ML20059C042

Special Rept:On 900519,loose Parts Monitor Channel 1 Malfunctioned.On 900606,reactor Trip Occurred Due to Bad Cable.On 900722,loose Parts Monitor Channel 3 Declared Inoperable.Channels 1 & 3 Will Be Repaired Next Outage

ML20059C042
Person / Time
Site:	Millstone
Issue date:	08/23/1990
From:	Scace S NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
MP-90-945, NUDOCS 9008310011
Download: ML20059C042 (2)

Text

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General Offices e Selden Street. Berkn. Connecticut

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1 .wm w wn,we cwn p_o pay 270 H ART FORD. CONNECTICUT 06141-0270 k k J C 2 [,2.'*,""j 7 (203) % 5 5000 Docket No: 50-423 Re: 100FR50.36 August 23, 1990 MP-90-945 U. S. Nuclear Regulatory Comission Document Control Desk h shington, D.C. 20555 ..

References:

(1) Special Report, Stephen E. Scace Letter (MP-13448) to U.S. Nuclear Regulatory Com tission, Millstone Nuclear Power Station, Unit No. 3, Malfunctioning Loose Parts Monitor Channels, dated August 25, 1989 (2) Special Report, Stephen E. Scace/ Carl H. Clement Letter (MP-13 906) to U. S. Nuclear Regulatory Comission, Millstone Nuclear Power Station, Unit No 3, Malfunctionino Loose Parts

~4onitor Channels, dated January 2,1990 (3) Special Report, Stephen E. Scace Letter (MP-90-614) to U. S. Nuclear Regulatory Commission, Millstone Nuclear Power Station, Unit No. 3, Malfunctioning Loose Parts Monitor Channel, dated June 22, 1990 Gentlemen:

Millstone Nuclear Power Station, Unit No. 3 Malfunctioning Loose Parts Monitor Channel This Special Report is being submitted p suant to Millstone tinit 3 Technical Specification 3.3.3.8 a: Loose Part Detection System. Plant Technical Specification 3.3.3.8.a requires a Special Report be submitted to the NRC 10 days following one or more channels of the Loose Part Detection System inoperable for more than 30 days. This Special Report also supplements the August 25, 1989, January 2, 1990, and June 22, 1990 Special Reports on Malfunctioning Loose Parts Monitor Channels (referenced above)

On May 19, 1990, with the plant in Mode 3 (Hot Standby), 0% pot.er, 2250 psia, and 585'r, Loose Parts Mcnitor (LPM) Channel 1 was placed out of service as '

reported in Reference 3. At that time, all the other LPM channels were operating normally, 7 h .

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2 The malfunctioning channel was turned off to clear'the main control board blarm and remove the data acquisition trigger signal from the compute'. This allowed valid loose part impact alarms from the operable channels to be monitored and recorded.

On June 6, 1990, an Automatic Reactor Trip occurred due to a bad CRDM cable, as j

' reported by License Event Report 90-019-00. At that time, the operation of the >

LPM equipment, exclusive of Chaanel 1, was verified to be satisfactory.

However, the out of service channs1 was not repairec due to the short' duration ,

of the plant shutdown. The out of service channel is still scheduled for repair during the next refueling out ;e.

On July 22, 1990, with the plant in Mode 1, at 100% power, 2250 psia, and 586*F, i LPM Channel 3, Reactor Head, was declared inoperable after data analysrs  !

verified that looso part impacts were not occurring. Further investigation ,

datermined that the alarms were caused by malfunctioning LPM equipment lochted  ;

inside the Containment Building. The redundant LPM Channel monitoring the I Reactor Head is operating satisfactorily. Assessment of the equipment j determined that immediate repair with the Unit at power would not have increased j plant safety and' containment entry was not prudent for personnel exposure i considerations.- Channel 4, along with the previously reported Channel 1, will 3 be repaired during the next refueling outage. ]

The licensee contact for this Special Report is Robert Conway, wh6'may be  ;

contacted at (203)' 444-5422. j 1

Very truly yours, NORTHEAST NUCLEL:. ENERGY COMPANY For: Stephen E. Scace Director, Millstone Station

-i By: CarlII hI'ement

, Millstone Unit 3 Director SES/GTB:cle f cc: T. T.~ Martin,. Region I Administrator W. J. Raymond, Senior Resident Inpsector, Millstone Unit Nos. 1, 2, and 3 D. H. Jaffe, NRC Project Manager, Millstone Unit No. 3 1

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