ML20084S969
| ML20084S969 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 03/26/1974 |
| From: | Sewell R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Oleary J US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20084S972 | List: |
| References | |
| NUDOCS 8306200329 | |
| Download: ML20084S969 (2) | |
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General Officas 212 West Michigan Avenue. Jackson, Michigan 49201. Area Code S17 788-OS50 tO1 Q
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Mr. John F. O' Leary, Directorp k
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L Docket 50-255 j
Directorate of Licensing
- WJ License DPR-20
[j M y"j,47 US Atomic Energy Costission Washington, DC 20545 4/
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Dear Mr. O' Leary:
This letter is written to inform you of an abnormal occurrence at the Palisades Plant which involved the reactor protective system high j
containment pressure trip function. This abnormal occurrence was dis-covered on March 16, 1974, while performing routine refueling surveillance testing of the high containment pressure trip function. Three of the four pressure switches were found to Nye a set point outside of the limits specified in Table 2 3.1 (f. 5 psig) of the Technical Specifications.
The as-found set points for the high containment pressure trip function of the reactor protective system were:
As-Found Set Tag No Function Point (Psig)
PS-1801 RFS Channel A 5.h0 FS-1802 RPS Channel B 5 70 PS-1803 RPS Channel C 5.35 PS-180h RPS Channel D 4.85 During review cf this abnormal occurrence, it was determined that the set point specified in Table 3.16.1, " Engineered Safety Features System Initiation Instrument Setting Limits," for the high containment is meaning-less. The set point is specified as less than or equal to 5 psig (plus 0 75 minus 0.25).
If this set noint is interpreted "within the tolerance band" and not "less than or eque co," one of the pressure switches for the high -
containment pressure engineered safety features system initiation set point was below the allowable tolerance band (4.50 psig).
The cause of this abnormal occurrence was that the previous cali-bration'and set points did not provide sufficient margin for instrument drift. The calibration did not take account for the drift that might be' expected from the. type of pressure switches that are installed at, the Palisades Plant.
The maximum drift over the period between calibrations (8/27/72 to 3/19/74) was 0 7 psi.
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