ML20003C379

AO 50-219/74/29:on 740423,electromatic Relief Valve Pressure Switches 1A83B & 1A83D Tripped at Pressures in Excess of Max Allowable Value of 1,070 Psig.Caused by Instrument Drift. Switches Reset

ML20003C379
Person / Time
Site:	Oyster Creek
Issue date:	04/26/1974
From:	Menning J JERSEY CENTRAL POWER & LIGHT CO.
To:
References
AO-50-219-74-29, NUDOCS 8103030122
Download: ML20003C379 (3)

Text

P00R ORlGlNAl.

Initial Telephcne E

Date of Report Date:

4/2S/74 Occurrence:

4/23/74 Initial Written Time of Report Date:

4/26/74 Occurrence:

1720 OYSTER CREEK NUCLEAR GENERATING STATION FORKED RIVER, NEW JERSEY 08731 Abnormal Occurrence Report No. S0-219/74/29 IDENTIriCAT10N Violation of the Technical Specifications, paragraph 2.3.4, OF OCCURRENCE:

Electromatic Relief Valve Pressure Switches,1A83B and 1A83D, were found to trip at pr'essures in excess of the mxi-mum allowable value of 1070 psig.

This event is considered to be an abnormal occurrence as de-fined in the Technical Specifications, paragraph 1.1SA.

CONDITIONS PRIGk Steady State Power Routine Shutdown TO OCCU"!";NCE :

!!ot Standby Operaticn Cold Shutdown Load Changes During X

Refueling Shutdown.

Routine Power Operation Routine Startup Other (Specify)

Operation The reactor mode switch was in the REFUEL position with reactor coolant temperature approximately 100 F.

DESCR1PTIOh On Tuesday, April 23, 1974, while performing surveillance OF OCCURRE CE-on the five Electromatic Relief Valve Pressure Switches, it was found that 1AS3B and 1A83D tripped at 1090 psig and 1096 psig, respectively. These values r.re in excess of the maximum allowable trip points of 1084 psig and 1082 psig, respectively, which are derived by adding appropriate head correction factors to the Technical Specification limit of 1070 psig.

It is noted here that switches 1A83D and 1A83D are associated with valves NRIOSB and NRIOSD, respectively.

57aag4 M /c2 A O

P00R OR G NM Abnormal Oc'currence Report No. 50-219/74/29 Page 2 The "as found" and "as Icft" switch settings were:

Associated "As Found" "As Le f t "

Swit:h Valve Setting Setting 1A83A NR10SA 1079 psig 1079 psig 1AS3D NR10SB 1090 psig 1084 psig 1A83C NR10SC 1077 psig 1077 psig 1AS3D NR10SD 1096 psig 1082 psig 1A83E NR10SE 1082 psig 10S2 psig APPARENT CAUSE X

Design Procedure OF OCCURRENCE:

14anuf actur e Unusual Service Condition Installation /

Inc. Environmental Construction Component Failure

_ Operator

_ _ Other (Specify)

Instrunent drift has been tentatively identified as the caur.c of this occurrence.

ANALYSIS OF The relicf valves are provided to, remove sufficient energy OCCURPINCE:

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 systen to functien.

Under these conditions, the five (S) relief valved are re-quired to operate in order to prevent reaching the lowest set point of the primary systen safety valves.

It should be noted that a 25 psi margin exists between the resulting peak pressure and the lowest safety valve set point as added assurance that the safety valves will not lift dur this transient. b'ith valves NR108B and NR108D actuating 6 psig and 14 psig, respectively, above the maximun allow-able trip point of 1070 psig, and assuming the most limiting

POOR ORIGINAL ~

Abnormal Occurrence Page 3 Report No.'50-219/74/29 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 is based upon providing sufficient vessel over-pressure pro-tection upon failure of all pressure release devices, in addition to a failure of the reactor to scram, over-pressuriza-tion of the vessel would not have occurred.

CORRECTIVE.

The involved pressure switches, IA83B and 1 A83D, were immed-ACTION:

intely reset to trip at allowable pressure IcVels. Additional items of corrective action will be deterrained following re-view of this occurrence by the Plant Operations Review Committee.

8 FAILURE DATA:

Manufacturer data portinent to these switches are as follows:

Manufacturer. - Dresser Type - 1539VX '

Serial Nos. - BK3339 (I AS3B)

BK3338 (1AS3D) 1 Ic

, Prepared by:

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Date:

4/26/74

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