05000416/LER-2016-002, Regarding Automatic Actuation of the Reactor Protection System Due to B Main Transformer Wiring

Regarding Automatic Actuation of the Reactor Protection System Due to B Main Transformer Wiring

ML16146A768
Person / Time
Site:	Grand Gulf
Issue date:	05/25/2016
From:	Nadeau J Entergy Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
GNRO-2016/00026 LER 16-002-00
Download: ML16146A768 (7)

LER-2016-002, Regarding Automatic Actuation of the Reactor Protection System Due to B Main Transformer Wiring

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 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)(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
4162016002R00 - NRC Website

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=;YEnfergy GNRO-2016/00026 May 25,2016 u.s. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Entergy Operations, Inc.

P. O. Box 756 Port Gibson, MS 39150 James Nadeau Manager, Regulatory Assurance Grand Gulf Nuclear Station Tel. (601) 437-2103

SUBJECT:

Dear Sir or Madam:

Licensee Event Report (LER) 2016-002-00, Automatic Actuation of the Reactor Protection System due to IB' Main Transformer Wiring Grand Gulf Nuclear Station, Unit 1 Docket No. 50-416 License No. NPF-29 Attached is Licensee Event Report (LER) 2016-002-00, Automatic Actuation of the Reactor Protection System due to 'B' Main Transformer Wiring. This report is-submitted in accordance with Title 10 Code of Federal Regulations 50.73(a)(2)(iv)(A).

This letter contains no new commitments. Should you have any questions or require additional information, please contact James Nadeau at (601) 437-2103.

Sincerely, Attachment: Licensee Event Report (LER) 2016-002-00 cc: (See Next Page)

GNRO-2016/00026 Page 2 of 2 cc:

U.S. Nuclear Regulatory Commission ATTN: Mr. Jim Kim, NRR/DORL (w/2)

Mail Stop OWFN 8 B1 Rockville, MD 20852-2738 U.S. Nuclear Regulatory Commission ATTN: Mr. Marc Dapas (w/2)

Regional Administrator, Region IV 1600 East Lamar Boulevard Arlington, TX 76011-4511 NRC Senior Resident Inspector Grand Gulf Nuclear Station Port Gibson, MS 39150

Attachment to GNRO-2016/00026 Licensee Event Report (LER) 2016-002-00

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVEDBY OMB: NO. 3150-0104 EXPIRES: 10/31/2018 (11-2015) the NRC may not conduct or sponsor, and a person is not required to respondto, the informationcollection.

13. PAGE Grand Gulf Nuclear Station, Unit 1 05000416 1 OF 4

4. TITLE Automatic Actuation of the Reactor Protection System due to 'B' Main Transformer Wiring

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

8. OTHER FACILITIES INVOLVED YEAR I SEQUENTIAL I REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR NUMBER NO.

MONTH DAY YEAR N/A 05000 N/A FACILITY NAME DOCKET NUMBER 03 29 2016 2016 - 002 - 00 05 25 2016 N/A 05000 N/A

9. OPERATING MODE

11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply) 1 D 20.2201 (b)

D 20.2203(a)(3)(i)

D 50.73(a)(2)(i)(C)

D 50.73(a)(2)(vii)

D 20.2201 (d)

D 20.2203(a)(3)(ii)

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

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

D 20.2203(a)(1)

D 20.2203(a)(4)

D 50.73(a)(2)(ii)(B)

D 50.73(a)(2)(viii)(B)

D 20.2203(a)(2)(i)

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

D 50.73(a)(2)(iii)

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

10. POWER LEVEL D 20.2203(a)(2)(ii)

D 50.36(c)(1 )(ii)(A)

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

D 50.73(a)(2)(x) 37 D 20.2203(a)(2)(iii)

D 50.36(c)(2)

D 50.73(a)(2)(v)(A)

D 73.71(a)(4)

D 20.2203(a)(2)(iv)

D 50.46(a)(3)(ii)

D 50.73(a)(2)(v)(B)

D 73.71 (a)(5)

D 20.2203(a)(2)(v)

D 50.73(a)(2)(i)(A)

D 50.73(a)(2)(v)(C)

D OTHER D 20.2203(a)(2)(vi)

D 50.73(a)(2)(i)(B)

D 50.73(a)(2)(v)(D)

Specifyin Abstract below or in =

2. DOCKET 05000416 YEAR I

3. LER NUMBER SEQUENTIAL NUMBER 2016-002-00 I

REV.

NO.

PLANT CONDITIONS PRIOR TO THE EVENT At the time of the event, Grand Gulf Nuclear Station (GGNS) Unit 1 was in Mode 1 and ascending in power at approximately 37%

rated thermal power. All systems, structures and components that were necessary to mitigate, reduce the consequences of, or limit the safety implications of the event were available. No safety significant components were out of service.

DESCRIPTION

On March 29, 2016, Grand Gulf Nuclear Station (GGNS) was ascending in power for the unit startup following Refueling Outage 20 (RF 20). As reactor power reached approximately 37%

rated thermal power, a generator lockout was received followed by a turbine control valve fast closure and turbine trip which resulted in an uncomplicated automatic reactor SCRAM. The generator lockout was the result of the Main Transformer

'B' Differential Relay Trip. The reactor protection system (RPS) [JC] and all safety systems functioned as designed and expected.

During the investigation, it was discovered inside the 'B' Main Transformer control cabinet that the high voltage current transformer (CT) [XCT] turns ratio wiring was incorrect. The CT wiring was connected in a manner that produced a turns ratio of 1000:5 versus the designed 2200:5. Due to this erroneous configuration the CT trip setpoint was lower than designed. Therefore, the CT and current differential relay actuation was not an equipment failure but an actual sensed actuation based on an incorrect wiring scheme. Work orders that involved working inside this panel during RF 20 were reviewed to determine when the wiring was altered. No work on CT wiring found incorrectly landed was intended to be performed during RF 20. Current Transformer ratio wiring work was not within the scope of the transformer rewiring project carried out during RF20. The most likely time the wiring was incorrectly removed and re-Ianded would have been during the post modification testing which was performed under a work order at the conclusion of the wiring project.

REPORTABILITY

This Licensee Event Report (LER) is being submitted pursuant to Title 10 Code of Federal Regulations (10 CFR) 50.73(a)(2)(iv)(A) for an automatic actuation of the RPS.

Telephonic notification was made to the U.S. Nuclear Regulatory Commission (NRC)

Emergency Notification System on March 29, 2016, within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of the event pursuant to 10 CFR 50.72(b)(2)(iv)(B) and 10 CFR 50.72 (b)(3)(iv)(A) for a valid RPS actuation while the reactor was critical.

NRC FORM (11-2015) 366A U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER)

CONTINUATION SHEET APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2018

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

1. FACILITY NAME Grand Gulf Nuclear Station, Unit 1 NARRATIVE

2. DOCKET 05000416 YEAR I

3. LER NUMBER SEQUENTIAL NUMBER 2016-002-00 I

REV.

NO.

The cause of LER-2015-001-00 was not similar to the event being reported, and the corrective actions would not have prevented the March 29, 2016 reactor SCRAM.

The cause of LER-2012-008-00 and LER-2013-001-00 was inadequate workmanship and work instructions that did not specify the minimum cold clearance of 0.5 inch between the CT and the micarta plate bolts during installation. The corrective actions addressed revising procedures, testing notes, work instructions, and drawings to ensure the minimum 0.5 inch cold clearance is maintained. Although these two events were attributed to inadequate work instruction, the corrective actions would not have prevented the March 29, 2016 reactor SCRAM.

=;YEnfergy GNRO-2016/00026 May 25,2016 u.s. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Entergy Operations, Inc.

P. O. Box 756 Port Gibson, MS 39150 James Nadeau Manager, Regulatory Assurance Grand Gulf Nuclear Station Tel. (601) 437-2103

SUBJECT:

Dear Sir or Madam:

Licensee Event Report (LER) 2016-002-00, Automatic Actuation of the Reactor Protection System due to IB' Main Transformer Wiring Grand Gulf Nuclear Station, Unit 1 Docket No. 50-416 License No. NPF-29 Attached is Licensee Event Report (LER) 2016-002-00, Automatic Actuation of the Reactor Protection System due to 'B' Main Transformer Wiring. This report is-submitted in accordance with Title 10 Code of Federal Regulations 50.73(a)(2)(iv)(A).

This letter contains no new commitments. Should you have any questions or require additional information, please contact James Nadeau at (601) 437-2103.

Sincerely, Attachment: Licensee Event Report (LER) 2016-002-00 cc: (See Next Page)

GNRO-2016/00026 Page 2 of 2 cc:

U.S. Nuclear Regulatory Commission ATTN: Mr. Jim Kim, NRR/DORL (w/2)

Mail Stop OWFN 8 B1 Rockville, MD 20852-2738 U.S. Nuclear Regulatory Commission ATTN: Mr. Marc Dapas (w/2)

Regional Administrator, Region IV 1600 East Lamar Boulevard Arlington, TX 76011-4511 NRC Senior Resident Inspector Grand Gulf Nuclear Station Port Gibson, MS 39150

Attachment to GNRO-2016/00026 Licensee Event Report (LER) 2016-002-00

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVEDBY OMB: NO. 3150-0104 EXPIRES: 10/31/2018 (11-2015) the NRC may not conduct or sponsor, and a person is not required to respondto, the informationcollection.

13. PAGE Grand Gulf Nuclear Station, Unit 1 05000416 1 OF 4

4. TITLE Automatic Actuation of the Reactor Protection System due to 'B' Main Transformer Wiring

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

8. OTHER FACILITIES INVOLVED YEAR I SEQUENTIAL I REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR NUMBER NO.

MONTH DAY YEAR N/A 05000 N/A FACILITY NAME DOCKET NUMBER 03 29 2016 2016 - 002 - 00 05 25 2016 N/A 05000 N/A

9. OPERATING MODE

11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply) 1 D 20.2201 (b)

D 20.2203(a)(3)(i)

D 50.73(a)(2)(i)(C)

D 50.73(a)(2)(vii)

D 20.2201 (d)

D 20.2203(a)(3)(ii)

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

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

D 20.2203(a)(1)

D 20.2203(a)(4)

D 50.73(a)(2)(ii)(B)

D 50.73(a)(2)(viii)(B)

D 20.2203(a)(2)(i)

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

D 50.73(a)(2)(iii)

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

10. POWER LEVEL D 20.2203(a)(2)(ii)

D 50.36(c)(1 )(ii)(A)

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

D 50.73(a)(2)(x) 37 D 20.2203(a)(2)(iii)

D 50.36(c)(2)

D 50.73(a)(2)(v)(A)

D 73.71(a)(4)

D 20.2203(a)(2)(iv)

D 50.46(a)(3)(ii)

D 50.73(a)(2)(v)(B)

D 73.71 (a)(5)

D 20.2203(a)(2)(v)

D 50.73(a)(2)(i)(A)

D 50.73(a)(2)(v)(C)

D OTHER D 20.2203(a)(2)(vi)

D 50.73(a)(2)(i)(B)

D 50.73(a)(2)(v)(D)

Specifyin Abstract below or in

2. DOCKET 05000416 YEAR I

3. LER NUMBER SEQUENTIAL NUMBER 2016-002-00 I

REV.

NO.

PLANT CONDITIONS PRIOR TO THE EVENT At the time of the event, Grand Gulf Nuclear Station (GGNS) Unit 1 was in Mode 1 and ascending in power at approximately 37%

rated thermal power. All systems, structures and components that were necessary to mitigate, reduce the consequences of, or limit the safety implications of the event were available. No safety significant components were out of service.

DESCRIPTION

On March 29, 2016, Grand Gulf Nuclear Station (GGNS) was ascending in power for the unit startup following Refueling Outage 20 (RF 20). As reactor power reached approximately 37%

rated thermal power, a generator lockout was received followed by a turbine control valve fast closure and turbine trip which resulted in an uncomplicated automatic reactor SCRAM. The generator lockout was the result of the Main Transformer

'B' Differential Relay Trip. The reactor protection system (RPS) [JC] and all safety systems functioned as designed and expected.

During the investigation, it was discovered inside the 'B' Main Transformer control cabinet that the high voltage current transformer (CT) [XCT] turns ratio wiring was incorrect. The CT wiring was connected in a manner that produced a turns ratio of 1000:5 versus the designed 2200:5. Due to this erroneous configuration the CT trip setpoint was lower than designed. Therefore, the CT and current differential relay actuation was not an equipment failure but an actual sensed actuation based on an incorrect wiring scheme. Work orders that involved working inside this panel during RF 20 were reviewed to determine when the wiring was altered. No work on CT wiring found incorrectly landed was intended to be performed during RF 20. Current Transformer ratio wiring work was not within the scope of the transformer rewiring project carried out during RF20. The most likely time the wiring was incorrectly removed and re-Ianded would have been during the post modification testing which was performed under a work order at the conclusion of the wiring project.

REPORTABILITY

This Licensee Event Report (LER) is being submitted pursuant to Title 10 Code of Federal Regulations (10 CFR) 50.73(a)(2)(iv)(A) for an automatic actuation of the RPS.

Telephonic notification was made to the U.S. Nuclear Regulatory Commission (NRC)

Emergency Notification System on March 29, 2016, within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of the event pursuant to 10 CFR 50.72(b)(2)(iv)(B) and 10 CFR 50.72 (b)(3)(iv)(A) for a valid RPS actuation while the reactor was critical.

NRC FORM (11-2015) 366A U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER)

CONTINUATION SHEET APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2018

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

1. FACILITY NAME Grand Gulf Nuclear Station, Unit 1 NARRATIVE

2. DOCKET 05000416 YEAR I

3. LER NUMBER SEQUENTIAL NUMBER 2016-002-00 I

REV.

NO.

The cause of LER-2015-001-00 was not similar to the event being reported, and the corrective actions would not have prevented the March 29, 2016 reactor SCRAM.

The cause of LER-2012-008-00 and LER-2013-001-00 was inadequate workmanship and work instructions that did not specify the minimum cold clearance of 0.5 inch between the CT and the micarta plate bolts during installation. The corrective actions addressed revising procedures, testing notes, work instructions, and drawings to ensure the minimum 0.5 inch cold clearance is maintained. Although these two events were attributed to inadequate work instruction, the corrective actions would not have prevented the March 29, 2016 reactor SCRAM.