ML19317F859
| ML19317F859 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 06/03/1977 |
| From: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| Shared Package | |
| ML19317F860 | List: |
| References | |
| FOIA-80-145 NUDOCS 8002210598 | |
| Download: ML19317F859 (2) | |
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f#' SACRAMENTO MUEICIPAL UTILITY DISTRICT O 6201 S Street. Scx 15830, Sacramento, California 95813; (916) 452 3211 v
1 June 3, 1977
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Mr. R. H. Engelken p.f; '
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Director of Regulatory Operations Ei N
NRC Operations Office, Region V
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1990 N. California Boulevard copy a
Walnut Creek Plaza,' Suite 202 Walnut Creek, California 94596 Re: Operating License DPR-54
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Docket No. 50-312 Reportable Occurrence 77-6 I
Dear Mr. Engelken:
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In accordance with Regulatory Guide 1.16, Revision 4, Section 6.9/1, and Technical Specifications for Rancho Seco Nuclear Generating Station, Section 6.9.1, the Sacramento Municipal Utility District is hereby reporting the following Reportable Occurrence as RO 77-6.
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' On April 22, 1977,. the unit was shut down for repair of a Control Rod
- Drive Stator which had failed.
Following completion of the repair work, two power and one position indication cables that had been disconnected to allow access to the damaged equipment were reconnected and the unit returned to power operation. The surveillance procedure for performing a CRD program verification check on the subject cables was not performed as required by G,
Technical Specifications Section 4.7.2.2.
It was not recognized until May,12, 1
1977, that the repair work actually performed required this s'urveillance check. At that time a report of the incident was submitted and review of the incident was initiated. This report is being filed within thirty days following the' discovery and reporting of this occurrence.
On April 21, 1977, Rod 4 of Control Rod Group 7 (regulating) dropped into tha core when the stator of its CRDM failed. The unit was shut down and a work request was issued to troubleshoot the CRDM and repair as necessary.
The work request specified that if only one power cable and one position
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indication cable were removed, a verification check using the surveillance j
procedure was not necessary. This requirement was based on the assumption that if only one cable is removed, it is not possible to reconnect it impro-
-perly, giving an automatic verification that the cable is connected to the proper CRDM. The stator for Rod 4 Group 7, required replacement, so both the power' cable and PI cable were disconnected.
In addition, the power cable for Rod 1 in. Group 2 (safety) was disconnected to make reference measurements.
After the stator was replaced, the cables were reconnected and the reactor was taken critical.
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Mr. R. H. Engelken June 3, 1977 1-Through a lack of communication between Operations and Maintenance personnel, the fact that more than one power cable had been disconnected was never transmitted to the Control Room. As a result, no verification of the cable connections was performed as required prior to returning the system to Ei service. This omission was detected by engineering review of the completed work request on May 12.
The circumstances of this occurrence will be dis-cussed with all affected personnel to assure future compliance with Technical Specifications when performing maintenance on Control Rod Drive mechanisms.
Because of the particular cables removed and the testing performed
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on the stator that was replaced, it is possible to determine that all cabics were properly replaced. Only one PI cable (on Rod 4, Group 7) was removed; therefore it was replaced on the correct Control Rod.
Rod 4 of Group 7 was individually withdrawn and inserted to test the new stator.
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was selected on the Control Rod Drive operator's panel and the proper rod movement was noted on the position indicator, the power cable had to have been properly connected. This provides assurance that at no time were Control Rods improperly withdrawn.
2' There was no plant transient as a result of this occurrence.
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Respectfully submitted, O.L, h
[J'J.J.Mattimoe tf.
Assistant General Manager and Chief Engineer
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