ML19263C919

Forwards LER 79-001/03L-0

ML19263C919
Person / Time
Site:	Cooper
Issue date:	01/22/1979
From:	Lessor L NEBRASKA PUBLIC POWER DISTRICT
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19263C920	List: ML19263C919 ML19263C923
References
CNSS790045, NUDOCS 7903120341
Download: ML19263C919 (2)

Text

COOPER NUCLEAR ST AlloN P.o. box 98, URoWNVILLE, NE DR A5KA 68 321 Nebraska Public Power Distn.c t roumoNo non on-3en

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CNSS790045 January 22, 1979 Mr. K. V. Seyfrit U.S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region IV 611 Ryan Plaza Suite 1000 Arlington, Texas 76011

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 January 3, 1979. A li-censee event report form is also enclosed.

Report No.: 50-298-79-1 Report Date: January 22, 1979 Occurrence Date: January 3, 1979 Facility: Cooper Nuclear Station Brownville, Nebraska 68321 Identification of Occurrence:

A condition which lead to operation in a degraded mode permitted by a limiting conditon 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 level of approximately 100%

of rated thermal power.

Description of Occurrence:

During steady state operation, the gas channel of the drywell atmospheric radiation monitor (RMV-RM-4C) failed downscale.

Designation of Apparent Cause of Occurrence:

The cause of the failure of the Atmospheric Radiation Monitor Gas Channel has been attributed to detector failure due to moisture accumulation in the detector chamber.

, oI nL 7903120 N d k .. g b /s

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Mr. K. V. Seyfrit January 22, 1979 Page 2.

Analysis of Occurrence:

The function of radiation monitor RMV-RV-4 is to indicate and record the radiation levels of the atmosphere within the primary containment. It monitors particulate, iodine, and gaseous ac-tivity, and will alarm in the control room when any of these channels go above or below a preset value. There is no redundant system, however the particulate and iodine channels remained op-erable. The primary containment was not vented while the monitor was inoperable. This occurrence presented no adverse consequences from the standpoint of public health and safety.

Corrective Action:

The detector assembly was replaced and the interior of the detector chamber was dried. A heater was setup to keep the detector chamber warm to prevent water condensation around the detectors from the sample. The drywell atmospheric radiation monitor was tested and after satisfactory results was returned to service.

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