ML19343C207

LER 76-022/03L-0:on 760910,acceptance Criteria in Procedures 629 & 614 for Low & low-low Reactor Level Trip Points Found Less Conservative than Tech Specs.Caused by Faulty Surveillance Test Procedure.Trip Point Settings Calibr

ML19343C207
Person / Time
Site:	Oyster Creek
Issue date:	10/08/1976
From:	Ross D JERSEY CENTRAL POWER & LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
LER-76-022-03L, LER-76-22-3L, NUDOCS 8103020105
Download: ML19343C207 (3)

Text

LICENSEE EVENT REPORT

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OYSTER CREEK NUCLEAR GENERATING STATION Forked River, New Jersey 08731 Licensee Event Report '

Reportable Occurrence No. 50-219/76-22-3L Report Date October 8, 1976 Occurrence Date September 10, 1976 Identification of Occurrence Violation of the Technical Specifications, Section 2.3, Items 9,10 and 11, when it was discovered that the instrument trip point settings for low and low low reactor water level were set less conservatively than the required limiting safety system settings. This event is considered to be a 30-day reportable occurrence as defined in the Technical Specifications, paragraph

6. 9. 2.b (1) .

Conditions Prior to Occurrence Pcwer: Reactor, 1846 MWt Generator, 623 MWe (g)

Flow: Recirculation, 56.0 x 106 lb/hr Fecdwater, 6.9 x 10 6 lb/hr Stack Gas: 14,300 pei/sec Description of Occurrence

On Friday, September 10, 1976, it was discovered that the acceptance criteria stated in Procedures 629 " Reactor Low Level Test Calibration" and 614 " Core Spray System Test" for the low and low low reactor water level trip points re pectively, were less conservative than those specified in the Technical l

Specifications. The Technical Specifications require the low and low low l

reactor water set points to be set at 11'-5" and 7'-2" above the top of the i active fuel respectively. In terms of reactor water level instrumentation (Yarway), these limiting safety system settings are SI-S/6" and 5/16".

Contrary to the Technical Specification requirements, the acceptable trip points of the two procedures specified was as low as S1" and 0" indicated water level.

Apparent Cause of Occurrence The cause of this occurrence is attributed to a faulty surveillance test procedure.

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Reportable Occurrence No. 50-219/76-22-3L October 8, 1976 Analysis of Occurrence The low water level trip setting of 11'-5" above the top of the active fuel has been established to assure that the reactor is not operated at a water 1cvel below that for which the fuel cladding integrity safety limit is applicable.

With the scram set at this point, the generation of steam, and thus the loss of inventory, is stopped. For example, for a loss of feedwater flow, a reactor scram at the value indicated and isolation valve closure at the' low low water level set point results in more than 4' of water remaining above the core after isolation. The safety significance of this occurrence is, there-fore, minor compared with the coaservatism already used in selecting the trip points.

Corrective Action Actions were taken immediately to correct the deficiencies previously stated by correcting the Surveillance Test Procedures. In addition, the Plant Operations Review Committee directed the instrument trip point settings be calibrated in accordance with the revised procedure.

Failure Data Not applicable.

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