05000311/LER-2022-001, Invalid Safety Injection and Valid Reactor Trip Due to Inaccurate Steam Generator Pressure Indications
| ML23052A211 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 02/21/2023 |
| From: | Mulholland T Public Service Enterprise Group |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| LR-N23-0015 LER 22-001-00 | |
| Download: ML23052A211 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation |
| 3112022001R00 - NRC Website | |
text
PSEG Nuclear LLC P.O. Box 236, Hancocks Bridge, NJ 08038-0236 0 PSEG LR-N23-0015 February 21, 2023 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-001
Subject:
Salem Generating Station, Unit 2 Renewed Facility Operating License No. DPR-75 Docket No. 50-311 Licensee Event Report 2022-001-00, Nuclear LLC 10 CFR 50.73 Invalid Safety Injection and Valid Reactor Trip Due to Inaccurate Steam Generator Pressure Indications PSEG Nuclear LLC submits Licensee Event Report (LER) Number 2022-001-00, "Invalid Safety Injection and Valid Reactor Trip Due to Inaccurate Steam Generator Pressure Indications" per 10 CFR 50.73(a)(2)(iv)(A) and limiting condition for operation 3.5.2 ACTION b.
There are no regulatory commitments contained in this letter.
Please contact Bernadette Cizin at (856) 339 - 2206 should you have any questions.
Sincerely, Thomas P. Mulholland for Richard J. Desanctis, Jr.
Plant Manager, Salem Generating Station Attachment: Licensee Event Report 2022-001-00
Document Control Desk Page 2 LR-N23-0015 cc:
USNRC Regional Administrator - Region 1 USNRC NRR Project Manager - Salem USNRC Senior Resident Inspector-Salem NJ Department of Environmental Protection, Bureau of Nuclear Engineering President & Chief Nuclear Officer, PSEG Nuclear Senior Vice President, PSEG Nuclear Operations Site Vice President, Salem Plant Manager, Salem Vice President, PSEG Nuclear Engineering Executive Director Regulatory Affairs & Nuclear Oversight Director Site Regulatory Compliance, Regulatory Affairs Manager, Nuclear Oversight Corporate Commitment Coordinator, PSEG Nuclear, LLC Records Management
Abstract
On December 24, 2022, at 0222, Salem Unit 2 automatically tripped from full power. Reactor Protection, Emergency Core Cooling, and Auxiliary Feedwater (AFW) systems actuated as expected in response to an invalid Safety Injection (SI) signal. Motor driven and turbine driven AFW pumps started in response to the SI signal and low steam generator water level, respectively. The direct cause of the invalid SI was inaccurate indication from the SG steam pressure instruments due to the localized freezing of water-filled instrument tubing. A root cause evaluation is ongoing and a supplement to this report will be submitted if causes or corrective actions differ significantly from those described in this report. Preliminary evaluation identified the root cause as incomplete implementation of previous corrective actions.
This event is reportable per 10 CFR 50. 73(a)(2)(iv)(A) and limiting condition for operation 3.5.2. ACTION b.
PLANT AND SYSTEM IDENTIFICATION
Westinghouse - Pressurized Water Reactor {PWR/4}
Plant Protection System/ Indicator, Pressure {JC/Pl}
- Energy Industry Identification System (EIIS) codes and component function identified codes appear as {SS/CCC}
IDENTIFICATION OF OCCURENCE Event Date: December 24, 2022 Discovery Date: December 24, 2022 CONDITIONS PRIOR TO OCCURENCE Salem Unit 2 was in MODE 1 operating at full power.
DESCRIPTION OF OCCURRENCE On December 24, 2022, at 0222, an automatic reactor trip occurred at Salem Unit 2 as a result of an invalid Safety Injection (SI) signal. Inaccurate Steam Generator (SG) pressure indication for SGs 22 and 24 resulted in two high differential pressure setpoint signals. This met the 2-out-of-3 coincidence logic, generating the invalid SI signal. A valid reactor trip signal was generated due to SI actuation. The Emergency Core Cooling (ECCS) and Reactor Protection Systems (RPS) functioned as expected. Motor and steam driven Auxiliary Feedwater (AFW) pumps actuated appropriately. Operators stabilized the plant, no equipment complications occurred, and the Emergency Operating Procedures were exited.
This was the thirteenth ECCS actuation reportable pursuant to Technical Specification (TS) 3.5.2 ACTION b.
CAUSE OF EVENT
The inaccurate indications from the SG pressure sensors were caused by localized freezing of water-filled instrument tubing located directly below the outer penetration area intake dampers. Ambient temperatures were less than 10 degrees Fahrenheit with winds averaging up to 45 miles per hour. Plenum dampers near instrument tubing for 22 and 24 SG steam pressure sensors were open.
An ongoing root cause analysis preliminarily identified incomplete implementation of corrective actions from a similar cold weather event in 2003. A supplement will be submitted if the completed root cause analysis identifies causes or corrective actions that significantly differ from those reported herein.
SAFETY CONSEQUENCES AND IMPLICATIONS
There were no safety consequences as a result of this event. Plant response to the failed SG pressure instrumentation was per design.
PREVIOUS EVENTS In January 2003, a Salem Unit 2 main steam line pressure channel failed high due to suspected freezing of the indicating lines. This did not result in a reportable plant event; however, a root cause evaluation of the occurrence was completed in 2003. In 2009 and 2019, cold weather conditions degraded main condenser heat removal and led to Salem Unit 2 plant trips (LER 2010-001-00, ADAMS Accession No. ML100640546 and LER 2019-001-00, ADAMS Accession No. ML19091A260).
CORRECTIVE ACTIONS
- 1. The water-filled tubing was thawed;
- 2. The affected water-filled lines for both units were insulated;
- 3. The dampers were secured in a closed position via temporary modification;
- 4. An extent of condition review was performed;
- 5. The ongoing root cause analysis is evaluating and will develop additional corrective actions to prevent recurrence;
- 6. This evaluation and any identified improvements will be tracked in PSEG's corrective action program.
COMMITMENTS
There are no regulatory commitments contained in this LER. Page 3
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