ML20002C641
| ML20002C641 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 02/21/1973 |
| From: | Walker G CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Oleary J US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 8101100640 | |
| Download: ML20002C641 (3) | |
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avd e c Mr. John F. O' Leary, Director Re:
Docket No 50-155 Directorate of Licensing License No BRP-6 United States Atomic Energy Commission Washington, DC 20545
Dear Mr. O' Leary:
This letter vill provide information regarding the control circuit design review of safety-related equipment at our Big Rock Point Plant as requested by Mr. D. J. Skovholt's letter of December 22, 1972.
Two systems will require modification or a design change.
These systems are: The 480-volt Bus 2B emergency power system; and the reactor building emergency backup spray system (Valve MO-7068).
The autostart relay must sense an undervoltage on both 1A and 2A buses (27-1 and 27-2) before the diesel generator breaker will close and supply load to the 23 bus in the 480-volt, Bus 2B power system. The IA-2B and the 2A-2B tie breakers open by a shunt trip with the loss of voltage on lA and 2A buses coincident with a normal emergency diesel voltage oucput.
- Thus, the breaker closing circuit is interlocked with 1A-2B and 2A-2B tie breakers to prevent closure of the emergency gener-ator on an energized bus. If either, or both, lA-2B or 2A-2B breakers are removed for maintenance, the emergency generator breaker closing circuit cannot be completed. Thus, the e=ergency generator vill not close automatically onto the 2B bus. Design changes will be made to correct this deficiency as soon as possible. Until tha t time, proce-dures will be instituted that will allow the emergency zenerator breaker to close if either or both breakers are removed.
The reactor building emergener backup spray system requires the automatic init$ation of Relay 62-1/PD to supply power from lY-23 for the operation of Valve MO-7068. If the lY-23 power source were unavailable, then Valve MO-7068 could not operate automatically. A modification of rerouting the power srpply for the 62-1/TD relay to Valve MO-7068 control circuit will be completed by April 1,.1973 A
temporary procedure denoting this deficiency vill be in effect until this change is completed.
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t Mr, John F. O'L.ary 2
Dock;t No 50-155.
License NO BRP-6 February 21, 1973 We have conducted an investigation to determine if procedural changes are required to ensure that whenever a safety-related component is removed from service, redundant equipment is tested. The Big Rock Point Technical Specifications preclude the removal from service of most redundant equipment that is safety related during plant operation.
Even though removal from service of a channel of instrumentation is al-lowed in the reactor protective system, the removal of that channel is accompanied by a trip signal such that no redundancy is lost. Based on thic investigation, we have concluded that no further action is required with respect to testing of redundant components.
Yours very truly, 7
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1 rs RBS/mel Gerald J. Walk.
Nuclear Fuels Administrator h
AEC DIMIBUTION FOR PART 50 DOCKET MAF'IAL (TEMPORARY FORM)
CONTROL NO: 1293 -
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DATE OF DOC:
__DATE REC'D LTL MEMO RP2 ODiER Consumers Power Company Jackson, Michigen 49201 Gerald J. Walke 2-21-73 2-26-73 X
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40 50-155 DESCRIPfl0N:-
ENCLOSURES:
Ltr re our 12-2@-72 ltr..... furnishing info ra control circuit destgn review of safety-rel ited equipment at the Big Rock Point Plant......
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