ML19208D476

Forwards LER 79-023/03L-0

ML19208D476
Person / Time
Site:	Cooper
Issue date:	09/07/1979
From:	Lessor L NEBRASKA PUBLIC POWER DISTRICT
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19208D477	List: ML19208D476 ML19208D488
References
CNSS790469, NUDOCS 7909280468
Download: ML19208D476 (2)

Text

. ss CooPcR NUCLEAR STATION

. P.o. Box 98, BRoWNVILLe, NEBR ASKA 68321 Nebraska Publ.ic Power D. is trict TeLemoNe son .2s.3.u a

CNSS790469 September 7, 1979 Mr. K. V. Seyfrit U.S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region IV 611 Ryan Plaza Suite 1000 Arlington, Teras 76011

Dear Sir:

This report is submitted in accordance with Section 6.7.2.B.1 of the Technical Specifications for Cooper Nuclear Station and discusses a reportable occurrence that was discovered on August 9, 1979. A licensee event report form is also enclosed.

Report No.: 50-298-79-23 Report Date: September 7, 1979 Occurrence Date: August 9, 1979 Facility: Cooper Nuclear Station Brownville, Nebraska 68321 Identification of Occurrence: .

Operation with an engineered safety feature instrument setting less conservative than those established in Table 3.2. A of the Technical Specifications.

Conditions Prior to Occurrence:

The reactor was in a cold shutdown condition due to a scram which had occurred earlier in the day.

Description of Occurrence:

While performing routine surveillance test procedure 6.2.1.4.2, dif ferential pressure indicating switch MS-DPIS-119B was found set at a setpoint higher than allowed by Technical Specifications.

Designation of Apparent Cause of Occurrence:

The microswitch in the subject differential pressure indicating switch failed.

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Mr. K. V. Seyfrit September 7, 1979 Page 2.

Analysis of Occurrence:

The function of MS-DPIS-149B is to monitor the steam flow in the "D" main steam line and initiate a main steam line isolation ac 140% rated steam flow. There are three other differential pressure indicating switches on "D" main steam line, MS-DPIS-119A,119C, and 119D. All three of these instruments were operating properly and would have provided the isolation if it had been required, conse-quently this occurrence presented no adverse consequences from the standpoint of public health and safety.

Corrective Action:

The switch was readjusted to the correct setpoint at the time of the occurrence. The setpoint of the switch was monitored period-ically during the next few weeks. It was determined that the switch continued to drift. The microswitch assembly was replaced.

The instrument was returned to service following calibration and performance of Surveillance Procedure 6.2.1.4.2.

Sincerely, f >

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

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