ML20101C384
| ML20101C384 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 05/29/1992 |
| From: | Woodard J SOUTHERN NUCLEAR OPERATING CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9206090186 | |
| Download: ML20101C384 (3) | |
Text
F Soutnem Near Operat:ng Company Post Ofree Box 1295
.- Barrangham, Alabama 35201 Telephone 205 868 5086 L
Southern Nudear Operating Company J. D. Woodard
$,Pr May 29, 1992 the southem electoc system t
p 10 CFR 2.201 Docket Nos. 50-364 U. S. Nuclear Regulatory Commission Attention:
Docum0nt Control Desk Washington, D. C. 20555 Joseph M. Farley Nuclear Plant, Unit 2 Reply tu Notice of Violation Report Number 50-364/92-09 ltem Number 50-364/92-09-01 NRC Inspection of March 9 - April 13. 1992 Gentlemen:
.This letter refers to the violation cited in the subject inspection report.
The violation states:
10 CFR Part 50, Appendix B, Criterion XVI, and the J. M. Farley Plant Operations Quality Assurance Policy. Manual, requires measures to assure that conditions adverse to quality, such as failures, malfunctions and dofective equipment are promptly identified and corrected. Such measures are to be taken to assure that the cause of the condition is determined and corrective action taken to preclude repetition.
Contrary to the above, on March 6, 1992, during a plant shutdown for a planned Unii. 2 refueling outage, a preventable, automatic reactor trip occurred. This trip was caused by a change in reactor nuclear flux distribution characteristics and related "high neutron flux" effects on the intermediate range nuclear instrumentation trip circuitry.
Similar "high neutron flux" effects on the intermediate range instruments resulted in a February 1984, Unit I reactor trip, and a bypassing of the Unit 2 ir.termediate range instruments in order to cor. duct a planned shutdown in October 1990.
If the licensee's proposed corrective actions had been implemented in a timely mainer for the February,1984 and the October,1990 events, this challenge to the Unit 2 reactor protection system and the resulting trip may have been prevented.
This is a Severity Level IV violation (Supplement I).
Admission or Denial The above violation occurred as described in the subject report.
- However, while the February 1984 event was similar with regard to an intermediate range reactor trip, the cause of the 1984 event versus the 1990 and 1992 events was different. Corrective action taken in 1984 was adequate to r,.,
.,,.r;esolve the cause of the 1984 event.
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' U.- S. - Nuclear Regulatory Commission Page 2 Reason for Violatior-This_ violation was' caused by personnel error in that there was a failure to implement and track corrective actions associated with the October 1990 reactor trip event.
On February 10,_1984, an event occurred at FNP in which the reactor tripped at 10% power when intermediate range (IR) detector high flux trip histables were unblocked. This event was caused by overly conservative trip setpoints having been utilized on new IR detectors.
The event was not caused by a change in the neutron flux distribution as was the case in the March 6,1992 reactor trip.
Corrective action, as documented in LER 84-002, adequately addressed the February 1984 event. The corrective action for the 1984 event did not prevent _the March 6, 1992 reactor trip because the IR trip reset point was below P-10 for a different reason.
On October 13,1990,-during a scheduled Unit 2 reactor shutdown for refueling, Technical Spacification 3.0.3 war voluntarily entered. This was necesrary because both IR instruments were inoperable.
One was inoperable due to loss of cover gas and the other was due to bypassing its high level trip function.
Level trip bypass was selected because the operators recognized that the IR' trip bistable was still in the trip condition prior to automatic reinstatement of the IR reactor trip function.
Corrective actions to' address this event included replacement of the first IR detector and recalibration of the second instrument.
These corrective actions were documented in LER 90-003 and the corrective actions were completed during the fall 1990 outage.
In-iddition to the LER, an incident report had been written as a result of the reportable event of having two IR instruments inoperable.
Although the corrective actions specified in LER 90-003 were hit to be adequate, further f
investigation of the event by Reactor Engineering resulted in additional recommended actions.
Due to personnel error, these.recommenh d actions were not-taken.
Personnel in the Reactor Engineering group did not act on the corrective actions because they were not. notified that their recommended-actions had been approved by the Operations Manager.
This notification did not occur because the personnel responsible for tracking incident report corrective actions incorrectly assumed that. incident report corrective actions could be cmsidered complete if associated LER corrective acticns were complete. Since LER 90-003 corrective actions had been completed, the corrective action tracking group did not notify Reactor Engineering to perform their additional recommended action in the associated incident report. Thus, there was no feedback from the corrective action tracking group to the group responsible for implementation.
Corrective Action Taken and Results Achieved The IR high flux trip reset setpoints have been raised on both units to increase the probability for the IR trip to reset prior to the P-10 trip re-enable setpoint.
In addition, operations procedures have been revised to verify IR high flux _ trip bistables are clear prior to reaching the P-10 re-enable setpoint. An investigation is still in progress to determine if further actions are considered necessary to account for the flux redistribution impact on the IR instruments due to rod height and core life.
- U.-S. Nuclear Regulatory Commission Page 3 With regard to the implementation of corrective actions, a review of all incident reports associated with LERs for tne last five years was conducted.
Corrective actions associated with the incident reports and LER's were verified to have been completed or currently identified in the corrective action tracking system as open items.
Carrective Steos To Avoid Further Violations Pe-sonnel tracking incident report corrective actions have been reinstructed concerning the need to track all incident report cc.rective actions and provide notification to the group (s) responsible for implementation.
Date of Full Comoliance All corrective actions are complete with the exception of the investigation associated with the flux redistribution which will be complete by June 30, 1992.
Confirmation I affirm that s response is true and complete to the best of my knowledge, inf..rmation, and belief.
The information contained in this letter is not considered to be of a proprietary nature.
Respectfully submitted, SOUTHERN NUCLEAR OPERATING COMPANY Dbtr k
'd D. Woodard JDW/EFB: map 2513 cc: Mr. S. D. Ebneter Mr. S. T. Hoffman Mr. G. F. Maxwell
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