ML19317F840
| ML19317F840 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 09/24/1975 |
| From: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| Shared Package | |
| ML19317F841 | List: |
| References | |
| NUDOCS 8002210586 | |
| Download: ML19317F840 (1) | |
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49 SACRAMENTO M' NICIPAL UTILITY DISTRICT O G201 S Street. Box 15830. Sacramento. Californla 95813; (916) 452-3211 U
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September'24, 1975'
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.Mr. R.'H.'
Engc*1 ken
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Director of Regulatory Operations, Region V f
NRC Operations Office 1
1990 N.-Californla Boulevard Walnut Creek Plaza,. Suite 202 Walnut Creek, California 94596 i
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Re: Operating License DPR '
Docket No. 50-312
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l Abnormal-Occurrence 75-14
Dear Mr. Engelken:
K EPILE COPY t
As defined by Proposed Amendment No. 30 to Technical Specifications "
for the Rancho'Seco Nuclear Generating Station, Section 6.9.1, and Regulatory Cuide 1.16, Revision 3, Section C.2.B.2, we are reporting the following j
Abnormal Occurrence as A0-75-14.
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'1 On September 10,'1975, with the reactor in a cold shutdown for main--
tenance, an attempt was made to place the "B" Decay Heat Removal ;ystem into service. - The DHR "B cooler outlet valve (SFV-26040) failed to ' respond, and -
j the system'.was shut down. The valve h a Fisher 10" V-B n11 type SMB-00.
- H2BC-V with a Philadelphia. Gear "Limicbrque" operator. An electrician sent-f to investigate the failure discovered the motor running but the valve stem was not rotating. A key on the shaft had sheared, causing the valve failure by disconnecting'the motor shaft from the valve stem.- The torque limit switches i
I on tha valve were operating and had been set at a fairly low value, no damage
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was evident in the keyway, and the key is not under torque if the valve is manually operated. For these reasons it is felt chat this was a random failure of the key material. The key was 1/4" square, 5/8" long, made from standard key stock; the-size of the item prevented a metallurgical. examination to l'
determine if indeed a material-defect was at fault. A review showed no previous i
key failures on valves of ' this. type at-our plant, and upon being contacted the '
,-W manufacturer stated that this'was not a common failure mode for these valves.
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The manufacturer has received very few reports of keys shearing and confirmed that the key-size was. correct.'
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The key was replaced and testing verified the valve's operability.- The "A" Decay Heat Removal System was ~available at the time of the failure and no transient's-resulted from the outlet valve's inoperability.
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.-k Respectfully,.
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- COPY SENT REGION
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-- l Enclosure =
. Mattimoe
.ces:: Director, MIPC(3).
-Assistant, General. Manager
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LDirector, IE(30) and Chief Engineer 8002.210 3
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'ANiELECTRIC3 SYSTEM S E RVIN G :MORE :TH AN 600,000 IN THE-HEART OF C ALIFO R NI A
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