ML20040E647
| ML20040E647 | |
| Person / Time | |
|---|---|
| Site: | Zimmer |
| Issue date: | 01/18/1982 |
| 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-1556, QA-155650.55E, NUDOCS 8202050207 | |
| Download: ML20040E647 (2) | |
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sEh THE CINCINNATI GAS & FLECTRIC COMPANY CINCINN ATt. OHIO 4520t January 18, 1982 QA-1556 E. A. BORGMp
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U. S. Nuclear Regulatory Commissien G
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Region III
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Attention:
Mr. James G. Keppler, Director Le%'E I
RE:
WM. H. ZIMMER NUCLEAR POWER STATION - UNI %#
10CFR50.55(e) - ITEM M RESIDUAL HEAT 4
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REMOVAL HEAT EXCHANGERS, DOCKET NO. 50-358, CONSTRUCTION PERMIT CPPS-88, W. O. #57300, JOB E-5590, FILE NO. NRC-8 Gentlemen:
This letter constitutes a final report on the subject deficiency, initially reported under 10CFR50.55(e).
The Zimmer Residual Heat Removal (RH) system consists of three in-dependent loops, A, B, and C.
-Loops A and B are capable of performing suppression pool cooling, shutdown cooling, low pressure coolant injec-tion, and steam condensing depending upon the mode of operation. Each of these two loops is equipped with an independent heat exchanger. Loop C is designed to provide water inventory to the reactor (RPV) in the event of a loss of coolant.tecident, and contains no heat exchanger.
In the pool cooling mode on locps A and B, the system takes suction from the pool, pumps it throagh the heat exchanger, and returns the cooled water to the suppression pool.
In the shutdown cooling mode, suction is taken from the liquid in the RPV, pamped through the heat exchanger and returned to the RPV.
In the steam condensing mode, steam is taken from the RPV, condensed in the heat exchanger and returned to the RPV.
In the low pressure coolant injection mode water is taken from the suppression pool and injected into the IPV through three separate nozzles to provide core cooling.
During certain transient / accident conditions (e.g. Stuck Open Relief Valve (SORV), isolation scram, or Small Break Accident (SBA), with only one (1) heat exchanger loop available, both the pool cooling and shutdown modes are required to function at different times during the events to ob-tain acceptable final bulk suppression pool temperatures.
8202050207 820118 FEB 1E PDR ADOCK 05000358 f
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o Mr. James G. Keppler, Director U. S; Nuclear Regulatory Commission Region III.
January 18, 1982
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Page #2 RH motor operated inboard isolation valve lE12F009 is located inside the Primary Containment. This valve must be open to allow the implementation of the shutdown cooling mode. This valve and RH loops B and C are all supplied with power from Electrical Division II.
A Division II failure would nullify the use of shutdown cooling on RH loops B and C.
This postulated failure would leave only RH loop A in service in the pool cooling mode which could result in high. suppression pool temperatures.
An Engineering' Change Request #386 Rev. 1, has been approved to correct this situation. A kwik key interlock system will provide valve lE12F009 with a primary power supply from Division II and a Division I backup supply.
This fix assures that the shutdown cooling mode is available if either i
Division I or Division II is operable. Parts necessary to implement this fix are being ordered and installation will be completed before April 30, 1982.
We trust the above will'be found acceptable as a final report under 10CFR50.55(e).
Very truly yours, THE CINCINNATI GAS & E!.ECTRIC COMPANY l
By "f/
E. A. BORGMANN SENIOR VICE PRESIDENT FKP:ec cc: NRC Resident Inspector Attn:
W. F. Christianson l
NRC Office of Inspection & Enforcement Washington, D.C. 20555
.