05000387/LER-2020-002-01, Inoperability of Unit 1 B Residual Heat Removal Service Water Pump Due to the Circuit Breaker Spring Charging Motor Contact Actuator Being Out of Adjustment
| ML21041A348 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  (NPF-014) |
| Issue date: | 02/10/2021 |
| From: | Cimorelli K Susquehanna, Talen Energy |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| PLA-7916 LER 2020-002-01 | |
| Download: ML21041A348 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3872020002R01 - NRC Website | |
text
February 10, 2021 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 50-387 /2020-002-01 UNIT 1 LICENSE NO. NPF-14 PLA-7916 TALEN~
ENERGY 10 CFR 50.73 Docket No. 50-387 Attached is Licensee Event Report (LER) 50-3 87/2020-002-01. The LER supplement reports an event involving the failure to start of the Unit 1 "B" Residual Heat Removal Service Water pump that was determined to be reportable in accordance with 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by Technical Specifications.
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 50-387/2020-002-01 Copy:
NRC Region I Mr. C. Highley, NRC Senior Resident Inspector Ms. S. Goetz, NRC Project Manager Mr. M. Shields, PA DEP/BRP
Abstract
On July 1, 2020 at approximately 20:26, the Unit 1 B Residual Heat Removal Service Water (RHRSW) pump did not start when being placed into service for Spray Pond Cooling testing, resulting in the pump being declared inoperable.
Upon the discovery of the condition, Susquehanna entered Technical Specification (TS) 3.7.1 Condition B for one RHRSW subsystem being inoperable. Investigation at the pump circuit breaker identified the closing springs did not recharge following the circuit breakers last closing operation. Following maintenance, the spring charging motor operated as expected and the breaker was tested successfully. TS 3.7.1 Condition B was exited on July 2, 2020 at approximately 02:44.
Based on the investigation completed, the condition is considered to have existed for longer than allowed by TS 3.7.1.
The condition is being reported in accordance with 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by TS. The direct cause of the event was the Eaton/Cutler-Hammer 4.16kV vacuum circuit breaker spring charging motor contact actuator being out of adjustment. Actuator age was determined to be the most likely causal factor, combined with the original equipment manufacturer vendors failure to recommend a periodic replacement for the circuit breakers two limit switches. Key corrective actions include: replaced the 1B RHRSW pump circuit breaker and a planned revision to the preventive maintenance strategy for the spring charging motor actuator based on vendor recommendations. There were no actual consequences to the health and safety of the public as a result of this event.
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CONDITIONS PRIOR TO EVENT
Unit 1 - Mode 1, approximately 100 percent Rated Thermal Power Unit 2 - Mode 1, approximately 100 percent Rated Thermal Power There were no structures, systems, or components that were inoperable at the start of the event that contributed to the event.
EVENT DESCRIPTION
On July 1, 2020 at approximately 20:26, the Unit 1 B Residual Heat Removal Service Water (RHRSW) pump (1P506B) [EIIS System Code/Component Code: BI/P] did not start when being placed into service for Spray Pond Cooling testing, resulting in the pump being declared inoperable. Upon discovery of the condition, Susquehanna entered Technical Specification (TS) 3.7.1 Condition B for one RHRSW subsystem being inoperable.
On July 2, 2020, investigation at the pump circuit breaker (1A20408) [EIIS Component Code: 72]
identified the closing springs did not recharge following the circuit breakers last closing operation on June 21, 2020 at approximately 07:35. Following maintenance, the spring charging motor operated as expected and the breaker was tested successfully. TS 3.7.1 Condition B was exited on July 2, 2020 at approximately 02:44.
Based on the investigation completed, the condition is considered to have existed for longer than allowed by TS 3.7.1. The condition is being reported in accordance with 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by Technical Specification.
CAUSE OF EVENT
The direct cause of the event was the Eaton/Cutler-Hammer 4.16kV vacuum circuit breaker spring charging motor contact actuator being out of adjustment with the motor cut off cam, resulting in the spring charging motor contact not experiencing full travel. Additionally, age was determined to be the most likely causal factor, combined with the original equipment manufacturer vendors failure to recommend a periodic replacement for the circuit breakers two limit switches.
ANALYSIS/SAFETY SIGNIFICANCE
During the period the 1B RHRSW pump was inoperable, the 1A RHRSW pump was verified to be operable. An engineering evaluation was completed to analyze having only the 1A RHRSW pump available with the 1B RHRSW pump inoperable. The engineering evaluation concluded that, with only the 1A RHRSW pump in operation, the accident analysis assumptions were met and the RHRSW system could perform its design function. Based on the engineering evaluation and verification that the 1A RHRSW pump was operable during the period the 1B RHRSW pump was inoperable, 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
Key corrective actions include:
- 1. Replaced 1B RHRSW pump circuit breaker 1A20408.
- 2. Revise the preventative maintenance strategy for the spring charging motor contact actuator and associated limit switch based on overhaul vendor recommendation.
COMPONENT FAILURE INFORMATION
Component failure information is as follows:
Manufacturer: EATON/Cutler-Hammer Model No.: 50DHP-VR-250U
Description
5kV Vacuum Replacement Metal Clad Circuit Breaker
PREVIOUS OCCURRENCES
None.