05000270/LER-2021-005, Automatic Reactor Trip Due to Spurious Trip Signal Concurrent with System Testing
| ML22039A333 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 02/08/2022 |
| From: | Snider S Duke Energy Carolinas |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| RA-22-0063 LER 2021-005-00 | |
| Download: ML22039A333 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i) |
| 2702021005R00 - NRC Website | |
text
Steven M. Snider Vice President Oconee Nuclear Station Duke Energy ON01SC l 7800 Rochester Hwy Seneca, SC 29672 o. 864.873.3478 f: 864.873.5791 Steve.Snider@duke-energy.com RA-22-0063 February 8, 2022 10 CFR 50.73 Attn: Document Control Desk U. S. Nuclear Regulatory Commission 11555 Rockville Pike Rockville, MD 20852-2746 Duke Energy Carolinas, LLC Oconee Nuclear Station Unit 2 Docket Number: 50-270 Renewed Operating Licenses: DPR-49
Subject:
Licensee Event Report 270/2021-005, Revision 00 - Unit 2 Automatic Reactor Trip Due to Spurious Trip Signal Concurrent with System Testing Licensee Event Report 270/2021-005, Revision 00, is being submitted pursuant to the requirements of 10 CFR 50.73 to provide notification of the subject event.
There are no regulatory commitments associated with this LER.
There are no unresolved corrective actions necessary to restore compliance with NRC requirements.
If there are questions, or further information is needed, contact Sam Adams, Regulatory Affairs, at (864) 873-3348.
Sincerely, Steven M. Snider Vice President Oconee Nuclear Station Enclosure: Licensee Event Report 270/2021-005 Rev.00
RA-22-0063 February 8, 2022 Page 2 cc (w/Enclosure):
Ms. Laura Dudes, Administrator, Region II U.S. Nuclear Regulatory Commission Marquis One Tower 245 Peachtree Center Ave., NE, Suite 1200 Atlanta, GA 30303-1257 Mr. Shawn Williams, Project Manager U.S. Nuclear Regulatory Commission 11555 Rockville Pike Mail Stop O-08B1A Rockville, MD 20852-2738 Mr. Jared Nadel NRC Senior Resident Inspector Oconee Nuclear Station
NRC FORM 366 (08-2020)
NRC FORM 366 (08-2020)
U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 08/31/2023 LICENSEE EVENT REPORT (LER)
(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/)
- 1. Facility Name Oconee Nuclear Station Unit 2
- 2. Docket Number 0500000270
- 3. Page 1 OF 3
- 4. Title Unit 2 Automatic Reactor Trip Due to Spurious Trip Signal Concurrent with System Testing
- 5. Event Date
- 6. LER Number
- 7. Report Date
- 8. Other Facilities Involved Month Day Year Year Sequential Number Rev No.
Month Day Year Facility Name NA Docket Number 05000 12 10 2021 2021 005 00 02 08 2022 Facility Name Docket Number NA 05000
- 9. Operating Mode 1
- 11. This Report is Submitted Pursuant to the Requirements of 10 CFR §: (Check all that apply) 20.2201(b) 20.2203(a)(3)(i) 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(A) 20.2201(d) 20.2203(a)(3)(ii) 50.73(a)(2)(ii)(B) 50.73(a)(2)(viii)(B) 20.2203(a)(1) 20.2203(a)(4) 50.73(a)(2)(iii) 50.73(a)(2)(ix)(A) 20.2203(a)(2)(i) 50.36(c)(1)(i)(A) 50.73(a)(2)(iv)(A) 50.73(a)(2)(x)
- 10. Power Level 073 20.2203(a)(2)(ii) 50.36(c)(1)(ii)(A) 50.73(a)(2)(v)(A) 73.71(a)(4) 20.2203(a)(2)(iii) 50.36(c)(2) 50.73(a)(2)(v)(B) 73.71(a)(5) 20.2203(a)(2)(iv) 50.46(a)(3)(ii) 50.73(a)(2)(v)(C) 73.77(a)(1) 20.2203(a)(2)(v) 50.73(a)(2)(i)(A) 50.73(a)(2)(v)(D) 73.77(a)(2)(ii) 20.2203(a)(2)(vi) 50.73(a)(2)(i)(B) 50.73(a)(2)(vii) 73.77(a)(2)(iii) 50.73(a)(2)(i)(C)
Other (Specify in Abstract below or in
CORRECTIVE ACTIONS
Immediate:
- 1. Revised IP/2/A/0315/018 A,B,C,D TXS RPS Channel A,B,C,D Statalarm and Event Recorder Verification Test and Manual Trip Keyswitch Test procedures to separate the tests, allowing the trip portion to be performed during mode 3 and the alarm verification during mode 1 with a channel in bypass.
- 2. Replaced 2NI-5 upper linear amplifier.
- 3. Completed electrical testing for 2NI-5.
Planned:
- 1. Process procedure revision to change unit status for completion of Manual Trip Keyswitch portion for IP/1,2,3/A/0315/018 A,B,C,D TXS RPS Channel A,B,C,D Statalarm and Event Recorder Verification Test and Manual Trip Keyswitch Test procedures.
- 2. Training to Operations, Maintenance, and Engineering.
- 3. Address degradation issues found during electrical testing.
SAFETY ANALYSIS
The automatic reactor trip of Oconee Unit 2 on December 10, 2021 is considered to be an uncomplicated reactor trip event with no impact on public health and safety. The post-trip response was as expected with main feedwater flow to the steam generators maintained throughout the event. No Emergency Core Cooling System (ECCS) or other automatic safety system actuations occurred in response to this event and no other equipment problems were experienced that required unusual operator actions. It was noted that one main steam relief valve failed to fully reseat at the normal expected pressures; however, the steam leakage was relatively small, and no safety limits were challenged. The valve was subsequently reseated by following procedural guidance to incrementally lower steam generator pressure. A post-trip review found no procedural or human performance issues with the operator response to the event. With the exception of the Standby Shutdown Facility (SSF) Reactor Coolant Makeup Pump (RCMUP)
[P], there were no important plant systems out of service or other safety significant activities being conducted at the time of the trip. The SSF RCMUP being out of service does not have a significant impact on core damage risk for a reactor trip event where all electrical power sources and normal RCP seal cooling are maintained. Therefore, it is it is concluded that the impact on core damage risk was very small and the event had no impact on public health and safety.
ADDITIONAL INFORMATION
A review of Duke Energys Corrective Action Program did not identify any Oconee LERs or events in the last 3 years that involved the same underlying concerns or reasons as this event.
This event is considered INPO IRIS Reportable. There were no releases of radioactive materials, radiation exposures or personnel injuries associated with this event.