Senior Group of Experts for Nuclear Safety: Support Facilities for Existing and Advanced Reactors (SESAR/SFEAR2)

At its 61st meeting in June 2017, the CSNI decided to establish a Senior Expert Group on Safety Research (SESAR) to update previous assessments of capabilities and facilities required to support safety of nuclear installations. A report on this activity was issued by NEA in 2001 titled Senior Group of Experts for Nuclear Safety Research: Facilities and Programmes (SESAR/FAP). Six years later, a follow-on activity resulted in the publication SESAR/SFEAR: Nuclear Safety Research in OECD Countries – Support Facilities for Existing and Advanced Reactors (2007) The activity described in this report builds upon and updates the previous work, expanding scope to cover additional advanced reactor types, including evaluations performed by the CSNI Task on Advanced Reactors Experimental Facilities (TAREF) for High Temperature Reactors and Sodium Fast Reactors. The scope also identifies general safety issues for several proposed Molten Salt and Small Modular Reactor designs. Accordingly, the title of this activity is SESAR: Support Facilities for Existing and Advanced Reactors (SESAR/SFEAR2). The current document can be considered a follow-on to the previous two reports. In addition, although the need to maintain experimental data bases was recognised as an important issue, but not treated specifically in previous reports, there are some direct recommendations regarding experimental data preservation in this report. Since publication of the SESAR/SFEAR report in 2007 there are several facilities that have been shut down. Accordingly, loss of critical research infrastructure (i.e. facilities, capabilities and expertise) remains a concern and is a major factor in conducting the current study. However, it should be recognized that the SESAR/SESAR effort led to CSNI actions that preserved several key facilities during the 2007-2019 time period. These are discussed in Chapters 1 and 4. The focus of this report is on the safety issues, research needs and supporting research facilities associated with currently operating water-cooled reactors in NEA member countries. These reactors include PWRs, BWRs, PHWRs, VVERs and advanced or evolutionary designs of these types. For these reactors, the main purpose of this report is to:  Summarise current safety issues, whose resolution depends upon additional research work.  Provide the current status of research facilities that support resolution of the safety issues.  Recommend actions the CSNI could take in the short-term to help maintain facilities, which require a substantial investment of resources and are in danger of premature closure.  Provide recommendations on long-term nuclear safety research facility infrastructure needs and preservation. The report also provides information on safety issues and research needs not unique to the nuclear industry and on safety issues and research needs associated with advanced reactor designs such as Gas Cooled Reactors, Sodium Fast Reactors, Molten Salt Reactors and Small Modular Reactors. This information is presented for completeness and for use by designers, operators and researchers in planning and conducting future work. The issues addressed in this report are those associated with nuclear reactor safety and are organised into the following technical areas: v a) Those unique to the nuclear industry:  Thermalhydraulics.  Nuclear Fuel.  Reactor physics.  Severe Accident and containment phenomena.  Integrity of equipment and structures. b) Those not unique to the nuclear industry:  Human and organisational factors.  Plant control and monitoring.  Cyber security  External events.  Fire assessment. The second group of issues address phenomena, safety issues and facilities that are relevant to the nuclear industry are also supported in a major way by other industries and, thus, may not require support from CSNI. In general, in developing recommendations for CSNI consideration, the group focused on those facilities that have unique capabilities and have high relevance to the resolution of safety issues for Generation II designs as well as the potential to be highly relevant in support of the resolution of safety issues for new and emerging Generation III and IV designs. The questions if it would be very expensive (>5M€) to replace the facility or if it is a unique one, were raised as well. Due to the costs of operating many larger facilities, further co-operative efforts would most likely be needed to maintain them in the longer-term. The conclusions and recommendations in Chapter 4 are organised into short-term, long-term, and general items as follows: a) Short-term conclusions and recommendations To assess short-term concerns, the facilities in Chapter 3 were examined, and those that were unique, versatile, and in danger of being shut down in the next 1-3 years were identified. The CSNI is encouraged to support, to the extent possible, joint projects proposed for these facilities. In the Thermalhydraulics area, three facilities are in short-term danger. These include PKL and LSTF which support PWR thermal-hydraulic work and PANDA, which supports both LWR and BWR thermal-hydraulic safety issues, as well as severe accident and containment phenomena. It should be noted that both PANDA and PKL were identified as being at short-term risk as early as 2001 but have been used to conduct several important CSNI research initiatives via NEA joint projects in the intervening years. Both PANDA (PSI, Switzerland) and PKL (Areva, Germany) proponents are anticipated to propose new NEA projects prior to the current projects coming to an end (2021 for PANDA and 2020 for PKL, respectively). The short-term fate of the LSTF (Japan) is similar, indications are that Japan will likely propose a new joint project in the near future. In the Severe Accident and Containment Phenomena technical area, the aforementioned PANDA facility, the VERDON facility (France) and the THAI facility (Germany) have been identified as being at risk in the near-term, all were identified as being at risk, or to require long-term monitoring, in the last report. There are future NEA joint projects planned for each of them in order to justify their operation for some more years. The CHROMIA platform (fission product release and transport facilities at IRSN in France) is also at risk, and, like the THAI facility, have vi been utilized extensively by NEA projects (STEM 1, 2 and 3) over the past 10 years. A new NEA joint project proposal, ESTER is being prepared, which will utilize both the CHROMIA and the VERDON facilities. A new NEA joint project proposal, THEMIS, is also being prepared, which will utilize the THAI facility. In the fuel and materials areas, several large, versatile reactors have been closed since 2007. However, regardless of them being previously identified as being at short-term risk (PHEBUS) or facilities to monitor in the long-term, substantial national support is required to sustain/refurbish such aging or specialized reactors. The National Research Universal Reactor in Canada, the Halden Reactor at IFE Norway both closed in 2018, and this represents a significant loss worldwide, for both materials and fuel testing. Additionally, JMTR in Japan, a test reactor used primarily for materials testing has been shut down as well. Reactors worldwide, including CABRI, BR-2, LVR-15, MIR, TREAT, HFR, ATR and others have been identified as being suitable to replace some of the capabilities lost by the closure of these reactors. The NEA has recently taken some measures to protect existing infrastructure by proposing the establishment of the FIDES network, which, along with joint projects for a variety of irradiation activities will allow members to access various reactors and test programs for materials and fuels. This step towards collaborative irradiation projects, if successful, will provide both short and medium-term activities that can be supported by the CSNI to mitigate the current irradiation gap. A review of sub-critical and zero-power reactors by the Nuclear Science Committee (NSC) found that several of these reactors have been closed since the last report, and recommended that they should monitor the remainder (VENUS in Belgium, ZED-2 in Canada, LR-0 in the Czech Republic and KUCA in Japan) closely. The STACEY facility (Japan) was mentioned as a candidate to replace some capacity, but it is currently shut down. The CROCUS facility in Switzerland also may have some capacity. None of the above facilities have been identified as being in imminent danger of shutdown. Finally, although the scope of the previous 2007 activity focussed solely on facilities unique to the nuclear industry, the GALAXIE fire platform at IRSN was identified in this evaluation as being at risk in the near-term. Although other fire research facilities exist, the co-location of separate effects, intermediate and large scale facilities in this platform, as well as the experience gained from 3 phases of NEA joint projects such as PRISME make GALAXIE ideal for addressing fire safety issues unique to the nuclear industry (e.g. glove-box fires, propagation through ventilation systems, fire initiated in cable trays). An NEA joint project is planned to be proposed once the current PRISME project ends (2021). b) Longer-term conclusions and recommendations Many of the factors used in the last two reports to arrive at conclusions and recommendations have resulted in effective measures for retaining key facilities at risk. These measures should continue to be used in the future, with consideration of the factors below:  Cost of facility operation and replacement (i.e., limit CSNI involvement to large facilities needing multi-national support).  Consistency with SFEAR recommended list of facilities for long-term preservation (discussed below). vii  Ability to define a useful experimental programme (i.e., one that will provide information useful to the resolution of one or more safety issues).  L

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