05000336/LER-2014-002, 2 Regarding DC Circuit Hot Shorts

2 Regarding DC Circuit Hot Shorts

ML14129A463
Person / Time
Site:	Millstone
Issue date:	05/05/2014
From:	Scace S Dominion Nuclear Connecticut
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
14-184 LER 14-002-00
Download: ML14129A463 (6)

LER-2014-002, 2 Regarding DC Circuit Hot Shorts

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 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)(viii)(B) 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)(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
LER closed by
IR 05000245/2016008 (4 January 2017)
3362014002R00 - NRC Website

text

~Dominioiii Dominion Nuclear Connecticut, Inc.

Rope Ferry Rd., Waterford, CT 06385 Mailing Address: P.O. Box 128 Waterford, CT 06385 dora.corn U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 MAY 0 5 2014 Serial No.14-184 MPS Lic/LES RO Docket No.

50-336 License No.

DPR-65 DOMINION NUCLEAR CONNECTICUT, INC.

MILLSTONE POWER STATION UNIT 2 LICENSEE EVENT REPORT 2014-002-00 DC CIRCUIT HOT SHORTS This letter forwards Licensee Event Report (LER) 2014-002-00 documenting a condition at Millstone Power Station Unit 2 on March 12, 2014. This LER is being submitted pursuant to 10 CFR 50.73(a)(2)(ii)(B).

If you have any questions or require additional information, please contact Mr. William D. Bartron at (860) 444-4301.

Sincerely,

/Stepen E. Scace Site Vice President - Millstone Attachments: 1 Commitments made in this letter: None

Serial No.14-184 Docket No. 50-336 Licensee Event Report 2014-002-00 Page 2 of 2 cc:

U.S. Nuclear Regulatory Commission Region I 2100 Renaissance Blvd, Suite 100 King of Prussia, PA 19406-2713 M. C. Thadani NRC Project Manager Millstone Units 2 and 3 U. S. Nuclear Regulatory Commission One White Flint North Mail Stop 08 B-1 11555 Rockville Pike Rockville, MD 20852-2738 NRC Senior Resident Inspector Millstone Power Station

Serial No.14-184 Docket No. 50-336 Licensee Event Report 2014-002-00 ATTACHMENT LICENSEE EVENT REPORT 2014-002-00 DC CIRCUIT HOT SHORTS MILLSTONE POWER STATION UNIT 2 DOMINION NUCLEAR CONNECTICUT, INC.

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 01/31/2017 (02-2014)

Estimated burden per response to comply with this mandatory collection request: 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />.

Reported lessons learned are incorporated into the licensing process and fed back to industry.

Send comments regarding burden estimate to the FOIA, Privacy and Information Collections ICENS ET RE RT (Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by LICENSEE EVENT RE T

intemet e-mail to Infocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and (See Page 2 for required number of Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC sfor each block) 20503. If a means used to impose an information collection does not display a currently valid OMB digits/characters control number, 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 2 05000336 1 OF 3

4. TITLE DC Circuit Hot Shorts

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

8. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR SEUENTIAL REV FACILITY NAME DOCKET NUMBER NUMBER N

MONTH DAY05000 FACILITY NAME DOCKET NUMBER 03 12 2014 2014 -

002 00 05 05 2014 05000

9. OPERATING MODE

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

LI 20.2201(b)

[I 20.2203(a)(3)(i)

[I 50.73(a)(2)(i)(C)

El 50.73(a)(2)(vii)

[_

20.2201(d)

El 20.2203(a)(3)(ii)

[I 50.73(a)(2)(ii)(A)

El 50.73(a)(2)(viii)(A)

El 20.2203(a)(1)

El 20.2203(a)(4)

Z 50.73(a)(2)(ii)(B)

El 50.73(a)(2)(viii)(B)

El 20.2203(a)(2)(i)

El 50.36(c)(1)(i)(A)

[]

50.73(a)(2)(iii)

El 50.73(a)(2)(ix)(A)

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

[1 50.36(c)(1)(ii)(A)

El 50.73(a)(2)(iv)(A)

[i 50.73(a)(2)(x)

[I 20.2203(a)(2)(iii)

El 50.36(c)(2)

El 50.73(a)(2)(v)(A)

El 73.71(a)(4) 10 20.2203(a)(2)(iv)

El 50.46(a)(3)(ii)

El 50.73(a)(2)(v)(B)

El 73.71(a)(5) 100 El 20.2203(a)(2)(v)

El 50.73(a)(2)(i)(A)

El 50.73(a)(2)(v)(C)

El OTHER El 20.2203(a)(2)(vi)

LI 50.73(a)(2)(i)(B)

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

Specify in Abstract below or in

1. EVENT DESCRIPTION

While Millstone Power Station Unit 2 (MPS2) was operating at 100 percent power in Mode 1 on March 12, 2014, operations determined that a concern identified by Engineering as a result of recent industry operating experience (NRC Event 49889) could result in an unanalyzed condition. Engineering's review of the direct current (DC) circuits associated with the main turbine emergency lube oil system determined the described condition to be applicable to MPS2.

The vulnerability identified includes DC circuits connected to a 125VDC power source without appropriate rated protective device, and at MPS2 these are the Main Turbine Emergency Lube Oil pump control and indication circuits. The following fire areas are affected by the postulated hot shorts in DC circuits: the turbine battery room located in the 31' 6" elevation of the turbine building, the 25' elevation cable vault, the plant equipment operator (PEO) meeting area, and the control room.

This condition is reportable pursuant to 10 CFR 50.73(a)(2)(ii)(B) as an unanalyzed condition that significantly degraded plant safety.

2. CAUSE

The cause of the condition was a manufacturer's design error that was installed during plant construction.

3. ASSESSMENT OF SAFETY CONSEQUENCES

The following fire areas are affected by the postulated hot shorts in DC circuits listed above: the turbine battery room located in the 31'6" elevation of the turbine building, the 25' elevation cable vault, plant equipment operator (PEO) meeting area, and the control room. The zones where the initial fire occurs that could lead to a secondary fire are the control room, the 25' cable vault, and the PEO meeting area.

Each fire area contains safe shutdown equipment. A primary fire in any area (except the cable vault and the PEO meeting area) could cause a secondary fire in a separate safe shutdown fire zone. The secondary fire would be expected to be low energy.

The majority of these fire areas have fire detection installed and several have reliable automatic fire suppression systems. The control room is constantly manned by personnel who are trained to extinguish fires. Therefore, any low energy secondary fire will be quickly detected and extinguished. On this basis, the safety consequences of these postulated secondary fires is considered low.

4. CORRECTIVE ACTION

Compensatory fire watches have been implemented for affected areas of the plant. Plant modifications are planned that will protect or isolate the affected circuits leaving the initial fire area.

4. CORRECTIVE ACTION (Continued)

Additional corrective actions are being taken in accordance with the Station's corrective action program.

5. PREVIOUS OCCURRENCES

MPS2 LER 2013-003-00.

6. ENERGY INDUSTRY IDENTIFICATION SYSTEM (EIIS) CODES 125V DC [EI/EJ]

DC Circuits [11]