05000456/LER-2002-001
| Docket Number04 08 2002 2002-001-00 6 7 2002 N/A N/A | |
| Event date: | 04-08-2002 |
|---|---|
| Report date: | 6-7-2002 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| Initial Reporting | |
| 4562002001R00 - NRC Website | |
B. Description of Event:
There were no systems or components inoperable at the beginning of this event that contributed to the severity of the event.
As part of refueling outage A1R09 activities (A1R09 occurred between September 22, 2001 and October 12, 2001), the three PSVs (i.e., 1RY8010A, 1RY8010B and 1RY8010C) were removed in accordance with the IST program and replaced with three spare valves which had been previously verified to be within the TS required tolerance of +/- 1 percent.
The three PSVs that were removed were sent to the NWS Technologies facility for as-found lift setpoint testing and refurbishment. The PSVs acceptance criteria for the as-found lift setpoint is 2485 psig +/- 1 percent, as required by TS 3.4.10. Two of the three PSVs exceeded this criterion. One valve lifted at 2513 psig (i.e., 1.1 percent high), and the other lifted at 2449 psig (i.e., 1.4 percent low). The third valve was within tolerance. Although outside of the TS required tolerance, the valve lift setpoints were within the American Society of Mechanical Engineers, Section XI, "Rules For Inservice Inspection of Nuclear Power Plant Components," part OM-1 acceptance criteria of +/- 3 percent. Also, the valves were subjected to subsequent bench tests where the valves tested within the +/- 1 percent of the TS acceptance criteria without any repairs being made to the valves.
Since both of the valves that failed the as-found lift setpoint testing had been replaced with operable valves during A1R09, no TS action applied at the time the valve test failures were discovered. However, the condition of multiple pressurizer safety valves being outside of their required lift setting tolerance band is reportable in accordance with 10 CFR 50.73(a)(2)(i)(B), "Any operation or condition prohibited by the plant's Technical Specifications.
C. Cause of Event
The safety valves were inspected by the vendor and no material condition issues were found that may have contributed to the out of tolerance condition.
An Electric Power Research Institute (EPRI) evaluation concerning safety and relief valve testing indicates that the PSVs at Braidwood are performing within their design capabilities. The test failures are mainly due to the close tolerance required by the current plant safety analysis and reflected in TSs and the inability of the valves to perform within those tolerances.
E. Corrective Actions:
Revision of the safety analysis to support relaxation of the TS lift tolerance for pressurizer safety valves is being investigated as the corrective action to prevent future PSV lift test failures.
F. Previous Occurrences:
Test data from the last five refueling outages at Braidwood Station show that out of 15 valves tested, eight were out of tolerance. Five of those eight were out of tolerance low, three were high. Only one of the valves exceeded 2 percent; none exceeded 3 percent.
There have been no previous corrective actions applied to PSV lift test failures.
Until the valve failures from refueling outage A1R09 were determined to be outside of the TS limits, station management interpreted the TS as being met if the as-found condition of the valve was within 3 percent, as required by the IST program, and the as-left setpoint was within 1 percent as required by the TS.
G. Component Failure Data
� � Mfg. Part Number Manufacturer Nomenclature Model� � N/A Crosby Pressurizer Safety Valve HB-BP-86