05000424/LER-2018-002, Manual Reactor Trip Due to Receiving Rod Control Urgent Failure Alarm During Low Power Physics Testing

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Manual Reactor Trip Due to Receiving Rod Control Urgent Failure Alarm During Low Power Physics Testing
ML18337A188
Person / Time
Site: Vogtle Southern Nuclear icon.png
Issue date: 12/03/2018
From: Myers D
Southern Nuclear Operating Co
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-18-1425 LER 2018-002-00
Download: ML18337A188 (4)
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LER-2018-002, Manual Reactor Trip Due to Receiving Rod Control Urgent Failure Alarm During Low Power Physics Testing
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)(ix)(A)
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)(i)
4242018002R00 - NRC Website
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text

A Southern Nuclear DEC 0 3 2018 Docket No:

50-424 U.S. Nuclear Regulatory Commission A TIN: Document Control Desk Washington, D.C. 20555-0001 Darin J. Myers Vice President Vogtle Units 1-2 Vogtle Electric Generating Plant - Unit 1 Licensee Event Report 2018-001-00 7821 River RD Waynesboro GA, 30830 706-848-0004 tel 706-848-3321 fax NL-18-1425 Manual Reactor Trip due to receiving Rod Control Urgent Failure Alarm during Low Power Physics Testing Ladies and Gentlemen:

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, 2018-002-00 for Vogtle Electric Generating Plant Unit 1. This letter contains no NRC commitments. If you have any questions, please contact Matt Horn (706) 848-1544.

Respectfully submitted, Darin J. Myers Vice President Vogtle 1& 2 DJM/KCW Enclosure: Unit 1 Licensee Event Report 2018-002-00 Cc: Regional Administrator NRR Project Manager-Vogtle 1 & 2 Senior Resident Inspector - Vogtle 1 & 2 RType: CVC7000

Vogtle Electric Generating Plant - Unit 1 Licensee Event Report 2018-002-00 Manual Reactor Trip due to receiving Rod Control Urgent Failure Alarm during Low Power Physics Testing Enclosure Unit 1 Licensee Event Report 2018-002-00

NRCFORM366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-4104 EXPIRES: 03131/2020 (04-2018)

, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

.Page Vogtle Electric Generating Plant, Unit 1 05000424 1 OF2 4.Title Manual Reactor Trip due to receiving Rod Control Urgent Failure Alarm during low Power Physics Testing

5. Event Date
6. LER Number
7. Report Date
8. Other Facilities Involved Sequential Rev Facility Name pocket Number Month Day Year Year Number No.

Month Day Year N/A

~5000 10 04 2018 2018

- 002
- DO 12 03 2018 Facility Name pocket Number N/A

~5000

9. ()pending Mode
11. This ReportisSubmitlad Pursuant to the-- d10 CFR§:_(Check all that apply) 2 0 20.2201(b) 0 20.2203(a)(3)(i) 0 50.73(a)(2)(ii)(A) 0 50.73(a)(2)(viii)(A) 0 20.2201(d) 0 20.2203(a)(3)(ii) 0 50.73(a)(2)(ii)(B) 0 50.73(a)(2)(viii)(B) 0 20.2203(a)(1) 0 20.2203(a)(4) 0 50.73(a)(2)(iii) 0 50.73(a)(2)(ix)(A) 0 20.2203(a)(2)(i) 0 50.36(c)(1 )(i)(A) 18150.73(a)(2)(iv)(A) 0 50.73(a)(2)(x)
10. Power Level 0 20.2203(a)(2)(ii) 0 50.36(c)(1 )(ii)(A) 0 50.73(a)(2)(v)(A) 0 73.71(a)(4) 000 0 20.2203(a)(2)(iii) 0 50.36(c)(2) 0 50.73(a)(2)(v)(B) 0 73.71(a)(5) 0 20.2203(a)(2)(iv) 0 50.46(a)(3)(ii) 0 50.73(a)(2)(v)(C) 0 73.77(a)(1) 0 20.2203(a)(2)(v) 0 50.73(a)(2)(i)(A) 0 50.73(a)(2)(v)(D) 0 73.77(a)(2)(ii) 0 20.2203(a)(2)(vi) 0 50.73(a)(2)(i)(B) 0 50. 73(a)(2)(vii) 0 73.77(a)(2)(iii) 0 50.73(a)(2)(i)(C) 0 Other (Specify in Abstract below or in NRC Form 366A
12. Licensee Contact for this LER icensee Contact

~:lephone Number (Include Area Code)

~ogtle Electric Generating Plant, Matthew Hom, Regulatory Affairs Manager 06-848-1544

13. Ccmplele One Uneforeach Failure Desc:rbld in this Report

Cause

System Component Manufacturer Reportable To ICES

Cause

System Component Manufacturer Reportable To ICES P<

'M RECT W351

~

N/A

14. Supplemental Report Expected Month Day Year 0 Yes (If yes, complete 15. Elcpected Submission Date) 18] No
15. Expected Submission Date NIA NIA NIA f"bstract (Lim~ to 1400 spaces, i.e.. approximately 14 single-spaced lypewritlen Unes)

~t 0544 EDT on October 4, 2018, with Unit 1 in Mode 2 with reactor power in the intermediate range performing Low Power Physics Testing, the reactor was manually tripped due to a Rod Control Urgent Failure alarm. The trip was not complex, with all systems responding normally. Operations stabilized the plant in Mode 3. Decay heat was removed through the main steam system through the steam dumps and into the condenser.

This event had no adverse effects on the health and safety of the public and is of very low safety significance. This event is eportable under 1 OCFR50. 73(a)(2)(iv)(A) due to manual actuation of systems listed in 1 OCFR50. 73(a)(2)(iv)(B).

Unit 2 was not affected.

NRC FORM 366 (02-2018)

A. Event Description

3. LER IUt'IBER SEQUENTIAL NUMBER
- 002 REV NO.
  • 00 On October 04, 2018, at approximately 0544 EDT, Unit 1 was in Mode 2, 0 percent power performing Low Power Physics Testing (LPPT) following a restart from refueling. During this testing, individual control rods are fully inserted into the core to test their amount of negative reactivity. While this testing was occurring, a rod control urgent failure alarm was received in the Control Room. Operators responded by tripping the reactor. This initiated a Reactor Protection System actuation. Feedwater was already isolated, and the auxiliary feedwater system continued to feed the steam generators. Decay heat was removed via the main steam system through the steam dumps and into the condenser.

8. Cause of Event

The cause of the event was a failure in the Rod Control System of three Power Control Bridge Lift Thyristor.

C. Safety Assessment

When the Control Room Operators manually initiated the trip, all systems responded as designed. The Reactor Protection System (RPS) actuated as designed, and all the control rods fully inserted into the core. A turbine trip was not necessary because turbine was not online at the time. Because all systems responded as required and there were no adverse effects on the health and safety of the public, the safety signifrcance of this event is very low.

D. Corrective Actions

The thyristors, controller cards, and other components for the Control Rod control system were replaced and the system was tested successfully.

E. Previous Similar Events

ICES #143200 -Wolf Creek Unit 1; Failed rod control thyristor caused urgent rod control failure and forced manual scram for shutdown to repair.

ICES# 306329 - Farley Unit 1; Rod Control System Urgent Failure Alarm Light Came In Due to an Intermittent Thyristor Failure

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