ML16342D941
| ML16342D941 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 01/06/1998 |
| From: | Steven Bloom NRC (Affiliation Not Assigned) |
| To: | Rueger G PACIFIC GAS & ELECTRIC CO. |
| References | |
| TAC-M98283, TAC-M98284, NUDOCS 9801130332 | |
| Download: ML16342D941 (6) | |
Text
january 6, 1998 Hr. Gregory M. Rueger Pacitic Gas and Electric Company'PG
- Hail Code A10D P. 0.
Box 770000 San Francisco, California 94177
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION -
PROPOSED W* STEAM GENERATOR TUBE REPAIR CRITERIA,(TAC'OS. H98283 AND H98284)
Dear Mr. Rueger:
By letter dated March 10,'997, as supplemented by letter dated Hay 20,
- 1997, Pacific Gas and Electric Company (PG8E),submitted Revision 1 of Westinghouse Electric Corporation (Westinghouse) technical reports of WCAP-14797 (proprietary) and WCAP-14798 (nonproprietary),
"Generic W* Tube Plugging Criteria for 51, Series Steam Generator Tubesheet Region WEXTEX Expansions."
These reports are to be used as the basis for License Amendment Request 97-04, to modify the steam generator tube plugging criteria in Technical Specification (TS) 3.4.5 and the allowable operational leakage limit in TS 3.4.6.2.
The staff has identified a potentially significant assumption in the analyses that, without further technical justification, may invalidate the licensee's conclusions.
The staff's request for additional information is enclosed.
Please submit your response within 60 days of 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 January 6,
1998 cc w/encl:
NRC Resident Inspector Diablo Canyon Nuclear Power Plant c/o U.S. Nuclear Regulatory Commission P. 0.
Box 369 Avila Beach, California 93424 Dr. Richard Ferguson.
Energy Chair Sierra Club Cali fornia 1100 11th Street.
Suite 311 Sacramento, Cali forni a 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, Cali fornia 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 8 Payillion 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, Cali fornia 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 ATTN:
Managing Editor 1321 Johnson Avenue P.O.
Box 112 San Luis Obispo, California 93406
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J ENCLOSURE RE UEST FOR ADDITIONAL INFORMATION PACIFIC GAS AND ELECTRIC COMPANY DIA8LO CANYON POWER PLANT UNITS 1 AND 2 DOCKET NOS. 50-275 AND 50-323 The structural and leak analyses documented in WCAP-14797, Revision 1, "Generic W* Tube Plugging Criteria for 51 Series Steam Generator Tubesheet Region WEXTEX Expansions." rely on the ability to accurately calculate the radial contact pressure between the outside diameter of the tube and the tubesheet.
The expression for determining this contact pressure is given in equation 4.4-7.
The basis for the formulation'f this equation utilized thick shell equations included in Reference
- 9. 11 of'CAP-14797.
The staff notes that the equations presented in the noted reference and used in the derivation of the radial contact pressure expression appear to assume there is no longitudinal loading on the, tube.
Such a condition could be established by locking between the tube and the tube support plates.
However, this assumption is not stated in the report.
Discuss whether the derivation of the expression for the radial contact pressures between the tube and tubesheet assumes locked tube conditions.
If locked tube conditions are assumed in the report. explain.how such a condition is validated for inservice steam generator tubes proposed to be repaired by a W* approach.
If the'tubes are not assumed to be in a locked state, explain how the interaction between the longitudinal tube stresses and the radial contact pressure is accounted for in the expression included in WCAP-14797.
If this interaction is not accounted for in equation 4.4-7, discuss how this effect is addressed in each of the calculations that utilized the radial contact pressure expression.
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