ML20196C649
| ML20196C649 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 11/20/1998 |
| From: | Kozak T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Jeffery Wood CENTERIOR ENERGY |
| Shared Package | |
| ML20196C654 | List: |
| References | |
| 50-346-98-19, NUDOCS 9812020079 | |
| Download: ML20196C649 (3) | |
See also: IR 05000346/1998019
Text
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UNITED STATES
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NUCLEAR REGULATORY COMMISSION
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REGION 111
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801 WARRENvlLLE ROAD
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November 20. 1998
Mr. John K. Wood
Vice President - Nuclear
Davis-Besse Nuclear Power Station
Centerior Service Company
5501 North State Route 2
Oak Harbor, OH 43449
SUBJECT:
DAVIS-BESSE SPECIAL INSPECTION REPORT 50-346/98019
Dear Mr. Wood:
On October 23,1998, the NRC completed a special inspection which was initiated on
October 14 shortly after operators manually tripped the Davis-Besse nuclear reactor. The
inspectors reviewed the circumstances surrounding the events leading up to and following the
reactor trip. The enclosed report presents the results of that inspection.
Prior to the reactor trip, electrical train 2, which is powered from electrical buses D1 and D2,
was considered to be the protected train. Transformer AC, which is the attemate power supply
for buses D1 and D2, had been tagged out-of-service to allow maintenance activities to occur in
the vicinity of the transformer. Work had also been authorized to occur on circuit
breaker AACD1, which is the supply breaker from transformer AC to bus D1. While installing
the breaker back into its cubicle after maintenance activities were completed, a ground
occurred which caused a lockout of buses D1 and D2 and ultimately led to the manual reactor trip. The authorization of work to occur on components associated with a protected train while
the plant is being operated brings into question the effectiveness of your work control
processes and the risk matrix used when evaluating and approving online maintenance work
activities.
Once the lockout occurred, operators communicated effectively and generally executed their
responsibilities conservatively and professionally. Although operators were slow to enter the .
overcooling section of an emergency procedure, overall, the operators performed well during
the event. Procedures were appropriately used, and problems that complicated the event were
properly diagnosed and addressed.
A thorough review of the circumstances surrounding the event was conducted by your staff.
The approach to identifying and resolving equipment problems encountered during the event
was methodical and comprehensive. Equipment anomalies were documented and entered into
the corrective action program. Engineering personnel support for resolving equipment
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problems was thorough and effective. Troubleshooting and equipment repairs were performed
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professionally. Personnel did not appear to be pressured to complete activities to meet the
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restart schedule and all restart issues identified by your staff were addressed properly before
the decision was made to restart the unit.
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9812O20079 981120
ADOCK 05000346
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In accordance with 10 CFR 2.790 of the NRC's " Rules of Practice," a copy of this letter and its
enclosure will be placed in the NRC Public Document Room.
Sincerely,
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Original signed by
Thomas J. Kozak, Chief
Reactor Projects Branch 4
Docket No.: 50-346
1
License No.: NPF-3
Enclosure:
Inspection Report
50-346/98019(DRP)
cc w/ encl:
J. Stetz, Senior Vice President - Nuclear
J. Lash, Plant Manager
J. Freels, Manager, Regulatory Affairs
M. O'Reilly, FirstEnergy
State Liaison Officer, State of Ohio
R. Owen, Ohio Department of Health
C. Glazer, State of Ohio Public
Utilities Commission
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