DCL-86-334, Responds to IE Bulletin 86-003, Potential Failure of Multiple ECCS Pumps Due to Single Failure of Air-Operated Valve in Min Flow Recirculation Line. Problem Does Not Exist at Facilities.Eccs Composite Drawing Encl
| ML20214P589 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 11/14/1986 |
| From: | Brand D PACIFIC GAS & ELECTRIC CO. |
| To: | Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| DCL-86-334, IEB-86-003, IEB-86-3, NUDOCS 8612040276 | |
| Download: ML20214P589 (3) | |
Text
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PACIFIC GRAS AND ELECTR,IC
'C,O M PANY
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77 BEALE STREET. SAN FRANCISCO, CALIFORNIA 94106 k!5) 7814211. TWX 910 372-6587 November 14, 1986 UU PGandE Letter No.: DCL-86-334 Mr. John B. Martin, Regional Administrator U. S. Nuclear Regulatory Commission, Wegion V 1450 Maria Lane, Suite 210 Halnut Creek, CA 94596-5368 Re: Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 Diablo Canyon Units 1 and 2 Response to IE Bulletin No. 86-03
Dear Mr. Martin:
In accordance with IE Bulletin 86-03, " Potential Failure of Multiple ECCS Pumps Due to Single Failure of Air Operated Valve in Minimum Flow Recirculation Line," dated October 8,1986, PGandE hereby submits the written report requested by action item 3(a) of the bulletin.
In accordance with action item 3(a), the enclosure reports the review performed as specified by action item 1.
Since PGandE has concluded that the problem discussed in the bulletin does not exist at Diablo Canyon Power Plant, no action is required in response to items 2, 3(b), and 4.
Kindly acknowledge receipt of this material on the enclosed copy of this letter and return it in the enclosed addressed envelope.
l Subscribed in San Francisco, California, this 14th day of November 1986.
Respectfully submitted, Pacific Gas and Electric Corhny l
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By h_a I
YA.M.UQ(nd l
Robert Ohlbach Vice President l
Philip A. Crane, Jr.
Engineering Richard F. Locke Attorneys'for Pacific Subscribed and sworn to before me Gas a Electric omp y this 14th day of November 1986 h@'g b
l By i~
Phili[A. Crape,Jr.
Mildred Hilliads, Notary Public in I
and for the City and County of l
hbR 000 75 San Francisco, State of California f
O PDR Hy commission expires August 7, 1989.
cc:
L. J. Chandler S. A. Varga
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M. M. Mendonca Document Control Desk a
3.nn nummuummus MILDRED J. WILLIAMS
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B. Norton CPUC
' H. E. Schierling Diablo Distribution NOTARY PUBUC-CALIFORNIA j
?,GTY & COUNTY OF SAPIltMIOSCO :
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PGandE Letter No.: DCL-86-334 ENCLOSURE
' Response to IE Bulletin 86-03 Diablo Canyon Power Plant.(DCPP) has no single-failure vulnerability in the minimum flow recirculation line of any emergency core cooling system (ECCS) pumps that c6uld cause a failure of more than one ECCS train. PGandE's evaluation of.the ECCS pumps revealed that the problems experienced with air-operated valves addressed in the bulletin do not exist at DCPP since the isolation valves on the ECCS pump recirculation lines are all motor-operated.
Therefore, no further action is required.
A summary of the evaluation for each ECCS recirculation loop is provided below, and a simplified schematic showing the ECCS alignment during normal operation is attached.
I Safety Iniection (SI) Pumns At DCPP, the tafety injection pumps share a common minimum flow recirculation line. Flow through this recirculation line is routed from the safety 4
injection pumps to the refueling water storage tank through two normally open motor-eperated isolation valves in series, 8974 A and 8974 B.
These valves are required to be open with power to the valve operators removed (Technical Specification Surveillance Requirement 4.5.2a).
Centrifuaal Charaina Pumns (CCP)
The centrifugal charging pumps minimum flow path recirculates through a common header to the seal water heat exchanger inlet. This line has two motor-operated valves in series, 8105 and 8106. These valves are maintained in the open position, with power available, and fail as is. Also, since the CCP has a shutoff pressure of 2511 psig, it is unlikely to encounter plant conditions in which deadheading is a concern.
Emergency operating procedures provide operator guidance for closure and reopening of the valve (s) based on l
RCS pressure.
I Residual Heat Ramnval (RHR) Pumns Each RHR train contains. Its own minimum flow recirculation line, returning flow to the RHR pump suction. The miniflow isolation valves, FCV-641A and FCV-6418, are motor-operated and fail as is. Each valve is powered from a separate vital bus. Therefo e, since each train has its own recirculation line, and power is supplied from separate buses, no single failure will disable both RHR pumps.
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