ML20090D278

AO 50-219/75-16:on 750614,electromatic Relief Valve Pressure Switches 1A83P & E Tripped at Pressures Exceeding Tech Spec Limit.Caused by Instrument Setpoint Drift.Switches Reset

ML20090D278
Person / Time
Site:	Oyster Creek
Issue date:	06/24/1975
From:	Ross D JERSEY CENTRAL POWER & LIGHT CO.
To:	Giambusso A Office of Nuclear Reactor Regulation
References
AO-50-219-75-16, NUDOCS 8302250474
Download: ML20090D278 (4)

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.ersey Central Power & Light Company g%b:/r; MADISON AVENUE AT PUNCH DOW1. ROAD

• MORRISTOWN.N.J.07960

• 201539-6111 au ua er s.,a General {~]"*, Public Utahties Corporation 3rgia m

. June 24, 1975

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e_ va.ng Mr. A. Giambusso Director, Division of Reactor Licensing ' ",7 f#'s ' '? *g

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2 i Office of Nuclear Reactor Regulation ['.M United States Nuclear Regulatory Corrtission Washington, D. C. 20555 .

Subject:

Oyster Creek Station Docket No. 50-219 Abnormal Occurrence Report No. 50-219/75-16 The purpose of this 1ctter 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, f M) '

nl Donald A. Ross, Manager b )he-l Concrating Stations-Nuclear pk ,

Enclosures cc: Mr. J. P. O'Reilly, Director ,

Office of Inspection and Enforcement, Region 1  !

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G886 8302250474 750624 PDR ADOCK 05000219 S PDR I.

COPY SENT REGION

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. O O Jersey Central Power & Light Company k 7 J

MADISON AVENUE AT PUNCH BOWL ROAD

• MORRISTOWN.N.J.07960

• 201-539-6111

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OYSTER CREEK NUCLEAR GENERATING STATION Forked River, New Jersey 08731 Abnormal Occurrence Report No. 50-219/75-16 Report Date June 24, 1975 Occurrence Date_

June 14, 1975 I

Identification of Occurrence Violation of the Technical Specifications, paragraph 2.3.4, Electromatic

. Relief Valve Pressure Switches, IA83B and 1A83E, were found to trip at pressures in excess of the maximum allowable value of 1070 psig. nis event is considered to be an abnormal occurrence as defined in the Technical Specifications, paragraph 1.15A.

Conditions Prior to Occurrence The reactor mode switch was in the REFUEL position with reactor coolant temperature less than 212*F.

Description of Occurrence On Saturday, June 14, 1975, while performing surveillance on the five Electromatic Relief Valve Pressure Switches, it was found that 1A33B and 1A83E tripped at 1089 psig and 1085 psig, respectively. Rese values are in excess of the maximum allowabic trip points of 1084 psig and 1082 psig, respectively, which are derived by adding appropriate head correction factors to the Technical Specif! cation limit of 1070 psig. It is noted here that switches 1A83B and 1A83E are associated with valves NR108B and NR108E, respectively.

as s Abriornal Occurrence Report No. 50-219/75-16 Pags 2 The "as found" and "as left" switch setting's were:

Associated "As Fotsid" "As Left" Switch Valve Setting Setting 1A83A NR108A 1077 psig 1079 psig 1A83B NR108B 1089 psig 1084 psig 1A83C NR108C 1077 psig 1077 psig 1A83D NR108D 1082 psig 1082 psig 1A83E NR108E 1085 psig 1081 psig Apparent Cause of Occurrence Instrument set point drift is identified as the cause of this occurrence.

This has been discussed in Supplement No. 8 to the Application for a Full Term 1.icense (i.e. , Amendment No. 68) for the Oyster Creek Nuclear Generat-ing Station.

Analysis of Occurrence The relief valves are rovided to remove sufficient energy from the primary

} system to prevent the ,afety 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 conultions, the five relief valves are required te 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 re-sulting peak pressure and the lowest safety valve set point as added assurance that the safety valves will not lift during this transient. With valves NR108B and NR108E actuating at 5 psig and 3 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 over-pressure protection against failure of all pressure release devices in addition to a failure of the reactor to scram, over-pressurization of the vessel would not have occt.rred.

Corrective Action The involved pressure switches, IA838 and 1A83E, were immediately reset to trip at allowable pressure levels. There are continuing efforts to resolve the incompatibilities between the Technical Specification setpoint limits and the sensor performance limits. It is felt that the conservative design margins associated with the derivation of the plant safety limits will permit

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Abnormal Occurrence Report No. 50-219/75-16 O Paga 3 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 sensor setpoint within the design margins of the plant safety limits.

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Failure Data Manufacturer data pertinent to these switches are as follows:

Manufacturer -- Dresser Type --

1539VX Serial Nos. --

BK3339 (IA83B)

BN7126 (1A83E)

Previous abnormal occurrence reports:

Abnormal Occurrence Report No. 50-219/74-28 Abnormal Occurrence Report No. 50-219/74-39 i

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