05000281/LER-2014-001
| Surry Power Station, Unit 2 | |
| Event date: | 04-30-2014 |
|---|---|
| Report date: | 06-23-2014 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 2812014001R00 - NRC Website | |
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1.0 DESCRIPTION OF THE EVENT On April 30, 2014, with Unit 2 in cold shut down for a refueling outage, the Unit 2A pressurizer safety valve (PSV) [El IS-AB-RV] failed its as-found test during scheduled setpoint testing and overhaul performed at Wyle Laboratories. The PSV was tested in accordance with ASME OMa Code, Section 1-1330 (Test Frequencies, Class 1 Pressure Relief Valves) and failed to lift within the +/- 3% Technical Specification 3.1.A.3.b requirement (i.e., 2485 psig +/- 3% (2410-2510)) for as-found setpoint. The Unit 2A PSV as-found lift setting was 2401 psig which is 3.4% below the nominal value of 2485 psig.
In accordance with ASME OMa Code, Section 1-1330, the remaining two PSVs were subsequently sent to Wyle for setpoint testing.
On May 6, 2014, the Unit 2C PSV also failed to lift within the as-found set pressure requirement. The as-found lift setting did not meet the +/- 3% tolerance allowed by Technical Specifications. This PSV exhibited an as-found lift setpoint of 2336 psig which was 6.0% below 2485 psig.
NUREG-1022, Event Reporting Guidelines 10CFR50.72 and 50.73, documents an example of multiple test failures involving testing of safety valves found to lift with setpoints outside of Technical Specification limits. The guideline discusses how similar discrepancies found during testing in multiple valves that may have arisen over a period of time during plant operation is a reportable condition. Therefore, this report is being submitted, pursuant to 10 CFR 50.73(a)(2)(i)(B), for operation prohibited by Technical Specifications.
2.0 SIGNIFICANT SAFETY CONSEQUENCES AND IMPLICATIONS The as-found setpoints were evaluated and it was determined opening of the PSVs sooner than expected would not have a significant impact on the accident analysis transient response and the reactor protection system functions would continue to meet their design function of actuating to protect the reactor. Furthermore, the PSVs continued to meet their design function and the safety analysis continued to meet all acceptance criteria. The PSVs opening below the nominal setpoint did not have any impact on the ability for the PSVs to open or reclose in response to a RCS pressure transient. Therefore, the health and safety of the public were not affected.
3.0 CAUSE An apparent cause evaluation was initiated and the preliminary cause for the low as-found setpoint was due to setpoint drift.
Surry Power Station 05000 - 281 4.0 IMMEDIATE CORRECTIVE ACTION(S) An overhauled spare safety valve was sent from Wyle and installed as the Unit 2A PSV.
5.0 ADDITIONAL CORRECTIVE ACTIONS Subsequent to the Unit 2A PSV test failure, the two remaining Unit 2 PSVs were sent to Wyle for setpoint testing. The Unit 2B PSV passed as-found testing and was returned for installation. The Unit 2C PSV was disassembled, inspected, groomed and passed subsequent testing. The valve was returned for installation.
6.0 ACTIONS TO PREVENT RECURRENCE Corrective actions from the apparent cause evaluation for the low as-found setpoint will be implemented.
7.0 SIMILAR EVENTS None 8.0 MANUFACTURER/MODEL NUMBER Crosby, 6K26HB-86-BP 9.0 ADDITIONAL INFORMATION None