ML20031C233
| ML20031C233 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 03/12/1974 |
| From: | Sowell R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20031C230 | List: |
| References | |
| AO-1-74, NUDOCS 8110060656 | |
| Download: ML20031C233 (3) | |
Text
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v Mr. John F. O' Leary, Director
//;f M d Re: Docket No 50-155 Directorate of Licensing License No DPR-6 United States Atomic Energy Commission Big Rock Point Washington, DC 205h5
Dear Mr. O' Leary:
This letter is written to report an abnormal occurrence (AO.-1-Th) which occurred at the Big Rock Point Plant on March 1,1974.
'Ihis abnomal occurrence involved the failure of the Channel 3 neutron flux level instrumentation.
At the time this instrument failure occurred, the plant was operating st a steady power level of 166 MW. The Channel 3 neutron t
flux level dropped to zero and imediately returned to a slightly higher indication, 101 percent. (The present 100 percent setting corresponds to 180 IN ')
t Troublesheating revealed that the instrunent channel vould not respond to either high-voltage changes on the chcmber or to input changes. The spare picon==eter was installed, tested and the instru-cent channel was returned to service. The instrument channel was out of cervice for a total of one hour and eleven minutes.
The failure of this instru=ent channel did not result in a loss of any protective function in the reactor protection system.
Three neutron flux instru=ent channels provide a reactor protection system tripping function with two out of three logic. With Channel 3 failed, the ot.her two channels were btill capble of performing the required protective function.
I This is the first known nenfail-safe failure of the a=plifier's function of the picon==eters at Big Rock Point. As bench testing of the faulty unit has failed to detect the esuse, the manufacturer has l
been requested to analyze and provide correcti e measures in an effort i
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8110060656 740312 PDR ADOCK 05000155
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O Mr. John F. 0%ary, Direct:r 2
Docket No 50-155-License No DPR-6 Big Rock Point March 12, 1974 gQ to prevent recurrence. In addition, instructions have been issued to plant operations personnel explaining how to put the monitor in a trip condition if the problem recurs.
Yours very truly, Ralph B. Sewell (Signed)
RBS/ sam Ralph B. Sewell Nuclear Licensing Administrator CC: JCKeppler, USAEC l
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STARTUP AND POWER ASCENSION G-SHUTDOWN (HOT OR COLD.
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