05000245/LER-1981-036, Forwards LER 81-036/03L-0.Detailed Event Analysis Encl

Forwards LER 81-036/03L-0.Detailed Event Analysis Encl

ML20039B117
Person / Time
Site:	Millstone
Issue date:	12/11/1981
From:	Mroczka E NORTHEAST NUCLEAR ENERGY CO.
To:	Haynes R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20039B118	List: 05000245/LER-1981-036, Forwards LER 81-036/03L-0.Detailed Event Analysis Encl 05000245/LER-1981-036-03, /03L-0:on 811112,pressure Switch 2206-1621D Tripped Outside Allowable Band.Caused by Setpoint Drift. Switch Readjusted
References
MP-1-1961, NUDOCS 8112220307
Download: ML20039B117 (2)

LER-1981-036, Forwards LER 81-036/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
2451981036R00 - NRC Website

text

.

IMHrrHI!AST IFFII.rFII!S 5

tCOll'J

:"U70'7""

feffdnE constericuT o6ioi

• 'D:::::O%CL;"""

(2m) 666-6911 L

L J :::::::DJ,,:2,Cl'!?"

December 11, 1981 MP-1-1961 Mr. Ronald C. Haynes Regional Administrator Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, Pennsylvani?. 19406

Reference:

Provisional License DPR-21 Docket No. 50-245 Reportable Occurrence R0-81-36/3L

Dear Mr. Haynes:

This letter forwards the Licensee Event Report for Reportable Occurrence R0-81-36/3L 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,

[,

c

~

E. J. Mroczka Station Superintendent fiillstone Nuclear Power Station EJM/TST:mo l

Attachment:

LER R0-81-36/3L 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 D ).b I s[I 8112220307 811211 PDR ADOCK 05000245

//

S pgg

4 ATTACHMENT TO LER 81-36/3L NORTHEAST NUCLEAR ENERGY COMPANY MILLSTONE NUCLEAR POWER STATION - UNIT 1 PROVISIONAL LICENSE NUMBER DPR-21 D0CKET NUMBER 50-245 IDENTIFICATION OF OCCURRENCE A reactor protection system instrument setting was found to be less conservative than that established by Technical Specifications.

CONDITIONS PRIOR TO OCCURRENCE Prior to the occurrence, the plant was operating at a steady state power level of 100 percent.

DESCRIPTION OF OCCURRENCE On November 12,1981, at 1415 hours0.0164 days <br />0.393 hours <br />0.00234 weeks <br />5.384075e-4 months <br />, while performing Drywell High Pressure Scram and Containment Isolation Functional and Calibration Test, it was discovered that pressure switch 2206-1621D tripped at 2.35 PSIG. The trip level setting of this switch is required by Technical Specifications to be less than or equal to 2 PSIG.

APPARENT CAUSE OF OCCURRENCE The failure of this switch to trip at its desired setpoint was attributed to setpoint drift.

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 high primary containment pressure for input to the Reactor Protection System scram logic and the containment isolation logic. This pressure sensing is used as a back-up to the reactor water level instrumentation in order to detect a loss of coolant accident and initiate the emergency core cooling equipment.

Failure of the switch to trip at its desired setpoint did not impair operability of the system.

The remain-ing switches were found to be at the proper setpoint and would have initiated the required action upon receipt of a primary containment high pressure.

CORRECTIVE ACTION

The pressure switch was adjusted to its required trip level setting, tested satisfactorily and returned to service.

The switch in question is a Barton 288 pressure indicating switch with a range of 0-5 psi. Several similar occurrences have involved switches of this type.