ML20137S458
| ML20137S458 | |
| Person / Time | |
|---|---|
| Site: | 05200003 |
| Issue date: | 04/11/1997 |
| From: | Martin T NRC (Affiliation Not Assigned) |
| To: | Liparulo N WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP. |
| References | |
| NUDOCS 9704150142 | |
| Download: ML20137S458 (3) | |
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UNITED STATES 1
-S-NUCLEAR REGULATORY COMMISSIGN f
WASHINGTON D.C. SpeeH001 I
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April 11,.1997 4....
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:
AP600 ISOLATION REQUIREMENTS FOR NORMAL RESIDUAL HEAT REMOVAL SYSTEM-(RNS)
Dear Mr. Liparulo:
In.a letter dated December 6,1996, we sent you 'a list of potential critical path issues in the design certification process for the AP600. One of the issues (key.hsue #10) involves the automatic containment isolation. of non-safety-related normal RNS. Many systems that have traditionally been safety-related systems are nonsafety-related in the AP600 design. The staff has generally required that nonsafety-related systems be automatically isolated on a containment isolation signal using diversity in the parameters sensed for generating the containment isolation signal. The AP600 nonsafety-related RNS does not isolate on a generic containment isolation signal, but rather on a high containment radiation signal.
In a February 20, 1997 letter, Westing-house states that the RNS does not isolate on a generic containment isolation signal in order to permit the RNS to perform its nonsafety-related defense-in-depth function, while still protecting the integrity of containment by isolating on a high radiation signal.
-The staff has accepted exceptions to the automatic containment isolation criteria (such as diversity) where the applicant has justified the system's importance to safety. Westinghouse states in its February 20, 1997, letter that the overall plant safety is enhanced by utilizing a non-generic, non-diverse, containment isolation signal for the RNS to provide defense-in-depth response to accidents. However, Westinghouse has not provided any quan-titative risk assessment to support this claim.
It is the staff's position that Westinghouse should either provide a' diverse automatic containment isolation signal for the RNS or provide a risk informed justification that non-automatic isolation of the RNS on a containment isolation signal is safer than automatic isolation.
If Westinghouse elects to establish that non-automatic containment isolation of the RNS is a safer design, Westinghouse must still provide leak detection instrumentation in the RNS rooms Westinghouse must also demonstrate that the instrumentation will permit the plant operator to identify and manually actuate containment isolation of the RNS when a leak'is indicated in sufficient time to prevent exceeding the environmental qualification of the saft'./ related equipment in the RNS rooms. The staff would still expect the RNS to automatically isolate on a high radiation signal.
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b Mr. Nicholas J. Liparulo April 11, 1997 If you have any questions regarding this matter, you can contact Bill Huffman
'at'(301) 415-1141.
Sincerely, original signed by: Marylee Slosson Thomas T. Martin, Director Division of Reactor Program Management t
Office of Nuclear Reactor Regulation Docket No.52-003 cc: See next page a
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Mr. Nicholas J. Liparulo Docket No.52-003 Westinghouse Electric Corporation AP600 cc: Mr. 8. A. McIntyre Mr. Ronald Simard, Director Advanced Plant Safety & Licensing Advanced Reactor Programs Westinghouse Electric Corporation Nuclear Energy Institute Energy Systems Business Unit 1776 Eye Street, N.W.
P.O. Box 355 Suite 300 Pittsburgh, PA 15230 Washington, DC 20006-3706 Ms. Cindy L. Haag Ms. Lynn Connor Advanced Plant Safety & Licensing Doc-Search Associates Westinghouse Electric Corporation Post Office Box 34 Energy Systems Business Unit Cabin John, MD 20818 Box 355 Pittsburgh, PA 15230 Mr. James E. Quinn, Projects Manager LMR and SBWR Programs Mr. M. D. Beaumont GE Nuclear Energy Nuclear and Advanced Technology Division 175 Curtner Avenue, M/C 165 Westinghouse Electric Corporation San Jose, CA 95125 One Montrose Metro 11921 Rockville Pike Mr. Robert H. Buchholz Suite 350 GE Nuclear Energy Rockville, MD 20852 175 Curtner Avenue, MC-781 San Jose, CA 95125 Mr. Sterling Franks U.S. Department of Energy Barton Z. Cowan, Esq.
NE-50 Eckert Seamans Cherin & Mellott 19901 Germantown Road 600 Grant Street 42nd Floor Germantown, MD 20874 Pittsburgh, PA 15219 Mr. S. M. Modro Mr. Ed Rodwell, Manager Nuclear Systems Analysis Technologies PWR Design Certification Lockheed Idaho Technologies Company Electric Power Research Institute Post Office Box 1625 3412 Hillview Avenue Idaho Falls, ID 83415 Palo Alto, CA 94303 Mr. Frank A. Ross Mr. Charles Thompson, Nuclear Engineer U.S. Department of Energy, NE-42 AP600 Certification Office of LWR Safety and Technology NE-50 19901 Germantown Road 19901 Germantown Road Germantown, MD 20874 Germantown, MD 20874 a