05000348/LER-2012-002, Regarding Breaker Failure Results in Containment Cooling Train Inoperability
| ML12101A279 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 04/09/2012 |
| From: | Lynch T Southern Co, Southern Nuclear Operating Co |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| NL-12-0624 LER 12-002-00 | |
| Download: ML12101A279 (7) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(8) 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2) 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)(v), Loss of Safety Function |
| 3482012002R00 - NRC Website | |
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Thomas A. Lynch Southern Nuclear Vice President* farley Operating Company, Inc, farley Nuclear Plant Post OHice Drawer 470 Ashford, Alabama 36312 Te l 334.814.4511 Fax 334.814.4728 SOUTHERN.\\'
COMPANY April 9, 2012 Docket No.:
50-348 NL 0624 U. S. Nuclear Regulatory Commission ATIN: Document Control Desk Washington, D. C. 20555-0001 Joseph M. Farley Nuclear Plant - Unit 1 Licensee Event Report 2012-002-00 Breaker Failure Results in Containment Cooling Train Inoperability Ladies and Gentlemen:
In accordance with the requirements of 10 CFR 50.73 (a)(2)(i)(8), Southern Nuclear Operating Company (SNC) is submitting the enclosed Licensee Event Report. This letter contains no NRC commitments. If you have any questions, please contact Doug McKinney at (205) 992-5982.
Sincerely,
~0 T. A. Lynch Vice President - Farley TAUWDO Enclosure: Unit 1 Licensee Event Report 2012-002-00
U. S. Nuclear Regulatory Commission NL 0624 Page 2 cc: Southern Nuclear Operating Company Mr. S. E. Kuczynski, Chairman, President & CEO Mr. D. G. Bost, Executive Vice President & Chief Nuclear Officer Mr. B. L. Ivey, Vice President - Regulatory Affairs Mr. B. J. Adams, Vice President - Fleet Operations Mr. M. J. Ajluni, Director - Nuclear Licensing RTYPE: CFA04.054 U. S. Nuclear Regulatory Commission Mr. V. M. McCree, Regional Administrator Mr. R. E. Martin, NRR Project Manager - Farley Mr. E. L. Crowe, Senior Resident Inspector - Farley
Joseph M. Farley Nuclear Plant - Unit 1 Licensee Event Report 2012-002-00 Breaker Failure Results in Containment Cooling Train Inoperability Enclosure Unit 1 Licensee Event Report 2012-002-00
~RC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10131/2013 1(02010)
, the NRC may not conduct or sponsor, and a person Is not required to respond to, the Infonnatlon collection.
- 13. PAGE Joseph M. Farley Nuclear Plant, Unit 1 05000348 1 OF 4
- 4. TITLE Breaker Failure Results in Containment Cooling Train Inoperability
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED
--~-
MONTH DAY YEAR YEAR SEQUENTIAL NUMBER REV NO.
MONTH DAY YEAR FACILITY NAME DOCKET NUMBER FACILITY NAME DOCKET NUMBER 02 15 2012 2012 - 002 -
00 04 09 2012
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check all that apply) o 20.2201 (b) o 20.2203(a)(3)(1) o 50.73(a)(2)(i)(C) o 50.73(a)(2)(vii) 1 o 20.2201 (d) o 20.2203(a)(3)(li) o 50.73(a)(2)(li)(A) o 50.73(a)(2)(vili)(A) o 20.2203(a)(1) o 20.2203(a)(4) o 50.73(a)(2)(li)(B) o 50.73(a)(2)(viii)(B) o 20.2203(a)(2)(i) o 50.36(c)(1 )(I)(A) o 50.73(a)(2)(iii) o 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL o 20.2203(a)(2)(il) o 50.36(c)(1)(li)(A) o 50.73(a)(2)(iv)(A) o 50.73(a)(2)(x) o 20.2203(a)(2)(iii) o 50.36(c)(2) o 50.73(a)(2)(v)(A) o 73.71 (a)(4) o 20.2203(a)(2)(lv) o 50.46(a)(3)(il) o 50.73(a)(2)(v)(B) o 73.71 (a)(5) 100 o 20.2203(a)(2)(v) o 50.73(a)(2)(Q(A) o 50.73(a)(2)(v)(C) o OTHER o 20.2203(a)(2)(vi) 181 50. 73(a)(2)(i)(B) o 50.73(a)(2)(v)(D)
Specify in Abstract below or In Although the failure mechanism is known, the events that took place in order to arrive at this condition are not. This failure (internal binding) could not be recreated under existing conditions. The motor cut off switch operated smoothly and showed no signs of defective components. The extensive number of successful switch cycles across the industry with only two identified possible failures of this type reported indicates that the design has been highly reliable.
Safety Assessment
The Containment Cooling system at Farley Nuclear Plant is comprised of two trains, each of sufficient capacity to supply 100 percent of the design cooling requirement. Each train consists of two fully redundant fan units supplied with cooling water from a separate train of service water (SW). Each fan unit has two speeds of operation, high speed for normal operation and slow speed for post-accident operation. Each fan motor has two separate windings (one high speed and one slow speed), that are powered from separate breakers. However, under post-accident conditions, a single fan unit from either train with at least 600 gpm of SW flow provides sufficient cooling capacity to meet post accident heat removal requirements. Air is drawn into the coolers through the fan and discharged to the steam generator compartments, pressurizer compartment, and outside the secondary shield in the lower areas of containment.
During normal operation, up to four fan units are operating in high speed with SW supplied to the cooling coils. The Containment Cooling System is designed to limit the ambient containment air temperature during normal unit operation to less than the limit specified in LCO 3.6.5, "Containment Air Temperature." This temperature limitation ensures that the containment temperature does not exceed the initial temperature conditions assumed for the Design Basis Accidents.
In post-accident operation following an actuation signal, unless a Loss of Site Power (LOSP) signal is present, the Containment Cooling System fans are designed to start automatically in slow speed if not already running. If an LOSP signal is present, only the two fans selected (one per train) will receive an auto-start signal and will start in slow speed. If running in high (normal) speed, the fans automatically shift to slow speed. The fans are operated at the lower speed during accident conditions to prevent motor overload from the higher water content in the containment atmosphere.
During the time period from January 23,2012 (date at which the 1 B containment cooling fan was selected for automatic start) until February 15, 2012 (discovery date of 1 B containment cooling fan failure), the A Train Containment Cooling system was rendered inoperable due to the unknown breaker malfunction. However, the B Train Containment Cooling system remained operable and capable of providing 100 percent of the design post-accident cooling requirement. In addition, the 1 A containment cooling fan (A Train) remained available and would have manually started upon demand and was further capable of providing 100 percent of the design post-accident cooling requirement. Therefore, the event did not result in a loss of safety system function. Also, there were no events which required a Containment Cooling system slow speed actuation during the period of unrecognized inoperability.
Based on these considerations, there was no adverse affect on plant safety or on the health and safety of the public.
4 LICENSEE EVENT REPORT (LER) u.s. NUCLEAR REGULATORY COMMISSION (10-2010)
CONTINUATION SHEET
- 1. FACILITY NAME
- 2. DOCKET S.LER NUMBER
- 3. PAGE SEQUENTIAL IREVISION YEAR NUMBER NUMBER I
Joseph M. Farley Nuclear Plant, Unit 1 05000348 4
of 2012 002 00 NARRAllVE This event is reportable pursuant to 10 CFR 50.73 (a)(2)(i)(8) for a condition prohibited by Technical Specifications.
Corrective Action
The A Train operability was restored in approximately 8 minutes when the 1 A containment cooling fan was selected to automatic start function on February 15, 2012.
The failed breaker was replaced with a suitable operable breaker. Surveillance testing was completed satisfactorily on this breaker on February 21, 2012.
Causal analysis was completed and the additional corrective actions identified were entered into the corrective action program (CAP). Work Orders to replace the motor cut-off switches with new style switches that supply safety related loads actuated from Safety Injection and LOSP sequencers were entered into the CAP.
Additional Information
Similar Events: None NRC FORM 36BA (10-2010)