ML20128D583
| ML20128D583 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 05/23/1985 |
| From: | Andrews R OMAHA PUBLIC POWER DISTRICT |
| To: | John Miller Office of Nuclear Reactor Regulation |
| References | |
| LIC-85-215, NUDOCS 8505290127 | |
| Download: ML20128D583 (3) | |
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Omaha Public Power District 1623 Harney Omaha. Nebraska 68102 402/536-4000 May 23,1985 LIC-85-215 Mr. James R. Miller, Chief Office of Nuclear Reactor Regulation Division of Licensing U. S. Nuclear Regulatory Commission Washington, DC 20555
References:
(1)
Docket No. 50-285 (2)
Letter NRC (J. R. Miller) to OPPD (R. L. Andrews) dated April 23, 1985
Dear Mr. Miller:
Request for Additional Infonnation j
Concerning Reactor Coolant Pump Trip The Omaha Public Power District received your letter (Reference (2)) concerning this subject.
Please find attached our responses to your questions.
Sinc el R. L. Andrews Division Manager Nuclear Production RLA/DJM/rh Attachmen t cc:
LeBoeuf, Lamb, Leiby & MacRae 1333 New Hampshire Avenue, N.W.
Washington, DC 20036 Mr. E. G. Tourigny, NRC Project Manager Mr. L. A. Yandell, NRC Senior Resident Inspector 85052901g{$$$$$$85 PDR ADO PDR P
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Question #1 Does any containment isolation signal result in the tennination of systems essential for continued operation of the reactor coolant pumps? If so, identify the signals and systens effected.
District Response The logic for the closure of containment isolation valves (HCV-438A through D) for the component cooling water going into containment is designed such that a CIAS (Containment Isolation Actuation Signal) and a low component cooling water pressure less than 60 psig must occur concurrently before the isolation valves will close. Thus, Fort Calhoun Station does not experience an isolation of an essential system needed for continued RCP operation upon CIAS.
Question #2 If essential water services are tenninated, provide a description of the oper-ator guidelines, training, and procedures in place (or to be implemented) which assure that these services are restored in a timely manner to prevent seal dam-age or failure, once a non-LOCA situation has been confinned.
District Response As discussed in response to Question #1, essential water services to the RCP's are not terminated on CIAS.
It should be noted that the operator has the capa-bility to override the isolation signal on the component cooling system, even if the pressure in the component cooling water system falls below 60 psig.
This capability is identified and discussed during operator training.
Question #3 Provide confinnation, including the technical basis, that containnent isolation with continued RCP operation will not lead to seal or pump damage or failure.
District Response Because all essential systems for operation of the RCP's continue to be avail-able upon CIAS (see answer to #1), the pumps can continue operating indefinite-ly.
Question #4A Since an RCP trip is required for LOCA events, assurance must be provided that an RCP trip, when required, will occur. To address this concern, provide the following infonnation:
Identify the components regt. ~2d to trip the RCP's.
Include relays, power supplies, and breakers. Address reliability and alternate trip methods.
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District Response
.The four RCP's are supplied from each of the four 4.16KV buses, RC-3A bus 1A1, RC-3B bus 1A2,.RC-3C bus 1A3, and RC-30 bus 1A4. Tripping of the RCP breakers in a DBA (Design Basis Accident) situation is accomplished, nomally, by trip-ping the breaker from the control switch in the control room.
This tripping requires the station's 130 VDC control power system, the control switch, the breakers, and their operating mechanisms.
In the event the control room switch fails to trip the breaker, the trip may be accomplished locally either. by electric control switch, or manually in the breaker cubical. It should be noted that for electrically tripped breakers the buses may be switched to an alternate control power supply which is operated from the switchgear room.
Reliability of the Fort Calhoun 4.16KV system is maintained through periodic breaker maintenance, relay maintenance, and trip check testing. The operating history of the 4.16KV system has been excellent. The District has a system in place to track information from INP0 and the NRC so that failures at other plants of variws electrical equipment are evaluated for their potential of occurring at the Fort Calhoun Station. Maintenance and service on the Fort Calhoun electrical system is affected by these notices. Thus, actions to modify equipment to prevent malfunctions observed at other plants, but not observed at Fort Calhoun, have been and will continue to be taken.
Question #4B If necessary, as a result of the location of any critical component, include the effects of adverse containment conditions on RCP trip reliability. De-scribe the basis for the adverse containment parameters selected.
District Response In accordance with the District's 10 CFR 50.49 program, (electrical equipment qualification) none of the equipment needed to trip the RCP's is considered to be in a " harsh" environment under postulated accident conditions. Access for local tripping will not be inhibited under any accident analyzed in the Updated Safety Analysis Report.
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