ML19270E905

LER 78-031/03L-0 on 781130:during Diesel Generator Automatic Actuation Test,Generator Failed to Excite Due to Unused Target Mechanical Linkage Binding.Svc Water Pumps 1 & 2 Did Not Start Due to Binding in Trip Mechanism

ML19270E905
Person / Time
Site:	Oyster Creek
Issue date:	12/28/1978
From:	Ross D JERSEY CENTRAL POWER & LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19270E904	List: ML19270E903 ML19270E905
References
LER-78-031-03L, LER-78-31-3L, NUDOCS 7901030119
Download: ML19270E905 (4)

Text

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LICENSEE EVENT REPORT

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REPORT DATE 80 6 60 61 DOCKET NUMBER 68 69 EVENT DATE EVENT DESCRIPTION AND PROBABLE CONSEOuENCES h O 12 l On November 30, 1978, while conductina a diesel cenerator auto actuation 1 0 3 l test, #1 diesel generator engine started but the cenerator failed to excite  !

O 4 I and pick up load. in addition, #1 service water pump failed to trio O 5 1 on undervoltage and restart in the proper secuence. #2 service water j 10 e 1 oumo also failed to trio and restart on a similar test on the #2 diesel. f O 17 l Both service water oumos started when the cenerator breaker closed. #1 1 O s i Rx building closed cooline water pumo did not start within T.S. limits.

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l3EZl@ J7 40 41 44 47 CAuSE DESCRIPTION AND CORRECTIVE ACTIONS i O l The failure of #1 diesel generator to excite was caused by an unused tar- l 1 i [ get mechanical linkage in relay FFC0 bindinc in the tarcet window. The i 7 unused targets were removed. The failure of the service water pumos is l 1 [

attributed to binding in the trip mechanism. Both pumo breakers were 1 1 2 l i ic I lubricated. The closed cooling water time delay was reset to T.S. limits. I 7 8 9 80 ST A S %80WER OTHER ST ATUS SCov AY DISCOVERY DESCRIPTION l H j@ NA Diesel Auto Actuation iest i 5 0 l 0 l 0 l@l l l B l@l l ACTivtTY CONTENT RELEASEC OF RELE ASE AMOUNT 05 ACTIVITY LOCATION OF RELE ASE c NA l NA l 7

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. Jersey Central Power & Light Company

' - ' ~g 6 * ' 'N ,j 1 yff y Madison Avenue at Punch Bowl Road Mornstown. New Jersey 07960 (201)455-8200 OYSTER CREEK NUCLEAR GENERATING STATION Forked River, New Jersey 08731 Licensee Event Report Reportable Occurrence No. 50-219/78-31/3L-0 Report Date December 28, 1978 Occurrence Date November 30, 1978 Identification of Occurrence Failure of diesel generator #1 to assume load during loss of power test and improper load sequencing on diesel generator #2. This event is considered to be a reportable occurrence as defined in the Technical Specifications, paragraph 6.9 2.b.2.

Conditions Prior to Occurrence The plant was in a refue~ing shutdown.

Reactor coolant temperatere - 159 F.

Mode switch in refuel.

Description of Occurrence On November 30, 1978, while conducting a diesel generator automatic actuation surveillance test (loss of power test), #1 diesel generator engine started but the generator failed to excite and pick up load. in addition, #1 service water pump failed to trip on undervoltage and restart in the proper sequence. No. 2 service water pump also failed to trip and restart during a similar test on diesel generator #2. Both service water pumps started when the diesel generator breaker closed. No. I reactor building closed cooling water pump started at 240 seconds vs. the Technical Specification limit of 166 + 24.9 seconds.

Several days of trouble shooting and retesting of #1 diesel generator followed with several malfunctions identified as described below.

Apparent Cause of Occurrence The failure'of #1 diesel generator to excite during the test on November 30, 1978, was caused by an unused target mechanical linkage in relay "FFC0",

Jersey Centrai Power & Lght Company is a Memoer of the Genera! Pubhc U%t.es System

Reportable Occurrence No. 50-219/78-31/3L-0 Page 2 December 28, 1978 field flashing relay, mechanically binding in the targ?t window. This target had been flipped out of use shortly af ter initial plant startup. 'ie target mechanism was found to, on occasion, catch on the window, preventing operation of its normally closed contacts.

During testing following repair to the above relay, the diesel engine tripped on overspeed prior to picking up load. This problem was identified as a mal function of the EGB-10 actuator, which contains the engine governor.

The failure of both service water pumps to trip was attributed to mechanical binding in the breaker trip mechanism for each pump. The undervoltage relays functioned but could not actuate the trip bar.

The late start of #1 reactor building closed cooling water pump is attributed to instrument setpoint drift in the time delay relay.

Analysis of Occurrence No. I diesel generator provides emergency power to the "C" 4160-V bus during loss of offsite power conditions. The station is designed and analyzed for failure of one (1) emergency diesel generator for all accident conditions.

Failure of #1 diesel generator represents a loss of redundancy.

The failure of #1 and #2 service water pumps to trip when required has little safety significance. The purpose of the undervoltage trip and sequential start is to prevent simultaneous starting of multiple high horsepower motors which may overload the diesel generator. Both #1 and #2 diesel generators, however, demonstrated the ability to start with the connected service water pump breaker closed.

The late start of #1 reactor building closed cooling water pump is of little safety significance. This is the last load added to the diesel generator by automatic sequencing and would not have started simultaneously with any other load. A delay of 40 seconds in starting this pump would not seriously affect any equipment cooled by reactor building closed cooling water under loss of power conditions. In addition, #2 reactor building closed cooling water pump started within the spec;fied time.

Corrective Action The unused targets were removed from the "FFC0" relay on both diesel generators and also from all other similar relays on both diesel generators.

The EGB-10 actuator on #1 diesel generator was replaced with a rebuilt spare obtained from the manufacturer. The diesel generator was then thoroughly tested and required adjustments and venting were completed. At the manu-facturer's recommendation, the engine overspeed trip was raised. Two complete diesel generator automatic actuation tests were performed following repairs.

Reportable Occurrence No. 50-219/78-31/3L-0 Page 3 December 28, 1978

'oth service water pump breakers were cleaned, lubricated and tested.

The #1 reactor building closed cooling water load sequencing time delay was reset and tested.

Failure Data Diesel Generator: Electro-Motive Division General Motors Corporation LaGrange, Illinois FFC0 Relay: Westinghouse Style: 1876094 Type: SV voltage relay 120 Volts 60 Cycles Circuit Breakers: General Electric Type AK-2A-25-1 Time Dealy Relay: Agastat Model: 2414 PE 10-200 seconds

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