ML20133M581
| ML20133M581 | |
| Person / Time | |
|---|---|
| Site: | 05200003 |
| Issue date: | 01/16/1997 |
| From: | Huffman W NRC (Affiliation Not Assigned) |
| To: | Liparulo N WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP. |
| References | |
| NUDOCS 9701220439 | |
| Download: ML20133M581 (4) | |
Text
--
pauc p-UNITED STATES 3
j NUCLEAR REGULATORY COMMISSION
- t WASHINGTON, D.C. 20666 4001
\\.....,#
January 16, 1997 x7 _
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:
CRITERIA FOR ESTABLISHING RISK SIGNIFICANT STRUCTURES, SYSTEMS, AND COMPONENTS (SSCs) TO BE CONSIDERED FOR THE AP600 RELIABILITY ASSUR-ANCE PROGRAM
Dear Mr. Liparulo:
The purpose of the design reliability assurance program (D-RAP) is to ensure that reliability is designed into the plant which is consistent with the probabilistic risk assessment (PRA) and to provide confidence that the reliability can be maintained throughout plant life. The specific goal of the D-RAP is to identify " risk significant" SSCs that will be included in the program during the plant design and procurement activities.
Ultimately, the designer will develop component maintenance and operational recommendations for the risk significant SSCs identified in the D-RAP that will be passed onto the combined license (COL) applicant.
Throughout the life of the plant, the COL holder will be responsible for assuring the validity of the baseline reli-ability values established by the designer for risk significant SSCs via operational and maintenance activities.
The principal program established to monitor SSC reliability for the COL applicant is defined in the maintenance rule (10 CFR 50.65).
SECY-95-132 states that applications for advanced reactor design certifica-tions must contain "... a list of the structures, systems, and components designated as risk significant..."
Although criteria for selecting " risk significant" SSCs are not directly defined in any Nuclear Regulatory Commis-sion (NRC) codes or regulatory guides, the criteria should be consistent with the objective of D-RAP to ensure that the reliability of selected SSCs can be maintained to their designed safety levels once the plant is built and operating.
Since a measure of the designed safety level is the magnitude of the plant risk as assessed in the PRA, the criteria for establishing " risk significant" SSCs should ensure that risk will not increase during plant construction and operation and will be consistent with the design certifica-tion PRA. The AP600 D-RAP uses probabilistic, deterministic, and other methods to identify risk significant SSCs for inclusion in its program. The probabilistic criteria for selecting risk significant SSCs specify three analytical measures: risk reduction worth, risk achievement worth, and the
(
Fussell-Vesely importance.
Westinghouse states that the bases for the D
probabilistic criteria used in selecting AP600 risk significant SSCs is from c
precedent set by the evolutionary reactor design certifications which were
/I 3 then modified to take credit for the AP600's lower calculated core damage frequency.
The NRC staff, in review of AP600 D-RAP risk significant SSCs m0058 NES N 9701220439 970116 PDR ADOCK 05200003 A
Mr. Nicholas _ J. Liparulo January 16, 1997.
that were derived from the probabilistic criteria, has been unable to reach closure with Westinghouse that the criteria is sufficiently conservative to bound the SSCs that should be considered for the D-RAP.
Upon further review of this issue, the staff notes that the nuclear industry has developed guidelines and criteria.used in identifying risk significant SSCs for application of the maintenance rule. This criteria can be found in NUMARC 93-01 which has been endorsed by NRC Regulatory Guide 1.160. Since one of the purposes of the D-RAP is to establish the baseline reliability in both design and performance goals that the COL applicant will ultimately use for the maintenance rule, it is the staff's position that the use of " risk significant" SSCs should be consistent between the two programs.
It should also be noted that the NUMARC criteria for risk significant SSCs is the same for all plants regardless of the absolute value of the plant's core damage I
frequency. The staff recognizes that this position is not entirely consistent with the evolutionary reactor design approvals. However, it is a rational and defensible basis for all future D-RAP reviews.
l The staff does not believe that the specification of the NUMARC criteria for risk significant SSCs will impose an unnecessary burden for the AP600 D-RAP.
It will only require that the SSCs that are derived from the NUMARC criteria be provided to the D-RAP expert panel.
The panel may exclude any SSC from the D-RAP provided it gives a justifiable basis that is documented and auditable.
The staff requests that Westinghouse revise the D-RAP section of the AP600 standard safety analysis report to be consistent with NUMARC 93-01 guidelines
)
for using PRA to identify risk significant SSCs.
Subsequent to implementing this revised criteria, Westinghouse should provide to the NRC a list, and the
. basis for exclusion, of any risk significant SSCs that fall within the NUMARC criteria but have been specifically excluded from the D-RAP based on the judgement of Westinghouse's expert panel.
If you have any questions regarding this matter, you may contact me at (301) 415-1141.
Sincerely, original signed by:
William C. Huffman, Project Manager Standardization Project Directorate Division of Reactor Program Management Office of Nuclear Reactor Regulation Docket No.52-003 cc:
See next page DISTRIBUTION:
See next page-DOCUMENT NAME: A: POLICY. RAP (A AP600 DISK)
Ta seeelve e sepy of this desument,indeste in the hon: *C' = Copy without ettschmentlenolosure
- E* = Copy with ettschment/ enclosure
'N' = No copy 0FFICE PM:PDST:DRPM l'
BC:HQMB:DRCHlv BC:SPSB_:DSSA l D:PDST:DRPM l l
NAME WCHuffman:si @ M SBlack Sih RJonetw'f/
TRQuay 1gu DATE 01/ 7 /97 01/ '(/97 01/////97 /
01/l4/97 OFFICIAL RECORD COPY
Mr. Nicholas J. Liparulo Docket No.52-003 Westinghouse Electric Corporation AP600 cc: Mr. Nicholas J. Liparulo, Manager Mr. Frank A. Ross Nuclear Safety and Regulatory Analysis U.S. Department of Energy, NE-42 Nuclear and' Advanced Technology Division Office of LWR Safety and Technology Westinghouse Electric Corporation 19901 Germantown Road P.O. Box 355 Germantown, MD 20874 Pittsburgh, PA 15230 Mr. Ronald Simard, Director Mr. B. A. McIntyre Advanced Reactor Program Advanced Plant Safety & Licensing Nuclear Energy Institute Westinghouse Electric Corporation 1776 Eye Street, N.W.
Energy Systems Business Unit Suite 300 Box 355 Washington, DC 20006-3706 Pittsburgh, PA 15230 Ms. Lynn Connor Mr. John C. Butler Doc-Search Associates Advanced Plant Safety & Licensing Post Office Box 34 Westinghouse Electric Corporation Cabin John, MD 20818 Energy Systems Business Unit Box 355 Mr. James E. Quinn, Projects Manager j
Pittsburgh, PA 15230 LMR and SBWR Programs GE Nuclear Energy Mr. M. D. Beaumont 175 Curtner Avenue, M/C 165 Nuclear and Advanced Technology Division San Jose, CA 95125 Westinghouse Electric Corporation i
One Montrose Metro Mr. Robert H. Buchholz 11921 Rockville Pike GE Nuclear Energy Suite 350 175 Curtner Avenue, MC-781 Rockville, MD 20852 San Jose, CA 95125 Mr. Sterling Franks Barton Z. Cowan, Esq.
U.S. Department of Energy Eckert Seamans Cherin & Mellott NE-50 600 Grant Street 42nd Floor 19901 Germantown Road Pittsburgh, PA 15219 Germantown, MD 20874 Mr. Ed Rodwell, Manager Mr. S. M. Modro PWR Design Certification Nuclear Systems Analysis Technologies Electric Power Research Institute Lockheed Idaho Technologies Company 3412 Hillview Avenue Post Office Box 1625 Palo Alto, CA 94303 Idaho Falls, ID 83415 Mr. Charles Thompson, Nuclear Engineer AP600 Certification NE-50 19901 Germantown Road Germantown, MD 20874 i
I DISTRIBUTION:
Letter to Mr. Nicholas J. Liparulo. Dated:
January 16, 1997 i
Docket File,
PUBLIC.
PDST R/F TMartin i
l DMatthews TRQuay TKenyon i
BHuffman i
JSebrosky DJackson JMoore, 0-15 B18 WDean, 0-17 G21 ACRS (11) i SBlack, 0-9 Al RCorrreia, 0-9 Al FTalbot, 0-9 Al TBergman, 0-9 Al i
BBoger, 0-9 E4 l
l NSaltos, 0-10 E4 l
JFlack, 0-10 E4 i
RJones, 0-10 E4 GHolahan, 0-8 E2 1
i l
i 4
i 1
l'
.. _ _