ML19347C032
| ML19347C032 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 10/06/1980 |
| From: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | Novak T Office of Nuclear Reactor Regulation |
| References | |
| TAC-42933, NUDOCS 8010160480 | |
| Download: ML19347C032 (1) | |
Text
esuun SACRAMENTO MUNICIPAL UTILITY o! STRICT O 6201 S Street, Box 15830, Sacramento, California 95813; (916) 452-3211 October 6, 1980 Director of Nuclear Reactor Regulatien Attention: Mr. Thomas M. Dovak, Assistant Director for Operating Reactors U.S. Nuclear Regulatory Commission Washington, D.C.
20555 Docket 50-312 Rancho Seco Nuclear Generating Station, Unit 1
Dear Mr. Novak:
The Sacramento Municipal Utility District has received your letter of August 15, 1980, requesting certain information concerning the operation of the atmospheric dump valves following a failure of the non-nuclear instrumentation (NNI) or the integrated control system (ICS) poder supply.
Your determination of the present failure modes is correct, and the District proposes to correct this anomaly as a part of our auxiliary feedwater system upgrade, as presented to you and your staff during a meeting on September 4, 1980.
Control of the atmospheric dump valves will be removed from the ICS/NNI sys tem. T.he new safety grade control system will be powered from four new battery-backed inverters and two new diesel generators, thus elimi-nating any possibility of the valves opening on loss of power The design
~
for the new auxiliary feedwater initiation and control system, including the. dump valve control and override,. is scheduled to be submitted to your staff for review on October 15,'1980. The schedule for implementation of this change is dependent upon hardware delivery and we presently estimate the best possible date for equipment delivery to be in the first quarter of 1982.
Installation would occur during the first extended outage fol-lewing delivery. If we can provide any additional information on this por-tion of the upgraded auxiliary feedwater system design, please advise.
Sincerely,'
L 9&A ohn J. Mattimoe 0(
Assistant General Manager 0
0 and Chief Engineer 80io i s o@o f
l A M - E l l. C T R I' c S Y S T E M -S E R V t N G MORE THAN 600.000 IN THE HEART Of C A LIF O R N I A
\\