ML19347C796
| ML19347C796 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 01/28/1974 |
| From: | JERSEY CENTRAL POWER & LIGHT CO. |
| To: | |
| References | |
| AO-50-219-74-7, NUDOCS 8103040546 | |
| Download: ML19347C796 (1) | |
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M!dC/M WI OYSTER CREEK NUCLEAR GENERATING STATION FORKED RIVER, NEW JERSEY 08731 Abnormal Occurrence Report No. 50-219/74/7 Report Date:
January 28, 1974 Occurrence Date:
January 23, 1974 Identification of Occurrence:
Violation of the Technical Specifications, paragraph 2.3.3, failure of the RE03D reactor high pressure sensor to trip at a point corresponding to a reactor pressure of <1060 psig. This event is considered to be an abnormal occurrence as deTined in the Technical Specifications, paragraph 1.15A.
Conditions Prior to Occurrence:
Routine plant startup was in progress.
The major plant parameters at the time of the event were as follows:
Reactor Thermal Power - 1080 MWt Electrical Power
- 342 MWe Recirculation Flow
- 27.8 x 106 lb/hr.
Reactor Pressure
- 1020 psig Description of Occurrence:
While performing a routine monthly surveillance test on the reactor high pressure sensors, RE03A, B, C, and D, it was observed that RE03D tripped at 1073 psig. This is 7 psig above its normal trip point of 1066 psig which reflects a sensor head correction of 6 psig. The surveillance test results were as follows:
As Found As Left Nominal Trip Point Trip Point Trip Point RE03A 1067 psig 1067 psig 1068 psig RE03B 1068 psig 1068 psig 1068 psig RE03C 1066 psig 1066 psig 1066 psig RE03D 1073 psig 1066 psig 1066 psig f/ogo1'o5/G
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Abnormal Occurrence Report No. S0-219/74/7 Page 2 Apparent Cause of Occurrence:
Design is a factor contributing to the cause of this occurrence.
The reason for the change in sensor set point is under investigation.
Several pressure sensors on other safety systens have displayed similar set point drift.
In most instances the instrument manu-facturer has been contacted but little information that would lead to a solution to the problem has been received.
Analysis of Occurrence:
The safety significance of this event lies in a loss of system redundancy. Had a pressure excursion occurred, the redundant sensor, RE03C, would have functioned properly and would have terminated the pressure transient in conjunction with the proper actuation of the RE03A and B Sensors.
Corrective Action:
The pressure sensor, RE03D, was recalibrated and returned to service.
Engineering assistance wil; be obtained to determine the cause of drift in the pressure sensors of concern and to recommend corrective solutions.
The plant staff will investigate possible Technical Specification changes that will allow for instrument tolerances and will reduce excessive conservatism in the analyses on which some of the limits are based.
Failure Data:
Manufacturer:
Barksdale Type:
Pressure Actuated Switch Switch No. :
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