ML11228A230
| ML11228A230 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom, Surry  |
| Issue date: | 04/14/2009 |
| From: | NRC/OCM |
| To: | |
| References | |
| FOIA/PA-2011-0083 | |
| Download: ML11228A230 (24) | |
Text
"t C LUS 0 Y-PRE CI NALI M
N State-of-the-Art Reactor Consequence Analyses 00, Semi-Annual Briefing for Commission Technical Assistants April. 14, 2009 rOF F'Ib ýUS E
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Outline SECY-09-0045 Risk Communication Security Scenarios External Spray
ýAT I N SECY Information Paper Responds to multiple SRMs to demonstrate how we followed Commission direction Provides the Commission the summary results of the Peach Bottom and Surry pilot-plants SECY information paper includes 4 enclosures:
- 1. Executive Summary to the Technical NUREG
- 2.
Communication Plan, rev. 3
- 3.
SOARCA information booklet
- 4.
ýEC I S N AýL IN FO ýAT IN 3
Summary of Results
° For unmitigated sensitivity cases - no LERF
" Offsite radiological releases are dramatically smaller and delayed from 1982 Siting Study (SST1)
- Latent cancer fatality predictions dominated by long term exposure from return criteria and LNT FIC USE Y-P ISI NF TIO4
.Key Accident Progression Timing for Unmitigated Sensitivity Cases - Peach Bottom Scenario Core damage Time to lower Time to start of frequency (per head failure release to reactor-year)
(hours) environment (hours)
Long-term SBO 3x10-6 20 20 Short-term SBO 3x0-7 8
8 An unmitigated case CDF assumes probability of B.5.b mitigation is zero 5
Key Accident Progression Timing for Unmitigated Sensitivity Cases - Surry Scenario Core damage Time to lower Time to start of frequency (per head failure release to reactor-year)
(hours) environment (hours)
Long-term SBO 2x1 0-5 21 45 Short-term SBO 3x10-6 7
25 Thermally induced 5x10-7 7.5 3.5 steam generator tube rupture Interfacing 3x10-8 15 10 systems LOCA
,F I AL S ON RED I ONA OR A ON 6
Cesium Release for Unmitigated Sensitivity Cases 0.1
, 0.09 0
E 0.08
> 0.07 0.06 0.05
.: 0.04 N0-,
0 c 0.03 0
0.02 (U
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0 12 24 36 Time (hr) 0 I
48 7
Cesium O0 I
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0.7 0.6 0.5 0.4 0.3 0.2 0.1 0
0 12 24 36 Time (hr)
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Health Consequences for Unmitigated Sensitivity Cases Assuming LNT - Peach Bottom Scenario Core damage Conditional risk of Absolute risk of latent frequency latent cancer fatality cancer fatality for an (per reactor-year) for an individual individual located within located within 10 miles 10 miles (per reactor-year)
Long-term SBO 3x10-6 2x10.4 6x1 0-10 Short-term SBO 3x10-7 2x10.4 7x10-11 An unmitigated case CDF assumes probability of B.5.b mitigation is zero
.!\\O)F A,ýI AL ýO N
ý-P ED Eý SINA ýINO
ýAT 9
Health Consequences for Unmitigated Sensitivity Cases Assuming LNT - Surry Scenario Core damage Conditional risk of latent Absolute risk of latent frequency cancer fatality for an cancer fatality for an (per reactor-year) individual located within individual located within 10 miles 10 miles (per reactor-year)
Long-term SBO 2x10-5 5x1O.5 7x10-10 Short-term SBO 2x10-6 9x1 0-5 lx10-10 Thermally induced steam generator 5x10-7 3x10 4 1x10-1 0 tube rupture (CTFP = 0.25)
Interfacing systems 3x1 08 7x10.4 2x10-11 LOCA FICI SEOL-P DOISINLINFRA N
10 10
Surry - Unmitigated ISLOCA Risk Dose and Distance Truncation Sensitivity n LNT o backgrou nd (360 mrem/yr) o backgrou nd (620 mrem/yr) m HPS (5 rem/yr;10 rem lifetime) 4-L_
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0-50 0-100 Distance (miles) o FICI SE
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- PR S ISON I
OR ýATION 111
Conclusions
- Effective B.5.b mitigation and more realistic treatment of other mitigation together with detailed realistic modeling (MELCOR) has significant benefits Scenarios that current PRAs say result in core damage were shown to not be core damage scenarios
" Peach Bottom long-term SBO, short-term SBO, loss of vital ac bus E12
" Surry long-term SBO, ISLOCA, spontaneous SGTR Surry short-term SBO resulted in core damage, because we assumed seismic event was severe enough to result in CST rupture and preclude operator action for more than 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />
- Currently assessing effect of seismic event on evacuation speed and offsite consequences
/FF01 LUS NL PRE ISO L N A
12
Conclusions
- Detailed more realistic modeling (MELCOR) without B.5.b shows more time to core damage and smaller releases Improved phenomenological treatment Research showed that early containment failure modes of alpha mode failure and direct containment heating were physically not feasible or of extremely low probability
- Some scenarios, previously important in PRA, were shown to be mitigated without B.5.b equipment. (Due to longer time to utilize existing equipment) Insight being factored into new PRA.
13
Conclusions
- Seismic events not well quantified - seismic PRA not required Neither NUREG-1 150 nor SOARCA included consequence results from large seismic event with the potential to fail containment and cause SBO and LOCA
- Discussed in December 2008 TA brief Issue to be addressed in a separate research program
ýOCIAL F NýLY P
Risk Communication Major element of project reflecting modeing HYPothetical Acide Commission interest at Nuclear Power Plants Latest risk communication principles for a diverse audience Communication Plan and Information Booklet developed by communications specialists in OPA, EDO, RES (with technical content expert input from all Offices)
~ fe Art fiewV Stteoft e.Ar,eaor Conseuence Analyses.
Integratin research anti exer c ao MoIYleSi acckenr Vwessio En 'I~ce abo~em msponse
- Z
, ant emergency F I L U ýONýL-P
ýEC ONA ýF ýRM ION 15
Target Audience
- People motivated to seek out this information will appreciate our efforts to be transparent, comprehensible, and "information-rich"
- Interested citizens
- Congress
- Advocacy groups
- Federal and State agencies
- Nuclear industry
- NRC personnel
° Focus group for testing achievement of communication objectives CIAL S
ýON
-P EDE IONA IN A ýN 16
Risk Communication Objectives.
- Our knowledge objectives for the audience understand more realistic consequences should an accident occur understand that NRC and industry have made many improvements in nuclear plants understand how the SOARCA project was conducted including basic risk analysis and modeling principles understand how accidents might occur at nuclear plants
- Our trust objectives for the audience believe that the NRC works to ensure safe operation of nuclear power plants believe that NRC research provides information to support the mission believe that the SOARCA project is credible VFF01),US NL -PR ECI IN N0 A ON 17
Make SOARCA Methods and Results Transparent Media Sources Audienc aay acOtess infc Each channel refer esk irmation'throu any channel U*
Fý IA EO N ED E C I A ALl 0I AT
ýN 118
Build Credibility
- Forthcoming external peer review
" Cross reference public communication (e.g.,information booklet) with technical report
" SOARCA is a research project that provides information to support NRC mission
- Connect SOARCA information to NRC regulatory activity Ex. Describe accident progression alongside background information about how reactors work and description of "General Design Criteria for Nuclear Power Plants" from 10 CFR 50, Appendix A
Communication Plan:
Public Rollout - Early 2010
" Early briefings on results to Regional and HQ staff
- Press release to coincide with the release of the SOARCA results; Chairman potentially holds a press briefing (e.g., National Press Club)
- Public website update
- Briefings on results to participating licensees
- All-Agreement States and Non-Agreement States letter
- Public release of NUREG and the NUREG/BR information booklet
- Public Workshop
- Regulatory Information Conference - 2010 RIC 20
- Separate slides containing Safeguards 0
SE LY-ECISIO L IN ATIG Security Sce narios
°Separate slides containing Safeguards Information 101 lýSEOýN PRýED ýISI NA N
ýA 10 21
SOARCA-Related Effort One mitigation measure that may mitigate the release is onsite external spray
- B.5.b requirement - minimum of 200 gpm spray to mitigate a release
- April 14, 2006 SRM that approved SOARCA also directed separate RES activity to quantify benefit for mitigating release
- Test results using same spray nozzle purchased by Peach Bottom and Surry
" Low decontamination factor (near 1)
" But initial plume height could also be lowered to the ground
- Analysis of Peach Bottom and Surry station blackouts showed no substantial reduction in offsite consequences
&F I LU LY-
ýRE ýECISIN LI 0
O 22
SOARCA-Related Effort
- Insight gained
- Spray flow rate (300 gpm) tested is insufficient to mitigate release
" Low decontamination factor
" Small release area covered
- Wind may blow spray away from leak location
- Specific leak location may not be known
- Not effective in cooling high energy plume
° Cost of setting up spray (lost time, exposure of response personnel) questionable
- Staff considering other options - to be discussed in separate TA briefing - July?
Fl
ýR U
LY R ýEýCI
ýNL IN ý 10 223
Upcoming Activities
- Complete technical NUREG (4 volu May mes) -
- Start Peer Review - June e Start Uncertainty Study - June
- Brief ACRS - July I A US Y-E CISI IN R AT 224