05000348/LER-2009-002

LER-2009-002, J. R. Johnson
Vice President — Farley
J. R. Johnson
Vice President — Farley
Southern Nuclear
Operating Company, Inc.
Post Office Drawer 470
Ashford, Alabama 36312-0470

Tel 334.814.4511
Fax 334.814.4728
SOUTHERN A
COMPANY
Enrrgytv Serve Your World- May 26, 2009

Docket Nos.: 50-348 NL-09-0772
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 2009-002-00
Turbine Driven AFW Pump Inoperable Due to Internal Flooding Concerns
Ladies and Gentlemen:
In accordance with the requirements of 10 CFR 50.73(a)(2)(i)(B), 10 CFR
50.73(a)(2)(ii)(B), and 10 CFR 50.73(a)(2)(v)(D), Southern Nuclear Operating
Company (SNC) is submitting the enclosed Licensee Event Report.
This letter contains no NRC commitments. If you have any questions, please
advise.
JRJ/CHM
Enclosure: Units 1 and 2 Licensee Event Report 2009-002-00
U. S. Nuclear Regulatory Commission
NL-09-0772
Page 2
cc: Southern Nuclear Operating Company
Mr. J. T. Gasser, Executive Vice President
Mr. J. R. Johnson, Vice President — Farley
Mr. P. M. Marino, Vice President — Engineering
RTYPE: CFA04.054
U. S. Nuclear Regulatory Commission
Mr. L. A. Reyes, Regional Administrator
Mr. R. E. Martin, NRR Project Manager — Farley
Mr. E. L. Crowe, Senior Resident Inspector — Farley
Joseph M. Farley Nuclear Plant — Units 1 and 2
Licensee Event Report 2009-002-00
Turbine Driven AFW Pump Inoperable Due to Internal Flooding Concerns
Enclosure
Units 1 and 2 Licensee Event Report 2009-002-00
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION
(9-2007)
LICENSEE EVENT REPORT (LER)
1. FACILITY NAME
Joseph M. Farley Nuclear Plant - Unit 1
4. TITLE
APPROVED BY OMB: NO. 3150-0104 EXPIRES: 08/31/2010
Estimated burden per response to comply with this mandatory collection
request: 80 hours. Reported lessons learned are incorporated into the
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and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and
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2. DOCKET NUMBER 3. PAGE
05000 348 1 of 3
Turbine Driven AFW Pump Inoperable Due to Internal Flooding Concerns

Joseph M. Farley Nuclear Plant - Unit 1
Event date:	03-27-2009
Report date:	05-26-2009
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition
3482009002R00 - NRC Website

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

Description of Event

On March 27, 2009 @ approximately 18:00 with Unit 1 in Mode 1 at 96 % power and Unit 2 in Mode 3 at 0 % power, SNC determined that the calculation for internal flooding did not account for a floor drain located in a pipe chase that is exposed to the Main Steam Valve Room (MSVR). This condition existed for Units 1 and 2. This open floor drain could allow water introduced into the MSVR during a Feed Water Line Break (FWLB), to reach the Lower Equipment Room. The Lower Equipment Room houses the Turbine Driven Auxiliary Feed Water (TDAFW) Pump [BA] and associated Uninterruptible Power Supply (UPS). Review of the flooding calculations was initiated to determine the projected level of water that could be expected in the Lower Equipment Room due to a FWLB in the MSVR. As a conservative measure, in the early morning hours of March 28, 2009, the floor drains in the pipe chase for Units 1 and Unit 2 were plugged, returning both Units to the design configuration consistent with the internal flooding calculation.

The review of the design calculation for internal flooding determined that during a FWLB in the MSVR, water was not assumed to reach the Lower Equipment Room and rise to a level to negatively affect equipment. An engineering evaluation determined that during a FWLB in the MSVR with the drain line unplugged, the water could reach a level in the Lower Equipment Room that could have made the TDAFW UPS inoperable thus rendering the TDAFW Pump inoperable.

Current design for a FWLB event requires two of the three AFW pumps to meet the AFW flow demand. With the assumed failure of the TDAFW Pump at the initiation of a FWLB in the MSVR, the single failure criteria could not be met. With the floor drains now plugged the TDAFW Pump will not be negatively affected by a FWLB in the MSVR.

Cause of Event

The open drain path from the MSVR to the Lower Equipment Room was an oversight by the design organization that prepared the internal flooding calculation.

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

The AFW System automatically supplies feedwater to the steam generators to remove decay heat from the Reactor Coolant System upon the loss of normal feedwater supply. The turbine driven and motor driven AFW pumps take suction through separate and independent suction lines (one for the turbine driven pump and one shared by both motor-driven pumps) from the condensate storage tank (CST) and pump to the steam generator secondary side via separate and independent lines up to the common connection to the main feedwater (MFW) piping to each steam generator outside containment.

� The AFW System consists of two motor driven AFW Pumps and one steam turbine driven pump configured into three trains. Each motor driven AFW Pump is powered from an independent Class lE power supply and feeds all steam generators through a common header. The steam turbine driven AFW pump receives steam from two main steam lines upstream of the main steam isolation valves. The turbine driven AFW pump supplies a common header capable of feeding all steam generators. Thus, the requirement for diversity in motive power sources for the AFW System is met.

The limiting Design Basis Accidents (DBAs) and transients for the AFW System are Feedwater Line Break (FWLB), Main Steam Line Break (MSLB), and Loss of Main Feedwater. A FWLB in the MSVR requires two of the three AFW pumps to meet the AFW flow demands. This is also the DBA that puts the most water in the MSVR.

With the drain from the MSVR to the Lower Equipment Room affecting the TDAFW Pump and assuming a single active failure (failure of a motor-driven AFW Pump), the AFW system could have challenged the required AFW flow for a FWLB event. This condition has been present since original design and construction of both Farley Units. In the past for both Units 1 and 2, equipment outages have occurred where a motor-driven AFW Pump was out of service. During these equipment outages, if a FWLB had occurred, FNP could have challenged the design requirements for AFW system. The event was evaluated using the FNP Probabilistic Risk Assessment (PRA) model and shown to be of very low safety significance. In the operating history of FNP, neither unit has experienced a FWLB. Therefore, the safety and health of the public was not adversely affected by the failure to isolate the drain path from the MSVR to the Lower Equipment Room.

Corrective Action SNC installed a Thaxton plug in each floor drain thus returning both Units to the design configuration consistent with the internal flooding calculation.

Plant procedures have been revised to show that the affected drains are required to be plugged.

A further review of the plant internal flooding calculation is being performed to ensure that the calculation properly reflects the floor drains as they are configured per plant procedures. Any problems identified during this review will be tracked and corrected under the site corrective action program.

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