05000416/LER-1917-007, Regarding Engineered Safety Feature System Actuations Due to the Loss of Engineered Safety Features Transformer 11

Regarding Engineered Safety Feature System Actuations Due to the Loss of Engineered Safety Features Transformer 11

ML18036A153
Person / Time
Site:	Grand Gulf
Issue date:	02/05/2018
From:	Emily Larson Entergy Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
GNRO-2018-00003 LER 17-007-00
Download: ML18036A153 (5)

LER-1917-007, Regarding Engineered Safety Feature System Actuations Due to the Loss of Engineered Safety Features Transformer 11

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)(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)(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
4161917007R00 - NRC Website

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GNR0-2018-00003 February 5, 2018 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Entergy Operations, Inc.

P. 0. Box 756 Port Gibson, MS 39150 Eric A. Larson Site Vice President Grand Gulf Nuclear Station Tel. (601) 437-7500 10CFR50.73

SUBJECT:

Licensee Event Report 2017-007-00, Engineered Safety Feature System Actuations *due to the loss of loss of Engineered Safety Features Transformer 11

Dear Sir or Madam:

Grand Gulf Nuclear Station, Unit 1 Docket No. 50-416 License No. NPF-29 Attached Licensee Event Report 2017-007-00, Engineered Safety Feature System Actuations due to the loss of loss of Engineered Safety Features Transformer 11.

• This letter contains no new commitments. If you have any questions or require additional information, please contact Dougias N~_ve at 601-437-2103.

Sincerely, Z-Ci*~

Eric A. Larson Site Vice President Grand Gulf Nuclear Station EAL/ram

• :~!

\\.. *

Attachment:

Licensee* Event Repo'rt 2017-007-00 I

cc: see next page

GNR0-2018-00003.

Page 2 of 2 U.S. Nuclear Regulatory Commiss.ion ATTN: Mr. Siva Lingam Mail Stop OWFN 8 81 Rockville, MD 20852-2738 NRC Senior Resident Inspector Grand Gulf Nuclear Station Port Gibson, MS 39150 U. S. Nuclear Regulatory Commission ATTN: Mr. Scott Morris, NRR/DORL (w/2)

Mail Stop OWFN 8 81 Washington, DC 20555-0001 I'-, *., **

NRC. FORM 366 (04-2017)

1. FACILITY NAME

'~*J U;S. NUCLEAR REGULATO-R.Y COM!'JIISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 0313112020 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-rmldoc-collectionslnuregslstaff/sr1022/r3/)

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

2. DOCKET NUMBER I

Grand Gulf Nuclear Station, Unit 1 05000 416 1

3. PAGE 1 OF3

4. TITLE Engineered Safety Feature System Actuations due to the loss of Engineered Safety Features Transformer 11

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

8. OTHER FACILITIES INVOLVED MONTH DAY YEAR 12 12 2017

9. OPERA TING MODE

10. POWER LEVEL 18%

YEAR I SEQUEN. TIAL I REV MONTH NUMBER NO.

DAY 2017 - 007 - 00 02 05 YEAR 2018 FACILITY NAME N/A FACILITY NAME N/A DOCKET NUMBER 05000 N/A DOCKET NUMBER 05000 N/A

11. THIS REPORT IS SUBMITTED PURSU~T TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)

D 20:2:2'6((~)..

[] 20.2203(a)(3)(i)

D 50.73(a)(2)(ii)(A)

D 50.73(a)(2)(viii)(A)

D 20.2201 (d)

[,] 20.2203(a)(3)(ii)

D oO. 73(a)(2)(ii)(B)

D 50. 73(a)(2)(viii)(B)

D 20.2203(a)(1)

D 20.2203(a)(4)

D 50.73(a)(2)(iii)

D 50.73(a)(2)(ix)(A)

D 20.2203(~)(2)(i)

D 50.36(c)(1 )(i)(A)

~ 50.73(a)(2)(iv)(A)

D 50.73(a)(2)(x) 0 20.2203(a)(2)(ii)

[] 50.36(c)(1)(ii)(A) 0 50.73(a)(2)(v)(A)

. 0 ?3.71(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 50. 73(a)(2)(v)(C)

D 73. 77(a)(1)

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) 0 50.73(a)(2)(i)(B)

D 50.73(a)(2)(vii)

D 73.77(a)(2)(ii) 0 50. 73(a)(2)(i)(C)

D OTHER. Specify in A~stract below or in =

DESCRIPTION

2: DOCKET YEAR 05000 416

~- LER NUMBER SEQUENTIAL NUMBER 2017-007-00 At approximately 0918 hours0.0106 days <br />0.255 hours <br />0.00152 weeks <br />3.49299e-4 months <br /> on Tuesday, December 12, 2017, while operating in MODE 1 at approximately 18 percent power, the Grand Gulf Nuclear Station (GGNS) experienced a loss of the Engineered Safety Features (ESF) Transformer 11 [EB] which was powering the Division 1 ESF bus [EA]: The transformer experienced an instantaneous ground resulting in a transformer lockout and loss of pow~(to the ESF bus. .:Subsequently, the station experienced an automatic start of the Division 1 Emergency Diesel Generator [EK] and the partial isolation of the primary and secondary containment buildings. Both of the system actuations were expected responses to a loss of ESF bus and both systems responded as designed. The direct cause of ESF actuations was the loss of ESF Transformer 11.

Additionally, GGNS experienced an unrelate,9: isolation of the Reactor Core Isolation Cooling System [BN] upon restoration of power. Thi/isolation of the Reactor Core lsolatia*n Cooling System did not result in a loss of safety function. The cause of this isolation is under investigation and will be documented in accordance with the GGNS corrective action program.

. REPORTABILITY This event is reportable to the NRC in accordance with 10 CFR 50. 72(b)(3)(iv)(A) and 10 CFR 50.73(a)(2)(iv)(A) as an event or condition resulting in a valid actuation of a ESF system.

The 10 CFR 50. 72 repqrjing requirements*.\\vvere met with the completion of Emergency Notification

. System (ENS) Notificatk,ri 5~115, at 17 40. lle>Urs eastern standard time on December 12, 2017.

CAUSE

Direct Cause:

The direct cause of the ESF actuation was the loss of ESF Transformer 11 and the opening of the transformer feeder breaker due to an instantaneous ground.

{';-

Apparent Cause:

The most probable cause is a ground on one of the feeder cables to ESF Transformer 11.

However, the investigation and causal analysis is ongoing at this time and this licensee event report will be supplemented upon completion of the GGNS causal analysis.

J

(

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NRC FORM (6-2016) 366A U.S. NUCLEARREGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 3/31/2020 LICENSEE;:EVEN17 REPORT (LER). ;

CONTI NUATiON *SHEET (See NUREG-1022, R.3 for instruction and guidance for completing this fotm http://www.nrc.gov/reading-rm/doc-collections/nureqs/staff/sr1022/r3[J

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

1. FACILITY NAME

2. D.QCKET Grand Gulf Nuclear Station, Unit 1 050()0.-416 NARRATIVE

CORRECTIVE ACTIONS

YEAR

3. LER NUMBER SEQUENTIAL NUMBER 2017-007-00 Spare Essential Transformer 21 was placed into service and normal power was restored.

The investigation and causal analysis is ongoing and this licensee event report will be.

supplemented upon completion of GGNS's causal analysis. The planned corrective actions will be included in the corrective action program and may be changed in accordance with the program..,

SAFETY SIGNIFICANCE

There were no nuclear safety consequences-or radiological consequences as a result of this event.

No Technical Specification Safety Limits w~re violated. Upon the loss of Engineered Safety Feature Transformer.11 all required accident mitigation ESF components responded as designed.

, The isolation of the Reactor Core Isolation :cooling System, although unexpected, did not adversely impact the plant's ability to respond to the event.

PREVIOUSLY SIMILAR EVENTS LER 2015-001, Automatic Actuation of the Reactor Protection System (RPS) due to. a Fault in the Protective Relaying Circuitry on the "B" Main Transformer LER 2016-Q_,02, Automatic Actuation of the Reactor Protection System due to "B" Main Transformer Wiring LER 2016-006, Multiple Valid Engineered Safety Feature Actuations Entergy has reviewep Jh,~,'3v~r1t.s listed in th~ licensee event reports (LER) documented above to determine if the correctiv,e actions should have prevented the event documented in this LER.

Based on a preliminary evaluation it has been concluded the established corrective actions would not have prevent this event.

1.;*

Entergy's investiga-tion into the cause. of thi'$ event and the development of corrective actions to preclude recurrence are ongoing. This secffon will be supplemented at the conclusion of this

• effort.

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