ML13196A428
| ML13196A428 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 07/15/2013 |
| From: | Atomic Safety and Licensing Board Panel |
| To: | |
| SECY RAS | |
| References | |
| ASLBP 10-906-02-LR-BD01, RAS 24821, 50-443-LR | |
| Download: ML13196A428 (5) | |
Text
NextEra Energy Seabrook, LLC (Seabrook Station, Unit 1)
License Renewal Application NRC Staff Answer to Motion for Summary Disposition of Contention 4B ATTACHMENT 4B-K
NUREG-1 150 Vol. 1 Reactor Risk Reference, Document Main Report Draft for Comment U.S. Nuclear Regulatory Commission Office of Nuclear Regulatory Research
10 percent to 80 percent for iodine, 5 percent to 70 percent for cesium, and 0.8 percent to 60 percent for tellurium.
Three variations of station blackout were also analyzed by IDCOR.
The release fractions obtained, for two of the cases with late containment failure were...
identical; Figure 5.5 compares the IDCOR values with the NUREG-1150 range for Bin 10, a late overpressure bin with leakage rather than rupture.
Also shown in the figure are Source Term Code Package results.
For each elemental group, the IDCOR resultsfall below or near the bottom of the.NUREG-1150 uncertainty band.
A station blackout scenario was also analyzed by IDCOR in which there was assumed to be a preexisting breach in containment at the-start of the accident.
These results are compared with the range obtained for the corresponding Bin 1 in NUREG-1150 and with a Source Term Code Package run for a'scenario within the bin.
Again, the MAAP results are consistently below the NUREG-1150 range, indicative of technical disagreements in the source term models.
5.3.3 Plant-Specific Perspectives The source term results for the Zion plant are quite similar to those obtained for the Surry plant and the plant-specific perspectives are the same.
The uncertainties in the estimated source terms are quite large.
The principal contributors to the uncertainties are basically the same as for the Surry plant.
Comparisons made between the Source Term Code Package results and MAAP results indicated that the MAAP estimates for environmental release fractions were significantly smaller.
It is very difficult to determine the precise source of the differences observed, however, without performing controlled comparisons for identical boundary conditions and input data.
5.4 Results for Sequoyah Nuclear Power Station Unit 1 5.4.1 Ranges of Source Term Results The source term issues included in the statistical sampling analysis are very similar to those considered for the other PWR plants (Ref. 5.21).
A few issues were added because of the unique aspects of the ice condenser design.
Decontamination Factor for Ice Condenser Retention of radionuclides in the ice condenser region is a very important aspect limiting the release of radionuclides to the environment in this plant design.
The effectiveness of the ice condenser is affected by the operability of the air-return fans.
On the one hand, prior to containment failure the air-return fans can recycle the containment air through the ice condenser a number of times providing an opportunity for additional retention at each pass.
By returning noncondensible gases to the lower compartment region, however, the air-return fans tend to reduce the effectiveness of the ice in retaining radionuclides for any single pass, since the decontamination factor is very~sensitive to the fraction of steam in the flowing gas.
Three boundary conditions were.considered:
(1) containment failure at vessel breach with the air-return fans operating, (2) containment failure prior to vessel breach with the air-return fans operating, and (3) containment failure at or before vessel breach with the air-return fans off.
5-14
Station Blackout with Early Failure n 4 eJease Fraction 1E-1 I 1E;-2 1E-3 IE-4 I -
I I
I 1
2 3
4 a
6 7
Elemental Group I
iodine 3 cesium 4 tellurium 5 strontium 6 ruthenium 7 lanthanum I
+
Source Term Code Package o
IDCOR Elemental Group Station Blackout with Late I Leakage Failure
- Failure, C:
f rtI i~J
.1=n!
=$W'U Ica%,
--n I 1E-3 15-4 IE-a 0
0 00 7
-1 1ý 1 2
3 4
6 6
7 Elemental Group Figure 5.5 Comparison of results for station blackout scenarios at Zion 5-15
NRC FORM 335 U.S. NUCLEAR REGULATORY COMMISSION I REPORT NUMBER (A$s,gnedby TIDC add Vol No. fanyj (2+841 NRCM 1102, N2oCM 3202 BIBLIOGRAPHIC DATA SHEET NUREG-I 150 SEE INSTRUCTIONS ON THE REVERSE Volume 1
- 2. TITLE AND SUBTITLE
- 3. LEAVE BLANK Reactor Risk Reference Document Main Report Draft for Comment 4 DATE REPORT COMPLETED MONTH YEAR PAuTH RC.BetuioE' Januaryv 1937 M. L.RErnst, NRC J. C. Glynn, NRC R.C. Bertucio,DT Jan A. Hurpby, NRC J. A. Mitchell, NRC R.J. Budnitz,FRP MONTH YEAR
.A.
Cuyningham NRC B. M. [Norris, NRC February I
- 3. A. Ma aro, NR R. S. Denning, BCD February_987
- 7. PERFORMING ORGANIZATION NAME AND MAILING ADDRESS II,,lude ZP Code) a PROJECT/TASKIWORK UNIT NUMBER Office of Nuclear Regulatory Research U.S. Nuclear Regulatory Commission 9, FIN OR GRANTNUMBER Washington, D.C.
20555
- 10. SPONSORING ORGANIZATION NAME AND MAILING ADDRESS (Include Zp Code) 1 la TYPE OF REPORT Office of Nuclear Regulatory Research Draft Technical U.S. N4uclear Regulatory Commission b, PERIOD COVERED...
,° Washington, D.C.
20555
- 12. SUPPLEMENTARY NOTES
- 13. ABSTRACT (200 words or !esI)
This document discusses the risks of severe accidents in a set of commercial nuclear power plants.
This risk is characterized by the types and frequencies of accidents leading to severe core damage, the performance of containment structures under severe accident loadings, possible radioactive releases into the environment if the containment were to fail, and the offsite consequences of such releases.
Volume 1 of this document summarizes the principal results of the risk analyses, and displays these results in the context of specific regulatory issues (e.g., safety goals).
14 DOCUMENT ANALYSIS -.
Ka PYWORDS/OESCRIPTORS
- 15. AVAILABILITY bevereCCl dents STATEMENT Core Meltdown Probabilistic Risk Assessment Unlimited Source Terms IB SECURITY CLASSIFICATION (Th,. 04ge)
IOENTIFIERSOPEN.ENDED TERMS Unclassified (Thls rePo,,)
Unclassified
- 7. NUMBER OF PAGES 1S PRICE