05000265/LER-2003-001
| 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)(D), Loss of Safety Function - Mitigate the Consequences of an Accident |
| 2652003001R00 - NRC Website | |
DOCKET NUMBER (2) PAGE (3) FACILITY NAME (1) LER NUMBER (6) Quad Cities Nuclear Power Station Unit 2 05000265 2003 � (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 to Reset Residual Heat Removal Injection Valve Containment Isolation Signal due to Inadequate Procedural Development and Review
A. CONDITION PRIOR TO EVENT
Unit: 2 � Event Date: January 9, 2003 Reactor Mode: 1 � Mode Name: Power Operation Power Operation (1) - Mode switch in the RUN position with temperature at any temperature.
Event Time: 0540 hours0.00625 days <br />0.15 hours <br />8.928571e-4 weeks <br />2.0547e-4 months <br /> Power Level: 100% average reactor coolant
B. DESCRIPTION OF EVENT
On January 9, 2003, at 0540 hours0.00625 days <br />0.15 hours <br />8.928571e-4 weeks <br />2.0547e-4 months <br />, the Unit 2 Control Room Operator was performing QCOS 1000-09, "RHR Power Operated Valve Test," as part of scheduled activities. The surveillance directed that the Low Pressure Coolant Injection (LPCI) [BO] injection valve [INV], 2-1001-29A, be stroked and timed in the open direction. When the valve reached the open position, the valve immediately began to stroke closed without operator action. The valve continued to the full closed position.
Upon investigation, the shift crew determined that a relay (10A-K63A) [RLY] in the valve logic was in the energized state. This was contrary to the expected de-energized state; this relay would normally only be energized if the Residual Heat Removal (RHR) system were in the Shutdown Cooling (SDC) mode of operation and a Group II Primary Containment Isolation (PCI) [JM] signal were received. The shift crew also reviewed the state of the relay for the other loop of RHR (10A-K63B) and found it to be energized as well.
When the RHR system is in the SDC mode of operation, the 2-1001-29A and B valves provide the path for SDC return to the vessel/injection. The 10A-K63A and B relays function to provide a Group II isolation signal to the 2-1001-29A and B valves when RHR is in the SDC mode of operation. The RHR Group II isolation circuit is enabled when the 2-1001-47 and 50 valves, Shutdown Cooling Suctions, are in the open position.
Further investigation has identified that surveillance QCOS 1600-44, "Unit 2 PCI Group 2 Partial Isolation Test at Power," had previously been performed on December 18, 2002. This surveillance verifies the Group II function of the RHR SDC mode of operation. Jumpers are installed to simulate the open position for the 2-1001-47 and 50 valves and the Group II isolation signal. The 10A-K63A and B relays are verified to be energized, and the 2-1001-29A and B are verified to close. The 10A-K63A and B relays are sealed-in upon receipt of the Group II isolation signal DOCKET NUMBER (2) LER NUMBER (6) FACILITY NAME (1) PAGE (3) Quad Cities Nuclear Power Station Unit 2 05000265 _ (If more space is required, use additional copies of NRC Form 366A)(17) and require manual reset.
To reset the Group II isolation signal to the 2-1001-29A and B valve logic, two reset pushbuttons on the control room panel must be depressed, one for the A loop of RHR and one for the B loop of RHR. The reset pushbuttons are depressed several times while performing QCOS 1600-44 to allow for reopening of the 2-1001-29A and B valves in preparation for additional Group II isolation signal testing. During review of QCOS 1600-44, it was determined that upon completion of the final Group II signal initiation, there was no procedural direction to reset the isolation signal.
Thus, the Group II isolation signal remained sealed in. As part of system restoration to a standby lineup, the 2-1001-29A and B valves are verified to be in the closed position. This was the position of the valves at the conclusion of QCOS 1600-44.
With the Group II isolation signal present (10A-K63A and B energized) during operation, the 2-1001-29 A and B LPCI injection valves will not open upon an initiation of the LPCI injection signal. The signal is blocked by the 10A-K63A and B relays. The 'seal in' condition for these relays is not annunciated nor are there any other secondary indications available for monitoring this portion of the RHR LPCI subsystems were considered inoperable. Technical Specifications (TS) 3.5.1.B (seven-day Allowed Outage Time) and 3.5.1.D (72-hour Allowed Outage Time) were entered at the time of discovery.
The shift crew reset the Group II signal by depressing the reset pushbuttons for both loops of RHR, verified the 10A-K63A and B relays had de-energized, and satisfactorily stroked the 2-1001-29A and B valves.
The TSs were exited at 0625 hours0.00723 days <br />0.174 hours <br />0.00103 weeks <br />2.378125e-4 months <br /> on January 9, 2003.
The Unit 1 RHR SDC Group isolation logic relays (10A-K63A and B) were inspected to determine their state. The relays were verified to be in the expected de-energized state.
C. C CAUSE OF EVENT The root cause of this event was inadequate procedural development and review such that it was not ensured that the valve logic was reset at the conclusion of the procedure.
In 1995, LER 2-95-003, "Shutdown Cooling (SDC) Was Not Available Due To MO 2-1001-29A Tripping Its Circuit Breaker and MO 2-1001-5B Valve Being Out Of Service," was issued. One of the corrective actions for that LER was to change QCOS 1600-13, "Refueling Outage PCI Groups 2 and 3 Isolation Test," to ensure that the reset pushbutton was pressed at the end of the procedure. Revision 1 of QCOS 1600-35 was created in February 1999. This procedure revision was not reviewed in sufficient detail to identify that the step to ensure that the isolation logic was reset after the final signal had not been included. In May 2000, QCOS 1600-44 was procedure.
DOCKET NUMBER (2) PAGE (3) LER NUMBER (6) FACILITY NAME (1) Quad Cities Nuclear Power Station Unit 2 05000265 (If more space is required, use additional copies of NRC Form 366A)(17)
D. SAFETY ANALYSIS
The safety significance of this event was minimal. Although the Unit 2 RHR injection valves would not have opened automatically between December 18, 2002, and January 9, 2003, the logic could have been reset and the valves opened manually from the control room. Additionally, the Core Spray system [BM] was operable during this time frame.
E. CORRECTIVE ACTIONS
Immediate Actions
The isolation logic was reset, the relays were examined to ensure that they were de-energized, and the RHR injection valves were stroked.
The corresponding relays on Unit 1 were examined to ensure that they were de-energized.
Corrective Actions Completed Other logic tests were reviewed to identify any similar discrepancies. No other cases were identified involving the capability to have logic not reset without any indication of that condition.
The following three procedures were revised:
- QCOS 1600-44, "Unit 2 PCI Group 2 Partial Isolation Test at Power," was revised to include reset of the Group II isolation signal during restoration activities.
- QCOS 1600-35, "Unit 1 PCI Group 2 Partial Isolation Test at Power," was revised to include reset of the Group II isolation signal during restoration activities.
- QCOP 1000-02, "RHR System Preparation for Standby Operation," was revised to include depressing of the reset pushbuttons for both loops of RHR as part of the preparation for standby line up.
Operations has completed a Focused Area Self-Assessment of the Procedure Review and Approval Process, which identified enhancements in process implementation.
Corrective Actions to be Completed QCOS 1600-44, "Unit 2 PCI Group 2 Partial Isolation Test at Power," and QCOS 1600-35, "Unit 1 PCI Group 2 Partial Isolation Test at Power," will be revised to include visually verifying 10A-K63A and B relay status to ensure that the logic has been reset for the Group II isolation signal during restoration activities.
QCOP 1000-02, "RHR System Preparation for Standby Operation," will be revised to include visually verifying 10A-K63A and B relay status to ensure that the logic has been reset for the Group II isolation signal for both loops of RHR as part of the preparation for standby line up.
DOCKET NUMBER (2) PAGE (3) LER NUMBER (6) FACILITY NAME (1) Quad Cities Nuclear Power Station Unit 2 05000265 � : ' (If more space Is required, use additional copies of NRC Form 366A)(17) F. � PREVIOUS OCCURRENCES A review of events for the last time three years identified the following similar event.
Coolant Injection Resulting in Air in Discharge Piping," was submitted on January 26, 2001. This event involved an inadequate fill and vent of the High Pressure Coolant Injection (HPCI) [13J] system following maintenance. The fill and vent was not performed correctly because the procedure was inadequate due to an inadequate review during the revision process. The corrective actions for this HPCI venting event would not have precluded the failure to reset the Group II isolation for RHR because the revision to the RHR procedure predated the HPCI venting event.
Additionally, as described in the "Cause of Event" section, LER 2-95-003 was a previous occurrence of this event.
G. � COMPONENT FAILURE DATA There were no component failures associated with this event.