|
|
| Line 1: |
Line 1: |
| {{Adams
| | #REDIRECT [[05000364/LER-2025-002, Two Pressurizer Safety Valves Lift Pressure Outside of Technical Specifications Limits Due to Setpoint Drift]] |
| | number = ML25143A135
| |
| | issue date = 05/23/2025
| |
| | title = Nuclear Plant, Unit 2, Two Pressurizer Safety Valves Lift Pressure Outside of Technical Specifications Limits Due to Setpoint Drift
| |
| | author name = Dean E
| |
| | author affiliation = Southern Nuclear Operating Co, Inc
| |
| | addressee name =
| |
| | addressee affiliation = NRC/NRR, NRC/Document Control Desk
| |
| | docket = 05000364
| |
| | license number =
| |
| | contact person =
| |
| | case reference number = NL-25-0190
| |
| | document report number = LER 2025-002-00
| |
| | document type = Letter, Licensee Event Report (LER)
| |
| | page count = 1
| |
| }}
| |
| {{LER
| |
| | Title = Nuclear Plant, Unit 2, Two Pressurizer Safety Valves Lift Pressure Outside of Technical Specifications Limits Due to Setpoint Drift
| |
| | Plant =
| |
| | Reporting criterion = 10 CFR 50.73(a)(2)(i)(B)
| |
| | Power level =
| |
| | Mode =
| |
| | Docket = 05000364
| |
| | LER year = 2025
| |
| | LER number = 2
| |
| | LER revision = 0
| |
| | Event date =
| |
| | Report date =
| |
| | ENS =
| |
| | abstract =
| |
| }}
| |
| | |
| =text=
| |
| {{#Wiki_filter:~ Southern Nuclear May 23, 2025 Docket No.:
| |
| 50-364 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Edwin Dean Ill Vice President - Farley Joseph M. Farley Nuclear Plant - Unit 2 Licensee Event Report 2025-002-00 Joseph M. Farley Nuclear Plant 7388 North State Hwy 95 Columbia, Alabama 36319 334.661.2 IOO tel 334.661.2512 fax EDDEANll(<'l southcmco.com NL-25-0190 Two Pressurizer Safety Valves' Lift Pressure Outside of Technical Specifications Limits due to Setpoint Drift Ladies and Gentlemen:
| |
| In accordance with the requirements of 10 CFR 50.73(a)(2)(i)(B), Southern Nuclear Company is submitting the enclosed Licensee Event Report for Unit 2. The enclosed LER describes a condition which was prohibited by Technical Specifications.
| |
| This letter contains no NRC commitments. If you have any questions regarding this submittal, please contact Mandy Ludlam, Licensing Engineer, at (334) 661-2886.
| |
| Respectfully submitted,
| |
| (£)/(Jo.B Edwin Dean Ill Vice President-Farley ED/mml/cbg Enclosure: Unit 2 Licensee Event Report 2025-002-00 Cc:
| |
| Regional Administrator, Region II NRR Project Manager - Farley Nuclear Plant Senior Resident Inspector-Farley Nuclear Plant RTYPE: CFA04.054
| |
| | |
| Joseph M. Farley Nuclear Plant - Unit 2 Licensee Event Report 2025-002-00 Two Pressurizer Safety Valves' Lift Pressure Outside of Technical Specifications Limits due to Setpoint Drift Enclosure Unit 2 Licensee Event Report 2025-002-00
| |
| | |
| =Abstract=
| |
| On March 24, 2025, while at 0% power level and Mode 5, it was discovered that a Unit 2 pressurizer safety valve (PSV),
| |
| which had been removed during the March 2025 refueling outage (2R30) and shipped off-site for testing, failed its as-found lift pressure test. The PSV lifted below the Technical Specification (TS) 3.4.10 allowable lift setting value and below the ASME code Value of three percent. Following inspection scope expansion, one additional PSV lifted outside of the TS allowance but within ASME code allowance. Setpoint drift is the cause of the PSV failures.
| |
| It is likely that the 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.
| |
| The PSVs were replaced during the spring 2025 refueling outage (2R30).
| |
| | |
| ==EVENT DESCRIPTION==
| |
| I
| |
| : 2. DOCKET NUMBER
| |
| : 3. LER NUMBER 364 I
| |
| YEAR SEQUENTIAL REV NUMBER NO.
| |
| ~-I 002 1-G During the Unit 2 March 2025 refueling outage (2R30), while at 0% power level and Mode 5, with the Reactor Coolant System (RCS) [EIIS: AB] at atmospheric pressure and 96 degrees Fahrenheit, the 2A pressurizer safety valve (PSV) [EIIS:
| |
| RV] was removed as part of the routine In-Service Testing (1ST) program and sent to an off-site testing facility. On March 24, 2025, the site was notified that the as-found lift pressure was discovered to be 2387.8 psig which was outside of the Technical Specification (TS) 3.4.10 allowable lift pressure settings of>/= 2423 psig and</= 2510 psig. The 2A PSV was also outside the ASME code acceptance band of +/- 3% (2410-2560 psig). The scope of the inspection was expanded to PSV 2B and 2C. The 2B PSV tested at 2418.8 psig which was outside of the TS allowable band but within ASME code allowances. The 2C PSV tested at 2452.3 psig which is within both TS and ASME code allowances.
| |
| | |
| ==EVENT ANALYSIS==
| |
| Setpoint drift of the PSVs (Manufacturer: Crosby, Model Number: HP-BP-86, Serial Numbers: N56963-01-0002 and N56963-01-0005) was determined to be the cause of the failures.
| |
| REPORTABILITY AND SAFETY ASSESSMENT:
| |
| This failure constitutes a condition that is reportable pursuant to 10 CFR 50.73(a)(2)(i)(B), "Any operation or condition which was prohibited by the plant's Technical Specifications." There is no firm evidence, prior to the time of discovery at the test facility, of when the failure occurred.
| |
| None of the associated PSV as-found setpoints affected or challenged the ASME code limitation and safety limit of 110% of RCS design pressure. The Farley accident analysis describes two events which could be impacted by pressurizer code safety valve low lift pressure: 1) Accidental depressurization of the RCS and 2) Inadvertent operation of the Emergency Core Cooling System (ECCS) [EIIS: BA].
| |
| Accidental Depressurization of the RCS:
| |
| While low safety valve set pressures are not specifically discussed in the accident analysis, a PSV actuating 3.9% low may be compared to an inadvertent opening. The 2A PSV as-found set pressure was 152.8 psig, approximately 6.8% above RCS normal operating pressure of 2235 psig. In testing, all 3 PSVs closed properly which would negate any findings of continued depressurization. The PSVs would not have created a depressurization event.
| |
| Inadvertent Operation of the ECCS:
| |
| This event addresses the consequences of spurious actuation of the safety injection (SI) [EIIS: BQ] system. The main concern of this event is pressurizer (PZR) [EIIS: AB] overfill that results in subcooled fluid flowing through the PSVs reducing the reliability of the PSVs to maintain system integrity. To mitigate the event, one power-operated relief valve (PORV) [EIIS:
| |
| RV] must be available to preclude RCS pressure reaching the PSV setpoint. Farley Unit 2 has two PORVs that were available during the cycle. The analysis only assumes the use of one and assumes approximately 7 minutes for operator action to confirm one PORV is available.
| |
| I
| |
| : 2. DOCKET NUMBER
| |
| : 3. LER NUMBER 364 I
| |
| YEAR SEQUENTIAL REV NUMBER NO.
| |
| ~-I 002 1-0 The PSVs are conservatively assumed to open at a pressure of 2410 psig which corresponds to a tolerance of -3% relative to the set pressure of 2485 psig. Considering the most limiting PSV (2A), with the as-found lift value of 2387.8 psig, it is reasonable that, with two PORVs (setpoint = 2335 psig), RCS pressure would be precluded from reaching the PSV as-found setpoint preventing ECCS flow through the PSV.
| |
| There was no loss of safety function for this event.
| |
| | |
| ==CORRECTIVE ACTIONS==
| |
| All three PSV were replaced during the March 2025 refueling outage. The as-left setpoints were within +/- 1 % tolerance.
| |
| Additionally, forensic analysis is in progress to determine if any additional corrective actions are warranted.
| |
| | |
| ==PREVIOUS SIMILAR EVENTS==
| |
| Similar events were reported over the past 3 years for Unit 1 in LER 2024-001-00 and Unit 2 in LER 2023-003-00.
| |
| OTHER SYSTEMS AFFECTED:
| |
| No other systems were affected by this event. Page 3
| |
| of 3
| |
| }}
| |
| | |
| {{LER-Nav}}
| |