05000461/LER-2011-009
| Clinton Power Station, Unit 1 | |
| Event date: | 12-01-2011 |
|---|---|
| Report date: | 04-11-2012 |
| 4612011009R00 - NRC Website | |
PLANT AND SYSTEM IDENTIFICATION
General Electric — Boiling Water Reactor, 3473 Megawatts Thermal Rated Core Power Energy Industry Identification System (El IS) codes are identified in the text as [XX].
EVENT IDENTIFICATION
Missed Surveillance Due To Preconditioning Valve Prior To Leak Rate Test
A. Plant Operating Conditions Before the Event
B. DESCRIPTION OF EVENT
On December 1, 2011, at approximately 1530 hours0.0177 days <br />0.425 hours <br />0.00253 weeks <br />5.82165e-4 months <br />, with the reactor in Mode 5 (Refueling) for refueling outage C1R13, an as-found Leak Rate Test (LRT) was performed for Residual Heat Removal [BO] A Reactor Pressure Vessel Isolation check valve [ISV] 1E12-F041A. In accordance with the station reactor coolant system pressure isolation valve testing program (Procedure CPS 9843.01, ISI Category "A" Valve Leak Rate Test) this as-found test was required to be performed. The LRT was performed in accordance with procedure CPS 9843.01V001, Leak Rate Testing of LPCI "A" Injection Valve Data Sheet. The recorded leakage for the as-found LRT was not within acceptable limits at 4.5 gallons per minute at 200 psig due to the testing sequence of other system valves unseating 1E12-F041A prior to testing.
Following performance of procedure CPS 9053.05, RHR/LPCS Valve Operability (Shutdown), which stroked the valve with no additional closing force applied, the LRT was completed with satisfactory results.
On February 13, 2012, during review of the performance of the LRT, a question arose regarding if stroking of the valve was acceptable preconditioning. A subsequent review of this activity concluded that stroking of the valve was unacceptable preconditioning. This initial surveillance test is considered to be a missed surveillance under Technical Specification 3.4.6.1, Reactor Coolant System Pressure Isolation Valves (PIV) Leakage, and is reportable under the provisions of 10 CFR 50.73 (a)(2)(i)(B) as a condition prohibited by the plant's Technical Specifications.
An analysis was performed to determine actual impact of the preconditioning activity on the test results. The preconditioning activity prior to the LRT did not unduly influence the final test results because the activity did approximate normal valve operation which indicates no evidence to suggest the valve may have been degraded prior to testing, such that the degradation was masked by the stroking of the valve.
During this event, reactor coolant temperature was being maintained within a band of 90 - 95 degrees Fahrenheit and pressure was atmospheric.
There were no structures, systems, or components that were inoperable at the start of the event that contributed to this event.
Issue Reports 1296786 and 1326252 were initiated on this event.
C. CAUSE OF EVENT
Test procedure CPS 9843.01V001 was inadequate in that the draining operation from the previous LLRT test on a motor-operated valve (MOV) in this line moved the check valve disc from its seat. Test procedure CPS 9053.05, RHR/LPCS Valve Operability (Shutdown), incorrectly allowed valve 1E12-F041A to be stroked to establish test configuration.
D. SAFETY CONSEQUENCES
There were no actual consequences for this event. An analysis concluded that there was reasonable assurance check valve 1E12-F041A would have performed its design function to isolate the reactor coolant system pressure boundary. Additionally, the as-found LLRT for the redundant MOV for this line was completed with satisfactory results and thus the MOV was capable of completing the safety function to isolate the line.
No loss of safety function occurred during this event.
E. CORRECTIVE ACTIONS
Procedure CPS 9843.01V001 is being revised to clarify draining requirements for the test set that includes check valve 1E12-F041A. Additionally, similar procedures for the other ECCS systems are being reviewed and revised as necessary.
F. PREVIOUS OCCURRENCES
A search of Issue Reports identified a previous similar event of unacceptable preconditioning for LLRTs in Issue Reports 1300655 and 1310612 on valve 1E51-F040 as reported in LER 2011-005. The event discussed in LER 2011-005 occurred during the same outage as the event described in LER 2011-009. Additionally, the event discussed in LER 2011-005 was caused by an incorrect procedure that directed preconditioning be performed prior to the LLRT.
G. COMPONENT FAILURE DATA
None