ML110620089

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

ML110620089
Person / Time
Site:	Braidwood
Issue date:	03/02/2011
From:	Enright D Exelon Generation Co, Exelon Nuclear
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
BW110021, IR-11-009
Download: ML110620089 (3)

Text

10 CFR 50.109 March 2, 2011 BW110021 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:

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

Reference:

Letter from Steven A. Reynolds (USNRC) 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; 05000457/2011009", dated February 1,2011 In the 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 event.

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.

EGC acknowledges the NRC's revised position concerning the application of single failure criteria, as denoted in 10 CFR 50, Appendix A, to Braidwood Station's SGTR analysis. This revised NRC position now places Braidwood Station's SGTR analysis in noncompliance with NRC regulations.

EGC also acknowledges the NRC's requirement for Braidwood Station to resolve this noncompliance in accordance with 10 CFR 50.109. EGC does not intend to appeal this determination.

March 2,2011 U. S. Nuclear Regulatory Commission Page 2 The NRC requested a response within 30 days of the date of the inspection report with EGC's assessment of the issue and a description of our intended actions and schedule for completion. The NRC also requested the extent of condition to be addressed by reviewing other transients and accidents outlined in Chapter 15 of the Updated Final Safety Analysis Report (UFSAR).

The issue has been entered into the Corrective Action Program (CAP) and EGC intends to bring Braidwood Station into compliance. Compensatory actions have already been implemented pending permanent actions to resolve this issue.

To resolve this issue, EGC commits Braidwood Station Units 1 and 2 to modify the power supplies to the Steam Generator 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. These modifications will be installed no later than Unit 1's April 2012 refueling outage and Unit 2's October 2012 refueling outage. However, if a determination is made once the design details are issued that the modifications can be installed on-line, then the installation schedule will be accelerated. EGC will supplement this letter by October 14, 2011, communicating any revisions to the installation schedule based on the on-line/outage determination.

EGC also commits to performing an extent of condition review of other transients and accidents outlined in Chapter 15 of the Braidwood Station UFSAR to identify similar discrepancies with respect to the inappropriate reliance or assumption of a single active failure. Identified discrepancies will be resolved within the CAP and communicated to the NRC Region III Regional Administrator. This extent of condition review is scheduled to be completed by August 4, 2011.

The Attachment to this letter contains a list of regulatory commitments made in this letter. Should you have any questions concerning this letter, please contact Mr. Terence K. Schuster at (815) 417-2800.

Respectfully,

~6~

Site Vice President Braidwood Station Attachment - Summary of Regulatory Commitments 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)

US NRC Director, Office of Enforcement

ATTACHMENT

SUMMARY

OF REGULATORY COMMITMENTS The following table identifies commitments made in this document. Any other actions discussed in this letter represent intended or planned actions. They are described to the NRC for the NRC's information and are not regulatory commitments.

COMMIITTED COMMITMENT TYPE COMMITMENT DATE OR "OUTAGE" ONE* PROGRAMMATIC TIME (Yes/No)

(Yes/No)

The power supplies to the Steam No later than Generator PORVs will be Unit 1's April 2012 modified with a safety related refueling outage Yes No battery backup. and Unit 2's October 2012 refueling outage A supplement to this letter will be issued to communicate any revisions to the modification October 14, 2011 Yes No installation schedule based on the online/outaQe determination.

An extent of condition review will be conducted of other transients and accidents outlined in Chapter 15 of the Braidwood Station UFSAR to identify similar The review to Yes No discrepancies with respect to the identify similar inappropriate reliance or discrepancies will assumption of a single active be completed by failure. Identified discrepancies August 4, 2011 will be resolved within the Corrective Action Program and communicated to the NRC Region III Regional Administrator.