ML20140B916
| ML20140B916 | |
| Person / Time | |
|---|---|
| Site: | 05200003 |
| Issue date: | 06/03/1997 |
| From: | Slosson M NRC (Affiliation Not Assigned) |
| To: | Liparulo N WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP. |
| References | |
| NUDOCS 9706060384 | |
| Download: ML20140B916 (3) | |
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UNITED STATES j
j NUCLEAR REGULATORY COMMISSION j,- :
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WASHINGTON, D.C. 2006H001 j
June 3, 1997 i
3 Mr. Nicholas J. Liparulo, Manager 3
4 Nuclear Safety and Regulatory Analysis Nuclear and Advanced Technoiogy Division Westinghouse Electric Corporation P.O. Box 355 Pittsburgh, PA 15230
SUBJECT:
AP600 TURBINE OVERSPEED TRIP
Dear Mr. Liparulo:
In a letter dated December 6,1996, the Nuclear Regulatory Commission NRC) sent Westinghouse a list of potential critical path issues for the design c(ertifica-tion review for the AP600.
One of the issues, Key Issue #14, involves the acceptability of the Westinghouse approach to the AP600 turbine overspeed trip.
In a letter dated April 25, 1997, and supplemented by a diagram on May 9, 1997, Westinghouse provided additional information on the turbine overspeed trip for
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the AP600 to resolve the issue. The staff has reviewed the information and finds that it is unacceptable for justifying Westinghouse's position. The following is the staff's evaluation of the information.
The AP600 turbine overspeed trip design does not have a mechanical trip; the staff identified this issue in the draft safety evaluation report (DSER) issued in November 1994 (DSER Open Item 10.2.4-1, OITS Item No. 358) in November 1994 and as Key Issue #14 as a deviation from Paragraph III.2.c of Standard Review Plan (SRP) Section 10.2.
In the AP600 Standard Safety Analysis Report (SSAR),
Westinghouse states that the AP600 turbine overspeed trip design is as reliable as the design recommended in the SRP.
However, Westinghouse has not provided sufficient information for the staff to review and confirm this statement.
In a telephone conference on April 11, 1996, and subsequent letters of November 13, 1996, and April 11, 1997, the staff requested Westinghouse to provide a quantitative engineering analysis or operating date to support its position.
In its letter of April 25, 1997, Westinghouse states th:t the AP600 design is in conformance with SRP Section 10.2.
However, the staff concludes that this is contrary to the staff's finding because Paragraph III.2.c of SRP Section 10.2 i
states that a mechanical overspeed trip device should be provided, and the AP600 turbine overspeed trip design does not have one.
Therefore, it deviates from Paragraph III.2.c of SRP Section 10.2.
In the April 25th letter, Westinghouse presented the results of a probabilistic risk assessment (PRA) analysis. Westinghouse defines the issue by stating that the AP600 design utilizes an electronic overspeed trip system in lieu of the mechanical overspeed trip device, and its PRA results show that the conditional probability of destructive overspeed is unchanged by replacing the mechanical 1
trip device with an AP600 electronic overspeed trip system. Although the staff
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does not have Westinghouse's PRA analysis, it believes that Westinghouse-has oversimplied this issue.
Paragraph III.2.b of SRP Section 10.2 states that an i
e MC FILE CENER COPY 9706060384 970603 PDR ADOCK 052000 3
Mr. Nicholas J. Liparulo June 3,1997 electro-hydraulic control system that is able to fully cut off steam should be 1
provided.
Paragraph III.2.c states that a mechanical overspeed trip device should be provided. Paragraph III.2.d states that an independent and redundant electrical overspeed trip should also be included in the design.
The AP600 i
design has an electro-hydraulic control system and an electronic trip system, but does not have a mechanical trip.
Therefore, the staff believes that this i
reduction in the number of turbine trip mechanisms decreases trip diversity in the AP600 design.
The staff does not believe that this reduction and decrease were considered in Westinghouse's PRA analysis because of it definition of the issue.
Therefore, the staff finds that Westinghouse's PRA results are not acceptable for justifying this position.
Furthermore, Westinghouse did not address the staff's concern for the potential for common-mode failures that may be associated with electronic trips, solenoid valves, oil systems, power sources, computer chips, and speed sensors.
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In summary, the staff does not believe that the information in Westinghouse's j
i letter and SSAR is sufficient enough to justify its position regarding the AP600 i
turbine trip design, and that it deviates from Paragraph III.2.c of SRP Section 10.2.
Westinghouse should either provide a justifiable analysis or operating data to support its position, or withdraw its proposal and comply with the guidance in SRP Section 10.2.
In order for the staff to reschedule its review of this issue and assess the impact on other review areas, if any, we request that Westinghouse provide a date for submittal of this information.
If you have any questions concerning this matter, you can call Thomas Kenyon at (301) 415-1120.
Sincerely, original signed by:
Marylee M. Slosson, Acting Director Division of Reactor Program Management Office of Nuclear Reactor Regulation Docket No.52-003 cc: See next page DISTRIBUTION:
Docket File PDST R/F MSlosson PUBLIC SWeiss TQuay l
TQuay TKenyon BHuffman JSebrosky DJackson GHolahan, 0-8 E2 ACRS (11)
JMoore, 0-15 818 WDean, 0-5 E23 CLi, 0-8 D1 HWalker, 0-8 D1 LMarsh, 0-8 D1 DOCUMENT NAME: A: TURBINE.TRP Ta seceive a copy of this W,indsete in the boa: "C" = Copy w%out ettechment/end$e e "E* = Copy w6th attachment / enclosure "N* = No copy 0FFICE PM:Pp%DRPM D:PDST:DRPM 910%A %\\b9 (A)D:DRPM l
NAME TJKe'n: %:sg TRQuay T Q f Gy61 ahan ^
MMSlosson HTe DATE 05/4% 87 05/2L/97~
05/10/97 05r/ S/97 0
0FFICIAL RECORD COPY J
Mr. Nicholas J. Liparulo Docket No.52-003
-Westinghouse Electric Corporation AP600 cc: Mr. B. 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 Mr. 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. S. M. Modro GE Nuclear Energy Nuclear Systems Analysis Technologies 175 Curtner Avenue, M/C 165 Lockheed Idaho Technologies Company San Jose, CA 95125 Post Office Box 1625 Idaho Falls, ID 83415 Mr. Robert H. Buchholz GE Nuclear Energy Mr. Sterling Franks 175 Curtner Avenue, MC-781 U.S. Departrent of Energy San Jose, CA 95125 NE-50 19901 Germantown Road Barton Z. Cowan, Esq.
Germantown, MD 20874 Eckert Seamans Cherin & Mellott 600 Grant Street 42nd Floor Mr. Frank A. Ross Pittsburgh, PA 15219 U.S. Department of Energy, NE-42 Office of LWR Safety and Technology Mr. Ed Rodwell, Manager i
19901 Germantown Road PWR Design Certification Germantown,~MD 20874 Electric Power Research Institute 3412 Hillview Avenue Mr. Charles Thompson, Nuclear Engineer Palo Alto, CA 94303 AP600 Certification NE-50 19901 Germantown Road Germantown, MD 20874 i
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