ML20086D818

Responds to 760520 Inquiry Re Potential Design Deficiency Concerning LPCI Pump Cavitation & Motor Overload.Pumps Not Subj to Damage Due to Cavitation or Motor Overload in Runout Condition

ML20086D818
Person / Time
Site:	Monticello, 05000000
Issue date:	06/07/1976
From:	Mayer L NORTHERN STATES POWER CO.
To:	Stello V NRC OFFICE OF INSPECTION & ENFORCEMENT (IE)
Shared Package
ML19289B550	List: 05000000/LER-1977-012, :on 770620,during Investigation of Cycle 5 Max Critical Power Ratio Limits,Ge Found That Pump Trip Delay Time Assumed in Original Cycle 5 Transient Analysis Not Appropriate.Amend Request Will Be Submitted 05000000/LER-1977-020-03, /03L:on 770404,RCS Leakage Determined to Be Greater than 10 Gpm.Caused by Packing Leakage Past Stems on RTD Bypass Throttle Valves 13RC20 & 14RC20.Valves Placed on Backseat & Stem Leakage Decreased 05000000/LER-1977-038-03, /03L:on 770519,RCS Leakage Determined to Be Greater than 10 Gpm from Stem Leakoff on Manual Isolation Valves 1PS24 & 1PS28 for Pressurizer Spray Valves.Caused by Packing Leakage.Valves Will Be Repacked at Next Outage ML20086D481 ML20086D514 ML20086D520 ML20086D537 ML20086D550 ML20086D554 ML20086D557 ML20086D561 ML20086D567 ML20086D606 ML20086D642 ML20086D691 ML20086D703 ML20086D760 ML20086D788 ML20086D818 ML20086D823
References
NUDOCS 8312050151
Download: ML20086D818 (1)

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i NSP l l NORTHERN STATES POWER COMPANY M IN N E A PO L.a s. M IN N E SOTA S S401 June 7, 1976 - x

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Mr Victor Stello, Director Division of Operating Reactors i~h % jJg. y, T .

U S Nuclear Regulatory Commission (y';3 i

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Washington, DC 20555 '

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Dear Mr Stello:

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MONTICELLO NUCLEAR GENERATING PLANT Docket No. 50-263 License No. DPR-22 Response to 5/20/76 Inquiry Concerning I LPCI Design

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i Your May 20, 1976 letter identified a potential design deficiency related to LPCI pump cavitation and motor overload. Monticello has the Loop Selection Logic System and does not have the LPCI modification. Therefore, item a j of your letter is applicable and item b .is not.

The Monticello piping layout and pump data have been reviewed. At runout

[ flow the NPSH requirements of the pump are met. The pump characteristic l curves show that at high flows, the brake horsepower and motor current de-A crease. Therefore, the Monticello LPCI pumps are not subject to damage due

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to cavitation or motor overload in the runout condition.

Yours Very truly, L 0 Mayer, PE Manager, Nuclear Support Services bb1 LQ4/MHV/ deb cc: J G Keppler C Charnoff i MPCA I Attn: J W Ferman 8312050151 780426 PDR ADOCK 05000263 g PDR COPY SENT REGION A_

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