05000423/LER-2013-007, Reactor Trip on Low-Low Steam Generator Level

Reactor Trip on Low-Low Steam Generator Level

ML13295A220
Person / Time
Site:	Millstone
Issue date:	10/07/2013
From:	Scace S Dominion Nuclear Connecticut
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
13-523 LER 13-007-00
Download: ML13295A220 (5)

LER-2013-007, Reactor Trip on Low-Low Steam Generator Level

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(iv)(B), 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
4232013007R00 - NRC Website

text

3~hDomi nion Dominion Nuclear Connecticut, Inc.

Rope Ferry Road, Waterford, CT 06385 Web Address: www.dom.com OCT @7 8~13 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 Serial No.

MPS Lic/LES Docket No.

License No.13-523 RO 50-423 NPF-49 DOMINION NUCLEAR CONNECTICUT, INC.

MILLSTONE POWER STATION UNIT 3 LICENSEE EVENT REPORT 2013-007-00 REACTOR TRIP ON LOW-LOW STEAM GENERATOR LEVEL This letter forwards Licensee Event Report (LER) 2013-007-00 documenting an event at Millstone Power Station Unit 3 on August 9, 2013. 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), initially reported via event notification 49260 pursuant to 10 CFR 50.72 (b)(2)(iv)(B) and 10 CFR 50.72 (b)(3)(iv)(A).

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

Sincerely,

/n e

cace Site Vice President - Millstone Attachments: 1 Commitments made in this letter: None

Serial No.13-523 Docket No. 50-423 Licensee Event Report 2013-007-00 Page 2 of 2 cc:

U.S. Nuclear Regulatory Commission Region I 2100 Renaissance Blvd, Suite 100 King of Prussia, PA 19406-2713 J. S. Kim Project Manager - Millstone Power Station U.S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 08 C2A Rockville, MD 20852-2738 NRC Senior Resident Inspector Millstone Power Station

Serial No.13-523 Docket No. 50-423 Licensee Event Report 2013-007-00 ATTACHMENT LICENSEE EVENT REPORT 2013-007-00 REACTOR TRIP ON LOW-LOW STEAM GENERATOR LEVEL MILLSTONE POWER STATION UNIT 3 DOMINION NUCLEAR CONNECTICUT, INC.

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2013 (10/2010)

, the NRC may not conduct or sponsor, digits/characters for each block) and a person is not required to respond to, the information collection.

3. PAGE Millstone Power Station - Unit 3 05000423 1 OF 2

4. TITLE Reactor Trip on Low-Low Steam Generator Level

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

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

__05000 FACILITY NAME DOCKET NUMBER 08 09 2013 2013-007-00 10 07 2013 05000 9.OPRAIN MDE11.

THIS REPORT IS SU..BMrI-rED PURSUANT TO THE REQ.*.UIREMENTS OF 10 CIFR4:.(Check all that apply) 20.2201(b) 20.2203(a)(3)(i) 50.73(a)(2)(i)(C) 50.73(a)(2)(vii) 20.2201(d) 20.2203(a)(3)(ii) 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(A) 20.2203(a)(1) 20.2203(a)(4) 50.73(a)(2)(ii)(B) 50.73(a)(2)(viii)(B) 20.2203(a)(2)(i) 50.36(c)(1 )(i)(A) 50.73(a)(2)(iii) 50.73(a)(2)(ix)(A) 20.2203(a)(2)(ii) 50.36(c)(1)(ii)(A)

X 50.73(a)(2)(iv)(A) 50.73(a)(2)(x)

10. POWER LEVEL 20.2203(a)(2)(iii) 50.36(c)(2) 50.73(a)(2)(v)(A) 73.71 (a)(4) 20.2203(a)(2)(iv) 50.46(a)(3)(ii) 50.73(a)(2)(v)(B) 73.71 (a)(5) 100 20.2203(a)(2)(v) 50.73(a)(2)(i)(A) 50.73(a)(2)(v)(C)

OTHER 20.2203(a)(2)(vi) 50.73(a)(2)(i)(B) 50.73(a)(2)(v)(D)

Specify in Abstract below or in

1.

EVENT DESCRIPTION

On August 09, 2013 at 2119, while in MODE 1 at 100 percent power, Millstone Power Station Unit 3 experienced an automatic reactor trip on steam generator (SG) "C" low-low water level. The low-low SG water level condition resulted from all main feed water pump recirculation valves failing full open following a loss of power from non safety-related 480 volt load center 32L. This bus powered the instrumentation loops for all three main feedwater pump recirculation valve controllers. Upon the loss of power, the valves went to their failure state of "Recirculation". The redirection of water into the recirculation lines and back to the main condenser resulted in a loss of feedwater header pressure and flow to the steam generators causing the unit to automatically trip on low-low steam generator level. All control rods fully inserted into the reactor. The auxiliary feedwater system started as designed and maintained steam generator levels.

Safety systems functioned as expected. There were no radiological challenges as a result of the event.

This event 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 direct cause of the event was the loss of power to the 480V bus that powered the three main feedwater pump recirculation valve controllers. Troubleshooting efforts did not reveal the cause of the ground that led to the loss of bus 32L.

3.

ASSESSMENT OF SAFETY CONSEQUENCES

There were no safety consequences associated with this event.

All control rods inserted following the reactor trip on SG low-low water level. The operating crew responded to the reactor trip by entering Emergency Operating Procedure (EOP) 35 E-0, "Reactor Trip or Safety Injection." Plant mitigating equipment responded as expected with no safety system failures.

The auxiliary feedwater system started automatically on the trip as expected, and restored the SG water levels to their normal operating band, maintaining reactor coolant system (RCS) heat removal. There were no challenges to the fuel, RCS or containment fission product barriers.

4.

CORRECTIVE ACTION

Power to the three main feedwater recirculation valves has been temporarily moved to another power supply. Additional corrective actions are being taken in accordance with the station's corrective action program.

5.

PREVIOUS OCCURRENCES

None

6.

ENERGY INDUSTRY IDENTIFICATION SYSTEM (EIIS) CODES Steam Generator [SG]

Feed Water [FW] pump [P] recirculation valves [VM Reactor Protection System [JC]

Auxiliary Feedwater System [BA)