05000298/LER-1981-012, Forwards LER 81-012/03L-0.Detailed Event Analysis Encl

Forwards LER 81-012/03L-0.Detailed Event Analysis Encl

ML20009E994
Person / Time
Site:	Cooper
Issue date:	06/18/1981
From:	Lessor L NEBRASKA PUBLIC POWER DISTRICT
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20009E995	List: 05000298/LER-1981-012, Forwards LER 81-012/03L-0.Detailed Event Analysis Encl 05000298/LER-1981-012-03, /03L-0:on 810519,during Testing HPCI-PS-68D Tripped at 89 Psig Instead of 100 Psig Tech Spec Limit. Caused by Random Instrument Drift.Instrument Immediately Recalibr & Returned to Svc
References
CNSS810360, NUDOCS 8107280593
Download: ML20009E994 (2)

LER-1981-012, Forwards LER 81-012/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
2981981012R00 - NRC Website

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COoPE R NUCLE AR ST ATION Nebraska Public Power District

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CNSS810360

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s 87 JUL 3 71981 w b Mr. K. V. Seyfrit, Director

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U.S. Nuclear Regulatory Commission

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Region IV

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Suite 1000 Arlington, Texas 76011

Dear Sir:

This report is submitred 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 May 19, 1981. A licensee event report form is also enclosed.

Report No.:

50-298-81-12 Report Date:

June 18, 1981 Occurrence Date: May 19, 1981 Facility:

Cooper Nuclear Station Brownville, Nebraska 68321 O

Identification of Occurrence:

Operation with an engineered safety feature instrument setting less conservative than thc,se established in Table 3.2.B of the Technical Specification.

Conditions Prior to Occurrence:

The reactor was in cold shutdown for refueling.

Description of Occurrence:

e While performing routine Surveillance Testing Procedure 6.2.2.3.3, a HPCI Low Steam Supply Pressure Switch, HPCI-PS-68D, was found to trip at lower pressure than allowed by Technical Specifications.

g Designation of A, parent Cause of Occurrence:

i The apparent cause of this occurrence was setpoint drift.

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l 8107280593 810618 PDR ADOCK 05000298 S

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,.k Mr. K. V. Seyfrit June 18, 1981 Page 2.

Analysis of Occurrence:

The function of preasure switch HPCI-PS-68D is to monitor the reactor pressure and to contribute to HPCI System turbine trip when the reactor pressure is at or below 100 psig. The switch setpoint had drif ted to 11 psig below the Technical Specification limit.

The redundant pressure switches, HPCI-PS-68A,B, and C were avail-able and operable at the time of the occurrence and were found set within Technical Specification limits. These switches would have provided for a turbine trip if it were required due to low reactor pressure. This occurrence presented no adverse affect on the public health and safety. A similar occurrence was reported previously. Reference A0-74-58.

The switch was examined and no apparent cause for the setpoint drift could be found. A review of the records indicates the switch has drifted outside of Technical Specification limits only one other time in plant life.

Corrective Action

The switch was immediately readj'isted to the correct setpoint. The switen has been re-tested three times since the occurrence and was within the Technical Specification limits on all three occasions.

No further action is planned.

Sincerely,

//@C L. C. Lessor Station Superir.tendent Cooper Nucle.ar Station LCL:cg Attach.

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