ML20206D587
| ML20206D587 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 11/14/1988 |
| From: | Swenson W Office of Nuclear Reactor Regulation |
| To: | Fay C WISCONSIN ELECTRIC POWER CO. |
| References | |
| IEB-88-002, IEB-88-2, TAC-67317, NUDOCS 8811170141 | |
| Download: ML20206D587 (4) | |
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I lbvanber 14, 1988 7
Docket Nos. 50-266 Distribution and 50-301 VN WSwenson
PO!!!-3 r/f EJordon MVirgilio BGrimes PKreutzer ACRS(10)
Gray File Mr. C. W. Fay, Vice President Nuclear Power Department
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Wisconsin Electric Power Company 231 W. Michigan Street, Room 308 Milwaukee, Wisconsin 53201 l
Dear Mr. Fay:
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SUBJECT:
POINT SEACH UN:T 2 - IMPLEMENTATION OF BULLETIN 88-02 (TAC 67317)
The NRC staff is reviewing the actions takcn by Wisconsin Electric Power l
Company to resolve the issues raised in NRC Bulletin 88-02, "Rapidly l
Propagating Fatigue Cracks in Steam Generator Tubes." It has been determined that additional infonr.ation is needed by the staff in order to complete the
.rsview. The enclosed Request for Additional Information (RAI) identifies the infonnation needed by the NRC to resolve the issues raised in Bulletin 88-02.
We would like to resolve these issues prior to restart from the current i
outage. A draft copy of this RAI previously has been provided to your t
technical staff ta expedite your response.
l l
The infonnation requested in this letter affects fewer than 10 respondents; t
I therefore, OMB clearance is not required under Pub. L. 96-51).
(
l sincerely,
)
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Warren H. Swenson, Project Manager f
Project Directorate III-3 Division of Reactor Projects - III, IV, Y and Special Projects
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Enclosure:
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Mr. C. W. Fay Point Beach Nuclear Plant Wisconsin Electric Power Compa;1y Units 1 and 2 CC:
Mr. Bruce Churchill, Esq.
Shaw, Pittman, Potts and Trowbridge 2300 N Street, N.W.
Washington, DC 20037 Mr. James J. Zach, Manager Point Beach Nuclear Plant Wisconsin Electric Power Company 6610 Nuclear P.oad Two Rivers, Wisconsin 54241 Town Chairman Town of Two Creeks Route 3 Two Rivers Wisc'onsin 54241 Chairman Public Service Commission of Wisceasin i
Hills Farus State Office Building Madison, Wisconsin 53702 Regional Aoministrator, Region !!!
U.S. Nuclear Regulatory Commission
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Office of Executive Director for Operations 799 Roosevelt Road Glen Ellyn, Illinois 60137 Resident Inspector's Office U.S. Nuclear Regulatory Commission 6612 Nuclear Road Two Rivers, Wisconsin 54241 9
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ENCLOSURE REQUEST FOR ADDITIONAL INFORMATION WISCONSIN ELECTRIC POWER COMPANY POINT BEACH UN!1 2 IMPLEMENTATION OF BULLETIN 88-02 C0997 Since issuance of WCAP-11666 for Point Beach 2. the Westinghouse generic suthodology has undergone a number of refinements. The staff believes that i
i these refinements should be critically reviewed to ensure that the results and conclusions reporteo in WCAP-11666 continue to be conservative. This review should address, but not necessarily be limited to, the following questionst OUESTION 1 WCAP 11666 does not specifically address the subject of uncertainties in the AVB insertion depth estimates.
For AVB configurations leading to potentially significant flow peaking facters (which we understand to include flow peaking factors potentially > 1.0). AYBs in more recent Westinghouse at.alyses Mye i
reportedly been positioned within measurement uncertainties to maximizu the flow peaking factor estimate. Please describe whether the AVBs were positioned in a similarly conservative manner during the Point Beach aralysis? (Ifnot.
we believe that potentially limiting tubes should be reassessed to ensure that i
conservative flow peaking factors have been incorporeted into the analysis]
QUESTION 2 The licensee's letter dated March 25, 1988 notes that more recent estimates since issuance of WCAP=11666 indicate a flow peaking factor of 1.47 for North Anna tube R9C51, compared to an earlier estimate of 1.16. The effect of this
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change is to reduce the ' relative" stability ratio estimate for tubes at Point Beach. The March 25,1988 letter, however, does not address revised air test data for idealized AVB configurations relative to what were considered in the
WCAP 11666 report. For example, AYB configuration no. 3 in Table 7-3 of WCAP-11666 is now believed to have a flow peaking factor of 1.11 rather than the value of 1.0 assumed in the WCAP-11666 analyses.
Do stability ratio, stress ratio, and fatigue usage factors for the limiting tube locations continue to be acceptable if the lat6st peaking factor data are used7 Please discuss how this conclusion was reached.
QUESTION 3 i
l Consider tube R10-C39 in Figure 6-6 of WCAP.11666. The AVB configuration pictured for this tube looks very much like the AVB configuration for tube R9-C47 at North Anna (see Figure 8-6 of WCAP-11799). What is the justification for considering a flow peaking factor 41.47 for tube R10-C39 at Point Beach 2. SG A?
QUESTION 4 i
During the October 25, 1988 telecon with the staff, the Westinghuuse representative j
indicated that in some instances, flow peaking factors for a given AVB configura-l tion may have been estimated based on interpolation between air test data obtained for different idealized AVB configurations.
Please describe the methodology gnd and validity of such aninterpolation.
[ Absent adequate justification for such I
an approach, the staff believes that flow peaking factors should be determined directly from air test data for idealized AVB configurations which conservatively envelope the actual AVB configurations being assessed.]
QUESTION 5 Discuss the basis for assuming a flow peaking factor of 1.0 for tubes locate ' in columns 2 and 91, rows 10, ll, and 12.
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