wolsong-1 stress test · 2018-01-01 · 8 eu stress test eu released its final report (october 4,...

Wolsong-1 Stress Test

June 23, 2014

Geun-Sun Auh

Korea Institute of Nuclear Safety

PHWR Safety 2014/CANSAS-2014

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Table of Contents

1. Stress Test Definition2. EU Stress Test3. Stress Test of Korea4. Wolsong-1 Stress Test

Status of Kori-1 Stress TestPost Fukushima Actions of Wolsong Site (CANDU)Post Fukushima Action Plan of Korea

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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 GroupKINS Homepage (http://voc.kins.re.kr/stresstest/)

Safety Margin Assessment of NPPs against Extreme Events such as Fukushima Daichi Accidents that can challenge safety function of NPPs and initiate severe accidents

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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

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Stress Test Definition for NPPs (Korea)

Status in quo

Augmented Fixed Facilities

Response Strategy

Safety

Margin

Cliff-

Edge

Augmented Movable Facilities

Off-Site Resources

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EU Stress Test

BackgroundFukushima 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) http://www.ensreg.eu/EU-Stress-Tests

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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 http://www.ensreg.eu/EU-Stress-Tests

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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 Systems5 Issues in Severe Accident Management

Each Nation is performing follow-up actionsEach Nation established its Action Plan (December, 2012)EU Peer Reviews on Action Plans (early 2013)To publish Implementation Status Report on June, 2014

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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 HazardsPeriodic 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

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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

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Stress Test of Korea

BackgroundConduct 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.

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ObjectiveTo 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 EvaluatedWolsong 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. 2007 when a license for 10-year continued operation was issued.

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Methodologybased 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 human-decision-making error

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Areas of Stress Test① 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.

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FrameworkThe 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 self-assessment

• Specifications (Regulatory Body)= > Self-Assessment (Operator)=> Adequacy Review

(2 Expert Review Teams of KINS and Non-government)=> Results Determination (NSSC Committees)

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TransparencyAn 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.

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ST Category EU Korea

ItemsEarthquake,Tsunami, Safety Function, Severe Accident

EU +Emergency Response +Operating and Human Factors (e.g., decision making)

StagesUtilities => Regulator=> EU Peer Review

Utilities => KINS + Non-Government => NSSC

Methodologies Deterministic Deterministic + Probabilistic

Guidelines ENSREG ENSREG + KINS which reflects US, Japan, IAEA, etc.

3rd Party Review Peer Review by EU Nations

Non-Government Review Team

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Assessment ScopeAssume 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 walk-down.

• Extreme natural disasters (earthquakes/tsunami/storm surge) have a return period of one in 10,000 years.

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(Area 1) Safety of SSCs against EarthquakesAdequacy 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

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(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 ManagementProvisions to maintain core cooling, containment integrity and spent fuel pool cooling, and to manage a severe accident resulting from loss of safety functions

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(Area 5) Emergency Preparedness and ResponseIntegrity 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

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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 cliff-edge effects occur, give an evaluation of minimization of human and/or decision-making errors that may accompany use of diverse components and equipment’s.

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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.

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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)

http://voc.kins.re.kr/stresstest/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)

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Wolsong 1 and Kori 1 Stress Test (KHNP Results)

Area KHNP Results (under Review)

Earthquake(10,000yr freq.)

- 0.28g(Wolsong-1), 0.21g(Kori-1)- Plant Safety Function up-to 0.3g

Tsunami(10,000yr freq.)

- 8.72m < 12m(Wolsong-1 ground level)- 8.66m < 10m(Kori-1 sea wall)

Safety Function- Plant Safety Function using on-site fixed &movable facilities, and off-site supports

- Need movable sea-water pumps, etc.

Severe Accidents- Need more mobile generators and mobile pumps against multi-unit accidents- Need to have Severe Accident Technical Advisory Group (“STAG”)

Emergency Response

- Improve off-site Dose Exposure Evaluation Computer Code against multi-unit accidents- Improve Habitability of on-site Emergency Response Facilities

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Important IssuesFacilities 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)

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Future PlanUnofficial 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 CommitteeReview and Approval by NSSC Commission

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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 Reviewxx KINS Experts (to be determined)

Non-government Team ReviewTeam Establishment of yy People (under discussion starting on March 25, 2014)

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Post Fukushima Action of Wolsong Site (CANDU)

No. Action Items Scheduled timeline

1 Installation of automatic seismic trip system 2013

2* Seismic performance improvement of safety shutdown andshutdown cooling system

2015(2014)(2012)

3 Study on maximum earthquakes in nuclear power plant site 2013

4* Improvement of seismic performance of earthquake alarm window in main control room

2013(2012)

5 Improvement of seismic performance of Wolsong site entrybridge 2012

6 Installation of watertight doors and waterproof drainpumps 2015(2014)

7 Study on design criteria for sea level at nuclear powerplant site 2013

8 Reinforcement of cooling water intake and improvement offacilities in case of tsunami 2015

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No. Action Items Scheduledtimeline

9* Securing of mobile generator vehicles and electric batteries etc. 2015(2014)(2012)

10 Anchoring of spare power transformersImprovement of fuel injection facility for EPS 2012

11 Change of SWYD facility ownership for operation and maintenance 2013

12 Setting safety measures in case of cooling function failure of SFP 2012

13 Flood prevention and restoration of ultimate heat sink facilities 2013

14 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 2012

17 Improvement of fire protection equipment 2015


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18 PAR installation in containment building 2014(2013)

19* Installation of vent or depressurizing facility in containment building 2015(2012)

20* Installation of external injection loop for emergency cooling water for reactor

2015(2012)

21 Strengthening of education and training for severe accident 2011

22 Revision of SAMG for increasing effectiveness of accident management strategy 2012

23 Development of SAMG for lower power operation during shutdown period 2012

24 Securing additional radiation protection equipment for residents near nuclear power plant 2012

25 Revision of radiological emergency response plan to include multi-unit accident 2011

26 Securing additional emergency equipment in case of long-term issue 2012


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27 Improvement of radiological emergency response drill 2013

28 Acquisition of essential information in case of long-term power loss 2013

29 Arrangement of protection plan for maintenance workers 2012

30 Improvement of emergency response facility 2015

31 Revision of procedure for information release to public in case of radiological emergency 2012

32 Assessment of protection measures for population outside emergency planning zone 2014

33 Improvement of emergency alarm system performance 2014

34 Drastic reinforcement of safety inspection such as periodic inspection 2012


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35 Management of performance parameters for main active components 2012

36 Reliability enhancement of trip related equipment 2012

37 Strengthening of purchasing quality assurance system check 2011

38 Performance-Oriented Fire Protection Design 201239 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)

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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

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Thank You for your Attention

wolsong-1 stress test · 2018-01-01 · 8 eu stress test eu released its final report (october 4,...

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