05000245/LER-1981-021, Forwards LER 81-021/03L-0.Detailed Event Analysis Encl

Forwards LER 81-021/03L-0.Detailed Event Analysis Encl

ML20010C830
Person / Time
Site:	Millstone
Issue date:	08/11/1981
From:	Mroczka E NORTHEAST NUCLEAR ENERGY CO.
To:	Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20010C831	List: 05000245/LER-1981-021, Forwards LER 81-021/03L-0.Detailed Event Analysis Encl 05000245/LER-1981-021-03, /03L-0:on 810710,pressure Switch 503D Tripped at Instrument Setting Less Conservative than Tech Spec During Testing.Caused by Setpoint Drift.Pressure Switch Reset
References
MP-1-1842, NUDOCS 8108210085
Download: ML20010C830 (2)

LER-1981-021, Forwards LER 81-021/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
2451981021R00 - NRC Website

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August 11, 1981 MP-1-1842 Mr. Boyce H. Grier Directon, Region I Office of Inspection and Enfo' cement U. S. Nuclear Regulatory Com:aission 631 Park Avenue King of Prussia, Pennsylvania 19406

Reference:

Provisional License No. DPR-21 Docket No. 50-245 Reportable Occurrence R0-81-21/3L

Dear Mr. Grier:

This letter forwards the Licensee Event Report for Reportable Occurrence R0-81-21/3L 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 enclosed.

Yours truly, Ul, NORTHEAST NUCLEAR ENERG'l COMPAN

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L 7 J. Mroczka 2(

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Attachment:

LER R0-81-21/3L g

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

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

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

20555 8108210085 810811 PDR ADOCK 05000245 S

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ATTACHMENT TO LER 81-21/3L NORTHEAST NUCLEAR ENERGY COMPnNY~

MILLSTONE NUCLEAR POWER STATION - UNIT 1 PROVISIONAL LICENSE NUMBER DPR-21 DOCKET NUMBER 50-245 Identification of Occurrence Reactor protection system instrument setting was found to be less conservative l

than those established by Technical Specifications.

Conditions Prict to Occurrence The plant was operating at a steady state power level of 100 percent.

Description of Occurrence On July 10,1981 at 1540 hours0.0178 days <br />0.428 hours <br />0.00255 weeks <br />5.8597e-4 months <br /> while performing routine surveillance (Condenser Low Vacuum Scram Functional Calibration Test), it was discovered that pressure switch 503D tripped at 22.4" Hg vacuum.

The trip level setting is required by-i l

Technical Specification 3.1 (Table 3.1.1) to be greater than or equal to 23" Hg l

decreasing.

A) parent Cause of Occurrence T1e failure of this switch to trip at its desired setpoint was attributed to setpoint drift.

l Analysis of Occurrence The pressure switch in question is one of four pressure switches arranged in'a one-out-of-two twice logic-system sensing low condenser vacuum for input to the Reactor Protection System scram logic.

At a condenser vacuum of greater than 23" Hg, the Reactor Protection System would scram the reactor.

The remaining three switches were found to be at the proper setpoint and would have initiated the required action upon receipt of a lcw condenser vacuum.

Corrective Accion j

The pressure switen was reset to its required setpoint and satisfactorily test.

The switch is a Barksdale Model No. DIT-H-1855 with a range of.8 to 29.2" Hg.

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