05000461/LER-2011-005
| Clinton Power Station, Unit 1 | |
| Event date: | 12-01-2011 |
|---|---|
| Report date: | 01-24-2012 |
| 4612011005R00 - NRC Website | |
PLANT AND SYSTEM IDENTIFICATION
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
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 1031 hours0.0119 days <br />0.286 hours <br />0.0017 weeks <br />3.922955e-4 months <br />, with the reactor in Mode 5 (Refueling) for refueling outage C1R13, an as-found Local Leak Rate Test (LLRT) was performed for Reactor Core Isolation Cooling [BN] turbine [TRB] exhaust check valve [ISV] 1 E51-F040, a containment isolation valve. In accordance with the station primary containment leakage rate testing program (Procedure CPS 1305.01) which implements the requirements of 10 CFR 50, Appendix J, this as-found test was required to be performed prior to a scheduled preventive maintenance (PM) activity to open and inspect the valve. The LLRT was performed in accordance with procedure CPS 9861.05D010, RCIC Turbine Exhaust Water Leak Rate Test Data Sheet. The recorded leakage for the as- found LLRT was within acceptable limits at 0.078 gallons per minute (minimum gauge reading).
The open and inspect PM activity found the valve internals to be in proper operating condition with no deficiencies identified and proper freedom of motion.
A post-maintenance, as-left, LLRT was completed following the PM activity with satisfactory results.
Following completion of the LLRT on the check valve, questions arose as to the acceptability of stroking the check valve prior to performing the test. A step in the procedure establishing the test lineup required valve 1E51-F040 to be stroked open with its lever arm and then the valve disk was allowed to drop closed, shut by normal means.
A subsequent evaluation of this activity concluded that the pre-test stroking of the valve was unacceptable preconditioning; therefore, the as-found LLRT was invalid. Because the existing as-found conditions no longer existed, the as-found leakage rate for the valve could no longer be quantified. The invalid surveillance test is considered to be a missed surveillance under Technical Specification 3.6.1.3, Primary Containment Isolation Valves, 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 as-found LLRT did not unduly influence the as-found test results because the activity did approximate normal valve operation and the subsequent inspection of the valve found 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.
There were no structures, systems, or components that were inoperable at the start of the event that contributed to this event and this event had no impact on reactor coolant temperature and pressure.
Issue Reports 1300655 and 1310612 were initiated to investigate this event.
C. CAUSE OF EVENT
Test procedure CPS 9861.05D010 was inadequate and incorrectly required valve 1 E51-F040 to be manually stroked prior to performing the LLRT as a step in establishing the test lineup.
D. SAFETY CONSEQUENCES
There were no actual consequences for this event. An analysis concluded that there was reasonable assurance check valve 1 E51-F040 would have performed its design function to isolate the primary containment penetration.
Additionally, the as-found LLRT for the redundant motor-operated valve (MOV) for this containment penetration was completed with satisfactory results and thus the MOV was capable of completing the safety function to isolate the primary containment penetration.
No loss of safety function occurred during this event.
E. CORRECTIVE ACTIONS
Procedure CPS 9861.05D010 is being revised to clarify stroking requirements for valve 1E51-F040.
Other similar Appendix J check valve test procedures are being reviewed to determine the extent of this condition.
F. PREVIOUS OCCURRENCES
A search of Issue Reports for the last five years did not identify previous similar events of unacceptable preconditioning for LLRTs.
G. COMPONENT FAILURE DATA
None