05000298/LER-1982-019, Forwards LER 82-019/03L-0.Detailed Event Analysis Submitted

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Forwards LER 82-019/03L-0.Detailed Event Analysis Submitted
ML20063A506
Person / Time
Site: Cooper Entergy icon.png
Issue date: 08/13/1982
From: Lessor L
NEBRASKA PUBLIC POWER DISTRICT
To: Jay Collins
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20063A507 List:
References
CNSS820478, NUDOCS 8208240369
Download: ML20063A506 (2)


LER-2082-019, Forwards LER 82-019/03L-0.Detailed Event Analysis Submitted
Event date:
Report date:
2982082019R00 - NRC Website

text

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CNSS820478 August 13, 1982 I

Mr. John T. Collins, Regional Administrator U.S. Nuclear Regulatory Commission Region IV -

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I 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76011 i

Dear Sir:

This report is submitted in accordance with Section 6.7.2.B.2 of the Technical Specifications for Cooper Nuclear Station and discusses a reportable occurrence that was discovered on July 26, 1982. A licensee event report form is also enclosed.

Report No.: 50-298-82-19 Report Date: August 13, 1982 Occurrence Date: July 26, 1982 Facility: Cooper Nuclear Station Brownville, Nebraska 68321 Identification of Occurrence:

A condition occurred which resulted in operation in a degraded mode permitted by a limiting condition for operation established in Section 3.6.C.2 of the Technical Specifications.

Conditions Prior to Occurrence:

The reactor was at a steady state power of 100% of rated thermal power.

Description of Occurrence:

During normal operation, the Drywell Equipment Sump 1G high level alarm was received and automatic sump pump-down initiated. The sump was pumped down, the alarm cleared, and the pumps were stopped automatically. The operator, however, noted that there was no flow indicated on the flow recorder or on the flow counter.

Designation of Apparent Cause of Occurrence:

The failure of the flow recorder and counter to register flow was found to be a blown fuse in the power supply.

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8208240369 820813 PDR ADOCK 05000298 S PDR

Mr. John T. Collins August 13, 1982 Page 2.

Analysis of Occurrence:

The flow recorder and flow counter (via flow integrator) are used to indirectly measure leakage in the drywell. The Technical Speci-fications give maximum limits on leakage from identified and un-identified sources, and measurement of flow from drain sumps is one method of leak detection. When a sump high level is reached, an alarm in the control room is actuated and a sump pump starts auto-matically. A measuring circuit senses pump discharge flow and records the flow on the recorder and counter.

At the time of the occurrence, the operator on duty noted the Drywell Equipment Sump 1G high level alarm and subsequent sump pump start. However, he also observed no flow indication on Flow Re-corder RW-FR-528. Further investigation by the operator determined that Flow Counter 20-530 on Panel 9-19 had not operated during sump pump-down. The sump, however, had been pumped down properly, the high level alarm had cleared, and the pump had stopped.

The cause of the recorder failing to register flow was traced to a blown fuse in Power Supply 20-545A. The fuse was replaced, Surveil-lance Procedure 6.2.3.2 (Drywell Equipment Sump 1G Flow Loop Cali-bration and Function Test) performed satisfactorily, and the flow measurement system returned to service. A search of instrument records showed no previous history of blown fuse problems, nor was there any record which indicated the fuse had ever been replaced.

The flow measurement system is presently operating satisfactorily, and no cause for the blown fuse was determined. This occurrence presented no adverse consequences from the standpoint of public health and safety.

Corrective Action:

The blown fuse was replaced. No further corrective action is planned.

Sincerely, L. C. Lessor Station Superintendent Cooper Nuclear Station LCL:cg Attach.

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