05000374/LER-2011-001
| Lasalle County Station, Unit 2 | |
| Event date: | 05-27-2011 |
|---|---|
| Report date: | 07-26-2011 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| Initial Reporting | |
| 3742011001R00 - NRC Website | |
LaSalle County Station Unit 2 is a General Electric Company Boiling Water Reactor with 3546 Megawatts Rated Core Thermal Power.
A. CONDITION PRIOR TO EVENT:
B. DESCRIPTION OF EVENT:
On May 27, 2011, Unit 2 was in Mode 1 at 100% power. At 1804 hours0.0209 days <br />0.501 hours <br />0.00298 weeks <br />6.86422e-4 months <br /> CDT, the 2A Turbine Control Valve Fast Closure Trip Oil pressure switch (2C71-N005A) (RP)[JC] was declared inoperable, following the discovery that incomplete post maintenance testing (PMT) had been performed after replacement of the switch during the previous refueling outage. Response time testing as required by Technical Specification (TS) Surveillance Requirement 3.3.1.1.17 had inadvertently been omitted. Technical Specification (TS) 3.3.1.1 Required Action (RA) A.1 was entered to place the channel in trip within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, and TS 3.3.4.1 RA A.1 was entered to restore the channel to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
The required TS surveillance was completed by 2114 hours0.0245 days <br />0.587 hours <br />0.0035 weeks <br />8.04377e-4 months <br />, and at 2153 hours0.0249 days <br />0.598 hours <br />0.00356 weeks <br />8.192165e-4 months <br /> on May 27, 2011, 2C71-N005A was declared operable, and the associated TS RA timeclocks were exited.
This occurrence is reportable under 10 CFR 50.73(a)(2)(i)(B) as an operation or condition prohibited by the plant's Technical Specifications.
C. CAUSE OF EVENT:
A root cause analysis was performed to determine why the required response time testing was not performed following replacement of 2C71-N005A. It was determined that the cause of the event was that procedure MA- AA-716-012, "Post Maintenance Testing," did not provide sufficient guidance to a work planner to determine that a response time test could be required for replacing of a pressure switch. The work planner was not led by procedures and processes to determine that TS surveillance requirements for a response time test were required to be performed.
D. SAFETY ANALYSIS:
The safety significance of this event was minimal. Following discovery of the missed response t17-ne test, the test was performed with acceptable results.
Had the response time been found out of tolerance, the remaining channels would have provided adequate protection. The pressure switch senses a TCV fast closure and actuates an input into Reactor Protection System (RPS) channel Al, providing one input to the 1 out of 2 taken twice reactor scram from RPS. It also Recirculation (RR)[AD] Pumps out of high speed to mitigate the fuel thermal transient associated with the response to the rapid TCV closure initiated by a Generator Load Reject event.
Given that the A2 and both B1 and B2 channels for RPS channel for TCV Fast Closure had current and satisfactory test results and were fully operable, the RPS actuation from an actual TCV Fast Closure event would not have impacted the scram response. Similarly, the EOC-RPT protection would still have provided a downshift of both RR pumps.
E. CORRECTIVE ACTIONS:
- Response time testing was performed on 2C71-N005A, with satisfactory results.
- A note will be placed in the Passport Work Management program to flag the work planner that response time testing is required following the replacement of all components listed in site procedure LIP-GM-937, "Administration of Response Time Tests." The TCV Fast Closure Trip Oil pressure switches are included in that list.
- A Procedure Change Request will be submitted to the Maintenance Director Peer Group to have corporate procedure MA-AA-716-012 revised to identify that a response time test must be considered as a possible PMT following pressure switch replacement.
F. PREVIOUS OCCURRENCES:
A review of Licensee Event Reports submitted by LaSalle over the past ten years found no previous occurrences of a reportable event due to incomplete or inadequate surveillance testing.
G. COMPONENT FAILURE DATA:
This is not applicable, as no component failure occurred.