ML20090D207
| ML20090D207 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 09/08/1975 |
| From: | Ross D JERSEY CENTRAL POWER & LIGHT CO. |
| To: | Anthony Giambusso Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20090D214 | List: |
| References | |
| AO-75-24, NUDOCS 8302240166 | |
| Download: ML20090D207 (4) | |
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MADISON AVENUE AT PUNCH BOWL ROAD + MORRISTOWN, N.J. 0796J + 101-539-6111
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OYSTER CREEK NUCLEAR GENERATING STATION Forked River, New Jersey 08731 Abnormal Occurrence Report No. 50-219/75-24 Report Date September 8, 1975 Occurrence Date l
August 29, 1975 l
l Identific: ' ion of Occurrence Violation of the Technical Specifications, paragraph 2.3.4, E1cetromatic Relief Valve Pressure Switches, 1A83C and 1A83D, were found to trip at pressures in excess of the maximum allowabic value of 1070 psig. This event l
is considered to be an abnormal occurrence as defined in the Technical Specifications, paragraph 1.15. A.
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Conditions Prior to occurrence The plant was in a routine shutdown operation with the reactor mode switch in the refuel position and reactor coolant temperature less than 212 F.
Description of Occurrence On Friday, August 29, 1975, while performing surveillance on the five Electro-matic Relief Valve Pressure Switches, it was found that 1A83C and 1A83D tripped at 1080 and 1084 psig, respectively.
These values are in excess of the maximwn allowable trip points of 1077 and 1082, which are derived by adding the appropriate head correction factors to the Technical Specification limit of 1070 psig.
It is noted here that switches 1A83C and 1A83D are associated with valves NR10SC and NR108D, respectively.
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Abnormal Occurrence Report No. 50-219/75-24 Page 2 The "As Found" and "As Left" switch settings were:
Associated "As Found" "As Left" Switch Valve Setting Setting 1A83A NR108A 1073 psig 1079 psig 1A83B NR108B 1071 psig 1084 psig 1A83C NR108C 1080 psig 1077 psig 1A83D NR108D 1084 psig 1082 psig 1A83E NR108E 1082 psig 1082 psig Apparent Cause of Occurrence Instrument set point repeatability is identified as the cause of this occurrence.
Analysis of Occurrence lhe relief valves are provided to remove sufficient energy from the primary system to prevent the safety valves from lifting during a transient. The limiting pressure transient is that which is produced upon a turbine trip from rated design power with a failure of the bypass system to function. Under these conditions, the five relief valves are required to operate in order to prevent reaching the lowest set point of the primary system safety valves.
It should be noted that a 25 psig margin exists between the resulting peak pressure and the lowest safety valve set point as added assurance that the safety valves will not lift during this transient. With valves NRIOSC and NR108D actuating at 3 psig and 2 psig, respectively, above the maximum allowable trip point of 1070 psig, and assuming the most limiting pressure transient had occurred, the lowest set point safety valve or valves may have been required to actuate in order to limit the pressure transient.
Since the safety valve capacity provides sufficient vessel overpressure protection against failure of all pressure relief devices in addition to a failure of the reactor to scram, overpressurization of the vessel would not have occurred.
Corrective Action The involved pressure switches, 1A83C and 1A83D, were immediately reset to trip at allowable pressure levels. There are continuing efforts to resolve the incompatibilities between the Technical Specification set point limits and the sensor performance limits.
It is felt that the conservative design margins associated with the derivation of the plant safety limits will pennit a change in the Technical Specifications to be made which will take into account the expected sensor performance variations.
This will climinate instances of abnormal occurrence reports caused by the normal variation in a sensor set point within the design margins of the plant safety limits.
Failure Data Manufacturer data pertinent to these switches are as follows:
Manufacturer - Dresser Type
- 1539VX Serial Nos.
- BK3340 (1A83C) and BK3338 (1A83D)
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'w) o Abnormal Occurrence Report No. 50-219/75-24 Page 3 4
Previous abnormal occurrence reports:
Abnormal Occurrence Report No. 50-219/74-28 Abnormal Occurrence Report No. 50-219/74-39 Abnormal Occurrence Report No. 50-219/75-16 4
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GN-75-008 Jersey Central Power & Light Company ]
MADISON AVENUE AT PUNCH BOWL ROAD e MORRISTOWN, N.J. 07960
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September 8, 1975
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Mr. A. Giambusso Director, Division of Reactor Licensing l
Office of Nuclear Reactor Regulation United States Nuclear Regulatory Commission Washington, D. C. 20555 l
Dear Mr. Giambusso:
Subject:
Oyster Creek Station becrrnceReportNo. 50-219/75-24 o a The purpose of this letter is to forward to you the attached abnormal occurrence report in compliance with paragraph 6.6.2.a of the Technical Specifications.
Very truly yours, W
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Donald A. Ross, Manager (
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Mr. J. P. O'Reilly, Director 4
Offi/a of :nspection and Enforcement, Region 1 (P
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