ML110530138
| ML110530138 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 02/18/2011 |
| From: | Tulon T Exelon Nuclear, Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 1.01.0101, 2011-0036 IR-11-010 | |
| Download: ML110530138 (3) | |
Text
Exel_n Nuclear 10 CFR 50.109 February 18, 2011 Byron Ltr 2011-0036 File: 1.01.0101 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Byron Station, Unit 1 and 2 Facility Operating License Nos. NPF-37 and NPF-66 NRC Docket Nos. STN 50-454 and STN 50-455
Subject:
Response to NRC Follow Up Inspection Report; 05000454/2011010; 05000455/20 1 1010
Reference:
Letter from Steven A. Reynolds (USNRC) to Michael J. Pacillio (Exelon Generation Company, LLC), Byron Station, Units 1 and 2 Follow Up Inspection of an Unresolved Item; 05000454/2011010; 050004552011010, dated January 19, 2011 In the referenced letter, the NRC notified Exelon Generation Company, LLC (EGC) of the completion of a follow-up inspection at Byron Station, Units 1 and 2. The inspection report documents the actions taken to review unresolved items (URIs) from the 2009 Component Design Bases Inspection (CDBI) at Byron Station (URI 05000454/2009007-03; URI 05000455/2009007-03). The URIs involved a concern with respect to the single failure assumptions used in Byron Stations analysis for a Steam Generator Tube Rupture (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 NRCs position previously communicated to Byron Station.
Therefore, the provisions of 10 CFR 50.109, Backfitting, are applicable.
EGC acknowledges the NRCs revised position concerning the application of single failure criteria, as denoted in 10 CFR 50, Appendix A, to Byron Stations SGTR analysis. This revised NRC position now places Byron Stations SGTR analysis in noncompliance with NRC regulations. EGC also acknowledges the NRCs requirement for Byron Station to resolve this noncompliance in accordance with 10 CFR 50.109. EGC does not intend to appeal this determination.
February 18, 201 1 Byron Ltr 2011-0036 U. S. Nuclear Regulatory Commission Page 2 The NRC requested a response within 30 days of the date of the inspection report with EGCs 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 Update Final Safety Analysis Report (UFSAR).
The issue has been entered into the Corrective Action Program (CAP) and EGG intends to bring Byron Station into compliance. Compensatory actions have already been implemented pending permanent actions to resolve this issue.
To resolve this issue, EGG commits Byron 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 ls October 2012 refueling outage and Unit 2s May 2013 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. EGG will supplement this letter by October 14, 2011 communicating any revisions to the installation schedule based on the on-line/outage determination.
EGG also commits to performing an extent of condition review of other transients and accidents outlined in Chapter 15 of the Byron 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 Ill 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. David Gudger at (815) 406-2800.
Tirffiy J. Tulon fe Vice President
,yron Station TJT/J ELJIm Attachment
- Summary of Regulatory Commitments
ATTACHM ENT
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 NRCs information and are not regulatory commitments.
COMMI1TFED COMMITMENT TYPE COMMITMENT DATE OR OUTAGE ONE-TIME PROGRAMMATIC (Yes/No)
(Yes/No)
The power supplies to the Steam No later than Unit Generator PORVs will be 1 s October 2012 modified with a safety related refueling outage Yes No battery backup.
and Unit 2s May 2013 refueling outage A supplement to this letter will be issued communicating any revisions to the modification October 14, 201 1 Yes No installation schedule based on the online/outage determination.
An extent of condition review will be conducted of other transients and accidents outlined in Chapter 15 of the Byron Station UFSAR to identify similar discrepancies with The review to Yes No respect to the inappropriate identify similar reliance or assumption of a single discrepancies will active failure. Identified be completed by discrepancies will be resolved August 4, 201 1 within the Corrective Action Program and communicated to the NRC Region Ill Regional Administrator.