05000245/LER-1981-026, Forwards LER 81-026/03L-0.Detailed Event Analysis Encl

Forwards LER 81-026/03L-0.Detailed Event Analysis Encl

ML20031D888
Person / Time
Site:	Millstone
Issue date:	10/05/1981
From:	Mroczka E NORTHEAST NUCLEAR ENERGY CO.
To:	Haynes R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20031D890	List: 05000245/LER-1981-026, Forwards LER 81-026/03L-0.Detailed Event Analysis Encl 05000245/LER-1981-026-03, /03L-0:on 810905,while Performing Isolation Condenser Instrument Functional & Calibr Test,Switch 1349B Failed to Trip at Desired Setpoint.Caused by Setpoint Drift. Pressure Switch Recalibr
References
MP-1-1899, NUDOCS 8110140336
Download: ML20031D888 (3)

LER-1981-026, Forwards LER 81-026/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
2451981026R00 - NRC Website

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L J ::::::::;12;lCJ'""l0l October 5, 1951 MP-1-1899 Mr. Ronald C. Haynes

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fg Director, Region I gf 0,k4-I Ih Office of Inspection and Enforcement LU 1 U. S. Nuclear Regulatory Commission

@O O-u.a.CT2 3 y 631 Park Avenue King of Prussia, Pennsylvania 19406 6

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Reference:

Facility Operating License No. DPR-21 Docket No. 50-245

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Reportable Occurrence R0-81-26/3L y

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Dear Mr. Haynes:

This letter forwards the Licensee Event Report for Reportable Occurrence R0-81-26/3L 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, NORTHEAST NUCLEAR ENERGY COMPANY l f6 C J. Mroczk Station Superintendent Millstone Nuclear Power Station EJM/TST:sjr

Attachment:

LER R0-81-26/3L 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.

20555 Y

0110140336 811005

/

PDR ADOCK 03C00245 6i!s S

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b ATTACHMENT TO LER 81-26/3L NORTHEAST NUCLEAR ENERGY COMPANY MILLSTONE NUCLEAR POWER STATION - UNIT 1 PROVISIONAL LICENSE NUMBER DPR-21 DOCKET NUMBER 50-245 Identification of Occurrence Engineered safeguard feature was found to be less conservative than those established by technical specification when the Isolation Condenser flow switch tripped above its allowable setpoint.

Cor.ditions Prior to :currence Prior to occurrence 7he unit was in the start up m de with reactor power at two (2) percent of rate; and reactor pressure at 470 psig.

Description of Occurrence On September 5, 1981, at 2230 hours0.0258 days <br />0.619 hours <br />0.00369 weeks <br />8.48515e-4 months <br />, while performing Isolation Condenser Isolation Instrucent Functional and Calibration Test, switch 1349B failed to trip at its desired setpint.

Technical Specification 3.2.c.1 (Table 3.2.c.1) requires autumatic isolation of the Isolation Condenser when a line break on the condensate return reaches a differential pressure measuring greater than 35 inches of water but less than 44 inches of water.

Designation of Apparent Cause of Occurrence FailureoftheswitchinquestiontotriDtitsdesiredsetpointwas attributable to setpoint drift.

Analysis of Occurrence The Isolation Condenser is a standby, high pressure system provided for the removal of fission product decay heat after a reacter scran.

It is initiated on high reactor pressure in excess of 10G5 psig sustained for fifteen (15) seconds or reactor 10-10 level.

It can also be manually initiated.

The Isolation Condenser operates by natural circalation, with steam flowing from the reactor through the condenser tubes, condensing and returning by gravity to the vessel via recirculation loop 'B'.

There are two pressure switches on the steam supply and the condensate return line that detect a line break oy sensing the differential pressure across pipe elbows located inside the drywell.

When any one of the switches senses a high differential pressure (above technical specification setpoint limits) the Isolation Condenser is automatically isolated.

Failure of the channel to trip at its desired setpoint did not result; in a condition that had not been previously a'alyzed.

The remaining switches would 4

have initiated the required isolation of he Isolation Condenser if an actual line break had existed.

o i.

Corrective Action

The pressure switch in question was recalibrated to within its acceptable a

setpoint range and was satisfactorily tested.

The pressure switch is a Barton, Model 286 witti e range of 0-100 inches.

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