ML19208C842

LER 79-029/03L-0:on 790822,rod Block Trip Setting Was Below 100 Counts Per Second 26 Times During QA Audit.Caused by Calibr Procedure Setting Rod Trip at Tech Spec Limit.Rod Withdrawal Block Setpoint Increased

ML19208C842
Person / Time
Site:	Oyster Creek
Issue date:	09/21/1979
From:	Ross D JERSEY CENTRAL POWER & LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19208C802	List: ML19208C801 ML19208C842
References
LER-79-029-03L, LER-79-29-3L, NUDOCS 7909270560
Download: ML19208C842 (2)

Text

LICENSEE EVE T REPORT -

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EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h O 2 l Durino a QA records audit of executed Source Rance Monitor Test and 1 0 3 1 Calibration Procedures, the rod block trip setting was below 100 cps l 0 4 l twenty-six times. Upon investigation, it was found that one of the four l 0 lsi l channels tripped ct a setpoint less than desired. The calibration l

!o e -] procedufe' set the rod block trip at the Tech Spec limit, allowing no l 0 7) I margin for instrument drift. l 0 ts I l ED 7 E D

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33 34 37 40 43 44 47 C AUSE DESCRIPTION AND CORRECTIVE ACTIONS h 1 O l The rod withdrawal block setpoint associated with the Source Range l 1 61 l Monitor detector position was increased to 500 cps with an acceptance i i 7 range of plus or minus 100 cps. l 1 3 I i 1 14 l l 7 8 9 80 STA  % POWER OTHE R STATUS DISCO RY DISCOVERY DESCRIPTION 1 s Ej@ l0l9l9l@l NA l lC l@l QA record review and tests. l ACTIVITY CO TENT RELE ASED OF RELE ASE AMOUNT OF ACTIVITY LOCATION oF RELEASE 6 NA l l NA 7

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201-455-8784

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NAME OF PREPARER

Jersey Central Power & Light Company I?Q hj$[ f J Madison Avenue at Punch Bowl Road WJ. - .

7 *7 Morristown, New .'ersey 07960 (201)455-8200 OYSTER CREEK NUCLEAR GENERATING STATION Forked River, New Jersey 08731 Reportable Occurrence No. 50-219/79-29/3L-0 Report Date September 21, 1979 Occurrence Date D D GQ_

August 22, 1979 m 3-n~

Identification of Occurrence 0

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g Exceeding a limiting condition for operation as defined in Technical Specifi-cations, Table 3.1.1.K.2, when the rod block associated with the SRM position was found to be set below 100 cps. This event is considered to be a reportable occurrence as defined in the Technical Specificat ions, paragraph 6.9.2.b.1.

Conditions Prior to Occurrence The plant was operating at steady state power.

, Power: Generator, 653 MWe Reactor, 1915.5 MWt Flow: Recirculating, 15.8 x 104 gpm Feedwater 7.175 x 106 lb/hr Stack Gas: 3.10 x 10 pCi/sec Description of Occurrence A quality Assurance records review of executed Source Range Monitor Test and Calibration (Front Panel Test) Procedures identified twenty-six times when the rod block trip setting was below one-hundred counts per second. Further investigation revealed that only one channel out of four tripped at a set-point less than that desired. Channel 22 tripped at 94 cps.

Apparent Cause of Occurrence The calibration procedure set the rod block trip at the Technical Specification limit, allowing no margin for instrument drift. The Front Panel Test called for the operator to note the setpoint when the indicated value was changing rapidly. Thus, the operator perception of the setpoint was a general check of the value rather than a calibration.

1042 227 Jersey Central Power & Light Company is a Member of the Genera! Pubhc Utat4es System

Reportable Occurrence No. 50-219/79-29/3L-0 Page 2

- September 21, 1979 Analysis of Occurrence The source range monitors consist of four fission chambers that provide neutron monitoring of the core during refueling and startup. The SRM's primary purpose is to guide the reactor operator by indicating neutron flux (pcwer) level and distribution. This information is needed for knowledgeable and efficient reactor startup and low level operations. The safety significance of this event is considered to be minimal since only one channel out of four tripped at a setpoint less than that desired. .in addition, procedural control does not permit the operator to withdraw the SRM detectors unless a count rate of 103 cps exists.

Corrective Action The rod withdrawal block setpoint associated with SRM detector position was increased to 500 cps + 100 cps.

Failure Data Not applicable.

1042 228