ML112870326

Supplemental Response to NRC Verification Inspection Report; 05000456/2011009; 05000457/2011009

ML112870326
Person / Time
Site:	Braidwood
Issue date:	10/14/2011
From:	Enright D Exelon Generation Co, Exelon Nuclear
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
BW110117, IR-11-009
Download: ML112870326 (2)

Text

10 CFR 50.109 October 14, 2011 BW110117 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Braidwood Station, Units 1 and 2 Facility Operating License Nos. NPF-72 and NPF-77 NRC Docket Nos. STN 50-456 and StN 50-457

Subject:

Supplemental Response to NRC Verification Inspection Report; 05000456/2011009; 05000457/2011009

Reference:

1) Letter from Steven A. Reynolds (US NRC) to Michael J. Pacillio (Exelon Generation Company, LLC), "Braidwood Station, Units 1 and 2 Verification Inspection Related to Analysis of Steam Generator Tube Rupture Event Margin to Overfill; 05000456/2011009; 050004572011009," dated February 1, 2011

2) Letter from Daniel J. Enright, Exelon Generation Company, LLC (EGC) to US NRC "Response to NRC Verification Report; 05000456/2011009; 05000457/2011009" dated March 2, 2011 In the above referenced letter, the NRC notified Exelon Generation Company, LLC (EGC) of the completion of a verification inspection at Braidwood Station, Units 1 and 2. The inspection report documents the actions taken to review a condition related to the analysis for a Steam Generator Tube Rupture (SGTR) event Margin to Overfill (MTO), previously identified at Byron Station with respect to the single failure assumptions used in the SGTR analysis.

The inspection concluded the NRC was not clear or consistent with communicating the need to assume passive failures of the electrical components for the SGTR analysis, even though passive failures were required to be evaluated under 10 CFR Part 50, Appendix A. Therefore, the current NRC staff position regarding the requirement to evaluate single passive failures of the electrical components is different than the NRC's position previously communicated to Braidwood Station. Therefore, the provisions of 10 CFR 50.109, "Backfitting," are applicable.

October 14,2011 U.S. Nuclear Regulatory Commission Page 2 The issue has been entered into the Corrective Action Program (CAP) and EGC intends to bring Braidwood Station into full compliance. Compensatory actions have already been implemented pending permanent actions to resolve this issue.

To resolve this issue, EGC has committed Braidwood Station Units 1 and 2 to modify the power supplies to the Steam Generator (SG) Power Operated Relief Valves (PORVs) by providing a safety related battery backup. This battery backup will restore the limiting single failure for the SGTR analysis to the loss of one SG PORV.

Based upon the current schedule, the SG PORV Uninterruptable Power Supplies (UPS) and attendant batteries are scheduled to be installed in the Spring of 2012 for both units. The final terminations of the Unit 1 UPS will occur during the Braidwood Spring outage, A1 R16, for the instrument bus feed. Final terminations for Unit 2 SG PORV UPS will be occurring during the Fall outage, A2R16, for the instrument bus feed. Therefore, there is no change to the original scheduled commitment date.

Should you have any questions concerning this letter, please contact Mr. Chris VanDenburgh, Regulatory Assurance Manager, at (815) 417-2800.

Respectfully, Daniel J. Enright Site Vice President Braidwood Station DJE/vak cc: NRR Project Manager - Braidwood Station Illinois Emergency Management Agency - Division of Nuclear Safety US NRC Regional Administrator, Region III US NRC Senior Resident Inspector (Braidwood Station)

Illinois Emergency Management Agency - Braidwood Rep