ML20057F882
| ML20057F882 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 10/11/1993 |
| From: | Rogers D CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9310190295 | |
| Download: ML20057F882 (3) | |
Text
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Plant Safety and Licensing Director POWERING MKNIGAN5 PROGRESS Palisades Nuclear Plant: 27780 Blue Star Memorial Highway, Covert, MI 49043 October 11, 1993 Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 DOCKET 50-255 - LICENSE DPR PALISADES PLANT - ROOT CAUSE, CORRECTIVE ACTIONS AND INDEPENDENT ASSESSMENT REGARDING DAMAGE TO FUEL ASSEMBLY I-024 AND INADVERTENT LIFTING 0F FUEL BUNDLE SAN FUEL ACCOUNTABILITY AND FAILURE DETECTION - CORRECTED PAGE Consumers Power Company's September 30, 1993 letter on the above subject included enclosures which contain descriptions of the associated analyses and actions implemented, completed, and planned.
Item three on page one of Enclosure I of that letter contains a typographical error which is not obvious and could mislead the reader.
Item three, as a result of that typographical error, mistakenly refers to "Lecondary hydrating" when it should refer to
" secondary hydriding." The attachment to this letter provides a corrected page one of Enclosure I of our September 30, 1993 letter.
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David W. Rogers Plant Safety and Licensing Director l
CC Administrator, Region III, USNRC NRC Resident Inspector - Palisades Attachment 1R00A3 0\\
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PDR A CAG Ovti72GY COMMNY 1
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y ATTACHMENT Consumers Power Company _
Palisades Plant Docket 50-255 t
f Corrected Page 1 to Enclosure I to CPCo Letter Dated 09/30/93 Entitled,
" Bundle I-024 Failed Rod Event Root Cause and Corrective Action" October 11, 1993 i
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BUNDLE I-024 FAILED R0D EVENT l
ROOT CAUSE ANALYSIS REMEDIAL CORRECTIVE ACTIONS CORRECTIVE ACTIONS TO PREVENT RECURRENCE EXECUTIVE
SUMMARY
Fragmented pieces of failed fuel rod S-15 from bundle I-024 were found in the reactor side tilt pit following the initial reactor cavity drain down during the end of Cycle 10 refueling outage.
Based on inspections of the failed bundle, fragmented rod pieces, and the core shroud corner location where I-024 was located, the following conclusions have been made:
1.
The fuel rod was failed and severely damaged during Cycle 10 operation.
2.
The upper portion of the fuel rod and the associated corners of. spacers 6 through 9 were rubbing against the core shroud during Cycle 10 operation.
3.
A circumferential break in Ssn 9 existed on the failed rod during Cycle 10 operation. This is believt.i to be due to secondary hydriding.
The l
initial primary failure is believed to have originated in Span 5 or 6 due to rod fretting against the core shroud.
4.
The rod was peeled from the bundle while being handled over the reactor side tilt pit during the initial end of Cycle 10 core fuel shuffle.
5.
As the rod was peeled from the bundle, it was broken into several pieces.
This peeling is believed to be the cause of damage to the corners of Spacers 1 through 5.
6.
A total of 6 fragmented rod pieces were found. The entire length of the failed rod has been accounted for, however, approximately three feet of partial circumferential cladding (1/3 to 1/2 circumference) is missing.
F 7.
The missing partial cladding is believed to have worn or broken away during Cycle 10 operation. One to three cladding shards may exist that i
are equivalent in size to one of the shards found (which was one foot long, about 90 degrees in circumference, and worn down by the core shroud).
8.
Approximately five feet of fuel (215 pellets) is missing from the retrieved fragmented rod pieces.
Several remedial corrective actions were required due to this rod failure event. All remedial corrective actions have been sufficiently addressed at this time. The root cause for the rod failure has been narrowed down to four possibilities; all of which deal with a shroud and fuel assembly interface problem. Additionally, six key contributing factors have been identified.
1 Page Revised 10/08/93
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