05200025/LER-2025-001, Condition Prohibited by Technical Specification Due to Pressurizer Safety Valves Lift Pressure Setpoint Drift
| ML25240B635 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 08/28/2025 |
| From: | Martino P Southern Nuclear Operating Co |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| NL-25-0320 LER 2025-001-00 | |
| Download: ML25240B635 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 0252025001R00 - NRC Website | |
text
.t,, Southern Nuclear August28,2025 Docket No.:
52-025 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Patrick Martino Site Vice President, Vogtle Units 3 & 4 Vogtle Electric Generating Plant (VEGP) - Unit 3 Licensee Event Report 2025-001-00 Condition Prohibited by Technical Specification 7825 River Road Waynesboro, Georgia 30830 (706) 848-6602 tel NL-25-0320 Due to Pressurizer Safety Valves' Lift Pressure Setpoint Drift Ladies and Gentlemen:
In accordance with the requirements of 10 CFR 50.73(a)(2)(i)(B), Southern Nuclear Operating Company is submitting the enclosed Licensee Event Report for VEGP Unit 3.
This letter contains no regulatory commitments. If you have questions regarding the enclosed information, please contact Will Garrett at (706) 848-7154.
Respectfully submitted, a~~
Patrick ~- ie;a-riino Site Vice President Vogtle Units 3 & 4 PAM/kjd/cbg
Enclosure:
Unit 3 Licensee Event Report 2025-001-00 CC:
NRC Regional Administrator, Region II NRR Project Manager - Vogtle Units 3 & 4 Senior Resident Inspector-Vogtle Units 3 & 4
Vogtle Electric Generating Plant - Unit 3 Licensee Event Report 2025-001-00 Condition Prohibited by Technical Specification Due to Pressurizer Safety Valves' Lift Pressure Setpoint Drift Enclosure Unit 3 Licensee Event Report 2025-001-00
Abstract
In October 2024, during the Unit 3 Refueling outage (3R01 }, while the unit was at O percent power level in Mode 5, two pressurizer safety relief valves (PSVs} were removed as part of the routine lnservice Testing Program and sent to an off-site testing facility. On July 2, 2025, while the unit was at 100 percent power level in Mode 1, the site was notified of the testing results and that the as-found lift set pressures were determined to be below the Technical Specification (TS} 3.4.6 allowable lift setting value. When discovered, both valves had already been replaced with pre-tested valves. Setpoint drift is the most likely cause of the PSV's setpoint failure.
It is likely that these PSVs were outside of the TS limits longer than the allowable completion times for the associated required action statements during the previous operating cycle in all applicable modes of operation. Therefore, this condition is being reported in accordance with 10 CFR 50.73(a}(2}(i}(B} as a condition prohibited by TS.
Vogtle Units 1, 2, and 4 were unaffected by this event.
EVENT DESCRIPTION
I
- 2. DOCKET NUMBER
- 3. LER NUMBER 00025 I
YEAR SEQUENTIAL REV NUMBER NO.
- - 1 001 1-G In October 2024, during the refueling outage {3R01) while Unit 3 was at O percent power in Mode 5 and with the reactor coolant system {RCS) [EIIS: AB] at atmospheric conditions, two pressurizer safety relief valves {PSV) [EIIS: AB/RV]) were removed as part of the routine lnservice Testing Program and sent to an off-site testing facility. On July 2, 2025, while the unit was at 100 percent power level in Mode 1, the site was notified that the as-found lift pressures were discoved to be 2395.7 psig and 2381.7 psig, which are outside the Technical specification {TS) 3.4.6 allowable lift pressure settings of plus or minus 1 percent of the RCS design pressure of 2485 psig, which is greater than or equal to 2460 psig and less than or equal to 2510 psig.
EVENT CAUSE ANALYSIS
Setpoint drift of the PSV {Manufacturer Crosby Model HB-86 BP, serial numbers N900028-00-009 and N900028-00-0010) was determined to be the most likely cause of the failure.
SAFETY ASSESSMENT AND REPORTABILITY
There were no other safety-related structures systems or components inoperable at the time that contributed to the event.
This event is reportable per 10 CFR 50.73{a){2){i){B) as a condition prohibited by TS. The two PSV lift pressure setpoints were likely outside the TS limits {and therefore inoperable) for longer than the allowed completion times for the associated required action statements in all applicable modes of operation. There is no firm evidence prior to the time of discovery at the test facility of when the failure occurred.
There were no safety consequences as a result of this event. The as-found lift pressure settings did not affect or challenge the ASME code limitations and safety limit of 11 O percent RCS design pressure. There was no impact to the RCS transients that credit PSVs for overpressure protection.
There was no loss of safety function for this event. The safety analyses that are evaluated using low-side PSV tolerances are being re-evaluated using the as-found lift setpoints to confirm that event-specific acceptance criteria were satisfied.
Vogtle Units 1, 2, and 4 were unaffected by this event.
CORRECTIVE ACTIONS
- The two affected PSVs were replaced during the October 2024, 3R01 refueling outage.
PREVIOUS EVENTS
- None Page 2
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