Actions taken in WANO-Moscow Centre to incorporate lessons learned from Fukushima Accident

Transcription

1 Actions taken in WANO-Moscow Centre to incorporate lessons learned from Fukushima Accident Sergey Vybornov Adviser, peer review programme World Association of Nuclear Operators Moscow Centre Technical Meeting on Novel Design and Safety Principles of Nuclear Power Plants IAEA Headquarters, Vienna, Austria 3 6 October 2016

2 Contents Actions taken among WANO members to prevent severe accidents and mitigate their consequences Changes in WANO peer reviews with focus on design vulnerabilities of existing plants 2

3 What is WANO Mission of the World Association of Nuclear Operators is to maximise the safety and reliability of nuclear power plants worldwide by working together to assess, benchmark and improve performance through mutual support, exchange of information, and emulation of best practices. Four main programmes: Operating experience exchange Technical and professional development Technical support and exchange of technical information Peer reviews 3

4 Lessons learned from Fukushima 4

5 SEVERE ACCIDENT MANAGEMENT PROJECT 5

6 WANO SAM Project: Background WANO Post-Fukushima Commission: The full focus of WANO since its formation has been accident prevention, and no procedures were in place to address nuclear response or mitigation. We have to shift from a focus on accident prevention to a focus on both prevention and mitigation. Recommendation No.1 resulted in the launching of the SAM Project. Overall responsibility for the SAM Project was delegated to the WANO Moscow Centre. 6

7 SAM project The purpose of the SAM Project was to: expand the scope of WANO programmes to include severe accident management establish a worldwide standard for performing station and corporate assessments in the area of severe accident management 7

8 SAM project As a result SAM Performance Objectives and Criteria (SAM PO&Cs) were developed and were supposed to be used during station peer reviews to review readiness of nuclear plants to manage beyond-design-basis and severe accidents. The SAM PO&Cs are a set of the following three performance objectives, with corresponding criteria: SAM.1: SAM MANAGEMENT AND LEADERSHIP SAM.2: SEVERE ACCIDENT MANAGEMENT PROGRAMME SAM.3: SEVERE ACCIDENT RESPONSE 8

9 SAM project Decision was made that all WANO member utilities/stations should carry out self-assessments. Self-assessments have been conducted for WANO member stations worldwide (Final report issued on 30 August 2015 ). Question: Are Severe Accident Management programs adequate: to provide effective direction and coordination of mitigation strategies to prevent the escalation of a beyond-design-basis event into a severe accident, to mitigate the consequences of a severe accident and achieve a long-term safe stable state if a severe accident has occurred. 9

10 Results of self-assessment Overall results: members meet most standards and are prepared to manage severe accidents effectively. However: Some not adequately provided with equipment and facilities (mobile emergency equipment to ensure long-term heat removal from the core and from spent fuel, equipment for in-containment hydrogen suppression, alternative paths for water supply, seismic protection of systems, structures and components, etc. Development of SAMGs and other documentation for severe accident response has not been completed. Sufficient capability is not ensured to manage severe accidents, including multi-unit events, from protected emergency control centres both during the design-basis phases and during prolonged events. Weaknesses in SAM training (simulator training, drills for SAM, handover of command and control during prolonged events, relief/rotation, communication, multiple-unit drills. 10

11 SAM self-assessment SAM Performance Objectives Implementation, WANO MC Performanc e Objective Category Number of Stations SAT AI UNSAT SAM.1 SAM.2 SAM MANAGEMENT AND LEADERSHIP SEVERE ACCIDENT MANAGEMENT PROGRAM Source: WANO-MC Director presentation WANO Post-Fukushima Severe Accident Management Project SAM.3 SEVERE ACCIDENT RESPONSE

12 Further steps revise the SAM PO&Cs based on the self-assessment results and comments from the members incorporate the revised SAM PO&Cs in the WANO PO&Cs make arrangements to review SAM on peer reviews proceed with adding SAM to the scope of WANO programmes and activities. 12

13 DESIGN INFORMED PEER REVIEWS 13

14 Design informed peer reviews WANO s mission is to maximise the safety and reliability of nuclear power plants ; for achieving this mission, it is very important to have in mind that nuclear safety of a plant strongly depends on two fundamentals: the design phase which results in the definition of the Design Basis and Beyond Design basis considerations of the plant, the operation phase which corresponds to the day-by-day life of the plant. The Design Project has been established by the 2011 with the mandate to provide recommendations to extend the scope of WANO activities to include some aspects of Design. The Design Project Design-Informed Peer Reviews = More global appreciation of the nuclear safety of a plant 14

15 Objectives of the Design Informed Peer Reviews To appreciate the nuclear safety performance of the plant taking into account the main characteristics of the design, To ensure potential design vulnerabilities are known and managed by the plant, To evaluate whether the Fundamental Safety Functions (control of reactivity, removal of heat from the reactor core and from the spent fuel, confinement of radioactive material), are challenged or not by the plant operation performance. As a result: More focused peer review teams An analysis of the available data in terms of safety function performance 15

16 Extreme Meteorological / Hydrological Conditions Seismic Design Information Survey (DIS) P1 Generic questions P2 External Events P3 Control of reactivity P4 Confinement P5 Heat Removal P6 Emergency Power supply P7 Monitoring of plant parameters Unit: X External Events Station name Is this event considered as Design Basis, Design If the event is not taken into Extension Condition, account for your station, Beyond Design Basis or explain why. not relevant for the station? Specify the Design Basis limit values and the duration for the specific event where appropriate and give a reference (e.g. maximum water (wave) height / temperature; frequency and acceleration; liquid equivalent, etc.). Provide the maximum values for which it is proven that the plant is protected against, if different from previous question (e.g. maximum water (wave) height / temperature; duration; frequency and acceleration; liquid equivalent, etc.) Has such an event occurred which challenged safety functions at your station since erection? If yes, provide the event code and characteristic value (e.g. Max. water height / temperature; duration; frequency and acceleration; liquid equivalent; etc. Did the Design Basis Limit values change since the plant was built? (Was the event originally foreseen for the station?) Earthquake Extreme air temperature (high and low) Extreme humidity / Drought Lightning Heavy Rain 16 WANOPC TG - 16 Dr. Mori

17 Probabilistic Safety Assessment Survey (PSAS) Initiating events and operational modes. Identifies the systems and components of higher importance 17 WANOPC TG - 17 Dr. Mori

18 Safety Function Examination (SaFE) A-B-C-X - Excel spreadsheets: facts and conclusions grouped for Safety functions 18

19 Results for the peer review team This information is then used in order to: Determine areas that might warrant particular focus of the peer review team, Highlight some priorities for the on-site Peer Review, Evaluate the potential cumulating challenge to Fundamental Safety Functions. DiPR were conducted for several technologies: BWR (different types), PWR (different types), PHWR, AGR, VVER Target: in 2019 all 100% member stations will host design informed peer reviews 19

20 Feedback from the customers Station A: Valuable feedback. The DiPR has identified aspects that need to be reconsidered before [ ] implementing any modifications, not necessarily design modification. Station B: The analysis shows that the DiPR analysis added value to the existing process by identifying gaps in safety function performance that were not otherwise identified by the peer review. Station C: Station has not got inputs and additional questions on design resulted from the peer review. Vienna, Austria October WANOPC

21 Conclusions The methodology has proved to be robust and valuable: New approach provides new insights e.g. aggregation of small gaps that can result in a cumulative challenge. Independent review provides a new perspective e.g. margin assessments for unexpected conditions. Results can be used to inform or validate decision making on e.g. capital projects, modifications, safety reviews 21

22 QUESTIONS??? WANO Moscow Centre Tel: Fax: Web: Sergey Vybornov Tel: Vienna, Austria. 3 6 October 22