05000456/LER-2004-003
| Docket Number06 16 2004 2004-003-00 08 16 2004 | |
| Event date: | 06-16-2004 |
|---|---|
| Report date: | 08-16-2004 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| Initial Reporting | |
| 4562004003R00 - NRC Website | |
B.Description of Event:
There were no additional structures, systems or components inoperable at the beginning of the event that. contributed to the severity of the event.
On March 3, 2004, at approximately 1300 hours0.015 days <br />0.361 hours <br />0.00215 weeks <br />4.9465e-4 months <br />, the OA Hydrogen Recombiner (WE].was started to perform maintenance testing. At approximately 2000 hours0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br />, the heater breaker for the Recombiner tripped resulting-in a Main Control Room annunciator alarm.' At 2112 hours0.0244 days <br />0.587 hours <br />0.00349 weeks <br />8.03616e-4 months <br />, the-breaker'Was reset and the'heaters were reenergized-and able to maintain temperature. Maintenance testing was completed and the Hydrogen RecoMbIner was secured. The Shift Manager reviewed Technical Specification (TS) 3.6.8,,"HYDROGEN RECOMBINERS," and its associated basis and determined that the OA Hydrogen Recombiner was operable based on the fact that the heater breaker re closed, remained closed, and maintained reaction chamber temperature in the Recombiner. The Shift Manager also understood that the Recombiner was not required until 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br /> after a Loss of Coolant Accident (LOCA). No TS Limiting Condition for Operation (LCO) entry was made at this time.
On March 12, 2004, during a follow-up review of this event, a condition report (CR) was generated to address the March 3, 2004, tripping of the heater breaker. The CR described the heater breaker tripping as a startup issue. Based on a review of previous calibration data and the determination that the instrumentation was within tolerance for its previous two calibration cycles, it was confirmed that the Recombiner remained operable.
On April 5, 2004, during a supervisor's review of the previous Hydrogen Recombiner's work window data, a CR was written to address whether operator action to gradually increase the temperature controller setting (in order to bring the Recombiner up to the required operating temperature without tripping the heater breaker) had an adverse effect on the ability of the Recombiner to perform its design function. It was determined that the OA Hydrogen Recombiner was capable of performing its design function and remained operable. It was later identified that manual operation of the temperature controller is contrary to the Updated Final Safety Analysis Report (UFSAR) description of how the Recombiner is operated.
On April 20, 2004, the OA Hydrogen Recombiner was started to support Hydrogen Analyzer modification work. On April 23, 2004, during the planned shutdown of the Recombiner, heater breaker CB-3 was found tripped with the indicated Recombiner
C.Cause of Event
The root cause for exceeding the TS AOT for the inoperable OA Hydrogen Recombiner was failure to apply an adequate technical evaluation in determining operability.
It was incorrectly determined that since the heater breaker could be reset and the Recombiner was able to maintain temperature, the Recombiner was operable.
Additionally, during this event the procedure governing the startup of the Hydrogen Recombiners was revised to allow for manual incremental increases of temperature controller setpoint during heat up of the Recombiner. Manual operation of the temperature controller is contrary to the UFSAR description of howthe Recombiner is operated, and the procedure change had not been evaluated with respect to this description.
D.Safety Consequences:
A risk assessment was performed for the Hydrogen Recombiner inoperability and it was determined to be of low risk. The online risk assessment remained green with one Hydrogen Recombiner inoperable. A second Recombiner was available during the event.
The installation of Hydrogen Recombiners was intended to address the limited quantity and rate of hydrogen generation that was postulated from a design-basis LOCA. The NRC has found, as documented in SECY-00-0198, "Status Report on Study of
F. Previous Occurrences:
There have been two previous similar instances where TS requirements have not been met based on a misunderstanding of the requirements. These situations differed in that decisions were based primarily on past operating practice:
1. September 11, 2002: LER 2002-003-01, "Isolated Loop Reactor Coolant System Boron Sample Outside of Technical Specification Frequency Requirement Due to Misapplication of the Implementing Procedure," submitted on November 26, 2002.
G. Component Failure Data:
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