ML19343C223

AO 50-219/74/39:on 740714,electromatic Relief Valve Pressure Switches 1A83A,1A83B,1A83C & 1A83E Tripped at Pressures in Excess of Max Allowable Value of 1,070 Psig.Caused by Lack of Allowance for Setpoint Tolerances in Tech Specs

ML19343C223
Person / Time
Site:	Oyster Creek
Issue date:	07/23/1974
From:	JERSEY CENTRAL POWER & LIGHT CO.
To:
References
AO-50-219-74-39, NUDOCS 8103040470
Download: ML19343C223 (2)

Text

~ lersey centril Power & Light Company %/

MADISON AVENUE AT PUNCH BOWL ROAD

• MORRISTOWN,N.J.07960

• 201-539-6111 !

. es ,re or ras l General P

• j) , Pu%c UtAties Corporation arsrs.

OYSTER CREEK NUCLEAR GENERATING STATION FORKED RIVER, NEW JERSEY 08731 Abnormal Occurrence .

Report No. S0-219/74/39 Report Date July 23, 1974 Occurrence Date July 14, 1974

. Identification of Occurrence Violation of the Technical Specifications, paragraph 2.3.4, electromatic relief valve pressure switches 1A83A, IA83B, IA83C, and 1A83E were found to trip at pressures in excess of the maximum allowable value of 1070 psig. This event is considered to be an abnormal occurrence as defined in the Technical Specifi-cations, paragraph 1.15A.

Conditions Prior to Occurrence The reactor mode switch was in the REFUEL position with reactor coolant temper-ature approximately 150*F.

l Description of Occurrence On Sunday,' July 14, 1974, while performing surveillance on the five electromatic relief valve pressure switches, it was found that switches 1A83A,1A83B,1A83C, and 1A83E tripped at 1083 psig, 1094 psig, 1085 psig, and 1089 psig, respectively.

These values are in excess of the maximum allowabic trip points indicated below which are derived by adding appropriate head correction factors to the Technical Specification limit of 1070 psig. These trip point valuer. are within the design limitations of the switch. The cicctromatic relief valv'.: pressure switches were immediately recalibrated to their correct set points as indicated below:

P00R ORIGINAL 77g

Abnormal Occurrence No. 50-219/74/39 Page 2

.: r Associated "Desirod" "As Found" "As Left" Switch Valve Setting Setting Setting 1A83A NR108A 1079 psig 1083 psig 1079 psig 1A83B NR108B 1084 psig 1094 psig 1084 psig 1A83C NR108C 1077 psig 1085 psig 1077 psig 1A83D hR108D 1082 psig 1080 psig 1082 psig 1A83E NR108E 1082 psig 1089 psig 1082 psig a

Apparent Cause of Occurrence The cause of this occurrence is the lack of allowance for set point tolerances in the Technical Specifications.

Analysis of Occurrence

'Ihe relief valves function to recove 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 the pressure excursion from reaching the lowest set point of the primary system 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 during this transient. h'ith valves NR108A, NRIOSB, NR108C, and NR108E actuating at from 4 psig tp 10 psig 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 is based upon providing sufficient vessel overpressure protection upon failure of all pressure relieving devices, in addition to a failure of the reactor to scram, overpressuri-a-tion of the vessel would not have occurred.

Corrective Action l Thes'c switches were reset and surveilled satisfactorily. Jersey Central Power 6 Light Company, GPU Service Corporation, and General Electric Company personnel, as stated in Abnormal Occurrence Report No. 50-219/74/35, are continuing to investigate this generic prob 1cm of set point tolerance.

Failure Data Manufacturer data pertinent to these switches:

Manufacturer - Dresser .

Type - 1539VX Serial Numbers - 1A83A - BK3337 1A83B - BK3339 1A83C - BK3340 DnnD nDIclNAi l UUn U HI U llin b 1A83E - BN7126

Reference:

Abnomal Occurrence Report No. 50-219/74/29 dated April 23. 1974