05000298/LER-1980-038, Forwards LER 80-038/03L-0

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: 05000298/LER-1980-038, Forwards LER 80-038/03L-0 05000298/LER-1980-038-03, /03L-0:on 801011,switch on NBI-LIS-101A Found Set at Lower Level than Tech Spec Limit.Caused by Excessive Drift.Switch Returned to Normal Setting & Will Be Replaced
References
CNSS800646, NUDOCS 8012030706
Download: ML19345C006 (2)

LER-1980-038, Forwards LER 80-038/03L-0

Event date:
Report date:
2981980038R00 - NRC Website

text

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~.4 CoOPE.' NUCLEAR STATION Nebraska Public Power District.

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5 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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~ 8012 03 0 706

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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.

Additionally, the setpoint drif t for these level switches will be

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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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