ML19308A500
| ML19308A500 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 06/03/1974 |
| From: | METROPOLITAN EDISON CO. |
| To: | |
| Shared Package | |
| ML19308A499 | List: |
| References | |
| NUDOCS 7910250700 | |
| Download: ML19308A500 (2) | |
Text
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J - l-1 .4 .w,$ ! Pk.w.)<e r _N'1 ..: ABNORMAL OCC1)RRENCE REPORT . i j 1. Report No. '50.-220/74-8 t2a. .Date .../ June.3,~1974 2b. Occurrence Date iMay 31, 197,4 .c .3. Facility .Nine Hile Point Nuclear Station Unit 1 /4. Ident'ification of Occurrence DhQO 5etpcint drift on Drywell High Pressure hgg M b;b 3 T ' S.
- Conditions Prior to Occurrence k~Y
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- Unit.1 was shutdown for annual refueling 26.
Descriptien of Occurrence During routine surveillance testing en May 31., Ic74 at approximately 1600 hours, two Barton Instru:ents used in the trywell High Pressure -(3.5 psig) RPS were found to ha' e drifted.'20 'ssi. higher than required. v 'The surveillance test consists of operating the switch thru regulated '(tercury cancreter) air signal to 'the sensor. The two Barten Instruments >Hodel 289,.E.P. 8RE04A4D are in separato RPS trip systems.
- With reactor in refuol mode and the drywell under atmospheric conditions v
no operator action was necessary, as the plant was in a safe condition. 7. ' Designation of Accarent Cause of the Occurrence Setpvint. drift c.
- 8.
- Analysis of occurrence
'The high drywell pressure trip requires a ono.out of two twice logic to. actuate the protective function. One channel in each trip systen 'would havo actuated at the required setpoint and thus produced the . protective function. Therefore,.no hazard would have been presented l to the general public or station had the protective function been l srequired. .9. . Corrective Action The im=ediato co rective action involved recalibration of the Barton . switch. The normal valvo of setpoint is 3.S +.053 psig. A modif-ication has been made to the Barton switch. I'new switch plate lacking device to prevent setpoint drift has been installed. (AOR 74-1). This modification should reduce setpoint drift problems with this switch. i l 7910250 7 0 0
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..n: 10. - Fallure Data ..w ...~ '. iNo previous setpoint drifting has cccurred on these switches this .Eyear. AOR 74 '1 concerning a Barten switch setpoint drift is the only .fother drift in setpoint taidate.in 1974. .r. ..e., '..G:,:, 1} - ~ W_ ,y.og
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