05000245/LER-1981-038, Forwards LER 81-038/03L-1.Detailed Event Analysis Encl

Forwards LER 81-038/03L-1.Detailed Event Analysis Encl

ML20040B817
Person / Time
Site:	Millstone
Issue date:	01/13/1982
From:	Mroczka E NORTHEAST NUCLEAR ENERGY CO.
To:	Haynes R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20040B818	List: 05000245/LER-1981-038, Forwards LER 81-038/03L-1.Detailed Event Analysis Encl 05000245/LER-1981-038-03, /03L-0:on 811117,annunciators on Control Room Panel 905 Indicated Loss of One Half of Reactor Protection Sys Generator Load.Caused by Isolated Pressure Switch PS-39 Due to Personnel Error.Valve Opened
References
MP-1-1982, NUDOCS 8201260441
Download: ML20040B817 (3)

LER-1981-038, Forwards LER 81-038/03L-1.Detailed Event Analysis Encl

Event date:
Report date:
2451981038R00 - NRC Website

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HARTFORD, CONNECTICUT 06101 (203) 666 6911 x

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j January 13, 1982 MP 1932 Mr. Ronald C. Haynes M-N Regional Administrator, Region I J')\\

N Office of Inspection and Enforcement x

s U. S. fluclear Regulatory Commission f

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631 Park Avenue i

King of Prussia, Pennsylvania 19406

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Reference:

Provisional License DPR-21 j

Docket fio. 50-245

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Reportable Occurrence R0-81-38/3L-1

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Dear Mr. Haynes:

This letter forwards the revised Licensee Event Report for Reportable Occurrence R0-81-38/3L submitted on December 17, 1981 pursuant to the requirements of the Millstone Unit I Technical Specifications, Section 6.9.1.9.c.

An additional three copies cf the report are enclosed.

Yours truly, NORTHEAST fiUCLEAR Ef1ERGY COMPAflY/

"Z 46/

E.

. Mroczka Station Superintendent Millstone fluclear Power Station EJM/TST:mo

Attachment:

LER R0-81-38/3L-1 cc:

Director, Office of Inspection and Enforcement, Washington, D.C. (30)

Director, Office of Management Information and Program Control, Washington, D.C. (30 U.S. Nuclear Regulatory Commission, c/o Document Management Branch, Washington, D.C.

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l 8201260441 820113 PDR ADOCK 05000245 g

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ATTACHMENT TO LER 81-38/3L-1 NORTHEAST NUCLEAR ENERGY COMPANY MILLSTONE NUCLEAR POWER STATION - UNIT I PROVISIONAL LICENSE DPR-21 DOCKET NUMBER 50-245 Identification of Occurrence Inadequacy In the implementation of procedural controls resulted in a reduction in the degree of redundancy provided in a reactor protectica system.

Condition Prior to Occurrence Prior to the occurrence, the plant-was operating at a steady state power level of one hundred percent.

Description of Occurrence Upon completion of Turbine Control Valve Fast Closure Functional Test and Calibration, pressure switch PS-39 was left isolated.

This instrument senses turbine control valve control oil pressure as part of the load reject logic.

At approximately 1850 hours0.0214 days <br />0.514 hours <br />0.00306 weeks <br />7.03925e-4 months <br /> on Tuesday, 11/17/81, the Reactor Operator observed Load Reject, Select Rod Insert, APRM Hi/Hi, and Channel "B" Scram annunciators on Control Room Panel 905.

These alarms indicate to the operator that one half of the Reactor Protection System had sensed a loss of generator load. As the turbine load and other plant parameters indicated that such a condition did not in fact exist, the operator attempted to increase the turbine control oil pressure as this is the parameter monitored to detect the loss of load. When it was determined that oil pressure was satisfactory, attention turned to the sensing device.

Apparent Cause of Occurrence Isolation of the pressure switch in question is attributable to personnel error during performance of routine surveillance.

Analysis of Occurrence The pressure switch in question is one of four switches arranged in a one-out-of-two-twice logic system that sense turbine control valve control oil pressure.

On receipt of low control oil pressure due to turbine control valve closure as a result of a load reject, these pressure switches initiate the required logic for select rod insert, APRM setdown to 90 percent of rated, and a reactor scram (unless the No. I and No. 6 turbine bypass valves are off-seat within 260 milliseconds).

The APRM setdown to 90% of rated caused the APRM Hi Hi condition.

I The inadvertent isolation of this pressure switch did not result in a condition that had not been previously analyzed.

The remaining switches in the logic system were operable and would have initiated the required actions on receipt of a load reject conditions.

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ATTACHMENT - Page 2 forrective Action The valve isolating PS-39 was opened as soon as control personnel determined that turbine oil pressure was satisfactory and the problem existed in the sensing device.

Millstone Unit I has revised all Instrumentation and Controls Surveillance Procedure data sheets to add a second sign off for the independent verification of the restoration, in addition to the restoration signature already on the form.