05000237/LER-2001-001
| Event date: | 12-21-2000 |
|---|---|
| Report date: | 01-19-2001 |
| 2372001001R00 - NRC Website | |
PLANT AND SYSTEM IDENTIFICATION:
General Electric — Boiling Water Reactor — 2527 MWt rated core thermal power Energy Industry Identification System (EDS) Codes are identified in the text as [XX] and are obtained from IEEE Standard 805-1984, IEEE Recommended Practice for System Identification in Nuclear Power Plants and Related Facilities.
EVENT IDENTIFICATION:
Primary Containment Isolation System Valve Adjusted During VOTES Test with No LLRT Performed
PLANT CONDITIONS PRIOR TO EVENT:
Unit: 2 � Event Date: 12-21-2000 Reactor Mode: 1 � Mode Name: Power Operation Reactor Coolant System Pressure: 1000 psig
B. DESCRIPTION OF EVENT:
Event Time: 1533 Power Level: 100% This condition is being reported pursuant to 10 CFR 50.73 (a)(2)(i)(B), which requires the reporting of any operation or condition prohibited by the plant's Technical Specifications.
On December 19, 2000, during the performance of a plant work request, VOTES testing was performed on Motor Operated Valve (MOV) 2-1402-25B in accordance with plant procedures. During the performance of this test the closing torque switch on this MOV was raised, resulting in an increase in thrust of about 20.4 percent.
On December 21, 2000, during a post job review of the work package, the MOV engineer identified that the incorrect thrust window values were placed in the work package. Note: These settings did not change the outcome of the VOTES test. While writing Condition Report for the error with the thrust window values, the MOV Engineer identified that a previous LLRT was associated with this valve. The engineer immediately recognized that this MOV had recently been adjusted on December 19, 2001 and suspected that no LLRT had been performed. Thrust changes greater than 5 percent result in the potential to change leakage rates and therefore are required to be tested in accordance with the 10 CFR 50 Appendix J Program. Subsequent investigation revealed that the As Found and As Left LLRT required by the 10CFR50 Appendix J program had not been performed. The change in torque switch settings resulted in the valve becoming inoperable due to the fact that a change in the torque switch setting could affect the leakage rate of the valve. Operations was notified and Valve 2-1402-25B was declared inoperable, and appropriate Technical Specification action statements were entered TS 3.7.D.1 requires with one or more primary containment isolation valve(s) inoperable, maintain at least one isolation valve OPERABLE in each affected penetration that is open and within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> either: a) Restore the the inoperable valve(s) to OPERABLE status, or b) Isolate each affected penetration by use of at least one deactivated automatic valve secured in the isolated position, or c) Isolate each affected penetration by use of at least one closed manual valve or blind flange.
Due to the delay in recognizing the LLRT requirements associated with the original MOV thrust setting, the required Limiting Condition for Operation (4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />) was exceeded, placing the plant in a condition prohibited by the plant's Technical Specifications. On December 21, 2000, the VOTES test was re-performed on this MOV. This test restored the seating thrust value to within 5% of the seating force noted prior to the last As Left LLRT test. The valve was subsequently declared operable upon completion of the test.
C. CAUSE OF EVENT:
The Root Cause is the lack of adequate precautions within the test procedure with regard to testing PCIS valves. If adequate precautions had been present in the work procedure, it would have noted this motor operated valve as an LLRT valve. (NRC Cause Code D)
SAFETY ANALYSIS
The purpose of the 2-1402-25B valve is to open in order to prevent over-pressurization of the core spray discharge piping, and to close in order to maintain core spray system integrity. This MOV also has a containment isolation function. The 2-1402-25B valve had adequate capability to perform all of its other design basis functions. Therefore, the core spray system itself was not inoperable until Technical Specification 3.7.D was entered on December 21, 2000. This valve was then repaired within the normal LCO window. Since the other MOV in series with this valve was still functioning, a complete loss of containment integrity did not occur.
The increase in thrust did not affect the valve's ability to open if the Core Spray System was needed for injection.
The Core Spray System remained available and, therefore the Core Damage Frequency was not affected by this event.
Based upon this evaluation, the safety significance of this event has been determined to be minimal.
E. CORRECTIVE ACTIONS:
The valve was re-tested, and returned to the previously established seating force. (Complete) A review of the current schedule was performed to verify that no work packages will perform thrust adjustments to Appendix J valves without the LLRT requirements being addressed. (Complete) Revise the appropriate VOTES procedure to include LLRT allowable thrust adjustments to MOVs included in the 10 CFR 50 Appendix J Program. (ATI #41146)
PREVIOUS OCCURRENCES:
None . COMPONENT FAILURE DATA:
None