ML11228A231

State-of-the-Art Reactor Consequence Analyses (Soarca); Semi-Annual Briefing for Commission Tas

ML11228A231
Person / Time
Site:	Peach Bottom, Surry
Issue date:	08/13/2009
From:	NRC/OCM
To:
References
FOIA/PA-2011-0083
Download: ML11228A231 (18)

Text

U US.NRC UNITED STATES NUCLEAR REGULATORY COMMISSION Protecting People and the Environment State-of-the-Art Reactor Consequence Analyses (SOARCA)

Semi-Annual Briefing for Commission TAs August 13, 2009 OF 9 AL

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Presentation Outline

" Status of Project

° Peer Review

" Upcoming Dates

" Communications Activities 9 Seismic (EP) Study OF AL ONLY -

NSIT ER LIN M

ION 2

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Status of Project

• Accomplishments since last (4/17/2009)

- Seismic (EP) study for Peach TA briefing Bottom and Surry

- Draft NUREG

- SRA Webinar Held 7/20/2009

- First Peer Review Committee Meeting Challenges

- Aggressive schedule to meet WITS Due Dates

- Staff continuity and available expertise e Sequoyah analysis is on hold Differing technical views remain "Fl L6S ONL- -SE ýSITýIVE

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Review of Draft ExecutiveSummary Differing technical views were not considered in the Executive Summary included with SECY-09-0045

- Met with staff to review comments

- Revised Executive Summary provided to Peer Review Committee July 2nd Draft provided to DEDMRT and management steering committee

• Work continues on revisions

• Engaging Peer Review Committee with subset of issues 0

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Management Steering Committee

• Met with steering committee July 2 2 nd

- Provided revised draft Executive Summary

- Summarized and discussed comments

• Steering committee suggested engaging the Peer Review committee

- Members to provide suggestions on which issues to provide for Peer Review

• May add Regional Representation FFI S

ONLY NSITIV N

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Peer Review

" Chair Karen Vierow (Associate Professor, Nuclear Engineering, Texas A&M)

PRA Sequence Selection & Mitigative Measures Bruce Mrowca (ISL)

Ken Canavan (EPRI)

Accident Progression and Radiological Release Bernard Clement (IRSN)

Robert Henry (Fauske and Associates)

Jeff Gabor (ERIN Engineering)

Offsite Radiological Consequences Kevin O'Kula (Washington Safety Management Solutions LLC URS Corporation -

Washington Division)

Dave Leaver (WorleyParsons Polestar)

Emergency Preparedness Roger Kowieski (Natural and Technological Hazards Management Consulting, Inc.)

Structural-Failure (Seismic) Expert John Stevenson (JD Stevenson Consulting Engineer)

Health Effects Jacquelyn Yanch (Professor, Nuclear Engineering, MIT)

OFI AL S NL-S SVE ITE N I

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Peer Review Charter

• Requesting individual input

- Non-FACA committee - no consensus sought

• Seeking review to "...insure that the study is best estimate and technically sound."

• Specifically requesting review of the robustness of conclusions and Executive Summary FFCI LU LY -

SITI TERA7

Preliminary Summary of Peer Review Comments 72 comments received August 7th Currently reviewing and prioritizing Summary of Comments Plans for uncertainty study

• not all members commented on the issue

• Committee "seemed" OK publishing without the uncertainty study

" interested in our parameters and their ranges Committee discussed the robustness of the MELCOR calculations

• focused on equipment performance and structural failure modeling

" requested sensitivity studies The probability of the success of mitigation

" can operators perform the functions?

• are mitigative measures included in current plant procedures?

• justification for our assumptions

• how to discuss the mitigated vs. unmitigated results in the Executive study.

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Upcoming Dates

• Peer Review Meetings 09/15-16/09 (scheduled) 11/10-11/09 (tentative)

• Uncertainty analysis estimated completion date April 2010 planning to request peer review input and feedback

• OECD/NEA workshop on Implementation of Severe Accident Management Measures, October 2009

• ACRS

- Subcommittee Meeting 11/4/09 Full Committee Meeting 11/5/09

• Final NUREG Including Peer Review and Recommendation Regarding Future Work to SECY 1/29/10 FF0 US 9Y-N TIVEI ALJ M

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AL FOMpTI Communications Accomplishments i SOARCA public website updated to reflect Communication Plan provided to Commission in SECY-09-0045.

• NRC Reporter and The Researcher articles published for staff communication

• OPA Briefed NEI Communications Staff on SOARCA

° Revised Communications Plan to Recognize the Need to Brief our Federal Partners such as FEMA, EPA, etc.

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Seismic (EP) Study

• Background - ACRS questioned adequacy of EP modeling (for seismically initiated SOARCA scenarios) which did not explicitly consider effect of seismic event on EP

• Past risk studies have not generally considered this effect except as simplified sensitivity calcs (delay times and evac speed)

• SOARCA Approach Seismic assessment of infrastructure by RES seismic experts

, Bridges, roads, power network (notification, traffic signals)

Reassessment of EP given impact on infrastructure and ORO's

• Route alerting assessment by SNL/NSIR staff

• New ETE assessment based on available road network

• New EP model developed for MACCS2 Recalculation of offsite consequences

• Conclusion - No substantial effect on offsite health consequences OAF I ALU 0LY-NTRN I EQ M TI11

Seismic (EP) Study Peach Bottom - Unmitigated Short-Term SBO Assuming LNT M Baseline EP U Seismic EP 8.0E-11

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4.OE-11 +/--

2.OE O.OE+00 4-0-10 0-50 Distance (miles) 0-100 FF1 L

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Seismic (EP) Study Surry - Unmitigated Thermally Induced Steam Generator Tube Rupture Assuming LNT l[Baseline EP N Seismic EP 2.OE-10 LL C

1.5E 1.OE-10 5.OE-11 -I---

0.OE+00 4--

0-10 0-50 0-100 Distance (miles)

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'Seismic (EP) Study

• Seismic effects of EP are site specific but with no substantial effect on health consequences

- Peach Bottom

" Sirens fail but alternative notification is adequate, larger shadow evacuation

" Free span bridges fail - but they are not key to evacuation, adequate road network remains and evacuation speeds are unchanged

" In addition, sequence timing predicted by realistic analysis is delayed so that there is some "margin" for EP activation and execution 14

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Seismic (EP) Study Surry

" Sirens function, public evacuation starts earlier, shadow evac occurs, schools delayed

" Bridge failures significantly retard evacuation -

major effect on evacuation speed

• Smaller radiological release, LCF dominated by long term 16

Seismic (EP) Study I

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Conclusions

• SOARCA represents major change from the way people perceive severe reactor accidents and their likelihood and consequences Mitigation is likely (due to time and redundancy) and, when it is implemented, effective in preventing core damage

• Impact on existing level 1 PRA Unmitigated accidents progress more slowly with smaller releases, no LERF

• Impact on existing level 2 PRA Early fatality risk lower than previous studies Dominance.of external-events suggests need for corresponding PRA focus o Seismic research needed:`

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