20and%20mitigation%20measures%20against%20severe%20
accident.pdf.

•

TR-APR1400WG-03, “Technical Report on the Findings of the Review of the Molten Core
Concrete Interaction (MCCI) Phenomena for the APR1400”, documents the technicalassessments performed by KINS, FANR, and the US NRC on the MCCI phenomena in theirrespective APR1400 designs. It also summarises applicable regulatory requirements in eachmember country relevant to MCCI, www.oecd-nea.org/mdep/documents/TR-APR140003%20on%20the%20findings%20of%20the%20review%20of%20the%20MCCI%20phenomena.pdf.

•

TR-APR1400WG-04, “Technical Report on Hydrogen Recombiner Survey Results for
APR1400 design in place, or proposed, for MDEP Member Countries”, presents a common
understanding of the regulatory requirements pertaining to hydrogen control for the
APR1400 designs of MDEP member countries. The report is based on a survey conductedamong the APR1400WG members on specific regulatory requirements applicable in eachcountry on hydrogen control, hydrogen control system design and implementation as wellas maintenance and availability, www.oecd-nea.org/mdep/documents/TR-APR1400WG04_hydrogenrecombiner_surveyreport_FINAL.pdf.

•

TR-APR1400WG-05, “Technical Report on the Comparison of the Regulatory Requirements
for Probabilistic Risk Assessment (PRA) of the APR1400 Nuclear Power Plants, for the MDEP
Member Countries”, documents each participating member country’s assessment in theform of a survey that compares the contents of the applicable regulations and regulatory
guides, probabilistic safety goals, scope of PRA, quality control, technical adequacy, peer
review, PRA maintenance and updates as well as the use of PRA for changes in licensing
basis between KINS and FANR, www.oecd-nea.org/mdep/documents/TR-APR1400WG05_ComparisonRegulatoryRequirements_PRA_NPP_Final.pdf.

•

TR-ABWRWG-01, “Technical Report on Design Comparisons”, accumulates comparative
information on ABWRs and similar designs. It is restricted to ABWRWG members at therequest of the members.

•

TR-ABWRWG-02, “Technical Report on Design Differences Identified from Comparisonof International ABWR Designs”, explains the noteworthy design differences identified
from report TR-ABWRWG-01. This report was important to document the regulatory
basis for severe accidents design differences. It is restricted to MDEP members at therequest of members.

•

TR-ABWRWG-03, “Technical Report on Comparison of Severe Accidents Regulatory
Positions for ABWR Reactors (Regulatory Differences)”, documents the regulatory basis,
where applicable, for differences in the design of severe accident features of reactors
considered within the scope of the ABWRWG. It is restricted to ABWRWG members at
the request of the members.

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26•

TR-VVERWG-01, “Regulatory Approaches and Criteria used in Severe Accident Analyses
and Severe Accident Management”, summarises key aspects of the regulatory
requirements and existing practices in the field of severe accident assessment andsevere accident management, highlighting the items where approaches of regulators in
VVERWG member countries are similar and also identifying the differences. The focusof the information presented in this report is on the events which lead to reactor core or
fuel damage, www.oecd-nea.org/mdep/documents/2017-11-30%20TR-VVERWG-01%20
Regulatory%20approaches%20and%20criteria%20used%20in%20severe%20accident%20a
nalyses%20and%20severe%20accident%20management.pdf.

•

TR-VVERWG-02, “Regulatory Approaches and Oversight Practices Related to Reactor
Pressure Vessel and Primary Components”, identifies differences in regulatory approaches
and oversight practices used in different countries within the VVERWG related to reactor
pressure vessel and primary components. It also identifies commendable practices in thisfield, www.oecd-nea.org/mdep/documents/vverwg-tr-02-2017.pdf.

•

TR-VVERWG-03, “Regulatory Approaches Related to Accidents and Transients Analyses”,
summarises the main findings from discussions between VVER Accidents and TransientsTESG participants concerning the regulatory requirements and existing practices in thefield of accident and transient analyses, highlighting the items where approaches ofregulators in VVER member countries are similar and also identifying the differences. The
focus of the information presented in this report is on all accident and transient issues,
including severe accidents, www.oecd-nea.org/mdep/documents/VVERWG_TR_%20
Accident_Transients_0_7_STC%20comm_FINAL.pdf.

•

TR-VVERWG-04, “Technical Report on Core Catcher”, creates a basis for a common
understanding of features of design, safety limits and conditions of the core catcher ofthe VVER design, in order to define safety concerns and to discuss the possibility of thecommon approach for licensing, www.oecd-nea.org/mdep/documents/tr-vverwg-04_
CoreCatcher_Final.pdf.

•

TR-VVERWG-05, “Technical Report on Hydrogen Recombiners”, identifies similarities
and differences in regulatory requirements and practices related to PARs in the new
VVER design. This report covers the rationale for PARs and for the location and numberof PARs, the justification of performance, and the safety classification, www.oecdnea.org/mdep/documents/TR-VVERWG-05_HydrogenRecombiners_FINAL.pdf.

•

TR-HPR1000WG-01, “Hydrogen Control During Severe Accidents”, identifies common
features of the HPR1000 design and develops a common understanding of the regulatory
requirements of the regulators that make up the HPR1000WG. A survey was produced andsent to all the regulators regarding various aspects of the HPR1000 Containment
Combustible Gas Control System (CCGCS). This document compiles the information
provided within the responses to the survey and summarises the information presented
by the regulators, www.oecd-nea.org/mdep/documents/TR-HPR1000WG-01%20Hydrogen%20Control%20During%20Severe%20Accidents_clean%20copy_FINAL.pdf.

•

TR-HPR1000WG-02, “Technical Report on Regulatory Requirements and Practices for
Severe Accidents”, summarises the regulatory requirements and expectations of theregulators that make up the HPR1000WG, and highlights where consensus or differences
exist. A survey was produced and sent to all regulators regarding various aspects of theregulation, analysis, and management of severe accidents. This report compiles theinformation provided within the responses to the survey and summarises theinformation presented by the regulators, www.oecd-nea.org/mdep/documents/TRHPR1000WG-02_TR_RegulatoryRequirements_Practices_Severe%20Accidents.pdf.

•

TR-VICWG-01, “MDEP Protocol: Witnessed, Joint, and Multinational Vendor Inspection
Protocol”, provides guidance to regulators that wish to carry out vendor inspections orparticipate in or witness other regulators’ vendor inspections. It also provides guidance
for the sponsoring regulator with regard to its interactions with inspecting, witnessingor participating regulators. CP-VICWG-02 replaces this technical report, www.oecdnea.org/mdep/documents/VICWG-01-V2-vendor-inspection-protocol.pdf.

MDEP PHASE 1 SUMMARY REPORT 2006-2021•

TR-VICWG-02, “Technical Report: Survey on Quality Assurance Program Requirements”,
presents a survey that was prepared using the requirements of Appendix B to 10CFR Part
50, “Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants.”
These requirements form the basis upon which the U.S. NRC oversees the activities ofvendors providing parts and services to the commercial U.S. nuclear power industry. The
member regulators’ responses to the survey are also provided, www.oecd-nea.org/
mdep/common-positions/tr-vicwg-02.pdf.

•

TR-VICWG-03, “Technical Report on Common QA/QM Criteria for Multinational Vendor
Inspection”, provides the “Common QA/QM Criteria” which will be used in theMultinational Vendor Inspection. The Common QA/QM Criteria provides the basic areas
for consideration when performing vendor inspections. The Criteria have beendeveloped in conformity with International Codes and Standards such as those of the
IAEA, ISO, etc., that MDEP member countries have adopted.

•

TR-VICWG-04, “Technical Report: Assessment of Multinational Vendor Inspection ofValinox Nuclear”, describes the first MDEP Multinational Vendor Inspection at Valinox
Nuclear in France, specifically, the inspection team, inspection scope and findings, and
VICWG assessment of the multinational inspection effort, www.oecd-nea.org/
mdep/common-positions/tr-vicwg-04.pdf.

•

TR-VICWG-05, “Technical Report: Assessment of Multinational Vendor Inspections of
AREVA NP Creusot Forge (ACF)”, describes the second MDEP Multinational Vendor
Inspection AREVA NP in its Creusot Forge plant (ACF) in France. It is restricted to VICWG
members at the request of the members.

•

TR-VICWG-06, “Technical Report on Assessment of Multinational Vendor Inspection of
ENSA” (Spain). It is restricted to VICWG members at the request of the members.

•

TR-VICWG-07, “Technical Report on Safety Culture in the Nuclear Supply Chain”,
provides a high-level summary of how each member country encourages or regulates
safety in the nuclear supply chain based on the responses to a survey. This report also
identifies commonalities and differences between regulatory practices of the member
countries in encouraging or regulating safety culture in the nuclear supply chain,www.oecd-nea.org/mdep/documents/TR-VICWG-07_TR_SafetyCulture_NuclearSupply
ChainFinal_Rev29Jan2021_FINAL.pdf.

•

TR-DICWG-01, “Technical Report on the Relational Structure of the DICWG Common
Positions”, describes the relational structure between the DICWG common positions, aswell as addressing their scope, content and how they relate to the mission of DICWG,
www.oecd-nea.org/mdep/common-positions/tr-dicwg-01-relational_structure_cp.pdf.

•

TR-CSWG-01, “Technical Report: Regulatory Frameworks for the Use of Nuclear Pressure
Boundary Codes and Standards in MDEP Countries”, documents how each MDEP
regulator utilises national or regional mechanical codes and standards in its safety
reviews and licensing of new reactors, www.oecd-nea.org/mdep/documents/cswgtechnical-report-tr-cswg-01.pdf.

•

TR-CSWG-02, “Technical Report on Lessons Learnt on Achieving Harmonisation of Codesand Standards for Press for Pressure Boundary Components in Nuclear Power Plants”,
documents the findings and overall conclusions of the CSWG pertaining to the adequacyand sufficiency of several MDEP member countries’ pressure boundary codes andstandards, and the potential for harmonisation of those pressure boundary codes andstandards based on the code-comparison work performed by the SDOs from April 2008
to December 2012. It also documents a strategy and process proposed by the SDOs forachieving code harmonisation, www.oecd-nea.org/mdep/documents/TR-CSWG-02technical-report.pdf.

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TR-CSWG-03, “Technical Report: Fundamental Attributes for the Design and Constructionof Reactor Coolant Pressure-Boundary Components”, provides the fundamental attributes
which have been developed for the codes and standards used in the design andconstruction of reactor coolant pressure boundary components in nuclear power plants.
The fundamental attributes are the basic concepts to be considered in the design, materials,
fabrication, installation, examination, testing and over-pressure protection requirementsfor pressure boundary components, www.oecd-nea.org/mdep/documents/TR-CSWG-03fundamental_attributes.pdf.

•

TR-CSWG-04, “Technical Report: The Essential Performance Guidelines for the Design
and Construction of Pressure Boundary Components”, provides the essential
performance guidelines for the codes and standards used in the design and constructionof reactor coolant pressure boundary components in nuclear power plants. These
guidelines are qualitative descriptions of the rules and practices derived from the codesand standards of MDEP member countries, which can be considered as essential,
www.oecd-nea.org/mdep/documents/2015-03-16_TR-CSWG-04-Essential-PerformanceGuidelines-March2015.pdf.

•

TR-CSWG-05, “Technical report on CSWG Past, Current and Future Activities”, expresses
CSWG members’ thoughts on their participation and hopes for future codes andstandards harmonisation potential howsoever that would be supported by international
bodies. It also summarises the results of a survey of CNRA members concerning theirviews of codes and standards, and the potential for an entity such as the CSWG tocontinue within the CNRA, www.oecd-nea.org/mdep/documents/TR-CSWG-05%20Past%20Current%20Future%20Activities%20May%202018.pdf.

www.oecd-nea.org/mdep

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