05000348/LER-2007-001

LER-2007-001, Vire President - Farley Operating Company, Inc.
Po51 Office Drawer 470
Ashford, Alabarid 36312-0470
Tel 334 814 4511
Fax 334 814 4728
SOUTHERN
June 22, 2007 COMPANY
Energy to Serve Your World
Docket Nos.: 50-348 NL-07-1231
50-364
U. S. Nuclear Regulatory Commission
ATTN: Document Control Desk
Washington, D. C. 20555-0001
Joseph M. Farley Nuclear Plant — Units 1 and 2
Licensee Event Report 2007-001-00
Technical Specification 3.8.1 Violation Due to
Failure of Breaker / Mechanism-Operated Cell Switch
Ladies and Gentlemen:
Joseph M. Farley Nuclear Plant - Licensee Event Report (LER) No. 2007-001-00 is
being submitted in accordance with 10 CFR 50.73(a)(2)(i)(B) and 10 CFR
50.73(a)(2)(v)(B).
This letter contains no NRC commitments. If you have any questions, please advise.
Sincerely,
7e.
R. Johnson
Vice President — Farley
Joseph M. Farley Nuclear Plant
7388 North State Highway 95
Columbia AL 36319
JRJ/CHM
Enclosure: Licensee Event Report 2007-001-00 - Unit 1
U. S. Nuclear regulatory Commission
NL-07-1231
Page 2
cc:� Southern Nuclear Operating Company
Mr. J. T. Gasser, Executive Vice President
Mr. J. R. Johnson, Vice President — Farley
Mr. D. H. Jones, Vice President — Engineering
RTYPE: CFA04.054; LC # 14596
U. S. Nuclear Regulatory Commission
Dr. W. D. Travers, Regional Administrator
Ms. K. R. Cotton, NRR Project Manager — Farley
Mr. E. L. Crowe, Senior Resident Inspector— Farley
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1. FACILITY NAME 2. DOCKET NUMBER 3. PAGE
Joseph M. Farley Nuclear Plant - Unit 1 05000 348 1 OF 4
4. TITLE
Technical Specification 3.8.1 Violation Due to Failure of Breaker / Mechanism-Operated Cell (MOC) Switch

Docket Number
Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat
3482007001R00 - NRC Website

Westinghouse -- Pressurized Water Reactor Energy Industry identification Codes are identified in the text as [XX]

Description of Event

The original Allis Chalmers breaker 1-DH07 was replaced with a new Cutler Hammer breaker on November 1, 2006. This breaker is the Emergency Diesel Generator (EDG) IC [EK] output breaker to emergency 4160V bus I H. The IC EDG and the new output breaker were functionally tested; however this testing was not sufficient to verify that all contacts on the mechanism operated cell (MOC) switch changed state.

While performing an EDG IC Operability Test on April 26, 2007, FNP determined that the normally open contacts on the MOC switch of breaker 1-DH07 were not being fully activated when the breaker was closed.

One of the affected contacts would have prevented the closure of bus tie breaker I -DF 13 and the automatic operation of the A-Train Loss of Site Power (LOSP) sequencer in the event of a dual unit LOSP with concurrent safety injection on Unit 2. Technical Specification 3.8.1 "Electrical Power Systems - AC Sources—Operating," Condition B, "One DG set inoperable," was entered at 01:40 hours on April 26, 2007.

The MOC switch and activation arm were examined. The inspection determined that the MOC switch rotation was not sufficient to fully engage the normally open contacts. Adjustments were made to the MOC fork height which increased the stroke of the activation arm and thus rotated the MOC switch farther. This ensured that the normally open contacts would fully close each time the breaker was closed. The IC EDG was tested and breaker 1-DH07 performed correctly. 1C EDG was returned to service at 22:07 hours on April 26, 2007.

Cause of Event

The event was the result of a fit-up discrepancy during replacement of the existing Allis Chalmers breakers with new Cutler Hammer breakers within the Allis Chalmers switchgear. A review of the factory testing of the MOC switch operation within the switchgear at AREVA revealed that the normally open MOC switch contacts were rotated at an angle of less than 90 degrees between Open and Closed positions. The normally open MOC switch contacts within the switchgear at Farley Nuclear Plant were set at a 90 degree angle, which required more travel of the MOC operator on the new Cutler Hammer breakers to obtain full closure of the contacts. The initial setting of the adjustable fork height on the MOC operator did not allow for this additional travel, resulting in the failure to close the normally open contacts. Functional testing failed to identify that all contacts on the MOC switch changed state.

Safety Assessment This event had no adverse effect on the safety and health of the public.

The Farley onsite standby power source is provided from four EDGs (I -2A, I B, 2B, and IC). The continuous service rating of IC EDG is 2,850 kW and 4,075 kW for EDGs 1-2A, I B, and 2B. EDG 1-2A and 1-C are A-Train and EDGs 1B and 2B are B-Train. Farley also has a fifth diesel generator (2C) that serves as a station blackout diesel which can be manually aligned to supply B-Train power to either unit and power LOSP loads.

The redundant train I B EDG was unavailable for operation due to maintenance activities on five occasions during the time period when the I C EDG was inoperable, resulting in a potential loss of safety function.

However, the only scenario which would have been affected by this failure is a dual unit loss of offsite power with a concurrent safety injection on Unit 2. If that event occurred with the 1C DG MOC switch inoperable, operator action would have been required to energize the IF 4160V bus and start the required safety related loads after the I C EDG automatically connected to the I H bus. This does not represent an increase in risk as calculated by the Farley Unit I Probability Risk Assessment (PRA) model. This is due to the fact that the PRA model conservatively assumes that the IC EDG will be started and loaded by the operator rather than crediting automatic start. This is a simplification of the model due to the complexities of modeling all possible combinations of swing diesel alignment.

Corrective Action The MOC operator on breaker 1-DH07 was adjusted to allow adequate travel of the MOC switch contacts.

This was completed on April 26, 2007.

Plant procedures were updated to provide instructions to have the Normally Open contacts of the MOC switch rotated to the correct angle. This was completed on May 5, 2007.

After receiving the additional guidance from AREVA, breaker I -DH07 was restored to match the factory setting for MOC switch operator height and the contact angle. This was completed on June I I , 2007.

Cutler-Hammer breakers which have been installed with MOC switches that provide essential functions have been adjusted to meet the factory setting for MOC switch operator height and contact angle. This was completed on June 1 1, 2007.

Additional Information

The following LER's have been submitted in the past two years on Technical Specification violations:

System Card Failure Troubleshooting