Risk-Informed Solution and Testing for Vogtle Plant Insulation Replacement

1. Option 2b Template Example Phillip Grissom – Southern Nuclear Based on Vogtle (more or less) 2012-10-19

2. Plant Information • Westinghouse 4-Loop PWR • 99.97% Nukon insulation • ~ 20 ft3 of Interam fire barrier in ZOI • 120 lbs Latent Debris (2x sampled amount) • GEH Stacked Disk Strainers 765 ft2 per each of 2 RHR trains , separate CS strainers (2) • TSP Buffer

3. GSI-191 Status • Strainer Head Loss and In-vessel issues remain open • Assuming Original 2007 Bypass Test (193 FA) • 111 gm/FA, very conservative but not rev’d by NRC • Previous chemical effects testing provided very promising results, but not accepted by NRC • Completed Laser scan of entire containment for insulation replacement contingency –both Units • Dose = 1083 mrem for 1 unit

4. GSI-191 Closure Decision • Essentially 100% Nukon high fiber plant • Replace all insulation with RMI & implement extensive & stringent containment cleanliness program – Option 1 • Replace most insulation with RMI, follow PWROG program, additional modification for debris bypass filter, and testing for reduced chemical effects, transport, head loss and bypass – Option 2a or 3 • Full Risk Informed (Vogtle and STP are very similar for this issue) - Option 2b

5. GSI-191 Closure Decision – Option 2b • Believe we could solve deterministically for Vogtle, but NRC approval and test results have some uncertainty • Fully risk informed solution, with ample testing and analysis to get best estimate results is very promising and provides insurance for very low probability event • Anticipate re-performing plant specific transport, head loss, bypass and fuel testing for DBE conditions as well as lesser events • Planning for modification to add debris bypass filter

6. Key Testing Anticipated • Chemical Effects for multiple break sizes and range of important parameters • Debris bypass filter – proof of concept testing • Strainer bypass – multiple scenarios • Strainer head loss – multiple scenarios • Debris transport, head loss, strainer bypass at DBE conditions • PWROG testing for BAP with fiber, Fuel • Fuel tests with Vogtle fuel type & source term?

7. Key Analysis Anticipated • LOCA frequency for each break location • System/containment response analysis for multiple break sizes and locations – expect similar results as STP • Boric Acid Precipitation with fiber • CASA Grande modification for Vogtle test results and analysis results • Sensitivity Studies

8. GSI-191 Schedule – Option 2b Clock Start 1/14 1/13 1/15 1/17 1/16 4/14 7/14 10/12 4/13 7/13 10/13 10/14 4/15 7/15 10/15 4/16 7/16 10/16 4/17 7/17 10/17 3rd Outage Industry Program WCAP SE PWROG Integrated Program U1 Outages U2 Outages Modification Timeline Design Design Readiness Review Vendor Dwgs Work Order Planning Specification and PO for Engineered Items U1 Mod U2 Mod Analysis & Testing, Conceptual Design Complete Laser Scan for measurements Schedule to NRC Vogtle RAI’s and SE Vogtle Complete RI Actions Discuss Plan with NRC Vogtle RI Submittal Vogtle Final Submittal STP Program STP Integrated Program STP RAI’s & NRC Issue SE

9. Template Considerations • Vogtle has completed measurements for contingency insulation replacement on both units • Vogtle has Level 2 PRA in good shape • Vogtle has started 3D-CAD model and RELAP5/MELCOR model for RI Option 2b • Insufficient time (because of 18 month cycle and RFO timing) to complete insulation removal by 3rd RFO after 1/1/2013 (April 2016 vs. 1/1/2019) if RI path not viable

10. Proposed Variance with Template • Complete any PRA justified necessary insulation replacements or remediation, or other identified plant changes during the next refueling outage, following issuance of an SE for the risk-informed resolution LAR for Vogtle 1& 2. • If it is determined during the risk-informed process that this option is not viable, Vogtle will complete a deterministic resolution path by January 1, 2019.