ML19305B300
| ML19305B300 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 03/14/1980 |
| From: | Hoffman D CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Ziemann D Office of Nuclear Reactor Regulation |
| References | |
| TASK-06-04, TASK-6-4, TASK-RR NUDOCS 8003190479 | |
| Download: ML19305B300 (2) | |
Text
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- Area Code 517 780-O550 March 14, 1980 Director, Nuclear Reactor Regulation Att Mr Dennis L Ziemann, Chief Operating Reactors Branch No 2 US Nuclear Regulatory Commission Washington, DC 20555 DOCKET 50-155 - LICENSE DPR BIG ROCK POINT PLANT - CONTAINMENT PURGE SYSTEM, SINGLE FAILURES Reference 1 provided the NRC staff with a single failure analysis of the existing Big Rock Point Plant Containment Purge System (Ventilation Supply and Exhaust Isolation Valves). The NRC then sent this analysis to EG&G who sub-stantiated our findings. Reference 2 requested Consumers Power Company to address each single failure postulated in the EG&G report (attached to Reference 2) and provide a justification and/or proposed modification to the purge system. Reference 3 outlines Consumers Power Company's action and schedule.
Reference 1 had already identified the same single failures as pointed out in the EG&G report and each single failure was addressed and justified by a combination of probabilities and equipment redundancies. Since the NRC did not respond to these justifications, and based on Reference 2, Consumers Power Company has redesigned the electrical control schemes for the containment ventilation supply and exhaust isolation valves. These new schemes are shown on Drawings SK-0740G30114, dated 11-30-79, and SK-0740G40125, dated 11-30-79, and were submitted to the NRC staff for consideration. The Big Rock Point Plant staff has reviewed these new schemes and found that all of the single failures have been eliminated.
The detailed design phase of this modification has not yet started. However, if delivery time for qualified equipment is not unreasonable, modification completion is expected prior to start-up from the next refueling outage (October 24, 1980).
Reference 2 also requested Consumers Power Company to respond to IE Bulletin 73-02 which is concerned with the failure of a single control switch which could result in the isolation valves failing to operate when required.
Both 6003190hK
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2 t e s ng e failure analysis submitted in Reference 1 and the single failure h
i l analysis prepared by EG&G (Reference 2) showed that the single hand switch does not violate the single failure criteria for this particular control scheme. The failure of this hand switch would not prevent isolation on a high radiation or. trip signal nor would it prevent opening the valves for vacuum relief. Therefore, no corrective actions are planned.
David-P Hoffman (Signed)
David P Hoffman Nuclear Licensing Administrator CC JGKeppler, USNRC
References:
(1) D A Bixel to NRC - letter dated November 29, 1978.
(2) NRC to D A Bixel - letter dated October 16, 1979.
(3) D P Hoffman to NRC - letter dated December 3,1979.
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