05000456/LER-2003-002
| Braidwood, Unit 1 | |
| Event date: | 02-02-2003 |
|---|---|
| Report date: | 04-03-2003 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| Initial Reporting | |
| 4562003002R00 - NRC Website | |
B. Description of Event:
There were no systems or components with the exception of the 1B RHR pump that were inoperable at the beginning of this event that contributed to the severity of the event.
On January 26, 2003 at 2200 hours0.0255 days <br />0.611 hours <br />0.00364 weeks <br />8.371e-4 months <br />, Braidwood Station Unit 1 entered TS LCO 3.5.2 Condition A for an inoperable Emergency Core Cooling System (ECCS) train to support planned maintenance on the Unit 1B Residual Heat Removal (RHR)[BP] pump.
The seven-day Completion Time to restore the 1B ECCS train to operable status expired at 2200 hours0.0255 days <br />0.611 hours <br />0.00364 weeks <br />8.371e-4 months <br /> on February 2, 2003.
On February 2, 2003 at 2200, the 1B RHR Pump planned work window was extended past the TS Completion Time. A NOED to extend the Completion Time was requested and subsequently granted by the NRC on February 2, 2003 at 1250 to extend the Completion Time by 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br />. The LCO was exited at the completion of the maintenance activities on February 3, 2003 at 0337.
The planned work window for the 1B RHR pump included numerous routine surveillance and preventive maintenance (PM) activities. The activities included maintenance activities associated with the 1B RHR pump, as well as performing an actuator overhaul of the 1B RHR pump minimum flow valve (i.e., 1RH611). However, the primary activity in the work window was to inspect the 1B RHR pump internals and replace the stuffing box extension as follow-up actions from a station operability determination and lessons learned from a previous 2B RHR pump repair. There were no performance issues with the 1B RHR pump prior to the work window and it had been satisfactorily meeting all surveillance requirements. The Original Equipment Manufacturer (OEM) was contracted to provide onsite support for the repair to provide technical assistance and facilitate resolution of emergent issues.
TS LCO 3.5.2 for an inoperable Emergency Core Cooling System (ECCS) train was entered at 2200 hours0.0255 days <br />0.611 hours <br />0.00364 weeks <br />8.371e-4 months <br /> on January 26, 2003 to support the 1B RHR pump maintenance activities. The LCO was expected to be exited on January 31, 2003 at 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br />. However, unforeseen difficulties encountered during the pump reassembly process delayed returning the 1B RHR pump and thus the 1B train of ECCS to operable status. Failure to complete the work as scheduled was entered into the Corrective Action Program.
Inspection of the 1B RHR pump internals was required for the following two reasons:
1. Verify the diffuser anti-rotation pin was installed, and 2. Measure the stuffing box extension (SBE) clearances.
C. Cause of Event
The root cause for exceeding the Completion Time was the lack of management oversight and the failure to recognize challenges related to planning, safety, dose and troubleshooting during work execution.
D. Safety Consequences:
Granting of enforcement discretion was of minimal safety consequence. The lA ECCS train was fully operable. In addition, the four safety injection accumulators were operable. These components were in the 10 CFR 50.65 "Requirements for monitoring the effectiveness of maintenance at nuclear power plants" a(2) category and have had no functional failures in the last two years.
This indicates they are meeting very stringent reliability and availability criteria. Additionally, Technical Specification Surveillances Requirements were completed to ensure that the lA ECCS train was properly aligned and full of water. Further, the 1B Centrifugal Charging (CV)[130] and 1B Safety Injection (SI)(13C] pumps were operable and capable of performing their functions, thus providing additional assurance that the ECCS function was preserved.
A risk assessment was performed, and it concluded that there was no net radiological risk increase as a result of extending the Completion Time by 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br />. This was based on the quantitative risk assessment which concluded that
E. Corrective Actions:
There were two Corrective Actions identified to prevent recurrence. The first is to examine the process used for outage preparation for applicability to on- line work windows. Based on this examination, methods of planning and execution of on-line work will be changed as required. The second is to establish a process that requires a peer review for all work windows that require entry into a short-term TS LCO.
Other Corrective Actions are being developed to address the individual weaknesses identified. Those weaknesses have been entered into the Corrective Action Process.
F. Previous Occurrences:
A review of previous occurrences identified an issue in which poor planning and execution of work involving the four Emergency Diesel Generators [EK] took place at Braidwood in 2002. Similar issues that adversely affected timely completion of the 1B RHR work were present in the Emergency Diesel Generator maintenance activities.
G. Component Failure Data:
Manufacturer � Nomenclature � Model � Mfg. Part Number N/A � N/A � N/A � N/A