05000364/LER-2020-002, Pressurizer Safety Valve Lift Pressure Outside of Technical Specifications Limits Due to Setpoint Drift
| ML20356A158 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 12/21/2020 |
| From: | Kharrl C Southern Nuclear Company |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-20-1331 LER 2020-002-00 | |
| Download: ML20356A158 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3642020002R00 - NRC Website | |
text
December 21, 2020
~ Southern Nuclear Docket No.:
50-364 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Charles Kharrl Vice President - Farley Joseph M. Farley Nuclear Plant-Unit 2 Licensee Event Report 2020-002-00 Pressurizer Safety Valve Lift Pressure Outside of Technical Specifications Limits due to Setpoint Drift Ladies and Gentlemen:
Joseph M. Farley Nuclear Plant 7388 North State Hwy 95 Columbia, Alabama 363 l 9 334.661.2 lOO tel 334.661.2512 fax ckharrl@southemco.com NL-20-1331 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.
This letter contains no NRC commitments. If you have any questions regarding this submittal, please contact Thomas Campbell at (334) 661-2673.
Respectfully submitted, Charles Kharrl Vice President - Farley CK/tec/cbg Enclosure: Unit 2 Licensee Event Report 2020-002-00 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 2020-002-00 Pressurizer Safety Valve Lift Pressure Outside of Technical Specifications Limits due to Setpoint Drift Enclosure Unit 2 Licensee Event Report 2020-002-00
12 21 2020
Abstract
On October 28, 2020, while at 0% power level and defueled, it was discovered that a Unit 2 pressurizer safety valve (PSV),
which had been removed during the October 2020 refueling outage (2R27) and shipped off-site for testing, failed its as-found lift pressure test. The PSV lifted conservatively early, 4 psig below the Technical Specification (TS) 3.4.10 allowable lift setting value. Setpoint drift is the cause of the PSV failure due to spring relaxation.
It is likely that the PSV was 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 PSV was replaced during the October 2020 refueling outage.
EVENT DESCRIPTION
During the Unit 2 October 2020 refueling outage (2R27), while at 0% power level and defueled, with the Reactor Coolant System (RCS) [EIIS:AB] at atmospheric pressure and 85 degrees Fahrenheit, a pressurizer safety valve (PSV)
[EIIS:AB:RV] was removed as part of the routine In-Service Testing (1ST) program and sent to an off-site testing facility.
On October 28, 2020 the site was notified that the as-found lift pressure was discovered to be 2456 psig which is outside of the Technical Specification (TS) 3.4.10 allowable lift pressure settings of>/= 2460 psig and</= 2510 psig. The tested valve was within the ASME code acceptance band of+/- 3% (2411-2559 psig). Based on the lift pressure meeting the 1ST program (ASME code) monitored requirements, there was no 1ST scope expansion for the PSVs.
EVENT ANALYSIS
Setpoint Drift of the PSV (Manufacturer: Crosby, Model Number: HB-86-BP, Serial Number: N56963-01-0012) due to spring relaxation was determined to be the cause of the failure.
REPORTABILITY AND SAFETY ASSESSMENT
This failure constitutes a condition that is reportable pursuant to 1 O 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. Since the as-found lift setpoint was lower than the allowed value in the TS, the condition did not have an adverse impact on its over-pressurization function. This is within the safety analysis assumptions that are credited for PSVs, and the plant remained bounded by the accident analyses in the Final Safety Analysis Report (FSAR). Therefore, this condition had no significant effect on the health and safety of the public. There was no release of radioactivity.
CORRECTIVE ACTIONS
The PSV was replaced on October 24, 2020 during the 2R27 refueling outage. The as-left setpoints were within +/- 1 %
tolerance. Based on previous events Farley has initiated further corrective actions including a spring replacement schedule for all PZR Safety Valves.
PREVIOUS SIMILAR EVENTS
Similar events were reported for Unit 1 in LER 2018-001-00, and LER 2019-001 and for Unit 2 in LER 2017-003-00 OTHER SYSTEMS AFFECTED:
No other systems were affected by this event. Page 2
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