05000424/LER-2020-001, Safety-Related Electrical Bus Deenergizing Results in Emergency Diesel Generator Starting
| ML20134J102 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 05/13/2020 |
| From: | John Thomas Southern Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-20-0329 LER 2020-001-00 | |
| Download: ML20134J102 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(B), System Actuation 10 CFR 50.73(a)(2)(iv)(A), System Actuation |
| 4242020001R00 - NRC Website | |
text
~ Southern Nuclear May 13, 2020 Docket No:
50-424 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Jesse Thomas Vice President Vogtle Units 1-2 Vogtle Electric Generating Plant - Unit 1 Licensee Event Report 2020-001-00 Safety-Related electrical bus deenergizing results in Emergency Diesel Generator Starting Ladies and Gentlemen:
7821 River RD Waynesboro GA, 30830 706-848-0004 tel 706-848-3321 fax NL-20-0329 In accordance with the requirements of 10 CFR 50. 73(a)(2)(iv)(A), Southern Nuclear Operating Company is submitting the enclosed Licensee Event Report, 2020-001-00 for Vogtle Electric Generating Plant Unit 1. This letter contains no NRC commitments. If you have any questions, please contact Matthew Horn at (706) 848-1544.
Respectfully submitted, i!~~
Vice President Vogtle 1 &2 JT/KCW Enclosure: Unit 1 Licensee Event Report 2020-001-00 Cc: Regional Administrator NRR Project Manager-Vogtle 1 & 2 Senior Resident Inspector-Vogtle 1 & 2 RType: CVC?OOO
Vogtle Electric Generating Plant-Unit 1 Licensee Event Report 2020-001-00 Safety-Related electrical bus deenergizing results in Emergency Diesel Generator Starting Enclosure Unit 1 Licensee Event Report 2020-001-00
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 04/30/2020 (04-2020)
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~~~
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tJ LICENSEE EVENT REPORT (LER)
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Regulatory Affairs, (3150-0104), Attn: Desk Officer for the Nuclear Regulatory Commission, 725
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(See NUREG-1022, R.3 for instruction and guidance for completing this form 17th Street NW, Washington, DC 20503; e-mail: oira_submission@omb.eop.gov. The NRC may
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. Page Vogtle Electric Generating Plant, Unit 1 05000424 1 OF2
- 4. Title Safety-Related electrical bus deenergizing results in Emergency Diesel Generator Start Signal
- 5. Event Date
- 6. LER Number
- 7. Report Date
- 8. Other Facilities Involved Sequential Rev Facility Name Docket Number Month Day Year Year Month Day Year N/A Number No.
05000 03 21 2020 2020
- - 001
- - 00 05 13 2020 Facility Name Docket Number N/A 05000
- 9. Operating Mode N/A N/A N/A Abstract (Limit to 1400 spaces, i.e., approximately 14 single-spaced typewritten lines)
At 1644 EDT, on March 21, 2020, with Unit 1 in Mode 6, at 000 percent power, approximately 83 degrees Fahrenheit, and depressurized, an actuation of the Unit 1 B-Train Emergency Diesel Generator (EDG) occurred during Engineered Safety Feature Actuation System (ESFAS) testing. The reason for the EDG auto-start signal was a loss of voltage on the Bravo rain, safety related, electrical bus due to the EDG output breaker opening. The EDG output breaker opened due to a Human Performance Error when testing steps were performed out of order. The causes were lack of adherence to accepted procedure use standards and ineffective oversight. The corrective actions include revisions to the ESFAS testing procedures to add clarifying direction on the order of procedure step performance and for resetting the EDG lockout relay and safety injection signal, and dynamic learning activities and oral boards will be performed to verify proper supervisor oversight proficiency.
The EDG was already running at the time of the loss of voltage on the bus. Due to the automatic actuation of systems listed in 10 CFR 50.73(a)(2)(iv)(B), specifically the Emergency Diesel Generator System, this event is reportable under 10 CFR 50.73(a)(2)(iv)(A). The operating crew responded correctly to the event. The applicable abnormal operating procedures were properly entered, and documentation met expectations.
NRC FORM 366 (02-2020)
A.
Event Description
SEQUENTIAL NUMBER
- - 001 REV NO.
- - 00 At 1644 EDT, on March 21, 2020, with plant operating conditions before the event consisting of Unit 1 in Mode 6, at 000 percent power, approximately 83 degrees Fahrenheit, and depressurized, an actuation of the Unit 1 B-Train Emergency Diesel Generator (EDG)[EK] occurred during Engineered Safety Feature Actuation System (ESFAS)[JE] testing. The reason for the EDG auto-start signal was a loss of voltage on the Bravo train safety related electrical bus due to the EDG output breaker opening. The EDG was already running at the time of the loss of voltage on the bus.
The EDG output breaker opened because steps in the ESFAS procedure were performed out of sequence by a Vogtle Licensed Operator. Specifically, the Safety Injection (SI) signal was reset before the lockout relay for the EDG was reset.
This caused the EDG to disconnect from the electrical bus and deenergize the bus. This caused a valid undervoltage signal to be sent to the EDG. In addition, necessary oversight from the Vogtle Senior Reactor Operator was not provided to prevent steps from being performed out of order.
There were no structures, components, or systems that were inoperable at the start of the event that contributed to the event.
Because of the automatic actuation of the Emergency Diesel Generator System, which is listed in 10 CFR 50.73(a)(2)(iv)(B),
this event is reportable under 10 CFR 50.73(a)(2)(iv)(A).
B.
Cause of Event
The causes were lack of adherence to accepted procedure use standards and ineffective oversight.
C.
Safety Assessment
There were no safety consequences as a result of this event. Specifically, Spent Fuel pool cooling was maintained via the 1A Spent Fuel Cooling system, core cooling was maintained via 1A Residual Heat Removal system, "A" train safety related 4160 volt power supplies remained unaffected, there was no radiological release as a consequence of the event, and the shutdown risk assessment remained unaffected.
The operating crew responded correctly to the event. The applicable abnormal operating procedures were properly entered, and documentation met expectations. The event was within the analysis of the UFSAR Chapter 15. There was not a release of radioactivity.
D.
Corrective Actions
The corrective actions included completing revisions to the ESFAS testing procedures to add clarifying direction on the order of procedure step performance and for resetting the EDG lockout relay and safety injection signal. Dynamic learning activities and oral boards are planned to verify proper supervisor oversight proficiency.
E.
Previous Similar Events
None