05000388/LER-2021-005-01, Condition Prohibited by Technical Specification Due to Setpoint Drift Attributed to Age Related Degradation
| ML22101A186 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 04/11/2022 |
| From: | Cimorelli K Susquehanna, Talen Energy |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| PLA-7997 LER 2021-005-01 | |
| Download: ML22101A186 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3882021005R01 - NRC Website | |
text
April 11, 2022 Kevin Cimorelli Site Vice President Attn: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Susquehanna Nuclear, LLC 769 Salem Boulevard Berwick, PA 18603 Tel. 570.542.3795 Fax 570.542.1504 Kevin.Cimorelli@TalenEnergy.com SUSQUEHANNA STEAM ELECTRIC STATION LICENSEE EVENT REPORT 50-388/2021-005-01 UNIT 2 LICENSE NO. NPF-22 PLA-7997 TALEN~
ENERGY 10 CFR 50.73 Docket No. 50-388 Attached is Licensee Event Report (LER) 50-388/2021-005-01. The LER supplement reports an event in which the Unit 2 'B' Reactor Protection System and Primary Containment Isolation System were inoperable for longer than allowed by Technical Specifications (TS). The condition is being reported in accordance with 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by TS.
There were no actual consequences to the health and safety of the public as a result of this event.
This letter contains no new or revised regulatory commitments.
K. Cimorelli Attachment: LER 50-388/2021-005-0l Copy:
NRC Region I Mr. C. Highley, NRC Senior Resident Inspector Ms. A. Klett, NRC Project Manager Mr. M. Shields, PA DEP/BRP
Abstract
At approximately 13:50 on December 15, 2021, during surveillance testing, personnel at the Susquehanna Steam Electric Station, Unit 2, found the setpoint for the Unit 2 B Reactor Vessel Water Level Narrow Range Indicator, LISB212N024B, had drifted outside of its Technical Specification (TS) Allowable Value (AV). Operators declared the Reactor Protection System and the Primary Containment Isolation System inoperable, and entered TS 3.3.1.1, Condition A, and TS 3.3.6.1, Condition A. The level indicators setpoint was adjusted to within the TS AV, and TS 3.3.1.1, Condition A, and TS 3.3.6.1, Condition A, were exited at 15:42 on December 15. Based on the information available, the condition is considered to have existed for longer than allowed by TS 3.3.1.1 and TS 3.3.6.1. Therefore, the condition is being reported in accordance with 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by the plants TS.
The cause of the event was determined to be an increase in instrument drift due to age related degradation of LISB212N024B internal micro switch 1A. Contributing to this was that a work order was previously generated to replace the switch but not scheduled. Corrective actions included replacement of LISB212N024B, which included internal micro switches 1A and 1B.
There were no actual safety consequences associated with the described condition.
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CONDITIONS PRIOR TO EVENT
Unit 1 - Mode 1, approximately 98 percent Rated Thermal Power (RTP)
Unit 2 - Mode 1, approximately 100 percent RTP
EVENT DESCRIPTION
At approximately 13:50 on December 15, 2021, during surveillance testing, personnel at the Susquehanna Steam Electric Station, Unit 2, found the setpoint for the Unit 2 B Reactor Vessel Water Level Narrow Range Indicator LISB212N024B [EIIS System/Component Code: JC/LIS] had drifted outside of its Technical Specification (TS) Allowable Value (AV). Operators declared the Reactor Protection System and the Primary Containment Isolation System [JM] inoperable, and entered TS 3.3.1.1, Reactor Protection System (RPS)
Instrumentation, Condition A, and TS 3.3.6.1, Primary Containment Isolation Instrumentation, Condition A.
LISB212N024B was adjusted to within the TS AV, and TS 3.3.1.1, Condition A, and TS 3.3.6.1, Condition A, were exited at 15:42 on December 15.
Based on the information available, the condition is considered to have existed for longer than allowed by TS 3.3.1.1 and TS 3.3.6.1. Therefore, the condition is being reported in accordance with 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by the plants TS.
CAUSE OF EVENT
The cause of the event was determined to be an increase in instrument drift due to age related degradation of LISB212N024B internal micro switch 1A. Contributing to this was that a work order was previously generated to replace the switch but not scheduled.
ANALYSIS/SAFETY SIGNIFICANCE
While LISB212N024B was outside of the TS 3.3.1.1 and TS 3.3.6.1 allowable value, the other trip system channel was available with the exception of a 6.5-hour window when its indicators were out of service for surveillance. Excessive drift of LISB212N024B would not have occurred in the approximate 6.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> taken to satisfactorily surveil the other trip system which immediately followed surveillance of LISB212N024B.
Therefore, RPS and Primary Containment Isolation System would have performed within their safety functions and the condition described herein did not result in a safety system functional failure. Accordingly, this event will not be counted as a safety system functional failure in the Reactor Oversight Process Performance Indicators. There were no actual consequences to the health and safety of the public as a result of this event.
CORRECTIVE ACTIONS
The switch was returned to within TS allowable values. Corrective actions included replacement of LISB212N024B, which included internal micro switches 1A and 1B.
COMPONENT FAILURE INFORMATION
Component: LISB212N024B Reactor Vessel Water Level Narrow Range System: Reactor Protection System Manufacturer: Barton Model: 288A Serial No: 28879
PREVIOUS OCCURRENCES
None.