05000265/LER-2002-005
| Quad Cities Nuclear Power Station Unit 2 | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat |
| 2652002005R00 - NRC Website | |
FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6 PAGE (3) Quad Cities Nuclear Power Station Unit 2 05000265 (If more space is required, use additional copies of NRC Form 366A)(17)
PLANT AND SYSTEM IDENTIFICATION
General Electric - Boiling Water Reactor, 2957 Megawatts Thermal Rated Core Power Energy Industry Identification System (EIIS) codes are identified in the text as [XX].
EVENT IDENTIFICATION
Failure of Low Pressure Coolant Injection Logic Test due to a Detached Wire A. C CONDITION PRIOR TO EVENT Unit: 2 Event Date: October 7, 2002 Event Time: 1044 hours0.0121 days <br />0.29 hours <br />0.00173 weeks <br />3.97242e-4 months <br /> Reactor Mode: 1 Mode Name: Power Operation Power Level: 097% Power Operation (1) - Mode switch in the RUN position with average reactor coolant temperature at any temperature.
B. DESCRIPTION OF EVENT
Residual Heat Removal (RHR) [BO] Emergency Core Cooling System (ECCS) initiation logic, expected relay [RLY] actuations did not occur. A wire associated with a fuse block (FF-F11) [FUB] in Division II of the RHR ECCS initiation logic was found detached from its connection in a panel in the auxiliary equipment room. Another wire held at the same connection point was determined to be improperly attached, with a portion of the insulation captured in the connection, indicating improper installation.
After troubleshooting was completed and the effect of the detached wire was determined, both wires were properly landed.
The detached wire affected the automatic initiation logic of the Low Pressure Coolant Injection (LPCI) system. With the wire detached, the Division II pumps [P] (C and D) would not have started automatically in response to an initiation signal.
The A and B pumps (Division I) would have started automatically. Additionally, had the B loop (Division II) of RHR been operating in the Suppression Pool Cooling mode, valves [V] in the B loop would not have automatically repositioned in response to a LPCI initiation signal, as required to direct flow to the vessel. Because the A and B loops are connected, a portion of the injection flow from each loop would have bypassed the vessel in this case. All pumps and valves could have been operated with manual switch operation from the control room control panels to start the pumps and align the valves to the correct position for injection.
During the investigation, it was determined that the panel that held the fuse block FF-Fl1 had been worked in on February 18, 2002. As part of this work, the fuse block, FF-Fll, had been moved, although it was not de-terminated. Following this movement of fuse block FF-F11, the integrity of this connection was not physically or visually checked. However, the logic test that was performed following the work demonstrated that the wire was still connected. Therefore, it appears that the DOCKET NUMBER (2) PAGE (3) FACILITY NAME (1) LER NUMBER (6 Quad Cities Nuclear Power Station Unit 2 05000265 (If more space is required, use additional copies of NRC Form 366A)(17) wires were loosened during the movement of the fuse block, but still made contact.
Additionally, it was determined that problems with indication lights [IL] encountered during a surveillance test performed in March 2002, were caused by the detached lead. During the March 2002 surveillance, the indicating lights were noted to flicker and then extinguish. This indicates that the loose connection that existed prior to March 2002 became detached at that time. The indicating lights were not a part of the acceptance criteria for the March 2002 surveillance. A work order initiated at that time to address the problem was prioritized based on the erroneous assumption that the failure of the lights was not associated with a loss of any RHR functions. At the time the loose wire was identified, the work order had not yet been completed.
C. CAUSE OF EVENT
A root cause of the detached wire was poor installation of control wiring at some time prior to February 18, 2002. A second root cause was a lack of formal expectations and written guidance to rigorously inspect or otherwise test equipment or components disturbed during work activities.
D. SAFETY ANALYSIS
The safety significance of this event was minimal. The Division I pumps would have started and the Division I valves would have operated properly at all times, and the Division II pumps and valves could have been manually controlled from the control room control panel, in accordance with station procedures and operator training.
E. CORRECTIVE ACTIONS
Immediate Actions:
The detached wire and improperly connected wire were properly connected and the surveillance logic test was performed successfully.
Wiring in the ECCS panels on Unit 1 and Unit 2 were inspected. No discrepancies were identified that would affect operability.
Corrective Actions to be Completed:
A detailed inspection of all fuse block compression fitting control wiring in the Control Room, Auxiliary Electric Room and Emergency Diesel Generator Rooms will be performed.
Expectations will be established and implemented concerning the performance of inspections for electrical components and equipment to ensure they remain intact following work activities.
F. PREVIOUS OCCURRENCES
A search of reportable events did not identify any examples of detached wires during the last five years.
FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6 PAGE (3) Quad Cities Nuclear Power Station Unit 2 05000265 (If more space is required, use additional copies of NRC Form 366A)(17) G. � COMPONENT FAILURE DATA There were no component failures associated with this event.