ML19296A929
| ML19296A929 | |
| Person / Time | |
|---|---|
| Site: | Washington Public Power Supply System |
| Issue date: | 02/11/1980 |
| From: | Renberger D WASHINGTON PUBLIC POWER SUPPLY SYSTEM |
| To: | |
| References | |
| GO1-80-68, NUDOCS 8002190474 | |
| Download: ML19296A929 (3) | |
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Washington Public Power Supply System A JOINT OPERATING AGENCY S
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-on rso.) avs-sooo February 11, 1980 G01-80-68 Nuclear Regulatory Commission Region V Suite 202 Walnut Creek Plaza 1990 N. California Boulevard Walnut Creek, California 94596 Attention:
Mr. R. H. Engelken, Director
Subject:
WPPSS NUCLEAR PROJECTS NOS. 1/4 DOCKET NOS. 50-460 AND 50-513 REPORTABLE CONDITION 10CFR50.55(e)
NONCONFORMING RETAINING CLIPS WKM GATE VALVES
Dear Mr. Engelken:
Mr. Al Toth, US NRC Region V-Resident Inspector, was verbally notified of this reportable condition on January 30, 1980 by the Supply System.
Appendix A to this letter contains the WPPSS final report on the subject condition.
If you have any questions or desire further information, please advise.
Very truly yours, 0k D. L. Renberger Assistant Director-Technology Attachment jds cc: CR Bryant - BPA BD Redd - UE&C, Phil.
AD Toth - NRC Region V
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s Attachment A WNP-1/4 Docket Nos. 50-460 and 50-513 Reportable Condition 10 CFR 50.55(e)
WKM-Marotta Relief Valve Retaining Ring Final Report
Background
B&W notified WPPSS on October 8,1979 of a defective condition which existed in the internal pressure relief valve of the WKM manufactured valves being supplied for WNP-1/4 and transmitted a copy of its evalu-ation on the condition on January 29, 1980 concluding that the incident is reportable. This condition existed in 12 valves per plant for both WNP-1 and WNP-4.
Description of Deficiency Relief valves manufactured by Marotta Scientific Controls are installed internal to the WKM valves and serve to relieve any increase in valve body cavity pressure (e.g. due to thermal expansion) to the flow path upstream of the gate.
These relief valves were supplied to WKM with carbon steel rather than stainless steel retaining rings.
These carbon steel rings will corrode in service resulting in the loss of function of the affected pressure relief assemblies or in loose parts.
These loose parts are segments of the retaining ring and/or the pressure relief assembly poppet retained by the ring.
Safety Implications The loss of function of the Marotta pressure relief valves result in the assembly failing in the relief position resulting in an open path between the valve body cavity and the process stream. Although some increase in leak off might occur, neither the integrity nor functioning of the valve is affected.
The potential for having loose parts in the systems is of greater concern.
Although the ring would either partially or completely dissolve and not be of significance as a loose part, it will release the.5" x.1" poppet. This poppet could be released into the valve body however, WKM has determined that it would not cause the valve to malfunction (fail to open or close).
Of greater concern is the possibility of a poppet interfering with the operation of Decay Heat Removal System pumps which also serve as the Low Pressure Injection System pumps. While the functioning of a pump would probably not be significantly affected, no definitive analysis currently supports this conclusion.
Also of concern is the affect of the poppet from the pressurizer relief isolation valve, RC-V11, entering the pressurizer power operated relief valve (PORV) and inhibit subsequent closure.
Reportability Based on the evaluation of this condition, it is determined that the condition, if left uncorrected "could have affected adversely the safety of operations" of the plant. Therefore, the condition has been determined to be reportable.
Corrective Action Taken The WM4 valves provided for WNP-1 and 4 have been returned to the manu-facturer for replacement of the carbon steel retaining ring with a stainless steel part.
In some cases, valves have already been returned to the site.
S&W has also determined that a similar condition exists on WKM valves being provided to the Pebble Springs 1 plant.
These valves have not yet been shipped and the condition will be corrected prior to shipment.
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