ML19256A800
| ML19256A800 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 12/16/1978 |
| From: | Reinaldo Rodriguez SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | |
| References | |
| RJR-78-553, NUDOCS 7901160167 | |
| Download: ML19256A800 (2) | |
Text
.
r d 'SMUD SACRAMENTO MUNICIPAL UTILITY DISTRICT O 6201 S Street, Box 15830, Sacramento, California 95813; (916) 452-3211 RJR 78-553 S
Decembe r 16, 1978 p ptr[,
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Mr.
R. 11. Engelken, Director Divir, ion of Inspection & Enforcement, Region V Yd}7 3
U.S. Nuclear Regulatory Comnission Walnut Creek Plaza, Suite 202 1990 North California Boulevard Walnut Creek, California 94596 Re: Operating License DPR-54 Docket No. 50-312 Special Report
Dear Mr. Engelken,
In accordance with Technical Specifications for Rancho Seco Nuclear Generating Station, Section 3.14.2.2 and 6.9.5E, the Sacramento Municipal Utility District is hereby submitting a Special Report concerning the status of Inoperable Fire Protection Equipment.
On November 30, 1978, failure of the engine to pump coupling on the diesel driven tire pump, P-996, rendered the unit inoperable.
A similar oc-currence, on September 13, 1978, was reported to your office by LER 78-9.
At that time the failure mode (sheared coupling bolts) was attributed to improper torque during inital installation. An alignment check (engine to pump) did not reveal any discrepancies and replacement of the bolts with emphasis on proper torque values restored the unit to an operable condition.
The latest failure, due to its similarity, as well as the chort time interval trom the first occurrence, prompted a closer investigation of the coupling itself. The investigation revealed that the bolt holes had been elongated.
The operating characteristics of the pump (starting in a loaded condition) places considerable torque on the coupling.
The elongated bolt holes subjected the coupling bolts to impact forces in addition to the normal shear stresses they are designed to accomodate.
The bolt failure is attributed to this additional impact force.
Replacement coupling bolts and flanges were ordered. Upon their receipt the coupling was repaired, the unit tested and then returned to oervice.
The unit was inoperable for a total of 8 (eight) days.
The redundant piece of
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AN ELECTRIC SYSTEM S E R VI N G MORE THAN 600,000 IN THE HEART OF C A LI F O R N I A
4 equipment, motor driven fire pump P-440, was available during this entire time period.
Respectfully,
\\'N q u>V 3
R. J.*Rodrigue Manager, Nucle r Operations RJR: RWC:llli:j lk cs:
J. J. Mattimoe R. P. O ub re '
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