ML20214F902
| ML20214F902 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 05/04/1987 |
| From: | Carey J DUQUESNE LIGHT CO. |
| To: | Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| 2NRC-7-106, NUDOCS 8705260343 | |
| Download: ML20214F902 (3) | |
Text
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'Af 2NRC-7-106 S.'E Bi Telecopy (41 3-Ext.160 P.O. Box 328 May 4, 1987 Shippingport, PA 15077 United States Nuclear Regulatory Commission Region I 631 Park Avenue King of Prussia, PA 19406 ATTENTION: Dr. Thomas E. Murley Administrator
SUBJECT:
Beaver Valley Power Station - Unit No. 2 Docket No. 50-412 Copes Vulcan Electro-Hydraulic Actuated Atmospheric Steam Dump Valves Potential Significant Deficiency Report 87-11 Gentlemen:
This Potentially Reportable Significant Deficiency Report is being submitted pursuant to the requirements of 10CFR50.55(e).
It-is anticipated that no additional reports will be ' required.
OllQUESNE LIGHT COMPANY By
/'
Sr i
Pe ent LMR/ijr NRC/LMR/SDR/8711 Attachment AR/NAR cc: Mr. P. Tam, Project Manager (w/a)
Mr. J. M. Taylor, Director (3) (w/a)
Mr. J. Beall, Sr. Resident Inspector (w/a)
Mr. L. Prividy, NRC Resident Inspector (w/a)
INPO Records Center (w/a)
NRC Document Control Desk (w/a) 870526C343 870504 PDR ADOCK 05000412
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S PDR qc:2
i ATTACHMENT 1.
Summary During initial stup and testing of a Copes-Vu? an electro-hydraulic (E/H) model 300 control valve, using a Borg-Werner E/H operator, leakage was discovered.
Subsequent investigation showed that the valve stem had separated from the inner plug.
It was determined that the parts had failed due to excessive closing thrust provided by the Borg-Warner hydrau-lic operator.
The stem and inner plug were pulled apart and the roll pin sheared off with no indication of stem rotation before the failure.
Of the four valves of this type at BVPS-2, only one failed.
2.
Immediate Action Taken A Nonconformance and Dispositon Report was written, and an investigation was initiated on the operator and valve design with the vendors, Borg-Warner and Copes-Vulcan.
Mr. L. M. Rabenau, Lead Compliance Engineer, Beaver Valley Power Station Unit No. 2, notified Mr.
D.
Limroth, NRC Region I, _ of this concern on April 3, 1987.
3.
Description of Deficiency The investigation of the operator and valve design revealed that Copes-Vulcan had not considered the maximum thrust available from the valve operator during all modes of operation.
Specifically, the modes of oper-ation not considered were; 1) during testing when the proper setpoints of the hydraulic relief valves are verified; and 2) during emergency oper-atiog when the accumulator is used to close the valve.
The relief valves are tested to ensure proper operation during normal service should ti,e pump motor continue to run after the actuator's present travel limit is released.
The accumulator is used to close the valve upon the loss of power or control signal to the actuator.
Either of these two modes will produce sufficient thrust to exceed the design strength of the stem / inner plug joint.
The maximum thrust of the operator during these modes of operation is almost twice that provided during normal operation.
4.
Analysis of Safety Implication Failure of the valve stem / inner plug joint could prevent the atmospheric
-l steam dump valves from stroking due to the plug jamming in the valve body.
This could lead to an uncontrolled cooldown which could exceed the related criteria in the Technical Specifications.
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5.
Corrective Action to Resolve'the Deficiency Copes-Vulcan has redesigned the stem / inner: plug threaded joint by-increas-ing the length of thread engagement and by ~ changing the. inner. plug mater-i al.
The necessary parts have been received from: Copes-Vulcan to modify
' all four' atmospheric stemn dump: valves..These parts have been installed and the valves have been satisfactorily stroke tested.- Future valve test-4 ing.will ~ provide further assurance of proper. valve' operation.
6.
Ad.ditional Report No' additional reports are expected.
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