05000443/LER-2020-001, Manual Reactor Trips Due to Control Rod Bank Unexpectedly Inserting
| ML20209A542 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 07/27/2020 |
| From: | Browne K NextEra Energy Seabrook |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| SBK-L-20101 LER 2020-001-00 | |
| Download: ML20209A542 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation 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)(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)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(v), Loss of Safety Function 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) |
| 4432020001R00 - NRC Website | |
text
July 27, 2020 10 CFR 50.73 Docket No. 50-443 SBK-L-20101 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 NEXTeraM EN~C§~~
Seabrook Station Licensee Event Report (LER) 2020-001-00 Manual Reactor Trips due to Control Rod Bank Unexpectedly Inserting Enclosed is Licensee Event Report (LER) 2020-001-00. This LER reports two similar events that occurred at Seabrook Station on May 29, 2020 and subsequently on June 06, 2020. These events are being reported pursuant to the requirements of 10 CFR 50.73(a)(2)(iv)(A).
Should you require further information regarding this matter, please contact me at (603) 773-7932.
Sincerely, rown Safety Assurance and Leaming Site Director cc:
D. Lew, NRC Region I Administrator J. Poole, NRC Project Manager P. Cataldo, NRC Senior Resident Inspector Nex!Era Energy Seabrook, LLC P.O. Box 300, Seabrook, NH 03874
Enclosure to SBK-L-20101
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 04/30/2020 (04-2020)
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LICENSEE EVENT REPORT (LER)
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3.Page Seabrook Station 05000 443 1
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- 4. Title Manual Reactor Trips due to Control Rod Bank Unexpectedly Inserting
- 5. Event Date
- 6. LER Number
- 7. Report Date
- 8. Other Facilities Involved I
Sequential I Rev Facility Name Docket Number Month Day Year Year Number No.
Month Day Year 05000 Facility Name Docket Number 05 29 2020 2020 -
001 -
00 07 27 2020 05000
- 9. Operating Mode
- 11. This Report is Submitted Pursuant to the Requirements of 1 O CFR §: (Check all that apply)
D 20.2201(b)
D 20.2203(a)(3)(i)
D 50.73(a)(2)(ii)(A)
D 50.73(a)(2)(viii)(A)
D 20.2201(d)
D 20.2203(a)(3)(ii)
D 50.73(a)(2)(ii)(B)
D 50.73(a)(2)(viii)(B) 1 D 20.2203(a)(1)
D 20.2203(a)(4)
D 50.73(a)(2)(iii)
D S0.73(a)(2)(ix)(A)
D 20.2203(a)(2)(i)
D 50.36(c)(1)(i)(A) 0 50.73(a)(2)(iv)(A)
D 50.73(a)(2)(x)
- 10. Power Level D 20.2203(a)(2)(ii)
D 50.36(c)(1)(ii)(A)
D 50.73(a)(2)(v)(A)
D 73.71(a)(4)
D 20.2203(a)(2)(iii)
D 50.36(c)(2)
D 50.73(a)(2)(v)(B)
D 73.71 (a)(5)
D 20.2203(a)(2)(iv)
D 50.46(a)(3)(ii)
D S0.73(a)(2)(v)(C)
D 73.77(a)(1) 100 D 20.2203(a)(2)(v)
D 50.73(a)(2)(i)(A)
D 50.73(a)(2)(v)(D)
D 73.77(a)(2)(i)
D 20.2203(a)(2)(vi)
D 50.73(a)(2)(i)(B)
D 50.73(a)(2)(vii)
D 73.77(a)(2)(ii)
D 50.73(a)(2)(i)(C)
D Other (Specify in Abstract below or in Analysis of the Event I Safety Consequences The function of the Rod Control System is to provide reactor power modulation by manual or automatic control of full length control rod banks in a preselected sequence and for manual operation of individual banks. During these events there was no loss in function of safety systems, structures, or components. There were no significant equipment abnormalities. The condition did not result in a safety system functional failure and had no adverse impact on the on the health and safety of the public.
Corrective Actions
Corrective actions taken after the first event: 1) The associated stationary gripper regulation card within the 1 BD power cabinet was determined to be the most likely cause of the event. A new stationary gripper regulation card was installed and was functionally checked satisfactorily.
Corrective actions taken after the second event: 1) Replaced the suspect phase multiplexing error detector card, phase control card, firing card and regulation card within the 1 BD power cabinet with spare cards that were tested on site by the card manufacturer. 2) Card frame back plane connector and card edge connector pin dimensions for the suspect card locations were measured. All pins associated with the card frame and card edge connectors were reformed to tighten the electrical connections. 3) All other associated card frame and card edge connectors were reformed. 4) Electrical termination point connections within the power control cabinet were inspected. 5) Card re-seating and alignment was verified. 6) Revising the Rod Control Maintenance Plan Preventive Maintenance to include card backplane connector pin reforming. 7) Revising the Single Point Vulnerability (SPV) analysis for the rod control system to include backplane and circuit card edge connectors. 8) Reviewing and revising associated Single Point Vulnerability mitigation strategies for the main feedwater system as well as the solid state protection system to ensure the extent of cause implications from these events are addressed.
Similar Events
There have not been any similar events experienced at Seabrook.
Additional Information
The Energy Industry Identification System (EllS) codes are included in this LER in the following format: [BA - Emergency Feedwater System, AB - Reactor Coolant System, JI - Turbine Steam Bypass System].
This event is being reported under 10 CFR 50. 73(a)(2)(iv)(A) as a safety system actuation of the Reactor Protection System. Page 3
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