05000461/LER-2011-003
| Clinton Power Station, Unit 1 | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 4612011003R00 - NRC Website | |
PLANT AND SYSTEM IDENTIFICATION
Clinton Power Station is a General Electric — Boiling Water Reactor, 3473 Megawatts Thermal Rated Core Power Energy Industry Identification System (EllS) codes are identified in the text as [XX].
EVENT IDENTIFICATION
Inadequate Procedure Direction Results in Missed Response Time Testing
A. CONDITION PRIOR TO EVENT
Unit: 1 Event Date: 8/31/2011 Event Time: 1658 hours0.0192 days <br />0.461 hours <br />0.00274 weeks <br />6.30869e-4 months <br /> CDT Reactor Mode: 1 Mode Name: Power Operation Power Level: 97.0 percent
B. DESCRIPTION OF EVENT
On 8/31/2011, the plant was in Mode 1 at 97 percent power. At 1658 hours0.0192 days <br />0.461 hours <br />0.00274 weeks <br />6.30869e-4 months <br />, a Clinton Power Station (CPS) system manager while performing a review of industry operating experience identified that incomplete post maintenance testing (PMT) had been performed after replacement of Turbine Control Valve (TCV)[TRB][PCV] Fast Closure Pressure Switches [PS] 1C71N005A, 1C71N005B, and 1C71N005C the last time the switches were replaced. Pressure switch 1C71N005A was replaced on 2/8/2006, pressure switch 1C71N005B was replaced on 1/22/2008, and pressure switch 1C71N005C was replaced on 5/30/2009.
Response Time Testing required by Reactor Protection System (RPS) [JC] instrumentation Technical Specification (TS) Surveillance Requirement (SR) 3.3.1.1.17 was not identified in the work order and thus was not performed for the affected channels of the three pressure switches prior to declaring the channels operable. Pressure switch 1C71N005D was replaced on 2/4/2004 and its affected channel was properly tested and thus was not impacted during this event.
Further investigation identified that TS SR 3.3.1.1.17 Response Time Testing was performed for each of the affected channels with acceptable results during subsequent refueling outages as part of planned TS required surveillances (1C71N005A was tested on 1/31/2008; 1C71N005B and 1C71N005C were tested on 1/30/2010). This testing provides reasonable assurance that the affected channels would have performed their safety functions following replacement of the pressure switches.
The TS SR 3.3.1.1.17 surveillances for the affected channels were found to be current at the time this event was discovered. Issue Report 1258051 was initiated to investigate this event.
This event is reportable under 10 CFR 50.73(a)(2)(i)(B) as an operation or condition that was prohibited by the plant's TS for not completing required Response Time Testing in accordance with TS SR 3.3.1.1.17 prior to returning the affected channels to operable status.
C. CAUSE OF EVENT
An apparent cause analysis was performed to determine why the required response time testing was not performed following pressure switch replacement. The cause of this event was that procedure MA-AA-716- 012, "Post Maintenance Testing," did not provide sufficient guidance to the work planner to determine that a Response Time Test could be required for replacing a pressure switch. The procedures and processes did not lead the work planner to determine that the TS SR of a Response Time Test was required to be performed.
D. SAFETY CONSEQUENCES
The safety significance of this event was minimal. Although the affected channels were not tested at the time of replacement, there is reasonable assurance that the channels would have performed their safety function as demonstrated by Response Time Testing conducted with acceptable results in subsequent refueling outages following the switch replacements. Therefore, there was no loss of safety function for any of the channels.
Additionally, had the TCV Fast Closure function for any of the affected channels not been able to meet TS SRs, at least two of the four channels were always available and properly tested with current surveillances and would have provided adequate protection to satisfy the two-out-of-four logic for RPS actuation.
E. CORRECTIVE ACTIONS
Procedure MA-AA-716-012, "Post Maintenance Testing," has been revised to identify that a Response Time Test needs to be considered as possible PMT for replacing a pressure switch.
Model Work Orders for TCV Fast Closure Pressure Switch Replacement will be revised to include the required Response Time Testing PMT.
F. PREVIOUS OCCURRENCES
A review for previous occurrences did not identify similar events at CPS.
G. COMPONENT FAILURE DATA
This is not applicable, as no component failure occurred.