ML20235F070
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NSF NORTHERN STATES POWER COMPANY Minneapolis, Minnesota 55401 August 3, 1972 Regulatory File Cy.
N Mr. A. Giambusso 7-Deputy Director for Reactor Projects e (/
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Q United States Atomic Energy Commission
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D Washington, D. C.
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Dear Mr. Giambusso:
NDNTICELLO NUCLEAR GENERATING PLANT
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Docket No. 50-263 License No. DPR-22 Fast Start Failure of the High Pressure Coolant injection System A condition occurred at the Monticello Nuclear Generating Plant recently which we are reporting to your office in accordance with provisions of Section 6.6.B.2 of Appendix A, Technical Specifications, of Provisional Operating License DPR-22. T he Region 1 l l Regulatory Operations Office has bee.n notified of the oCCu rrence.
During the plant startup on July 31, 1972, following maintenance of the HPCI exhaust line check valves, a simulated automatic initiation fast start of the HPCI system was attempted. The system failed to start and run properly.
Instru-mentatinn indicated that the turbine control valve was not responding properly to the governor control signal.
Inspection of the control valve hydraulic actuating system revealed several pieces of plastic pipe cap in the pilot valve oil inlet port. The plastic fragments were removed and the remainder of the valve was inspected and found satisfactory. The power piston and governor servo mechanism were also disassembled and inspected.
No further abnormalities were found.
After reassembly of the control valve actuating system, several fast starts were attempted.
In all cases, the system performed properly.
An Abnormal Occurrence Report will be available at site for the Regulatory Operations i nspectors.
Yours very truly, g
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(-f L. O. Mayer
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Director of Nuclear Support Services pk cc: B H Grier 6
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