05000457/LER-2002-001
| Braidwood, Unit 2 | |
| 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 | |
| 4572002001R00 - 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 During refueling outages A2R07 (May 1, 1999 - May 27, 1999) and A2R08 (October 21, 2000 - November 16, 2000), the three pressurizer safety valves [AB] (RY) (i.e., 2RY8010A, 2RY8010B and 2RY8010C) were removed in accordance with the IST program and replaced with three spare valves that had been previously verified to be within the TS required tolerance of +/- 1 percent.
In both refueling outages, the three PSVs that were removed were sent to the NWS Technologies facility for as-found lift setpoint testing and refurbishment. The 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 from both A2R07 and A2R08 exceeded this criterion. For valves removed during A2R07 the out of tolerance lift setpoints were -2.1 percent and +1.4 percent. For valves removed during A2R08 the out of tolerance lift setpoints were -1.1 percent and -1.2 percent. 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 0M-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.
Station management did not recognize the reportability requirement of multiple pressurizer safety valves being inoperable until a similar condition occurred with the PSVs tested from refueling outage A1R09; this event is reported in LER 2002-001-00. 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 plants Technical Specifications.
C. Cause of Event
The PSVs 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 Station are performing within their design capabilities. The test failures are mainly due to the close
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.
Identification and training of all personnel involved in the decision process for determining reportability is the corrective action to prevent future errors in reportability evaluation.
F. Previous Occurrences:
Test data from the last five refueling outages at Braidwood 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.
G. Component Failure Data:
Manufacturer � Nomenclature � Model � Mfg. Part Number Crosby � Pressurizer Safety Valve � HB-BP-86 � N/A