05000461/LER-2023-002, Reactor Core Isolation Cooling System Inoperable Prior to Mode Change
| ML24051A083 | |
| Person / Time | |
|---|---|
| Site: | Clinton  |
| Issue date: | 02/16/2024 |
| From: | Plumey N Constellation Energy Generation |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| U-604795 LER 2023-002-00 | |
| Download: ML24051A083 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 4612023002R00 - NRC Website | |
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U-604795 February 16, 2024 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Clinton Power Station, Unit 1 Facility Operating License No. NPF-62 NRC Docket No. 50-461 Subject: Licensee Event Report 2023-002-00
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t l 10 CFR 50.73 Enclosed is Licensee Event Report (LER) 2023-002-00: Reactor Core Isolation Cooling Inoperable Prior to Mode Change. This report is being submitted in accordance with the requirements of 10 CFR 50.73.
There are no regulatory commitments contained in this report.
Should you have any questions concerning this report, please contact Mr. David Livingston, Regulatory Assurance Manager, at (217) 937-2800.
Respectfully,
- l-LJ-~
Norha Z. Plumey Site Vice President Clinton Power Station
Attachment:
Licensee Event Report 2023-002-00 cc:
Regional Administrator - Region Ill NRC Senior Resident Inspector - Clinton Power Station Office of Nuclear Facility Safety - Illinois Emergency Management Agency
Abstract
On October 10, 2023, at 23:02 CST, the Reactor Core Isolation Cooling (RCIC) system tripped during performance of Surveillance Requirement (SR) 3.5.3.3. This SR is performed when RCIC steam supply pressure is at the higher operating ranges of the system to verify that the RCIC pump can develop the required flow rate against a system head corresponding to reactor pressure. The system was restored to operable on October 16, 2023, at 02:51 CST following replacement and calibration of the Electric Governor-Remote (EG-R). Engineering personnel suspected that the RCIC system trip was due to a faulty EG-R; however, subsequent failure analysis identified no significant issues with the EG-R. On December 19, 2023, Engineering personnel determined that work performed on August 28, 2023 affected functionality of the EG-R and caused RCIC to be inoperable per Technical Specifications (TS) 3.5.3, RCIC System.
This event is reportable in accordance with 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by TS 3.0.4. Specifically, on October 9, 2023, at 05:14 CST, during unit startup following a refueling outage, the Applicability for TS 3.5.3 was entered (i.e.,
Mode 2 with reactor steam dome pressure greater than 150 psig) with the RCIC system inoperable. In addition, the unit was taken to Mode 1 on October 10, 2023.
(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
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CAUSE OF THE EVENT
Cause information will be provided in a supplement to this LER.
SAFETY CONSEQUENCES
The condition described in this LER is reportable under 10 CFR 50.73(a)(2)(i)(B), any operation or condition which was prohibited by the plant's TS, due to entering the Applicability for TS 3.5.3 with the RCIC system inoperable. The were no actual safety consequences associated with the event. The RCIC system is not an engineered safety feature and no credit is taken in the safety analysis for its operation. Furthermore, RCIC does not meet the threshold for a failure of a single train safety system since it is not included in the safety analysis. High Pressure Core Spray (HPCS) system remained operable and therefore able to perform its safety function during the entire period that RCIC was inoperable.
There were no actual demands for either RCIC or HPCS during this period.
CORRECTIVE ACTIONS
The EG-R was replaced and the replacement unit calibrated in accordance with the EPRI Terry Turbine Maintenance Guide. Additional corrective actions will be provided in a supplement to this LER.
PREVIOUS OCCURENCES
A review of Licensee Event Reports for the past five years identified no previous similar occurrences at Clinton Power Station.