ML20056B727
| ML20056B727 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 09/09/1971 |
| From: | Duncanson R NORTHERN STATES POWER CO. |
| To: | Morris P US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 9102080440 | |
| Download: ML20056B727 (2) | |
Text
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- k NORTHERN STATES POWER COMPANY Minneapolis Minnesota 55401 3
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%8E!0E Dr. Peter A. Morris, Director n'[*$
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Division of Reactor Licensinn
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Dear Dr. florris:
5 L0fJTICELLO TUCLEAR GENERATITO PLANT Docket No. 50-263 License No. DPR-22 Reporting of Occurrence i
Two conditions have occurred recently at the Fonticello Nuclear Generating Plant which we interpret to be reportable to your office in accordance with Section 6.6.C of Appendix A, Technical Specifications, of the Provisional Operating License wR-22.
1.
Failure of a Grnon 31 solation Valve in Close On August 9, 1971 a reactor water cleanup demineralizer outboard
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isolation valve L6 2393 failed to close when a reactor low water level signal (Group 3 isolation signal) existed. The inboard isolation valve LO 2397 and the other outboard isolation valve !1 2399 isolated the reactor water cleanup system as regaired.
The cause of the problem was determined to be an improperly secured wi re i n t he cont rol ci rcui t fo r the val ve moto r.
The wire was not making proper contact at a terminal block because of wire insulation interference between the wire and the terminal block binding screw.
The problem was corret ied on August 9th and the valve control ci cuit functioned properly du -ing subsegaent testing.
l 2.
Fast 01nsure of LLin Ster.sniafinn valve 2 PAC On August 26, 1971, while performing routine surveillance testing, the closure time of a Main Steam Isolation Valve (!!GI V 2-86C) was measured to 9102000440 710909
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d En 9.0 seconds. The Technical Specifications require the closure tin ~_ of the TSI Vs to be greater than or equal to 3 seconds but s
less than or equal to'5, seconds.
The reason for the decrease in the valve closure time, which had been measured to be 3.4 seconds on flay 20, j
1971, is not known.
The closure tire for MSIV 2-86C was adjusted using the flow control valve on the MSI V oil dashpot.
The valve was tested several tires after the adjustment was made and a closure time of 3.7 seconds was measured cons i s t entl y.
"a Unusual Occurrence reports have been wriiten for boih conditions. The information will be available to the Region lli Compliance inspector for review during his next site inspection.
Yours very truly,
(_b tk^C< &
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F.O. Duncanson, Jr. P.E.
Gen. Supt. of Power Plants flechanical Chai rman Monticello Safety Audit Committee FOD/CEL/ car i
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