Option 2b Template Example Phillip Grissom – Southern Nuclear Based on Vogtle (more or less)

Plant Information  Westinghouse 4-Loop PWR  99.97% Nukon insulation  ~ 20 ft 3 of Interam fire barrier in ZOI  120 lbs Latent Debris (2x sampled amount)  GEH Stacked Disk Strainers 765 ft 2 per each of 2 RHR trains, separate CS strainers (2)  TSP Buffer

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

GSI-191 Closure Decision  Essentially 100% Nukon high fiber plant 1.Replace all insulation with RMI & implement extensive & stringent containment cleanliness program – Option 1 2.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 3.Full Risk Informed (Vogtle and STP are very similar for this issue) - Option 2b

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

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?

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

GSI-191 Schedule – Option 2b 10/12 1/13 4/137/1310/1310/14 1/15 4/157/1510/15 1/14 4/147/14 1/16 4/167/1610/16 1/17 4/177/1710/17 PWROG Integrated Program WCAP SE Industry Program Clock Start U1 Outages U2 Outages Modification Timeline Work Order Planning U1 Mod Design Vendor Dwgs Design Readiness Review Specification and PO for Engineered Items Analysis & Testing, Conceptual Design STP Integrated Program STP RAI’s & NRC Issue SE STP Program Vogtle RI Submittal Vogtle Complete RI Actions U2 Mod Complete Laser Scan for measurements Discuss Plan with NRC Schedule to NRC Vogtle RAI’s and SE Vogtle Final Submittal 3 rd Outage

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 3 rd RFO after 1/1/2013 (April 2016 vs. 1/1/2019) if RI path not viable

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.