ML20052E804

Final Deficiency Rept Re Svc Water Pump Mod,Initially Reported 790810.Internal Recirculation Caused Accelerated Impeller Cavitation.Program Implemented to Modify Pump & Svc Water Sys to Accommodate Lower Flow Rate

ML20052E804
Person / Time
Site:	Zimmer
Issue date:	04/29/1982
From:	Borgmann E CINCINNATI GAS & ELECTRIC CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
10CFR-050.55E, 10CFR-50.55E, QA-1723, NUDOCS 8205110437
Download: ML20052E804 (2)

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TIIIC CINCINNATI GAS & ICI ICCTitIC COAll'ANY cf 7 CINCINN ATI Omo 4 *5206 April 29, 1982 QA-1723 4

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U.S. Nuclear Regulatory Commission  ?>,

Region III 4-799 Roosevelt Road

, g ig Glen Ellyn, Illinois 60137 5 MYl%M25 Attention: Mr. J. G. Keppler \

Regional Administrator

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RE: WM. H. ZIMMER NUCLEAR POWER STATION UNIT I [

10CFR50.55(E) - ITEM M-13, SERVICE WATER PUMP MODIFICATION DOCKET No. 50-358 CONSTRUCTION PERMIT NO. CPPR-88, W.O. 57300, JOB E-5590, FILE NRC-8, M-13 Gentlemen:

This letter constitutes a final report concerning the subject design deficiency initially reported to Mr. G. Fiorelli of the NRC on August 10, 1979, under the requirements of 10CFR50.55(e) .

Each Service Water Pump was designed to accommodate maximum service water flow of 12,500 gpm associated with the worst case LOCA conditions.

The original design made no provision to assure that internal recirculation would not occur at flow rates less than maximum.

A test of flow measurement and pump vibration was conducted which point-ed to internal recirculation as the cause of accelerated impeller cavitation.

Programs have been implemented to modify the pump and service water system controls to accommodate a lower flow rate.

Pump modification includes the design of a new impeller inlet vane angic to reduce flow separation at lower flow conditions. This change allows a minimum flow rate of 7,500 gpm. At this time, new impellers have been installed in three of the four pumps. Machinery vibration signatures have been recorded for the refurbished pumps which indicates no random noise or vibration characteristic of internal recirculation. The fourth pump has been dismantled and is being examined for necessary repairs.

The Service Water System Control Modifications include the addition of a minimum flow valve for esch service water pump.. These valves modulate to assure that each pump operates above the minimum flow required.

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• Mr. J. G. Keppler April 29, 1982 - QA-1723 Page 2 In light of the repairs required for the fourth pump, all modifi-cations are now expected to be complete by December 30, 1982.

We trust the above will be found acceptable as a final report under the requirements of 10CFR50.55(e).

Very truly yours, THE CINCINNATI CAS & ELECTRIC COMPANY L

'Q h E. A. BORGMANN SENIOR VICE PRESIDENT FKP:ec cc: NRC Resident Inspector Attn: W. F. Christianson NRC Office of Inspection and Enforcement Washington, D. C. 20555