ML20140G281
| ML20140G281 | |
| Person / Time | |
|---|---|
| Site: | 05200003 |
| Issue date: | 05/08/1997 |
| From: | Joseph Sebrosky NRC (Affiliation Not Assigned) |
| To: | Liparulo N WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP. |
| References | |
| NUDOCS 9706160108 | |
| Download: ML20140G281 (4) | |
Text
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May 8, 1997 Mr. Nicholas J. Liparulo, Manager Nuclear Safety and Regulatory Analysis Nuclear and Advanced Technology Division Westinghouse Electric Corporation P.O. Box 355 Pittsburgh, PA 15230
SUBJECT:
FOLLOWON QUESTIONS REGARDING THE EX-VESSEL SEVERE ACCIDENT ANALYSIS FOUND IN THE PROBABILISTIC RISK ASSESSMENT (PRA) FOR THE AP600 1
Dear Mr. Liparulo:
As a result of its review of the June 1992, application for design certifica-tion of the AP600, tM staff has determined that it needs additional informa-tion.
Specifically, the enclosure to this letter contains requests for additional information concerning ex-vessel severe accident analysis found in the AP600 PRA.
You have requested that portions of the information submitted in the June 1992, application for design certification be exempt from mandatory public disclosure. While the staff has not completed its review of your request in accordance with the requirements of 10 CFR 2.790, that portion of the submitted information is being withheld from public disclosure pending the staff's final determination. The staff concludes that these followon ques-tions do not contain those portions of the information for which exemption is sought.
However, the staff will withhold this letter from public disclosure for 30 calendar days from the date of this letter to allow Westinghouse the opportunity to verify the staff's conclusions.
If, after that time, you do not request that all or portions of the information in the enclosures be withheld from public disclosure in accordance with 10 CFR 2.790, this letter will be placed in the Nuclear Regulatory Commission Public Document Room, l
If you have any questions regarding this matter, you may contact me at j
(301) 415-1132.
l Sincerely, original signed by:
Joseph M. Sebrosky, Project Manager Standardization Project Directorate Division of Reactor Program Management Office of Nuclear Reactor Regulation Docket No.52-003
Enclosure:
As stated 4
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i Mr. Nicholas J. Liparulo Docket No.52-003 Westinghouse Electric Corporation AP600 cc: Mr. B. A. McIntyre Ms. Cindy L. Haag Advanced Plant Safety & Licensing Advanced Plant Safety & Licensing Westinghouse Electric Corporation Westinghouse Electric Corporation Energy Systems Business Unit Energy Systems Business Unit P.O. Box 355 Box 355 Pittsburgh, PA 15230 Pittsburgh, PA 15230 Mr. M. D. Beaumont Mr. S. M. Modro Nuclear and Advanced Technology Division Nuclear Systems Analysis Technologies Westinghouse Electric Corporation Lockheed Idaho Technologies Company One Montrose Metro Post Office Box 1625 11921 Rockville Pike Idaho Falls, ID 83415 Suite 350 Rockville, MD 20852 Enclosure to be distributed to the following addressees after tts result of the proprietary evaluation is received from Westinghouse:
Mr. Ronald Simard, Director Ms. Lynn Connor Advanced Reactor Programs DOC-Search Associates Nuclear Energy Institute Post Office Box 34 1776 Eye Street, N.W.
Cabin John, MD 20818 Suite 300 Washington, DC 20006-3706 Mr. Robert H. Buchholz GE Nuclear Energy Mr. James E. Quinn, Projects Manager 175 Curtner Avenue, MC-781 LMR and SBWR Programs San Jose, CA 95125 GE Nuclear Energy 175 Curtner Avenue, M/C 165 Mr. Sterling Franks San Jose, CA 95125 U.S. Department of Energy NE-50 Barton Z. Cowan, Esq.
19901 Germantown Road Eckert Seamans Cherin & Mellott Germantown, MD 20874 600 Grant Street 42nd Floor Pittsburgh, PA 15219 Mr. Charles Thompson, Nuclear Engineer AP600 Certification Mr. Frank A. Ross NE-50 U.S. Department of Energy, NE-42 19901 Germantown Road Office of LWR Safety and Technology Germantown, MD 20874 19901 Germantown Road Germantown, MD 20874 Mr. Ed Rodwell, Manager PWR Design Certification Electric Power Research Institute 3412 Hillview Avenue Palo Alto, CA 94303
a AP600 PRA REVIEW REQUEST FOR ADDITIONAL INFORMATION REGARDING DETERMINISTIC CALCULATIONS OF EX-VESSEL PHENOMENA 720.387 The deterministic evaluation of ex-vessel fuel coolant interac-tions-(Appendix B to Revision 9 of the PRA) indicates that the impulse loads from ex-vessel steam explosions would fail the reactor cavity floor and wall structures, but that the embedded steel liner will stay intact. The evaluation also indicates that containment vessel integrity will not be compromised by the displacement of the RPV due to the impulse loading.
Please submit additional details regarding the calculation of containment vessel strains referenced in Section B.3.2.1 and the calculation of maximum lift of the RPV referenced in Section B.3.2.2.
720.388 Please provide a reassessment of the large release frequency and population doses for the baseline PRA, consistent with the argu-ments in Appendix B that the containment will sustain ex-vessel steam explosions.
720.389 The AP600 PRA documentation regarding the NAAP model (Chapter 44 of PRA), indicates that the AP600 basemat is assumed to be lime-stone concrete in order to maximize non-condensible gas genera-tion.
If this same assumption was retained in the deterministic calculations, the time to breach the embedded liner can be sub-stantially less than the 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> estimated in Appendix B of the PRA.
Please provide estimates of the time of melt-through of the embedded liner and the time of containment overpressure failure (e.g., Service Level C) if alternative concrete compositions are specified for the reactor cavity floor and walls.
The range of compositions evaluated should include those that would minimize and maximize the time of liner melt-through.
720.390 Given the relatively short estimated time to melt-through of the embedded liner in Appendix B, justify why a concrete composition that maximizes the time of melt-through is not prescribed as part of the AP600 design.
Include an estimate of related costs to specify a particular composition.
4 Enclosure
)ISTRIBUTLON Letter to Mr. Nicholas J. Lioarulo. Dated:
May 8. 1997 1.
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