05000245/LER-1981-023, Forwards LER 81-023/03L-0.Detailed Event Analysis Encl

Forwards LER 81-023/03L-0.Detailed Event Analysis Encl

ML20031A195
Person / Time
Site:	Millstone
Issue date:	09/09/1981
From:	Mroczka E NORTHEAST NUCLEAR ENERGY CO.
To:	Haynes R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20031A196	List: 05000245/LER-1981-023, Forwards LER 81-023/03L-0.Detailed Event Analysis Encl 05000245/LER-1981-023-03, /03L-0:on 810810,main Steam Line Hi Radiation Drawer Calibr Test & Main Steam Line Hi Radiation Functional Test Revealed Channel B Tripped Above Tech Spec Limit.Caused by Setpoint Drift.Subchannel Recalibr
References
MP-1-1869, NUDOCS 8109210186
Download: ML20031A195 (2)

LER-1981-023, Forwards LER 81-023/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
2451981023R00 - NRC Website

text

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Mr. Ronald C. Haynes

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Reference:

Facility Operating License No. OPR-21 Docket No. 50-245 Reportable Occurrence R0-81-23/3L Dear M.'.

Haynes:

This letter forwards the Licensee Event Report for Reportable Occurrence R0-81-23/3L required to be submitted within 30 days pursuant to the requirements of the Millstone Unit 1 Technical Specifications, Section 6.9.1.9.a.

An additional three copies of the report are ericlosed.

Yours truly, NORTHEAST NUCLEAR ENERGY COMPANY h

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E Mroczka Station Superintendent Millstone Nuclear Power Station EJM/TST:sjr

Attachment:

LER R0-81-23/3L cc:

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

Director, Office of Management Information and Program Control, Washington, D. C. (3)

U. S. Nuclear Regulatory Commission, c/o Document Management Branch, Washington, D. C.

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8109210186 810909 PDR ADOCK 05000245 S

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1 ATTACHMENT TO LER 81-23/3L NORTHEAST NUCLEAR ENERGY COMPANY MILLSTONE NUCLEAR POWER STATION - UNIT 1 PROVISIONAL LICENSE NUMBER DPR-21 DOCKET NUMBER 50-245 IDENTIFICATION OF OCCURRENCE A reactor protection system instrueent setting was found to be less conservative than that established by the technical specification.

CONDITIONS PRIOR TO OCCURRENCE Prior to occurrence the Unit was increasing power from 93 percent of rated.

DESCRIPTION OF OCCURRENCE On August 10,_1981 at 1530 hours0.0177 days <br />0.425 hours <br />0.00253 weeks <br />5.82165e-4 months <br />, while performing Main Steam Line Hi Radiation DrawerCalibrationTestandMginSteamLineHiRadiationFunctionalTest, Channel B tripped at 1.6 x 10 mR/hr.

Technical Specification 3.1 (Table 3.1.1) required that the trip level setting be less thaii or equal to seven (7) times the normal full power background dose rate, which corresponds to a 3

maximum trip level setting of 1.4 x 10 mR/hr.

DESIGNATION OF APPARENT CAUSE OF OCCURRENCE Failure of the subchannel to trip at its desired setpoint is attributable to instrument setpoint drift.

ANALYSIS OF OCCURRENCE The main steam line radiation monitoring system consists of four (4) radiation monitces arranged in one-out-of-two-twice logic system. On receipt of a main steam line radiation signal, the system initiates a reactor scram and isolation to reduce the source of radiation to the extent necessary to prevent excessive release of radioactive materials.

Failure of the subsystern in question to trip at its desired setpoint did not result in a condition that has not been previously analyzed.

The remaining subsystems were found to be within their desired setpoint range and would have initiated the required action if a main steam line high radiation condition had existed.

CORRECTIVE ACTION

The subsystem in question was recalibrated to within its acceptable setpoint range and was satisfactorily tested.

The radiation raonitor was manufactured by the General Electric Compnay and has 6

a scale maximum of 1 x 10 mR/hr.

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