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

US.NRC U

UNITED STATES NUCLEAR REGULATORY COMMISSION ProtectingPeople and the Environment State-of-the-Art Reactor Consequence Analyses (SOARCA)

Semi-Annual Briefing for Commission TAs August 13, 2009 OF 9 AL ýSE ýN ý-S ýIT I INT ýAý N FO ýA ION

Presentation Outline

" Status of Project

° Peer Review

" Upcoming Dates

" Communications Activities 9 Seismic (EP) Study OF AL ONLY - NSIT ER LIN M ION 2 N

Status of Project

• Accomplishments since last TA briefing (4/17/2009)

- Seismic (EP) study for Peach 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 ýT ýNAL I OR ýTIOýý 3

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 l LSOL-F TVILNO T - 4

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 5

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 R 0 6

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.

8

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 I9

m F icaLnSE Y-E ITI T AL FOMpTI Communications Accomplishments i SOARCA public website updated to reflect Communication Plan provided to Commission in SECY-09-0045.

• NRC Reporter and The Researcherarticles 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.

10

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 ~1 6.OE-11 4 --

.X CL 4)

It U. 4.OE-11 +/--

-C V

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

FF1 L L-s S0 I A E ATI 12

Seismic (EP) Study Surry - Unmitigated Thermally Induced Steam Generator Tube Rupture Assuming LNT l[Baseline EP N Seismic EP 2.OE-10 1.5E LL 1.OE-10 --

C 5.OE-11 -I---

0.OE+00 4--

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

ýNA ýI INT_ R ýON 13

!SSEOý L -S ý"IT I

'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

ebismic (EP) Study USE cST LY-iE T L IStud 15

ýsoý "ý

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 '- W7oro C.

0 "

V R G I A fN I 0.p.rtNewi 00, FO AN 17

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:`

18