ML19345C006

Forwards LER 80-038/03L-0

ML19345C006
Person / Time
Site:	Cooper
Issue date:	11/10/1980
From:	Lessor L NEBRASKA PUBLIC POWER DISTRICT
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19345C007	List: ML19345C006 ML19345C010
References
CNSS800646, NUDOCS 8012030706
Download: ML19345C006 (2)

Text

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CNSS800646 Ncvember '10,.1980 Mr. K. V. Seyfrit, Director U.S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region IV_

611 Ryan Plaza Drive Suite 1000 Arlington, Texas 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 October 11, 1980. A li-censee event report form is also enclosed.

Report No.: 50-298-80-38 Report Date: November 10, 1980 Occurrence Date: October 11,-1980 Facility: . Cooper Nuclear Station Brownville, Nebraska 68321 Identification of Occurrence:

The reactor was operated with an. engineered safety feature in-strument setting less conservative than those established in Table 3.2.B of the Technical Specifications.

Conditions Prior to Occurrence:

The reactor was operating at a steady state power level of ap-proximately 98% of rated power.

Description of Occurrence:

While performing routine Surveillance Test Procedure 6.1.9, level indicating switch NBI-LIS-101A was found set at a level lower than allowed by Technical Specifications.

Designation of Apparent Cause of Occurrence:

Examination of the surveillance records for reactor vessel low-high water level switches NBI-LIS-101 A, 8, C and D indicates excessive drift in the 101A high side microswitch.

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-Mr. K.-V. Seyfrit November 10, 1980 Page 2.

Analysis of Occurrence: .

NBI-LIS-101 ~ A, B, C, and D are Barton ' Instrument Company Model 288A level indicating switches. The function of the switch is to in-itiate a low water level scram at +12.5" indicated level. The

. logic for the low reactor level scram requires only one of the A or C switches to trip at the proper setpoint thereby deenergizing the Trip System "A" solenoids. .Since only the 101 A switch setting was below the Technical. Specification limit, .the logic would have trippec by the time-the scram setpoint (+12.5") was reached.

This occurrence presented no adverse consequences from the stand-point of public health and safety.

Corrective Action:

The switch setpoint was immediately returned to the normal setting.

.The switch assembly will be replaced when parts are available.

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Additionally, the setpoint drif t for these level switches will be closely observed in future surveillance testing.

Sincerely,.

JS?

L L:

cA J W L. C. Lessor Station Superintendent Cooper Nuclear Station LCL:cg Attach. '

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