ML19351C734
| ML19351C734 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 12/11/1989 |
| From: | Scace S NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| MP-13841, NUDOCS 8912200336 | |
| Download: ML19351C734 (2) | |
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General Offices e Selden Street, Berlin, Connecticut OiY.E5TiNcU"~
P.O. Box 270
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HARTFORD CONNECTICUT 061410270 k
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Dece:nbcr 11, 1989 MP-13841 Docket No. 50-423 Re:
10CFR50.36 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20$55 Gentlemen:
Millstone Nuclear Power Station, Unit Number 3 Initiation of a Plant Shutdown to Repair Turbine Electrical Solenoid Valve This Special Report is being submitted to provide further information regarding the failure of the Turbine Electrical Trip Solenoid Valve which occurred on November 10, 1989 at Millstone Unit 3.
On November 10, 1989, at 2000 hours0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br />, while operating in Mode 1 at 100 percent power, 587 degrees Fahrenheit and 2260 psia, the Turbine Electrical Trip Solenrid failed to meet its surveillance acceptance criteria.
To fulfill the requirements of Technical Specification 3.3.4, the Unit immediately began to I
downpower. Preparations were made to take the turbine off line to repair the solenoid.
Immediate notification per 10CFR50.72(b) (1) (i) was performed to document the initiation of a plant shutdown required by the plant's Technical Specifications.
However, there are no 30 day Report requirements per 10CFR50.73 which apply since the plant never completed the shutdown and was within the bounds of its Technical Specifications.
The plant was taken to 10% power and the turbine was taken off line at 0050 on November 11, 1989. The Electrical Trip Valve and the Electrical Trip Solenoid Valve were removed, disassembled, and inspected.
No camage was founc on any of the subcomponents, including the 0-rings and seals.
The limit switch linkage was removed prior to the valve replacements and the valves were stroked to verify the linkage was not causing the problem.
The cause of the failure had been determined to be particulate contamination of either the Electronic Trip Solenoid Valve Secondary Valve or the Electronic Trip Valve.
Electro Hydraulic Control (EHC) fluid samples were taken a week earlier and were within acceptable limits; however, monthly samples taken two weeks prior to the problem had slightly elevated particulates, although these samples were also within acceptable limits.
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t As corrective action, both the Electrical Trip Valve and the Electrical Trip Solenoid Valve were replaced with rebuilt valves. After these valves were
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successfully retested, the Unit was returned to 100 percent power. The removed
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F valves were sent to the vender to verify the root cause was particulate.
contamination. The verification by the-vender is' currently ong0ing. -The EHC i
filters were also replaced as a precaution to ensure EHC fluid remained free of.
i particulate contaminants.
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The Licensee contact for this Special Report is Gary L. Swider, who may be I
. contacted at _(203) 447-1791,- Extension 5381.
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L Very Truly Yours, NORTHEAST NUCLEAR ENERGY COMPANY
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f tw Sthp n E. Scace Station Superintendent Millstone Nuclear Power Station I
SES/CLS:cic cc:'W. T.1Russc11, Region I Administrator W. J. Raymond, Senior Resident Inspector, Millstone Unit Nos. 1, 2 and 3 I
D.LH. Jaffe, NRC Project Manager, Millstone Unit No. 3.
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