05000423/LER-2016-004, Manual Reactor Trip Due to Low Hydrogen Gas Pressure in Main Generator

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Manual Reactor Trip Due to Low Hydrogen Gas Pressure in Main Generator
ML16208A057
Person / Time
Site: Millstone Dominion icon.png
Issue date: 07/13/2016
From: Olsen C
Dominion Nuclear Connecticut
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
LER 16-004-00
Download: ML16208A057 (6)
v • d • e


LER-2016-004, Manual Reactor Trip Due to Low Hydrogen Gas Pressure in Main Generator
Event date:
Report date:
Reporting criterion: 10 CFR 50.73(a)(2)(iv)(B), 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)(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)(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)(vii), Common Cause Inoperability
10 CFR 50.73(a)(2)(i)
4232016004R00 - NRC Website
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text

Dominion Nuclear Connecticut, Inc.

Rope Ferry Rd., Waterford, CT 06385 Mailing Address: P. 0. Box 128 Waterford, CT 06385

<lorn.com U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 DOMINION NUCLEAR CONNECTICUT, INC.

MILLSTONE POWER STATION UNIT 3 LICENSEE EVENT REPORT 2016-004-00 MANUAL REACTOR TRIP DUE TO LOW HYDROGEN GAS PRESSURE IN MAIN GENERATOR JUL 1-3 2016 Serial No.

MPS Lic/GJC Docket No.

License No.16-233 RO 50-423 NPF-49 This letter forwards Licensee Event Report (LER) 2016-004-00 documenting a condition discovered at Millstone Power Station Unit 3, on May 15, 2016. This LER is being submitted pursuant to 10 CFR 50. 73(a)(2)(iv)(A) as an event that resulted in manual or automatic actuation of systems listed in 10 CFR 50.73(a)(2)(iv)(B).

If you have any questions or require additional information, please contact Mr. Jeffry A. Langan at (860) 444-5544.

Sincerely, Craig T. Olsen Plant Manager - Millstone Attachments: 1 Commitments made in this letter: None

. -:.4};

cc:

U.S. Nuclear Regulatory Commission Region I 2100 Renaissance Blvd.

Suite 100 King of Prussia, PA 19406-2713 R.V. Guzman Serial No.16-233 Docket No. 50-423 Licensee Event Report 2016-004-00 Page 2 of 2 NRC Senior Project Manager Millstone Units 2 and 3 U.S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 08 C-2 Rockville, MD 20852-2738 NRC Senior Resident Inspector Millstone Power Station

ATTACHMENT Serial No.16-233 Docket No. 50-423 Licensee Event Report 2016-004-00 LICENSEE EVENT REPORT 2016-004-00 MANUAL REACTOR TRIP DUE TO LOW HYDROGEN GAS PRESSURE IN MAIN GENERATOR MILLSTONE POWER STATION UNIT 3 DOMINION NUCLEAR CONNECTICUT, INC.

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2018 (11-2015)

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

3. PAGE Millstone Power Station Unit 3 05000 423 1 OF 3
4. TITLE Manual Reactor Trip Due to Low Hydrogen Gas Pressure In Main Generator
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 15 2016 2016 -

004 - 00 07 13 2016 05000

9. OPERATING MODE
11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 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) 1 D

20.2201(d)

D 20.2203(a)(3)(ii)

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

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

D 20.2203(a)(1)

D 20.2203(a)(4)

D so.73(a)(2)(iii)

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

D 20.2203(a)(2)(i)

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

[{] 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)(ili)

D so.36(c)(2)

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

D 73.71(a)(s)

D 20.2203(a)(2)(iv)

D so.46(a)(3)(ii)

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

D 73.77(a)(1) 074 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)(0 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)

~?*: ; '; : J'. >j ; ~::.* ;:: :.**

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

D OTHER Specify in Abstract below or in NRG Form 366A

12. LICENSEE CONTACT FOR THIS LER LICENSEE CONTACT TELEPHONE NUMBER (Include Area Code)

Jeffry A Langan, Manager Nuclear Station Licensing (860) 444-5544 CAUSE SYSTEM COMPONENT MANU-REPORTABLE I

CAUSE

SYSTEM COMPONENT MANU-REPORTABLE FACTURER TOEPIX FACTURER TOEPIX

14. SUPPLEMENTAL REPORT EXPECTED
15. EXPECTED MONTH DAY YEAR DYES (ff yes, complete 15. EXPECTED SUBMISSION DATE)

[{] NO SUBMISSION DATE ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)

On May 15, 2016, with Millstone Power Station Unit 3 (MPS3) operating in MODE 1 at 74% power, the operators observed decreasing hydrogen pressure in the main turbine generator. Upon field investigation it was determined there was an active hydrogen leak from the main generator. The operators manually tripped the reactor and vented the hydrogen from the main generator. The reactor trip was uncomplicated. The auxiliary feedwater (AFW) pumps started as designed on low steam generator level and operators maintained steam generator level.

The active hydrogen leak was the direct cause of the manual reactor trip. The hydrogen leak was caused by a dislodged plug on a port on the main generator. MPS maintenance procedures did not contain adequate procedural guidance in that there was no specific direction for installation, i.e., torque value and verifications. The procedures will be revised to include specific direction to tighten the plugs and applicable verifications (i.e., torque value, peer checking). Additional corrective actions are being taken in accordance with the station's corrective action program.

The actuation of the RPS and the automatic start of the AFW pumps is being reported in accordance with 10 CFR 50. 73 (a}(2)(iv)(A) as an event that resulted in manual or automatic actuation of systems listed in 10 CFR 50.73(a)(2)(iv)(B).

NRG FORM 366 (11-2015) (11-2015)

U.S. NUCLEAR REGULATORY COMMISSION

+~~'Allla""'>o f

\\

\\

-.. ****** # LICENSEE EVENT REPORT (LER)

CONT.i'NUATlbN SHEET 4

I

1. FACILITY NAME
2. DOCKET Millstone Power Station Unit 3 05000423
1.

EVENT DESCRIPTION

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

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

6. LER NUMBER
3. PAGE:

YEAR I

SEQUENTIAL I REV NUMBER NO.

2 of 3:

2016 004 00 On May 15, 2016, with Millstone Power Station Unit 3 (MPS3) operating in MODE 1 at 7 4% power, the~

operators observed decreasin'g hydrogen pressure in the main generator. The operators added hydrogen but it continued to decrease. bperators in the field identified a hydrogen leak from the main generator.*

Due to the active hydrogen leak, at 0645 hours0.00747 days <br />0.179 hours <br />0.00107 weeks <br />2.454225e-4 months <br /> eastern daylight time (EDT), the operators manually tripped the reactor and vented the hydrogen from the main generator to the atmosphere. The auxiliary feedwater (AFW) pumps started as designed on low steam generator level and operators maintained steam generator level. The reactor trip was uncomplicated.

The actuation of the reactor protection system was reported in accordance with 10 CFR 50.72(b)(2)(iv)(B),

as an event or condition that results in actuation of the reactor protection system (RPS) when the reactor is critical except when the actuation results from and is part of a pre-planned sequence during testing or reactor operation. The automatic start of the AFW pumps was reported in accordance with 10 CFR 50.72(b)(3)(iv)(A) as an event that resulted in manual or automatic actuation of systems listed in 10 CFR 50.72(b)(3)(iv)(B). (Event Number: 51929)

The actuation of the RPS and the automatic start of the AFW pumps is being reported in accordance with 10 CFR 50.73(a)(2)(iv)(A) as an event that resulted in manual or automatic actuation of systems listed in 10 CFR 50.73(a)(2)(iv)(B).

2.

CAUSE

The active hydrogen leak was the direct cause of the manual reactor trip. The hydrogen leak was caused by a dislodged plug from a port on the main generator. MPS procedures did not contain adequate procedural guidance in that there was no specific direction for installation of the plug, i.e.; torque value and verifications.

3.

ASSESSMENT OF SAFETY CONSEQUENCES

The operating crew responded to decreasing hydrogen pressure in the main generator as directed by approved procedures. The reactor was at 74% power. All control rods fully inserted into the reactor and all emergency systems functioned as designed. There were no radiological challenges as a result of the event. There were no detrimental effects to station equipment. No* safety limits were exceeded. The operator actions and plant mitigating equipment responded as expected with no safety system failures.

There were no challenges to any fission product barrier. Therefore, there were no safety consequences as the result of the reactor trip.

4.

CORRECTIVE ACTION

The plug was properly re-installed. Maintenance procedures will be revised to include specific direction to install the outer end shield pipe plugs and sealant and include direction to tighten the plugs and applicable verifications (i.e., torque value, peer checking). Additional corrective actions are being taken in accordance with the station's corrective action program. (11-2015)

U.S. NUCLEAR REGULATORY COMMISSION

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\\-...... !) LICENSEE EVENT REPORT (LER) 1 CONTINUATI0~

11SHEET

  • rF

! 1. FACILITY NAME

2. DOCKET Millstone:Power Station Unit 3 05000423
5.

PREVIOUS OCCURRENCES

NONE 1

6.

Energy Industry Identification System ;(EllS) codes Reactor Coolant System - AB Auxiliary/Emergency Feedwater System - BA Main Generator System...,... TB Main Generator Hydrogen Cooling System - TK Turbine - TRB Pump-P Valve-V APPROVED BYOMB: N0.. 3150-0104 EXPIRES: 10/31/2018

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

6. LER NUMBER I
3. PAGE I '

YEAR I

SEQUENTIAL ! I REV NUMBER l

NO.

3 of 3 2016 004 00

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