ML16342A335
| ML16342A335 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 12/06/1993 |
| From: | Peterson S Office of Nuclear Reactor Regulation |
| To: | Rueger G PACIFIC GAS & ELECTRIC CO. |
| References | |
| TAC-M86194, TAC-M86195, NUDOCS 9312150025 | |
| Download: ML16342A335 (8) | |
Text
December 6,
1993 ~
Docket Nos.
50-275 and 50-323 Hr. Gregory H. Rueger Nuclear Power Gener ation, B14A Pacific Gas and Electric Company 77 Beale Street, Room 1451 P.O.
Box 770000 San Francisco, California 94177
Dear Hr. Rueger:
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION RELATED TO ASME CODE RELIEF REQUEST FOR A BLOCK VALVE DOWNSTREAM OF A RELIEF VALVE FOR POSITIVE DISPLACEMENT PUMP AT DIABLO CANYON NUCLEAR POWER PLANT, UNIT NO.
1 (TAC NO. H86194)
AND UNIT NO.
2 (TAC NO. M86195)
By letter dated April 13, 1993, Pacific Gas and Electric Company (PG&E) requested relief from ASHE Code section III, subsection NC-7142 for a block valve installed downstream of a relief valve for the positive displacement pump.
By letter dated April 15, 1993, the NRC staff determined that your proposed alternatives were acceptable on an interim basis until an in-depth review was completed by the staff.
We have determined that additional information is necessary.
Enclosed is a request for additional information (RAI) that is needed to complete our review.
We request that you respond to the RAI within 60 days of your receipt of this letter.
This request for information affects fewer than 10 respondents.
Therefore, it is not subject to Office of Management and Budget review under Pub.
L.96-511.
Please contact me should you have any questions regarding this request.
Sincerely, Original signed by:
Sheri R. Peterson, Project Manager Project Directorate V
Division of Reactor Projects III/IV/V Office of Nuclear Reactor Regulation Enclosures; As stated cc w/enclosures:
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON> D.C. 20555-0001 December 6,
1993 Docket Nos.
50-275 and 50-323 Mr. Gregory M. Rueger Nuclear Power Generation, B14A Pacific Gas and Electric Company 77 Beale Street, Room 1451 P.O.
Box 770000 San Francisco, California 94177
Dear Hr. Rueger:
SUBJECT:
RE(VEST FOR ADDITIONAL INFORMATION RELATED TO ASHE CODE RELIEF REQUEST FOR A BLOCK VALVE DOWNSTREAM OF A RELIEF VALVE FOR POSITIVE DISPLACEMENT PUMP AT DIABLO CANYON NUCLEAR POWER PLANT, UNIT NO.
1 (TAC NO. H86194)
AND UNIT NO.
2 (TAC NO. H86195)
By letter dated April 13, 1993, Pacific Gas and Electric Company (PG&E) requested relief from ASME Code section III, subsection NC-7142 for a block valve installed downstream of a relief valve for the positive displacement pump.
By letter dated April 15, 1993, the NRC staff determined that your proposed alternatives were acceptable on an interim basis until an in-depth review was completed by the staff.
We have determined that additional information is necessary.
Enclosed is a request for additional information (RAI) that is needed to complete our review.
We request that you respond to the RAI within 60 days of your receipt of this letter.
This request for information affects fewer than 10 respondents.
Therefore, it is not subject to Office of Management and Budget review under Pub.
L.96-511.
Please contact me should you have any questions regarding this request.
Sincerely,
Enclosures:
As stated cc w/enclosures:
See next page Sheri R. Peterson, Project Manager Project Directorate V
Division of Reactor Projects III/IV/V Office of Nuclear Reactor Regulation
I
RE(UEST FOR ADDITIONAL INFORMATION RELIEF RE(VEST FROM ASME CODE SECTION III, SUBSECTION NC-7142 BLOCK VALVE DOWNSTREAM OF RELIEF VALVE FOR POSITIVE DISPLACEMENT PUMP AT DIABLO CANYON UNITS 1
AND 2 In the submittal dated April 13, 1993, the licensee states that the Chemical and Volume Control System (CVCS) positive displacement pump (PDP) is required for the following two functions:
For boration flow as required by Technical Specification (T/S) 3.1.2.3 and 3.1.2.4.
For post-fire safe shutdown to meet 10 CFR 50, Appendix R
requirements.
The submittal also postulates that if block valve 831 (CVCS-1-831 and CVCS-2-831) is inadvertently closed, the bonnet of drain valve 54 or the discharge flange of RV-8116 would deform to effectively relieve system pressure.
However, it is noted that with block valve 831 closed, back pressure at the relief valve discharge, either present due to a small leak through the relief valve or built up as the relief valve begins to open, could cause the relief valve not to open at all or immediately reseat.
This could prevent the discharge line from being pressurized as postulated such that excessive system pressure would not be relieved.
Even if the relief valve design is such that back pressure would not cause the relief valve to remain closed or immediately reseat, the valve response time could be adversely'ffected.
Since the pressurization rate from the PDP discharge can be very large if the system is completely isolated, it would appear that this could result in the rupture of the piping on the inlet side of the relief valve rather than on the outlet side which would then effectively disable the PDP.
Therefore, the inadvertent closure of block valve 831 could result in the inability of the PDP to perform the above safety functions.
Please describe the above safety functions in more detail including how important they are to plant safety.
2.
Please provide information about any alternative capability to perform these functions in the event the PDP is inoperable.
C fy
Hr. Gregory H. Rueger Pacific Gas and Electric Company Diablo Canyon CC:
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 California 6715 Rocky Canyon Creston, California 93432 Hs.
Nancy Culver San Luis Obispo Mothers for Peace P. 0.
Box 164 Pismo Beach, California 93448 Hs. Jacquelyn C. Wheeler 3303 Barranca Court San Luis Obispo, California 93401 Managing Editor The County Telegram Tribune 1321 Johnson Avenue P. 0.
Box 112 San Luis Obispo, California 93406 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, Rm.
4102 San Francisco, California 94102 Diablo Canyon Independent Safety Committee ATTN:
Robert R. Wellington, Esq.
Legal Counsel 857 Cass Street, Suite D
Monterey, California 93940 Hr. Steve Hsu Radiologic Health Branch State Department of Health Services Post Office Box 942732 Sacramento, California 94234 Regional Administrator, Region V
U.S. Nuclear Regulatory Commission 1450 Maria Lane, Suite 210 Walnut Creek, California 94596 Hr. Peter H. Kaufman Deputy Attorney General State of California 110 West A Street, Suite 700 San Diego, California 92101 Christopher J. Warner, Esq.
Pacific Gas 5 Electric Company Post Office Box 7442 San Francisco, California 94120 Hr. John Townsend Vice President and Plant Manager Diablo Canyon Power Plant P. 0.
Box 56 Avila Beach, California 93424
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