05000278/LER-2023-001, Standby Liquid Control Pump Inoperable for Greater than LCO Window Due to Gas Intrusion
| ML23311A061 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 11/07/2023 |
| From: | Searer J Constellation Energy Generation |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| CCN: 23-78 LER 2023-001-00 | |
| Download: ML23311A061 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 2782023001R00 - NRC Website | |
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10 CFR 50.73 CCN: 23-78 November 7, 2023 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001
Subject:
Peach Bottom Atomic Power Station (PBAPS) Unit 3 Subsequent Renewed Facility Operating License No. DPR-56 NRC Docket No. 50-278 Licensee Event Report (LER) 2023-001-00 Standby Liquid Control Pump Inoperable for Greater than LCO Window due to Gas Intrusion The subject report is being submitted in accordance with 50.73(a)(2)(i)(B) for any operation or condition which was prohibited by the plant's Technical Specifications.
There are no commitments contained in this letter. If you have any questions, please contact the Peach Bottom Regulatory Assurance Manager, Mr. Wade Scott at (717) 456-304 7.
Respectfully, 4-,r:2-Jeremy C. Searer Acting Plant Manager Peach Bottom Atomic Power Station Enclosure cc:
USNRC, Administrator, Region I USNRC, Senior Resident Inspector W. DeHaas, Commonwealth of Pennsylvania S. Seaman, State of Maryland B. Watkins, PSE&G, Financial Controls and Co-Owner Affairs
Abstract
On September 9, 2023, during performance of a functional test, the Unit 3 B Standby Liquid Control Pump did not produce discharge pressure. The pump was declared inoperable and Technical Specification Limiting Condition for Operation (LCO) 3.1.7 Condition B was entered. Troubleshooting identified that the pump and part of the discharge piping was not sufficiently filled with water. The most likely source of gas intrusion was the nitrogen filled accumulator located on the discharge piping between the pump and the discharge check valve. The piping was refilled and the accumulator was replaced, after which the pump was run successfully. The system was restored to operable and the LCO was exited on September 12, 2023. The gas leakage rate was slow and therefore, the system was likely inoperable longer than the LCO-allowed outage time (i.e., 7 days).
Therefore, the condition is being reported under 10CFR 50.73(a)(2)(i)(B). There were no other systems which were inoperable during this identified condition that contributed to this event. There were no actual safety consequences as a result of this event.
(See Page 2 for required number of digits/characters for each block)
(See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/) Page 3 of 3 a loss of coolant accident (LOCA) involving significant fission product releases. The SLC system consists of two redundant trains, either of which is sufficient to perform its safety function.
There were no other systems which were inoperable during this identified condition. The 3A SLC train demonstrated full functional capability by performance of a surveillance test on September 3, 2023. There were no actual safety consequences as a result of this event, because the redundant train maintained operability.
Corrective Actions
The Unit 3 B SLC accumulator bladder was replaced to restore the subsystem to full function. Investigation into the cause of the bladder leakage is ongoing. If the results of this investigation substantially change the assessment of this condition or planned corrective actions, a supplement to this LER will be submitted.
The remaining SLC discharge lines (2A, 2B, and 3A) were examined by ultrasonic testing on October 9, 2023.
All three discharge lines contained gas voids, which were significantly less than what was discovered on the 3B line. None of the discovered gas voids extended to the pump casings or internals. The 3A pump was operated with gas voids present, successfully demonstrating that this volume of gas intrusion posed no adverse impact to the pump function. The 3B pump was also examined at this time, and the piping was full of water. The SLC pump discharge process piping will be periodically monitored until replacement accumulator bladders can be procured and installed.
Previous Similar Events
Peach Bottom has not previously experienced a failure of a SLC system accumulator bladder that adversely impacted pump performance.