05000245/LER-1981-022, Forwards LER 81-022/03L-0.Detailed Event Analysis Encl

Forwards LER 81-022/03L-0.Detailed Event Analysis Encl

ML20031A203
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
ML20031A204	List: 05000245/LER-1981-022, Forwards LER 81-022/03L-0.Detailed Event Analysis Encl 05000245/LER-1981-022-03, /03L-0:on 810810,MSIV 1-MS-1C Did Not de-energize When Actuated to 10% Closed Position.Caused by Maladjusted Armature on Limit Switch.Armature Readjusted
References
MP-1-1870, NUDOCS 8109210193
Download: ML20031A203 (3)

LER-1981-022, Forwards LER 81-022/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
2451981022R00 - NRC Website

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NORTHEAST UTILITIES I $55555E

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September 9, 1981 MP-1-1870 Mr. Ronald C. Haynes 3'

hj Director, Region I

/.e[' 4 Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission v, 'g#. / hM Sp 631 Park Avenue 1g King of Prussia, Pennsylvania 19406

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Reference:

Facility Operating License No. DPR-21 s

Docket No. 50-245

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Reportable Occurrence R0-81-22/3L

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Dear Mr. Haynes:

This letter forwards the Licensee Event Report for Reportable Occurrence RC-81-22/3L required to be submitted within 30 days pursuant to the requirements of the Millstone Unit 1 Technical Specifications, Section 6.9.1.9.b.

An additional three copies of the report are enclosed.

Yours truly, NORTHEAST NUCLEAR ENERCY COMPANY U

E. J.W Mroczka Station Superintenden Millstone Nuclear Power Station EJM/TST:sjr I

Attachment:

LER R0-83-22/3L cc:

Director, Office of Inspection and enforcement, Wa@ington, D.C. (30)

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

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

20555 r

s 8109210193 010909 2

[I (s PDR ADOCK 05000245 t

S PDR i

f ATTACHMENT TO LER 81-22/3L NORTHEAST NUCLEAR ENERGY COMPANi MILLSTONE NUCLEAR POWER STATION - UNIT 1 PROVISIONAL LICENSE NUMBER OPR-21 DOCKET NUMBER 50-245 IDENTIFICATION OF OCCURRENCE Reactor protection signal was not generated from a Main Steam Isolation Valve ten percent closure.

CONDITIONS PRIOR TO OCCURRENCE Frior to occurrence the unit was sratdown.

DESCRIPTION OF OCCURRENCE On August 10,1981 at 2250 hours0.026 days <br />0.625 hours <br />0.00372 weeks <br />8.56125e-4 months <br /> while performing Main Steam Isolation Valve Closure Functional Surveillance Test, the relay did not de-energize when the Main Steam Isolation Valve (1-MS-1C) was actuated to a 10 percent closed position. Technical Specification 3.1 (Table 3.1.1) states reactor protecticn system scram trip level setting be less than or equal to 10 percent valve closure.

The 'C' Main Steam Line was isolated and the containment was entered for inspection of the MSIV switch which should have de-energized the relay.

APPARENT CAUSE OF OCCURRENCE Containment entry and investigation revealed that the armature on the limit switch was out of adjustment. This prevented the Reactor Protection relay from being de-energized at the ten percent closed valve position which in turn would prevent a scram.

ANALYSIS OF OCCURRENCE l

The Main Steam line isolation valve closure scram is set to scram when the j

isolation valves are ten percent closed from full open in three out of four i

lines.

This scram anticipates the pressure and flux transients,;hich occur during normal or inadvertent isolation valve closure.

By scramming at this setting the resultant transient is insignificant.

The occurrence provided no decrease in protection, Main Steam Isolation Valves l

are not required to be operable during shutdown.

If, however, this did occur during plant operation there would still have not been any decrease in l

protection, only decrease in redundancy.

Each valve has a switch / relay system in each protection system logic channel.

Although one logic channel for the

'C' switch did not trip, the other logic channel did trip and it would have initiated the required trip had the valve actually closed ten percent from full open.

O f.

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CORRECTIVE ACTION

~

The armature itaTreadjusted on.the limit switch and then tested satisfactorily.

?

The Main Steam Isolation Valve position switch is manufactured by NAMCo, type SL-3.

e The most recent reoccurrence of this situation was:

81-16/3L i

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