At 1231 on October 7, 2003, with the plant in mode 1, a depressurization of the High Pressure Core Spray ( HPCS) system [BG] occurred while the HPCS system waterleg piping was isolated during an unscheduled maintenance activity to replace the power frame on the waterleg pump motor. System pressure unexpectedly decreased to below the low pressure alarm point requiring plant operators to remove fuses for the main HPCS pump and perform a system fill and vent procedure. These actions rendered the single train HPCS system inoperable. With the HPCS system inoperable, the action required by Technical Specifications Limiting Condition for Operation (LCO) 3.5.1.B to verify operability of the Reactor Core Isolation Cooling system [BN] and restore HPCS within 14 days was taken. Approximately three hours later at 1538, after verifying the system was filled and vented, and the pump fuses reinstalled, the HPCS system was declared operable and all requirements of LCO 3.5.1 were met. The cause of this event is attributed to the judgment of control room operators who allowed the maintenance to proceed when contingency actions to be taken in the event of unexpected system conditions had not been pre- planned. Prior to the maintenance, the control room operators developed contingency actions that were not adequate to manage a rapid depressurization of the HPCS system. There were no safety consequences associated with the inoperable HPCS system and this event did not represent an actual loss of a safety function for greater than the time allowed by Technical Specifications.
26158 RI |
Event Description
At 1231 on October 7, 2003, with the plant in mode 1, a depressurization of the High Pressure Core Spray (HPCS) system [BG] occurred while the HPCS system waterleg piping was isolated during an unscheduled maintenance activity to replace the power frame on the waterleg pump motor. System pressure unexpectedly decreased to below the low pressure alarm point requiring plant operators to remove fuses for the main HPCS pump and perform a system fill and vent procedure. These actions rendered the single train HPCS system inoperable.
Immediate Corrective Action With the HPCS system inoperable, the action required by Technical Specifications Limiting Condition for Operation (LCO) 3.5.1.B to verify operability of the Reactor Core Isolation Cooling (RCIC) system [BN] and restore HPCS within 14 days was taken. Approximately three hours later at 1538, after verifying the system was filled and vented, and the pump fuses reinstalled, the HPCS system was operable and all requirements of LCO 3.5.1 were met. As an additional measure, control room operators have been instructed to maintain an oversight role of maintenance activities and be less involved in the work planning process.
Root Cause
The cause of this event is attributed to the judgment of control room operators who allowed the unscheduled maintenance to proceed when contingency actions to be taken in the event of unexpected system conditions had not been pre-planned. Currently, development of contingency plans is included in the work planning process only for higher risk maintenance activities. In this case, plant operators developed the contingency plan during a pre-job briefing that was conducted just prior to performance of the maintenance activity. The operator's plan was to start the main HPCS pump (HPCS-P-1) if system pressure decreased significantly (to below — 80 psi) from the initial pressure of approximately 105 psi while the power frame was being replaced. However, the system pressure decreased more rapidly than expected and HPCS-P-1 could not be started before the low-pressure alarm actuated.
Alternatives to the operator's contingency plan that would not have resulted in a reportable event would be to run HPCS-P-1 during the power frame replacement to maintain system pressure or remove the HPCS system from service in accordance with approved procedures and Technical Specifications prior to maintenance.
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Assessment of Safety Consequences
There were no safety consequences associated with this event and the HPCS system was not inoperable for greater than the 14-day outage time allowed by Technical Specifications.
Additionally, the independent RCIC system was available to perform the safety function of high-pressure injection during the time HPCS was inoperable.
Similar Events There have been no previous similar events in which a condition reportable pursuant to 10 CFR 10 CFR 50.73(a)(2)(v)(D) existed due to allowing maintenance to be conducted without pre-planned contingency actions.
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| | | Reporting criterion |
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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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