ML16342D891
| ML16342D891 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 12/02/1997 |
| From: | Steven Bloom NRC (Affiliation Not Assigned) |
| To: | Rueger G PACIFIC GAS & ELECTRIC CO. |
| References | |
| TAC-M99011, TAC-M99012, NUDOCS 9712090165 | |
| Download: ML16342D891 (6) | |
Text
December 2,
1997 Mr. Gregory M. Rueger, Senior Vice President and General Manager Pacific Gas and Electric Company Nuclear Power Generation N9B P.
0.
Box 770000 San Francisco, California 94177
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION - WCAP-14707, "MODEL 51 STEAM GENERATOR LIMITED TUBE SUPPORT PLATE DISPLACEMENT ANALYSIS FOR DENTED OR PACKED TUBE TO TUBE SUPPORT PLATE CREVICES" (TAC NOS.
H99011 AND H99012)
Dear Mr. Rueger:
By letter dated October 4, 1996, Pacific Gas and Electric Company (PG&E) submitted Westinghouse Electric Corporation (Westinghouse) technical reports WCAP-14707 (proprietary) and WCAP-14708 (nonproprietary),
"Model 51 Steam Generator Limited Tube Support Plate Displacement Analysis For Dented or Packed Tube To Tube Support Plate Crevices."
These reports describe the results of work performed to assess the potential for tube support plate (TSP) displacement in a postulated main steam line break event for a generic Model 51 steam generator (SG) with dented or packed tube-to-TSP crevices with TSP corrosion.
The NRC has performed an initial review, which focused on the results from Section 4.0, "Axial Pull Force Tests for TSP Displacement and Leakage Tests with Dented or Packed TSP Intersections'
" and the connection between these results and the conclusion drawn in Section 2.0.
"Summary and Conclusions."
In order to complete our review the staff requires the additional information described in the enclosure.
Please submit your response within 30 days from receipt of this letter.
Sincerely, Original Signed By Steven D. Bloom, Project Manager Project Directorate IV-2 Division of Reactor Projects III/IV Office of Nuclear Reactor Regulation Docket Nos.
50-275 and 50-323
Enclosure:
Request for Additional Information cc w/encl:
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Mr. Gregory M. Rueger December 2,
1997 cc w/encl:
NRC Resident Inspector Diablo Canyon Nuclear Power Plant c/o U.S. Nuclear Regulatory Commission P.
O.
Box 369 Avila Beach. California 93424 Dr. Richard, Ferguson.
Energy Chair Sierra Club California 1100 11th Street.
Suite 311 Sacramento.
Cali fornia 95814 Ms.
Nancy Culver San Luis Obispo Mothers for Peace P.
0.
Box 164 Pismo Beach, California 93448 Chairman San Luis Obispo County Board of Supervisors Room 370 County Government Center San Luis Obispo. California 93408 Mr. Truman Burns Mr. Robert Kinosian California Public Utilities Commission 505 Van Ness, Room 4102 San Francisco.
California 94102 Mr. Steve Hsu Radiologic Health Branch State Department of Health Services Post Office Box 942732 Sacramento, California 94232 Diablo Canyon Independent Safety Committee ATTN:
Robert R. Wellington, Esq.
Legal Counsel 857 Cass Street.
Suite D
Monterey. California 93940 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission Harris Tower
& Pavi llion 611 Ryan Plaza Drive, Suite 400 Arlington, Texas 76011-8064 Christopher J. Warner, Esq.
Pacific Gas 8 Electric Company Post Office Box 7442 San Francisco, California 94120 Mr. Robert P.
Powers Vice President and Plant Manager Diablo Canyon Nuclear Power Plant P. 0.
Box 56 Avila Beach, California 93424 Telegram-Tribune ATlN:
Managing Editor 1321 Johnson Avenue P.O.
Box 112 San Luis Obispo. California 93406
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ENCLOSURE RE UEST FOR ADDITIONAL INFORMATION PACIFIC GAS AND ELECTRIC COMPANY DIABLO CANYON POWER PLANT UNITS 1 AND 2 DOCKET NOS.
50-275 AND 50-323 1.
Provide References 1, 2.
3 and 4 for staff review.
2.
Provide the technical basis for concluding that the Dampier re'-1 test results (i.e., pull force and leak rate testing, before and after chemical cleaning) are applicable to all TSP intersections in all Model 51 steam generators despite potential differences in the TSP crevice conditions given differences in TSP location, SG service life, secondary side water chemistry, chemical cleaning process.
etc.
Provide the technical basis for concluding the presence of "some denting" indicates all TSP intersections have "packed crevices developing high forces resisting SLB displacement and resulting in negligible leakage (p.2-1)."
4.
Discuss how one can directly verify. on a site-specific basis.
that the TSP crevice conditions can be relied upon to ensure limited TSP displacement.
5.
6.
Discuss the methods used to ensure that all relevant worldwide data have been obtained.
In accordance with the staff's approach to risk informed regulation.
changes in licensing basis are to be accompanied by an assessment of the associated potential for changes in risk.
In view of future proposed changes to the design basis, address the implications for tube integrity under severe accident conditions.
Specifically. address the effect due to defects left in service.
0 I'