Wolsong-1 Stress Test

Transcription

1 PHWR Safety 2014/CANSAS-2014 Wolsong-1 Stress Test June 23, 2014 Geun-Sun Auh Korea Institute of Nuclear Safety

2 Table of Contents 1. Stress Test Definition 2. EU Stress Test 3. Stress Test of Korea 4. Wolsong-1 Stress Test Status of Kori-1 Stress Test Post Fukushima Actions of Wolsong Site (CANDU) Post Fukushima Action Plan of Korea 2

3 Stress Test Definition for NPPs Comprehensive and Transparent Risk and Safety Assessment ( European Council ) Targeted Safety Margin Re-assessment ( ENSREG ) ENSREG : European Nuclear Safety Regulators Group KINS Homepage ( Safety Margin Assessment of NPPs against Extreme Events such as Fukushima Daichi Accidents that can challenge safety function of NPPs and initiate severe accidents 3

4 Stress Test Definition for NPPs (Korea) 10,000 yr frequency Earthquake : PSA Method & SMA Method Tsunami : Increase sea water level Adequacies of Essential SCC s => Augment Facilities Response Capability Evaluation - Scenario Based Evaluation with Severe Natural Hazards - Coping of SBO and Ultimate Heat Sink Loss Cooling Capabilities of Core and Spent Fuel Pool Emergency Preparedness and Response Multi-Unit Events Habitability of Emergency Response Facilities 4

5 Stress Test Definition for NPPs (Korea) Response Strategy Safety Cliff- Edge Status in quo Margin Augmented Fixed Facilities Augmented Movable Facilities Off-Site Resources 5

6 EU Stress Test Background Fukushima Daichi Accidents (March 11, 2011) European Council s requested (March 25, 2011) Stress Test Scope and Method for EU NPPs to European Commission and ENSREG utilizing WENRA (Western European Nuclear Regulators Association) Technical Opinion WENRA proposed Stress Test Specifications (April 21, 2011) Stress Test Scope and Method per WENRA Task Force Team ENSREG accepted WENRA Specifications (May 13, 2011) 6

7 EU Stress Test 15 EU Nations and 2 voluntary Nations of Swiss and Ukraine stress-tested their NPPs Step I : Utilities' Assessment (about 4-5 months) Step II : Regulator Assessment (about 2 months) Step III : Peer Review (about 3 months) Review Team comprised of EU and Regulators of participating Nations (70 people of 24 nations) EU Stress Test Homepage 7

8 EU Stress Test EU released its Final Report (October 4, 2012) 10 Issues in 3 Areas : 4 Issues in External Hazards (Earthquake, Flooding, etc.) Minimum 0.1g for design basis earthquake 1 Issue in Safety Function of Safety Systems 5 Issues in Severe Accident Management Each Nation is performing follow-up actions Each Nation established its Action Plan (December, 2012) EU Peer Reviews on Action Plans (early 2013) To publish Implementation Status Report on June,

9 EU Stress Test Summary Report of ENSREG (April 26, 2012) WENRA should prepare evaluation guidelines on Cliff-Edge Effect, Margin Assessments on Beyond Design Basis and Natural Hazards Periodic Re-assessment of 10 years on Natural Hazards Final Report of ENSREG (October 4, 2012) External Hazards (4) 10,000yr frequency for earthquake and flooding Minimum 0.1g for design basis earthquake Protected areas for emergency response equipment's Earthquake measurement instruments in NPPs 9

10 EU Stress Test Final Report of ENSREG (October 4, 2012) Safety Function of Safety Systems (1) Rapid Electric Power Restoration Severe Accident Management (5) EOP s from Full Power to Shutdown Operation SAMG s for all operating modes PAR s within Containment Vessel Containment Filtered Venting Facilities Emergency Control Room Habitability 10

11 Stress Test of Korea Background Conduct a stress test for nuclear power plants in long-term operation to practice a national philosophy (President Park's campaign pledge) that puts public safety first <President's Campaign Pledge> Conduct EU-style stress tests to limit long-term operation of nuclear power plants strictly and decide on the decommissioning of Kori 1 and Wolsong 1. <= Execute a safety policy for plants in long-term operation that puts public safety first. 11

12 Stress Test of Korea Objective To evaluate plant response to large-scale natural disasters exceeding design basis as a way to strictly reassess the safety of nuclear plant in long-term operation. Plants to be Evaluated Wolsong Unit 1 (under review for continued operation) and Kori Unit 1 (in continued operation) (Wolsong Unit 1) PHWR 679 MWe / shut down after its design life expired on Nov. 20, 2102 and under review for continued operation (Kori Unit 1) PWR 587 MWe / in continued operation since Dec when a license for 10-year continued operation was issued. 12

13 Stress Test of Korea Methodology based on EU-style stress tests undertaken after the Fukushima accident. A comprehensive safety assessment in consideration of safety measures taken by the IAEA/USA/Japan and findings identified by international environmental groups (e.g. Greenpeace) In addition to the scope of EU Stress Test, the comprehensive safety assessment including emergency response and using probabilistic method that includes the analysis of wide area fire and the assessment of accident expansion due to a humandecision-making error 13

14 Stress Test of Korea Areas of Stress Test 1 Earthquake 2 Tsunami, Storm Surge and Other Natural Disasters 3 Loss of Electrical Power & Loss of the Ultimate Heat Sink 4 Severe Accident Management 5 Emergency Response Component Integrity, Operating and Human factors, Cliff- Edge Effects will be evaluated from various perspectives. 14

15 Stress Test of Korea Framework The safety regulatory body develops and presents stress test specifications and the operator performs a self-assessment and expert teams review the adequacy of results of selfassessment Specifications (Regulatory Body) = > Self-Assessment (Operator) => Adequacy Review (2 Expert Review Teams of KINS and Non-government) => Results Determination (NSSC Committees) 15

16 Stress Test of Korea Transparency An opinion collection system (e.g. Homepage) is established and implemented across the process and reports will be produced at each stage and made available to the public Stress test specifications are made public and a public hearings and presentation will be held. Information on stress tests will be transparently disclosed across the process at a separate website. Considering high public interest, expert team from the private sector including ones recommended by local communities participates in the expert review process. A presentation on the results of stress tests will be provided to form a public consensus. 16

17 Stress Test of Korea 17

18 Stress Test of Korea ST Category EU Korea Items Stages Earthquake, Tsunami, Safety Function, Severe Accident Utilities => Regulator=> EU Peer Review EU + Emergency Response + Operating and Human Factors (e.g., decision making) Utilities => KINS + Non-Government => NSSC Methodologies Deterministic Deterministic + Probabilistic Guidelines ENSREG ENSREG + KINS which reflects US, Japan, IAEA, etc. 3 rd Party Review Peer Review by EU Nations Non-Government Review Team 18

19 Stress Test of Korea Assessment Scope Assume scenarios that involve occurrence of earthquake/tsunami/storm surge beyond design basis => Loss of safety functions due to loss of electrical power and/or loss of the ultimate heat sink => Large-scale Accident Aging management is comprehensively assessed based on aging management evaluation made for the review of continued operation as well as seismic margin assessment and plant walkdown. Extreme natural disasters (earthquakes/tsunami/storm surge) have a return period of one in 10,000 years. 19

20 Stress Test of Korea (Area 1) Safety of SSCs against Earthquakes Adequacy of design basis earthquake, Inspection of seismic class components, Range of earthquake severity below which safety functions remain available, Plant response to wide area fire induced by an earthquake (Area 2) Safety of SSCs against Tsunami, Storm Surge and Other Natural Disasters Adequacy of design basis flooding, Inspection of flood protection equipment, Maximum flooding level above which loss of safety functions becomes unavoidable, and Impact of strong wind (tornado) and water temperature rise 20

21 Stress Test of Korea (Area 3) Plant Response to Loss of Electrical Power and/or Loss of the Ultimate Heat Sink Plant response such as accident scenarios involving loss of off-site power, station black out (SBO) and loss of the ultimate heat sink (UHS), and duration time of backup power sources (Area 4) Severe Accident Management Provisions to maintain core cooling, containment integrity and spent fuel pool cooling, and to manage a severe accident resulting from loss of safety functions 21

22 Stress Test of Korea (Area 5) Emergency Preparedness and Response Integrity of communication system in case of a prolonged SBO, Capability to monitor and measure environmental radiation and dose Adequacy of emergency organization and commend & control system 22

23 Stress Test of Korea Framework (Step I) Self-Assessment by KHNP To assess the integrity and response of structures, systems and components (SSCs) and indicate measures to prevent cliff edge effects in accordance with the specifications In addition to quantitative results such as time lapsed before cliffedge effects occur, give an evaluation of minimization of human and/or decision-making errors that may accompany use of diverse components and equipment s. 23

24 Stress Test of Korea Framework (Step II) Adequacy Review by Review Teams Technical review of the results of self-assessment (including plant walk-down). Includes expert review team composed of locally recommended experts, outside experts in efforts to ensure objectivity and reliability. Non-governmental review team across the process (Step III) Reporting of the Results of Stress Tests Report the results of self-assessment by the operator and the results of reviews by the review teams to the NSSC Committees. For safety improvement measures identified, decide on future plans and progress-check the status of implementation regularly. 24

25 Stress Test of Korea 25

26 Wolsong-1 Stress Test Draft KINS Stress Test Specifications (April 18, 2013) After reviews by external experts, KHNP and research institutions Final Stress Test Specifications to KHNP (April 30, 2013) KHNP Stress Test Report to NSSC/KINS (July 12, 2013) which includes Review Results of TUV-SUD (German Firm) KINS Team started Review (July 12, 2013) 47 KINS Experts Non-government Team started Review (August 20, 2013) Team Establishment of 19 People (August 9, 2013) 26

27 Wolsong 1 and Kori 1 Stress Test (KHNP Results) Area Earthquake (10,000yr freq.) Tsunami (10,000yr freq.) Safety Function Severe Accidents Emergency Response KHNP Results (under Review) g(Wolsong-1), 0.21g(Kori-1) - Plant Safety Function up-to 0.3g m < 12m(Wolsong-1 ground level) m < 10m(Kori-1 sea wall) - Plant Safety Function using on-site fixed & movable facilities, and off-site supports - Need movable sea-water pumps, etc. - Need more mobile generators and mobile pumps against multi-unit accidents - Need to have Severe Accident Technical Advisory Group ( STAG ) - Improve off-site Dose Exposure Evaluation Computer Code against multi-unit accidents - Improve Habitability of on-site Emergency Response Facilities 27

28 Wolsong-1 Stress Test Important Issues Facilities for Severe Accidents (e.g., performances of CFVS and PAR) Multi-Unit Accidents (e.g., more mobile generators/pumps) KHNP Response Capabilities against Severe Accidents (e.g., STAG) Habitability of Emergency Response Facilities (e.g., seismic isolation building) Long-Term Accident Measures (e.g., core cooling and liquid waste treatment for long-term) 28

29 Wolsong-1 Stress Test Future Plan Unofficial Reporting to NSSC Commissioners on Interim Review Results (April 21, 2014) Non-government Review Team Interim Report (e.g., Maximum Earthquake, Facilities for Severe Accidents) Open House Meeting to report to Wolsong Area Residents by KINS/Non-government Team (June 18, 2014) Integrated Review Report of KINS/Non-government Team 8 Members of Integrated Team (4 from each team) Review by NSSC Advisory Committee Review and Approval by NSSC Commission 29

30 Kori-1 Stress Test Draft KINS Stress Test Specifications (April 18, 2013) After reviews by external experts, KHNP and research institutions Final Stress Test Specifications to KHNP (April 30, 2013) KHNP Stress Test Report to NSSC/KINS (Dec. 20, 2013) which includes Review Results of TUV- Rheinland (German Firm) KINS Team Review xx KINS Experts (to be determined) Non-government Team Review Team Establishment of yy People (under discussion starting on March 25, 2014) 30

31 Post Fukushima Action of Wolsong Site (CANDU) No. Action Items Scheduled timeline 1 Installation of automatic seismic trip system * Seismic performance improvement of safety shutdown and shutdown cooling system 2015(2014) (2012) 3 Study on maximum earthquakes in nuclear power plant site * Improvement of seismic performance of earthquake alarm window in main control room Improvement of seismic performance of Wolsong site entry bridge Installation of watertight doors and waterproof drain pumps Study on design criteria for sea level at nuclear power plant site Reinforcement of cooling water intake and improvement of facilities in case of tsunami 2013 (2012) (2014)

32 Post Fukushima Action of Wolsong Site (CANDU) No. Action Items 9* Securing of mobile generator vehicles and electric batteries etc. 10 Anchoring of spare power transformers Improvement of fuel injection facility for EPS Scheduled timeline 2015(2014) (2012) Change of SWYD facility ownership for operation and maintenance Setting safety measures in case of cooling function failure of SFP Flood prevention and restoration of ultimate heat sink facilities Installation of protective barrier for outdoor tanks 2015(2014) 15 Supplementation of flooding preventive facilities for MSSV room and EWS pump room 2015(2014) 16 Improvement of firefighting plan and strengthening of a cooperative system Improvement of fire protection equipment

33 Post Fukushima Action of Wolsong Site (CANDU) No. Action Items Scheduled timeline 18 PAR installation in containment building 2014(2013) * Installation of vent or depressurizing facility in containment building (2012) Installation of external injection loop for emergency cooling water * for reactor (2012) 21 Strengthening of education and training for severe accident Revision of SAMG for increasing effectiveness of accident management strategy Development of SAMG for lower power operation during shutdown period Securing additional radiation protection equipment for residents near nuclear power plant Revision of radiological emergency response plan to include multiunit accident Securing additional emergency equipment in case of long-term issue

34 Post Fukushima Action of Wolsong Site (CANDU) No. Action Items Scheduled timeline 27 Improvement of radiological emergency response drill Acquisition of essential information in case of long-term power loss Arrangement of protection plan for maintenance workers Improvement of emergency response facility Revision of procedure for information release to public in case of radiological emergency Assessment of protection measures for population outside emergency planning zone Improvement of emergency alarm system performance Drastic reinforcement of safety inspection such as periodic inspection

35 Post Fukushima Action of Wolsong Site (CANDU) No. Action Items Scheduled timeline 35 Management of performance parameters for main active components Reliability enhancement of trip related equipment Strengthening of purchasing quality assurance system check Performance-Oriented Fire Protection Design AAC DG Design Basis Improvement 2014 Note) * : Shorten scheduled timeline for Wolsong-1 (5) Green : Items planned to finish before Wolsong-1 CO (23+1) Red : Scheduled timeline of Wolsong-1 (5) 35

36 Post Fukushima Action Plan of Korea Action items of the Fukushima lessons learned program (June 2011) 50 items, recommended by a Special Task Team (regulatory staff + experts) 10 additional items addressed by the licensee through their own voluntary self assessment Current Status 36 of 50 action items have been implemented by KHNP so far 22 items were reviewed by NSSC and KINS The remaining 14 items are being addressed by KHNP Effectiveness for all 50 items to be reviewed, additional action items to be raised by the end of 2014, and actions to be started in 2015 Additional action items to be drawn after reviewing overseas experiences 36

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38 Thank You for your Attention 38