ML20038A070
| ML20038A070 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 11/14/1973 |
| From: | Sewell R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Oleary J US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20038A071 | List: |
| References | |
| AO-14-73, AO-15-73, NUDOCS 8109170295 | |
| Download: ML20038A070 (3) | |
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18 November 14, 1973
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Re: Docket 50-155 Mr. John F. O' Leary. Director
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Directorate of Licensing E
License DPR-6 IB Atomic Energy Cmmission t
Washington, DC 20%5
Dear. Mr. O' Leary:
This letter vill infom you of two abnomal occurrences which occurred during our last shutdown on November 1-3. 1973. 'Ibey
.are described below:
A0-lL-73 The precautions and limitations section of the plant shut-down margin test procedure requires that neutron monitoring system checks be comp *eted prior to conducting shutdevn margin tests. On November 3,1973, shutdown cargin testing was cocnenced prior to con-ducting,the required neutron monitoring system checks. When it was recognized that the neutron monitoring ebacks had not been performed, the shutdown margin testing was halted until the neutron monitoring checks were completed.
The cause of this incident was due to incomplete infomation
-exchang at the shift change. The oncoming shift thought that all re-quirements of the procedures and limitations section of the procedure had been completed by the previous shift such that they could stsrt the actual shutdown margin testing. As stated above, it was later dis-covered that the neutron monitoring system checks had not been com-plated.
To preclude recurrence of a simiJar event in the future, the format of the shutdovr. margin test procedure is beleg changed to in-clude documentation of empletion.of items in the precautions, limits-tions and initial conditions sections.
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8276 8109170295 731114 PDR ADOCK 05000155 PDR
4' Mr. John F. O' Leary, Director November Ib, 1973 3
6 b
g AO-li-73 The Plant Operating Procedures Manual states that, "The in-core firx monitors will be recalibrated utilizing flux vires.
Calibrations vill be performed for approxicately every 20 notches of control rod movesent or when the root mean square deviation e
approaches 155."
However, based on a review of the records on November 7, 1973, the Reactor Engineer discovered that the in-core monitors had not been calibrated as required.
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The Big Rock Poir.t Plant in-core flux rnonitors are only used J
to monitor power distributions and detect deviations frcn predicted power distributions. The in-core detectors provide no automatic pro-tective ihnetion.
The Plant Review Ccamittee concluded that the 20-noter limit in the procedures manual La meaningless and will be eliminated as a requirement. The important requirement was concluded to be the root mean square deviation of 15 percent. The committee further concluded
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that a recurrence could best be prevented if the Reactor Engineering Department kept a trend log of the rect mean square deviations ; and, bssed upon the trends observed, initiate action to ensure that the in-core monitors are recalibrated prior to exceeding the 15 percent devi-ation limit.
The Plant Periev Committee recocimendations are being imple-mented by the plant staff.
Your s ve ry t ruly,
Ralph B. Seve11 (Signed)
RBS/ds Ralph B. Sevell Nuclear Licensing Administrator CC: James G. Keppler, I
USAEC I
.