ML20080K522
| ML20080K522 | |
| Person / Time | |
|---|---|
| Site: | Zimmer |
| Issue date: | 09/22/1983 |
| From: | Williams J CINCINNATI GAS & ELECTRIC CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, LOZ-83-0154, LOZ-83-154, M-92, NUDOCS 8309290206 | |
| Download: ML20080K522 (4) | |
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LOZ-83-0154 J. WILUAMS, JR stNsOP vict PatalDENT NUCLE AA QPERAf TONS Docket No. 50-358 U.S. Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, Illinois 60137 Attention:
Mr. J.G. Keppler Regional Administrator Gentlemen:
RE:
WM. H. ZIMMER NUCLEAR POWER STATION - UNIT 1 10CFR50. 55 (e) ITEM M-92, CRD VENT VALVES 1CllF101 AND 1CllF102 W.O. 57 300, JOB E-5590, FILE NO. 956C, M-92 This letter concerns the subject condition initially reported to the Commission on August 23, 1983 as a potential reportable deficiency under the requirements of 10CFR50.55 (e).
Upon further evaluation, CG&E has determined that this condition does not represent a reportable deficiency.
During a review of past Nonconformance Reports, a condition was identified with Control Rod Drive (CRD) high point vent valves on the Hydraulic Control Units.
The valves,1CllF101 and 1CllF102 (137 of each), we re subject to valve stem and valve body damage due to material galling and application of excess torque in the open or closing direction' The vendor drawing, applicable to this situation, did not permit the use of any form of lubricant.
This f act combined with a valve design which employs 316 stainless steel to 316 stainless steel threaded joints, resulted in galling, excessive friction and the need to apply additional torque to move the valve stem.
This situation caused valve stem twisting, stem breakage and deformation of the sten material at both the operator (key wrench end) and the valve disc end.
The original concern was a f ailure mechanism that could cause indeterminate leakage of control rod drive water.
The valves are located at the high points of each control rod hydraulic module and serve as high point vents since noncondensable gas would accumulate and be swept by the process fluid to these locations.
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Mr. J.G. Keppler Regional Administrator September 22, 1983 LOZ-83-0154 Page 2 Venting is accomplished prior to plant star t-up af ter work on the control rod hydraulic system has been completed, prior to initial plant star tup to vent non-condensables from the complete system, or af ter individual module maintenance has been completed during plant operation.
Thus, during power operation, operation of these valves is inf requent and the remote possibility of leakage resulting f rom a malfunctioning valve can be controlled by appropriate isolation.
Failure of the valve seat or stem disc to maintain its seal during power operations is backed up by the seal provided by a plug.
Referring to the accompanying diagram, venting is accomplished in accordance with an approved procedure, by use of a temporary hose connected to Port "A" (af ter first removing the pl ug), removal of the plug f rom Por t "B" a nd, using a special valve key, slowly opening the valve.
Following successful venting and reseating the valve, the plugs are replaced.
Unusual or abnormal valve ope ration is detected by the operator upon first opening the vent valve and should extreme force be needed ' b3 move the stem, the venting operation is suspended, the valve closed and plugs replaced until corrective measures are formulated.
In addition, a design change has been approved and been implemented, permitting the use of "Never-Seez" lubricant and changing of valve elastomers to viton, a material-compatable with the' approved lubricant.
These changes will.also be incorporated in appropriate maintenance and spare parts documents.
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Mr. J.G. Keppler Regional Administrator September 22, 1983 LOZ-83-0154 Page 3 Since no condition adverse to the safe operation of the plant would exist, this item is not reportable under 10CFR50.55 (e).
Very truly yours, THE CINCINNATI GAS & ELECTRIC COMPANY f
l By f
l SENIOR VICS PRESIDENT DJS/sfr cc:
NRC Office of Inspection & Enforcement Washing ton, D.C.
20555 NRC Senior Resident Inspector ATTN:
T.P. Gwynn NRC Zimmer Project Inspector, Region III ATTN:
E. R. Schweibinz I
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