Ml120600599 - Overview of u.s. Nrc Pra

7/31/2019 Ml120600599 - Overview of u.s. Nrc Pra

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Overview of U.S. NRC PRA

Kevin CoyneProbabilistic Risk Assessment Branch

Office of Nuclear Regulatory Research

US Nuclear Regulatory Commission

13thAnnual Meeting of WGRisk

March 7-9, 2012


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Presentation Outline

Overview of Key Research Projects

Emerging Focus Areas

Fukushima Res onse

Recent Publications

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Overall PRA Research Goals

Support the reactor oversight and operating

experience programs.

Using risk-informed approaches to improve the

effectiveness and efficiency of regulation.

Expand PRA infrastructure to encompass new

and advanced reactor concepts and designs.

Support continuous advancement in PRA state-of-the-art and state-of-practice.

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Supporting Reactor Oversight

SPAR Focus Areas in the Coming Year

Other hazard and NFPA-805 fire models.

Support system initiating events.

Inte rated ca abilities model.

One SPAR model with all modes/hazards/levels that SPARcurrently covers.

Confirmatory success criteria analysis 4-loop Westinghouse plant.

Resolution of ASME peer review findings and

observations.

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Supporting Reactor Oversight

(cont.)

Common-Cause Failures (CCF) in Event

Assessment Draft NUREG-XXXX, Common-Cause Failure

Analysis in Event and Condition Assessment:

,

(ML111890290).

Topics treated in the NUREG include: Treatment of CCF potential conditioned upon an observed

component failure. Limitations of current CCF modeling and issues with alpha-factor

estimates.

Future research needed for data collection, parameter estimation

and casual models.

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Improving Effectiveness: PRA

Standards

PRA standards under development:

Level 1 (CDF) and LERF for low power and shutdownconditions addressing both internal and external hazards for

operating LWRs.

Level 1 (CDF) and LERF for at-power conditions addressing

both internal and external hazards for LWRs in design stage(pre-operational).

Level 2 for at-power conditions addressing both internal and

external hazards for operating and advanced LWRs.

Level 3 for all operating modes, all hazards, and both lightwater and non-light water reactors.

Level 1 and Level 2 for all operating modes addressing both

internal and external hazards for non-light water reactors.

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Improving Effectiveness: PRA

Standards (cont.)

NEI has develop/developing peer review guidance NEI 00-02/NEI 05-04 addresses Level 1/LERF for at-power

conditions for operating LWRs for internal events and internalflood.

NEI 07-12 address Level 1/LERF for at-power conditions for

o eratin LWRs for internal fires.

NEI developing guidance for seismic PRA for Level 1/LERF forat-power conditions.

PRA Standards and peer review guidance

endorsed in RG 1.200. NRC issuing Interim Staff Guidance documents providing

interim staff endorsement on updates to the standard until next

revision.

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Improving Effectiveness: Fire

Research Fire PRA and HRA

NFPA-805 Support - NRC/EPRI Training (2 classes/year):

July 1620, 2012 (Washington DC Area).

September 2428, 2012 (Washington DC Area).

NUREG-1921, Fire HRA, Summer 2012.

Fire Modeling

- , uc ear ower an re o e ng pp ca on u e, ummer .

Fire and Electrical Systems Circuit Analysis

NUREG/CR-7100, Direct Current Electrical Shorting in Response to Exposure Fire

(DESIREE-Fire): Test Results, Summer 2012.

Electrical Circuit Phenomena PIRT in progress.

Fire Testing

NUREG/CR-7115, Performance of Metal and Polymeric O-Ring Seals in Beyond-Design-

Basis Temperature Excursions, in publication; expected in April.

NUREG/CR-7010, Cable Heat Release, Ignition, and Spread in Tray Installations During

Fire (CHRISTIFIRE), Spring 2012.

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Emerging Focus Areas

Investigate risk-informed Emergency Action

Levels (NUREG Report under development).

Support spent fuel pool limited-scope

consequence study.

Continued work in dynamic event tree Level 1

and Level 2 PRA.

Evaluating options for more holistic risk-informed, performance-based regulatory

approach (February 11, 2011 Tasking Memo).

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Spent Fuel Pool Scoping Study

Focus: reexamination of the potential

advantages associated with moving older fuel

stored in the SFP to dry cask storage in an

expedited manner.

deliberations and external stakeholder interest. The project isusing:

Available information/methods.

A representative operating cycle for a BWR Mark I.

Past studies to narrow scope.

Plan finalized in July 2011.

Study to be completed by Summer 2012.

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Site Level 3 PRA

Commission directed the staff to perform a full-

scope comprehensive site Level 3 PRA for an

operating plant. Staff engaged nuclear industry; Vogtle, Units 1 and 2,

volunteered for study (4-Loop Westinghouse PWR).

Objectives: Reflect technical advances in PRA modeling and improvements

in plant operations, safety, and security.

Enhance PRA scope and capability. Extract new insights to enhance regulatory decision-making.

Evaluate feasibility and cost of Level 3 PRAs.

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Site Level 3 PRA (cont.)

In general, based on current state of practice.

Scope includes main site radiological sources, allinternal and external initiating events, and all

modes of operation.

e s u y w e or a s ng e mu -un s e og e,Units 1 and 2).

Study to be completed over a 4-year period.

Currently developing project plans, securingcontractor support, collecting and assessing

information on current state-of-practice.

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Fukushima Follow-Up: Key

Documents SECY-11-0093 (July 12th) and SRM (August 19th), Near-Term Report

and Recommendations for Agency Actions Following the Events in

Japan.

SECY-11-0117 (August 26th) and SRM (October 19th) Proposed Charter

for the Longer-Term Review of Lessons Learned from the March 11, 2011,

Japanese Earthquake and Tsunami.

SECY-11-0124 (September 9th) and SRM (October 18th),

Recommended Actions to be Taken Without Delay from the Near-Term

Task Force Report a.k.a. the 21 day paper.

SECY-11-0137, October 3rd, Prioritization of Recommended Actions to

be Taken in Response to Fukushima Lessons Learned a.k.a. the 45

day paper.

SECY-12-0025, Proposed Orders and Requests for Information in

Response to Lessons Learned from Japan's March 11, 2011, Great

Tohoku Earthquake and Tsunami.

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Fukushima Follow-Up

SECY-11-0137 contains staffs prioritization of

the NTTF recommendations. Tier 1 Start without delay.

Tier 2 Start in the near term.

Tier 3 Longer term actions.

SECY-12-0025 contains draft orders and

response to previous Fukushima items. Draft orders on Mitigating Strategies for Beyond-Design-Basis

External Events, Hardened and Filtered Vents (Mark I and IIBWRs), and Spent Fuel Pool Instrumentation.

Draft 50.54(f) letter - External Hazards Reevaluation.

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Recently-Issued Reports

NRC Staff Reports

NUREG-1935, State-of-the-Art Reactor ConsequenceAnalyses (SOARCA) Report, Draft for Comment

(comment period ended March 1, 2012).

- , -

Analysis to Support Specific Success Criteria in the

Standardized Plant Analysis Risk ModelsSurry and

Peach Bottom, September 2011.

NUREG-2115, Central and Eastern United StatesSeismic Source Characterization for Nuclear Facilities,

January 2012.

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Recently-Issued Reports (cont.)

NRC Contractor Reports NUREG/CR-7004, Technical Basis for Regulatory Guidance on Design-Basis

Hurricane-Borne Missile Speeds for Nuclear Power Plants, November 2011.

NUREG/CR-7005, Technical Basis for Regulatory Guidance on Design-Basis

Hurricane Wind Speeds for Nuclear Power Plants, November 2011.

- , a e-o - e- r eac or onsequence na yses ro ec ,

January 2012.

NUREG/CR-7114, Methodology for Low Power/Shutdown Fire PRA, Draft for

Comment (comment period ended March 1, 2012).

NUREG/CR-7039, Systems Analysis Programs for Hands-on Integrated

Reliability Evaluations (SAPHIRE) Version 8: Technical Reference, June 2011.

NUREG/CR-7046, Design-Basis Flood Estimation for Site Characterization at

Nuclear Power Plants in the United States of America, November 2011.

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Recently Issued Regulatory Guides

RG 1.174, An Approach For Using Probabilistic Risk

Assessment In Risk-Informed Decisions On Plant Specific

Changes To The Licensing Basis, May 2011.

RG 1.177, An Approach For Plant-specific, Risk-informed

Decision-Making: Technical Specifications, May 2011.

RG 1.221, Design-Basis Hurricane and Hurricane Missilesfor Nuclear Power Plants, October 2011.

DG-1278, proposed Revision 3 to RG 1.160, Monitoring the

Effectiveness of Maintenance at Nuclear Power Plants,issued in September 2011, comment period closed, soon to

be issued as final.

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