Report RHWG Chair Report to WENRA Fall 2018 Meeting -

Transcription

1 Report RHWG Chair Report to WENRA Fall 2018 Meeting A status report by the RHWG Chair for the attention of WENRA 25 October 2018

2 Table of Contents RHWG Chair Report October Introduction SRL implementation at the plants, ALARP improvements and benchmarking Revision of the 2014 reference levels and safety objectives for new plants Current revision of the reference levels Periodic review of reference levels Safety Objectives for New Nuclear Power Plants 8 04 Practical elimination 9 05 Questionnaire on Reference Level F Topical Peer Review on ageing management RHWG work programme 12 Annex RHWG activities Page 2

3 01 Introduction Since the last WENRA Plenary Meeting, there have been two RHWG meetings: 57 June 2018 in Kiev, Ukraine 2528 September 2018 in St Pölten, Austria, The second of these was attended by 34 participants from 19 countries. This report summarises the status of all of the work that is underway or proposed in RHWG. Much of this is presented for information, but in some cases RHWG is seeking action from WENRA in the form of a decision or advice from WENRA or requesting WENRA to note a course of action that RHWG is proposing. This is clearly identified in a box at the start of each section. The matters for which RHWG is requesting action from WENRA are listed below, starting with the section number of the request. 02 WENRA members are requested to commit to providing sufficient resource for the task on SRL implementation at the plants, improvements and benchmarking to proceed efficiently and effectively WENRA is requested to agree that lists of hazards or initiating events should not be included as reference levels on the basis of the vote by RHWG members. The status of the matters in this report have been kept deliberately brief. Further detail will be provided in the presentation at the Plenary Meeting. RHWG has drafted a programme of work that it currently has programmed over the period This is presented in the annex. Page 3

4 SRL implementation at the plants, ALARP improvements and benchmarking WENRA members are requested to commit to providing sufficient resource for the task on SRL implementation at the plants, improvements and benchmarking to proceed efficiently and effectively. During its Fall 2017 meeting, WENRA recognised that RHWG was performing a number of tasks that were potentially overlapping. It therefore tasked RHWG to prepare a single proposal which covers the following: Implementation of the 2014 RLs on the plant Timely implementation of reasonably practicable improvements on nuclear power plants including: o Recently issued WENRA document o Implementation of VDNS Principle 2 o Implementation of NSD articles 8(a) to 8(c), especially 8(a) These improvements should be current as well as historical Benchmarking of specific safety improvements WENRA suggested that RHWG should review implementation of Issue F for plant faults with emphasis on severe accident management. Prior to the last WENRA meeting, RHWG had set up a subgroup with members from Bulgaria, Czech Republic, Finland, France, Germany, Japan and Sweden to develop a proposal and initiate an exploratory study by RHWG s next meeting. This is turning out to be a challenging task, as expected, but RHWG is making progress on how to do it. A proposal on the task has been drafted and has been circulated to WENRA members as a separate document for this meeting (item 08b), which provides details of the RHWG proposal for the task. RHWG has selected RLs F4.8 to F4.18 as candidates for the task and reviewed the technical solutions for compliance with these, with a number being identified for each RL. It is starting a pilot study to examine how the information for these technical solutions can be produced and compared. It has decided to collect information at a high level due, in part to is experi Page 4

5 ence in a study for RL F7.4 (see 05). Once the lessons have been learnt from this pilot, it will be rolled out to all RHWG members. The task is likely to require a significant amount of resource from all WENRA member countries. To proceed effectively all countries all WENRA members are asked to commit to providing sufficient resource for the task on SRL implementation at the plants, improvements and benchmarking to proceed efficiently and effectively. Page 5

6 03 Revision of the 2014 reference levels and safety objectives for new plants RHWG has been working on: short term revision of some reference levels periodic (10 year) review of the full set of reference levels potential review of the Safety Objectives for New Power Reactors 03.1 Current revision of the reference levels WENRA is requested to agree that lists of hazards or initiating events should not be included as reference levels on the basis of the vote by RHWG members. RHWG is currently working on revising the 2014 reference levels as follows: New Issue TU on external hazards covering both natural hazards (Issue T) and adding human induced hazards New Issue SV on all internal hazards, including fire which is currently in Issue S Revision of Issue C on Management Systems to include leadership Revision of Issue I on Ageing Management to include obsolescence and incorporate any learning from the ENSREG Topical Peer Review Since the last meeting RHWG has received comments from both ENISS and IAEA on both hazards issues. Members of the working group developing these documents met with IAEA on 28 September and ENISS on 16 October to discuss their comments. As a result of these meetings the working group has a number of matters to consider further. Earlier work on Issue C led to it largely repeating IAEA safety standard GSR Part 2. Further work has now been undertaken to ensure that it provides added value reflecting European practice. It is currently going through the RHWG written comment process with a view to RHWG agreeing to it being sent for ENISS and IAEA comment at its January 2019 meeting. Work on Issue I has been on hold for some time pending the outcome of the TPR. With the issue of the TPR report and discussions on it during this meeting, RHWG should be able to start work on it again. The revised reference levels and revised guidance will need to be issued simultaneously and the programme is largely being determined by the need to wait for the outcome of the TPR before revising Issue I. RHWG expects that it will seek WENRA approval at its Spring 2020 meeting. Page 6

7 RHWG agrees reference levels by consensus. There is, however, a matter where achieving consensus is proving to be very difficult and may be impossible. It relates to the hazards issues and also Issue E (Design Basis Envelope for Existing Reactors) and Issue F (Design Extension of Existing Reactors). Using a previous draft of Issue TU as an example, the matters relate to RLs TU2.1 & TU2.2, which were as follows: TU2.1 All external hazards that might affect the site shall be identified, including any related hazards (e.g. earthquake and tsunami, accidental aircraft crash with consequential aircraft fuel fire). Justification shall be provided that the compiled list of external hazards is complete and relevant to the site. TU2.2 External hazards shall at least include: Geological hazards; Seismotectonic hazards; Meteorological hazards; Hydrological hazards; Biological phenomena; External fire; Accidental aircraft crash; Accidents at facilities outside the site area; Transportation accidents; Electromagnetic hazards. RHWG has had many discussions on whether TU 2.2 is appropriate as an RL. RLs are usually high level goals and hence TU2.1 is an appropriate RL. TU 2.2, however, is not as it demonstrates how to achieve TU 2.2 and hence is more appropriate as guidance. Some members, however, believe that it is important to include the list. This has been debated many times at RHWG and the debate was reopened as ENISS commented on it. The discussions did not reach consensus and was showing no signs of doing so. A vote of WENRA member country representatives on the principle of whether such a list should be included in the RLs gave the following result: 5 were in favour of the list being left in 7 were in favour of the list being removed Hence the majority was in favour of it being removed. Normal practice is to achiever consensus, but in the absence of this, as an exceptional situation, I request that WENRA members agree that lists of hazards or initiating events should not be included as reference levels on the basis of the vote by RHWG members. Page 7

8 03.2 Periodic review of reference levels For information only. The foreword of the RLs states that: WENRA is committed to continuous improvement of nuclear safety. To this end WENRA is committed to regularly revising the RLs when new knowledge and experience are available. With a view to this statement, RHWG has been working on a programme to update the reference levels by 2024, ten years after the latest significant revision. The key steps in this, which have not changed since the last WENRA plenary meeting, are: 2019 develop detailed approach and programme gap analysis draft revised set of RLs 2024 review by ENISS and IAEA, public consultation and approval by WENRA RHWG has discussed the revision criteria and the format of individual reference levels, but has not made much progress on this, pending the outcome of WENRA s strategic review. RHWG is considering pausing any further work on this Safety Objectives for New Nuclear Power Plants For information only. The Safety Objectives for New Nuclear Power Plants includes the statement that WENRA deems these safety objectives should be reviewed no later than 2020 If the review is to be completed by 2020 it needs to be started in the near future. To progress this RHWG has set up a small subgroup to screen the safety objectives to determine whether it believes that they need revision. The work on this has recently been broadened to consider whether the RHWG Report on Safety of New NPP Designs (known as the booklet ) also needs revision. Page 8

9 04 Practical elimination For information only. RHWG has been working on a paper on practical elimination (PE) for some time. At the last meeting I reported that many of the difficulties had been overcome and a way forward identified. A report agreed by the working group was presented at the recent RHWG entitled: Demonstration of Avoidance of Early Releases and Large Releases for New Nuclear Power Plants using the Notion of Practical Elimination Key Elements and Expectations This is currently undergoing written review by RHWG members. The report describes three types of scenario for which the concept of practical elimination can be applied, which it summarises as Type I scenarios with an initiating event that leads directly to severe fuel damage and early failure of the containment function. Type II severe accident scenarios with phenomena that induce early failure of the containment function. Type III severe accident scenarios that result in late failure of the containment function. Some countries apply the concept of practical elimination to all three types of scenario and some only to the first two. The report provides a common understanding of the approach to demonstration of practical elimination, by considering: Demonstration of practical elimination via physical impossibility Demonstration of practical of practical elimination via extreme unlikeliness with a high degree of confidence The role of administrative measures Practical elimination during the lifetime of the plant The programme for this in the annex shows a draft for RHWG consideration in January 2019, ENISS and IAEA comment in Spring 2019 and a proposed date for WENRA approval of November Page 9

10 05 Questionnaire on Reference Level F4.7 For information only. RHWG has undertaken an internal exercise to review how its member countries comply with Reference Level F4.7. Issue F of the Reference Levels is Design Extension of Existing Reactors and Reference Level F4.7 is for heat removal and states: There shall be sufficient independent and diverse means including necessary power supplies available to remove the residual heat from the core and the spent fuel. At least one of these means shall be effective after events involving external hazards more severe than design basis events. The study has now been completed and two documents have been circulated for the WENRA Plenary Meeting: Item 08c WENRARHWG Safety Reference Level F4.7 Results derived from the answers to the related questionnaire to all WENRA countries Item 08d WENRARHWG Safety Reference Level F4.7 Lessons learned from the F4.7 exercise The study used a questionnaire which focused on the principles behind the measures to prevent severe fuel damage in the reactor core in DEC A conditions. To study compliance in detail, the questionnaire went beyond RL F4.7 and included other RLs within Issue F and also Issue T (Natural Hazards). As a result, the questionnaire, which is described in Item 08c, covered a broad range of detailed topics including natural hazards criteria as well as the design of the system itself and its power supply. The results showed a number of common basic features for the means necessary to fulfil RL F4.7, but variations in numerical levels of natural hazard criteria for design extension conditions. The process of designing the questionnaire, providing the responses and evaluating them all took considerable effort and hence RHWG undertook a lessons learnt exercise (item 08d) focusing on the questionnaire. This identified a number of areas where a similar exercise could be improved, but noted that a similar exercise might be very difficult and time consuming. RHWG does not intend to publish the reports from this study. Page 10

11 06 Topical Peer Review on ageing management For information only Following the development of the TPR technical specification, RHWG presented a report that described the development of it to learn any lessons for the next review. WENRA requested that this included the experience of its application to produce the national assessment reports. RHWG produced a questionnaire to go to the national contacts for the TPR and will incorporate any learning from the TPR workshop. At the last RHWG meeting, eleven countries had completed the questionnaire. Work on analysing the results of this is starting and RHWG hopes to be able to discuss them and agree the report at its next meeting. RHWG currently expects to present the results of the questionnaire and ask WENRA for approval of the report at its Spring 2019 meeting. Page 11

12 07 RHWG work programme For information only The RHWG work programme up to 2020 is shown in the annex to this report. This shows that it is expected that: By end 2019, RHWG expects to complete the following o the interim update of the RLs, o the study on practical elimination o work on the TPR specification The RL implementation, ALRP and benchmarking will go on until end of 2020, although this may be optimistic. The only work going beyond 2020 is the periodic review of reference levels. WENRA has yet to decide whether it supports this activity. RHWG will be busy over the next year, but it is not clear how much it will have to do after that. Page 12

13 Annex 2 RHWG activities RHWG activites (September 2018) Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec RH WEN RH WEN RH RH WEN RH WEN RH RH WEN RL implementation & ALARP & benchamark Prepare specification * * Pilot study Prepare draft report RHWG review Finalise reports * * 2 Review and revision of RLs 2.1 Interim update Complete draft of issues to be revised Review and issue update * * 2.2 Periodic review for update 2024 Develop detailed approach Gap analysis Future activities 3 Study on practical elimination Prepare draft report Review and finalise report * * 4 Questionnaire on implementation of F4.7 Review and finalise report * * 5 Topical Peer Review (TPR) on ageing management Completion of questionnaire Feedback from TPR workshop Revise and finalise TPR companion report * * Key RHWG activity * Approval of formal document by RHWG or WENRA Page 13