ML20062M519
| ML20062M519 | |
| Person / Time | |
|---|---|
| Site: | Zimmer |
| Issue date: | 11/30/1981 |
| From: | Sylvia B CINCINNATI GAS & ELECTRIC CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, QA-1540, NUDOCS 8112170276 | |
| Download: ML20062M519 (2) | |
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TIIE CINCINN ATI G AS & EIECTILIC COMI*ANY MbhMM ZIMMER NUCLEAR POWER STATION, P.O. BOX 201, MOSCCW, OH.
45153 cincissm.omo. moi November 30, 1981 QA-1540
-U.S. Nuclear Regulatory Commission.
Region III'
.799 Roosevcit Road.
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Glen Ellyn, ILL 60137 I
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hv Attention:
Mr. James G. Keppler, Director (f 'I i;
MCl 6 Iggb -9 RE:
WM.11. ZIMMER NUCLEAR POWER STATION, UNIT 1 ' ) 8%
ACCELE TED OCKET
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- 58 CONSTRUCTION PERMIT CPPR-88, W.O. 57300, 49, JOB E-5590, FILE NRC-8 g
Centlemen:
This letter constitutes an interim report to the subject deficiency ini-tially reported to Mr. Gaston Fiore111 of Region III on August 10, 1979 under 10CFR50.55 (c).
Each Service Water Pump was designed to accommodato.aaximura 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 pointed to internal recirculation as the cause of accelerated impeller cavitation.
-Programs have been implemented to modify the pump and service water system controls to accomodate a lower flow rate.
Pump modifications include the design of a new impeller ialet vane angle to reduce riow separation at lower flow conditions. This change allows a minimum flow rate of 7,500 gpm.
At this time, new impe11ers have been in-stalled in two of the four service water pumps. Machinery vibration signa-tures have been recorded for the refurbished pumps which indicate no random noise or vibration which is characteristic of interna 1' recirculation, rather they are indicative of normal machine' vibration.
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j' Mr. James G. Keppler, Director 2U. S.-Nuclear Regulatory Commission
-Region III-November 30.-1981
-Page 2-1The.' Service' Water system control modifications included.the' addition of.
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two service water minimum flow bypass loops, one per service water loop..These-bypass loops will maintain pump flows above the minimum flow condition.at
~ all: times. Two control valves have been installed in each bypass loop. The control scheme.for each pump is to modulate each pump's respective control valve,-assuring low flow protection'for'each pump. The control panel is the last remaining item in the control modification,,and is scheduled'to be-Lshipped January 1, 1982. It-is anticipated that all corrective action will be complete by April. 30, 1982, at which time a final report will'be submitted.
We trust the above will be found acceptable as an interim report under
- 10CFR50. 55(e).
Very truly yours, THE CINCINNNATI GAS & ELECTRIC COMPANY By B. R. S via VICE-PRESIDENT, NUCLEAR' OPERATIONS FKP/bjs cc: ' 'NRC Resident Inspector Attn:
W. F.-Christianson NRC Office of Inspector &' Enforcement Washington, DC 20555 y