ML19347C782
| ML19347C782 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 05/23/1975 |
| From: | CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | |
| References | |
| AO-12-75, NUDOCS 8102170106 | |
| Download: ML19347C782 (2) | |
Text
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ABNORMAL OCCURRENCE REPORT Big Rock Point Plant 1.
Report No: A0-12-75, Docket 50-155 2a.
Report Date: May 23, 1975 2b.
Occurrence Date: May 21, 1975, classified as A0 on 5-22-75 3
Facility: Big Rock Point Plant h.'
Identification of Occurrence: Core spray valves operator locknut loose.
5 Conditions Prior to Occurrence: Plant in cola shutdown for modification activities associated with A0-1-75 M0/7061 and M0/7051 being tested fol-loving relocation.
I.
Description of Occurrence: Excessive operator free play was noted during valve reversal while test operating the primary core spray valves M0/7051 and M0/7061 at 1200 hours0.0139 days <br />0.333 hours <br />0.00198 weeks <br />4.566e-4 months <br /> on 5-21-75 Inspection of the drive mechanism revealed that a locking unit had loosened several turns in each valve operator. The locking nut was then tightened and staked with a pin punch to the drive sleeve. Subsequent testing showed proper operation on 5-21-75 7
Designation of Apparent Cause of Occurrence: Design Deficiency 8.
Analysis of Occurrence: The valves did not fail to operate and, thus, no hazard existed. However, the potential for failure existed on both valves in the primary core spray system. The backup core spray system valve operators are from another manufacturer and have been operational as required by Technical Specifications and procedures; thus would have provided functional requirements if tiie primary core spray system had failed due to the defect.
9 Corrective Action: Immediate corrective action of staking the nut made the units operable. Past experience and inspections of valve operators indicate that the problem is limited to a particular model with only.a single locking nut; namely, SMA-00 made by Philadelphia Gear. Such safety-related units have been restaked and will be reinspected following surveillance test valve operations prior to plant start-up in June 1975 This problem has been discussed with the manufacturer and we believe that he is presently reviewing the design.
10.
Failure Data: Motor operators are Philadelphia Gear - Limitorque Model SMA-00.
A similar failure occurred in 1973 but was not reported at that time because of different reporting requirements.
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