On May 2, 2003 at 0605 with the reactor at 3.8 percent power during post refueling startup, an unplanned emergency safeguards actuation of the Auxiliary Feedwater ( AFW) System occurred. An unexpected 1B Steam Generator Feed Pump ( SGFP) speed increase led to a manual trip of the 1B SGFP. The IA SGFP was out of service at this time. Trip of the only operating SGFP caused both Motor Driven Auxiliary Feedwater ( MDAFW) Pumps to start. Reactor power was lowered from 3.8 percent to 2 percent and the reactor was stabilized on Auxiliary Feedwater.
Following extensive troubleshooting, the cause of the event on May 2 could not be determined. The sensing circuit was recalibrated and returned to service. Subsequently, on May 9, 2003, with the reactor at 100 percent power, an unexpected SGFP speed increase occurred again. The SGFP was removed from service and a replacement speed sensing circuit was installed in the SGFP speed control cabinet. No safeguards equipment actuation occurred in conjunction with this subsequent failure.
The cause of both events is believed to be an intermittent failure of the speed sensing circuit. On the initial failure, the speed sensing circuit was recalibrated. On the subsequent failure on May 9, the speed circuit was replaced. |
Westinghouse -- Pressurized Water Reactor Energy Industry Identification Codes are identified in the text as [XX]
Description of Event
On May 2, 2003 at 0605 with the reactor at 3.8 percent power during post refueling startup, an unplanned emergency safeguards actuation of the Auxiliary Feedwater (AFW) System [BA] occurred. An unexpected 1B Steam Generator Feed Pump (SGFP)[SJ] speed increase led to a manual trip of the 1B SGFP. The IA SGFP was out of service at this time. Trip of the only operating SGFP caused both Motor Driven Auxiliary Feedwater (MDAFW) Pumps to start. Reactor power was lowered from 3.8 percent to 2 percent and the reactor was stabilized on Auxiliary Feedwater.
Thorough troubleshooting of all components and electrical connections in the speed sensing and control circuits identified no problem. The speed sensing circuit was recalibrated. The SGFP speed sensing and control circuits [JK] were instrumented and a test run of the pump conducted. During this test run, the SGFP speed sensing and control circuits performed as expected. Based upon the test run with no problems, the SGFP was returned to service.
Subsequently, on May 9, 2003, with the reactor at 100 percent power, an unexpected SGFP speed increase occurred again. Power was reduced to approximately 60% to allow for removing the SGFP from service. The high pressure and low pressure governor valves were observed to be fully open while operations was in the process of isolating steam to the SGFP. Troubleshooting determined the cause of this condition to be a failed speed sensing circuit "Tach Pak." A replacement "Tach Pak" was installed in the SGFP speed control cabinet.
Due to its proximity to other SGFP control components for the operating IA SGFP, the faulted component was electrically disconnected, but was not physically removed from the cabinet. Therefore, the cause of the failed component is not known at this time. The failed component will be investigated at the next outage of sufficient duration.
Cause of Event
The cause of this event was intermittent equipment failure in that the output of the speed sensing circuit "Tach Pak" for the 1B SGFP control failed low, causing the unexpected speed increase which led to the operator trip of the SGFP.
Safety Assessment In neither the May 2 reportable event nor the May 9 subsequent equipment failure did the SGFP exceed its design overspeed trip setpoint of 5775 rpm. In both events, operator action was manually initiated to remove the 1B SGFP from service as a conservative response to the loss of speed control.
All safeguards equipment functioned as designed. Therefore, the health and safety of the public were unaffected by this event.
Corrective Action On May 9, the speed sensing circuit "Tach Pak" was replaced.
Additional Information
Due to its proximity to other SGFP control components, the faulted component was not physically removed from the cabinet during the repair on May 9. The failed component will be removed at the next outage of sufficient duration and the cause of failure investigated by December 17, 2004.
The calibration and maintenance history of the speed sensing circuits on the SGFPs on both units will be reviewed to determine the acceptability of current Periodic Maintenance (PM) practices. Reliability of new and refurbished Tach Paks from available sources will be evaluated. Based on these reviews and investigations, changes to the design, procurement and/or PM programs for this equipment will be made as appropriate. These actions will be complete by December 12, 2003.
The following LER has been submitted in the past two years involving SGFP control issues:
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| 05000397/LER-2003-010 | | | | 05000528/LER-2003-001 | Pressurizer Safety Valve As-Found Lift Pressure Outside of Technical Specification Limits | 10 CFR 50.73(a)(2)(v), Loss of Safety Function
10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | | 05000277/LER-2003-001 | | | | 05000282/LER-2003-001 | | | | 05000301/LER-2003-001 | | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | | 05000261/LER-2003-001 | | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | | 05000251/LER-2003-001 | Channel Failure of Qualified Safety Parameter Display System | | | 05000316/LER-2003-001 | Unit 2 Shutdown In Accordance With Technical Specification 3.8.1.1, A.C. Sources, Action b | 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown | | 05000324/LER-2003-001 | Main Steam Line Drain Isolation Valve Local Leak Rate Test Failures | 10 CFR 50.73(a)(2)(v)(C), Loss of Safety Function - Release of Radioactive Material
10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded | | 05000352/LER-2003-001 | | 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition
10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | | 05000353/LER-2003-001 | | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | | 05000397/LER-2003-001 | | 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition | | 05000364/LER-2003-001 | | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | | 05000529/LER-2003-001 | Reactor Trip with Loss of Forced Circulation Due to Failed Pressurizer Main Spray Valve | 10 CFR 50.73(a)(2)(iv)(A), System Actuation
10 CFR 50.73(a)(2)(v), Loss of Safety Function | | 05000278/LER-2003-001 | | | | 05000305/LER-2003-001 | | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | | 05000331/LER-2003-001 | | 10 CFR 50.73(a)(2)(iv)(A), System Actuation
10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition | | 05000313/LER-2003-001 | | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | | 05000352/LER-2003-002 | | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | | 05000301/LER-2003-002 | | 10 CFR 50.73(a)(2)(v), Loss of Safety Function
10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown | | 05000305/LER-2003-002 | | 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition | | 05000316/LER-2003-002 | Supplemental LER for Unit 2 Reactor Trip due to Instrument Rack 24 Volt Power Supply Failure | 10 CFR 50.73(a)(2)(iv)(A), System Actuation
10 CFR 50.73(a)(2)(iv), System Actuation | | 05000458/LER-2003-002 | | 10 CFR 50.73(a)(2)(v)(c) | | 05000348/LER-2003-002 | | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | | 05000341/LER-2003-002 | Automatic Reactor Shutdown Due to Electric Grid Disturbance and Loss of Offsite Power | 10 CFR 50.73(a)(2)(iv)(A), System Actuation
10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | | 05000261/LER-2003-002 | | | | 05000285/LER-2003-002 | 4 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | | 05000397/LER-2003-002 | | | | 05000499/LER-2003-002 | Safety Injection Actuation | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | | 05000440/LER-2003-002 | Reactor Scram as a Result of a Loss of Off-site Power | 10 CFR 50.73(a)(2)(iv)(A), System Actuation
10 CFR 50.73(a)(2)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident
10 CFR 50.73(a)(2)(vii), Common Cause Inoperability
10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
10 CFR 50.73(a)(2)(iii) | | 05000400/LER-2003-002 | 1 O OF 3 3 | | | 05000266/LER-2003-002 | | 10 CFR 50.73(a)(2)(iv), System Actuation | | 05000250/LER-2003-003 | Unescorted Access Inappropriately Approved Due to Falsified Pre-Access Information | | | 05000261/LER-2003-003 | | 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor | | 05000219/LER-2003-003 | | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | | 05000247/LER-2003-003 | | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | | 05000530/LER-2003-003 | | 10 CFR 50.73(a)(2)(v), Loss of Safety Function
10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | | 05000331/LER-2003-003 | | | | 05000529/LER-2003-003 | SOURCE RANGE MONITOR INOPERABLE DURING CORE RELOAD | 10 CFR 50.73(a)(2)(v), Loss of Safety Function
10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | | 05000440/LER-2003-003 | Unrecognized Diesel Generator Inoperability During Mode Changes | | | 05000348/LER-2003-003 | | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | | 05000482/LER-2003-003 | REACTOR PROTECTION SYSTEM ACTUATION AND REACTOR TRIP DUE TO FEEDWATER ISOLATION VALVE CLOSURE | 10 CFR 50.73(a)(2)(iv)(A), System Actuation
10 CFR 50.73(a)(2)(iv), System Actuation | | 05000301/LER-2003-003 | | | | 05000302/LER-2003-003 | Reactor Coolant System Pressure Boundary Leakage Limit Exceeded Due To Pressurizer Instrument Tap Nozzle Cracks | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded | | 05000382/LER-2003-003 | RCS Pressure Boundary Leakage Due to Primary Water Stress Corrosion Cracking (PWSCC) | 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded | | 05000397/LER-2003-003 | | 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat
10 CFR 50.73(a)(2)(v), Loss of Safety Function
10 CFR 50.73(a)(2)(iv), System Actuation | | 05000458/LER-2003-003 | | 10 CFR 50.73(a)(2)(v)(c) | | 05000454/LER-2003-003 | Licensed Maximum Power Level Exceeded Due to Inaccuracies in Feedwater Ultrasonic Flow Measurements | | | 05000282/LER-2003-003 | | | | 05000346/LER-2003-014 | Steam Feedwater Rupture Controls System Re-Energizes in a Blocked Condition | 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition
10 CFR 50.73(a)(2)(v), Loss of Safety Function
10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
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