Pressurized Water Reactor Owners Group Perspective on GSI-191 Closure Introduction of the PWROG GSI-191 Comprehensive Closure Program Jeff Brown Chairman PWROG SEESC

Pressurized Water Reactor Owners Group PWROG Mission Overarching mission Support generation of safe and reliable power Effective regulatory interface In accordance with it’s mission, the PWROG has supported the PWR utilities in the overall resolution of GSI-191 – additional support is needed for final closure

Pressurized Water Reactor Owners Group PWROG Perspective on GSI-191 Closure Plants are safe Outstanding issue – closure required Important that GSI‐191 be resolved in a manner that provides a stable resolution All aspects of ECCS performance have been addressed with the exception of in-vessel effects (fuel blockage) Evolving technical issues and complex phenomena have resulted in extended resolution time and conservative results WCAP 16793 Rev. 2 documents bounding value of 15g/FA

Pressurized Water Reactor Owners Group PWROG Perspective on GSI-191 Closure Revised deterministic program required - a “holistic” approach based on an appropriate scientific process Produce a range of fiber limits for groups of plants Balance needed between closure timeframe and necessary time to establish technically defensible, reasonable set of limits for in-vessel fiber

Pressurized Water Reactor Owners Group PWROG Program and Objectives PWROG technical support for the NEI GSI-191 resolution program “Tiger” Team assembled to provide technical guidance for closure program development and execution Industry representatives NSSS Vendors Other advisors and consultants

Pressurized Water Reactor Owners Group PWROG Program and Objectives Overall Program Objectives Establish range of fiber acceptance limits and applicability criteria for utility assessment toward plant specific goals for closure by deterministic methods (Option 2a) Program to improve upon WCAP 16793 Revision 2 results (15 g/FA) applicable to all plants Support risk informed closure methods (Option 3) Assist in closure process

Pressurized Water Reactor Owners Group PWROG Program and Objectives Program Defined “Concept for Closure” PWROG Projects (“PAs”) PA-SEE-1090 – Deterministic in-vessel fiber test program PA-SEE-1072 – Boric acid precipitation PA-SEE-0872 – General support PA-SEE-1088 – Independent third-party review (I3PR)

Pressurized Water Reactor Owners Group In-Vessel Deterministic Program Overview (Option 2a) Revised in-vessel deterministic approach Lessons learned Little margin available through additional “head loss” testing Significant increase above WCAP 16793 limit of 15 g/FA not expected with original bounding approach Actual cooling flow requirements are significantly less than maximum ECCS Timing and precipitation form are key ACRS concerns

Pressurized Water Reactor Owners Group In-Vessel Deterministic Program Overview Long term core cooling – 10CFR50.46 Establish required flow conditions to ensure long term core cooling LOCA analysis models Integrated system analysis Assess boric acid precipitation (BAP) Build the fiber bed Characterize fibrous debris and by-pass process Establish prototypical chemical precipitation conditions Address appropriate water chemistry for testing

Pressurized Water Reactor Owners Group In-Vessel Deterministic Program Overview Program considerations Diverse expertise Tiger Team NSSS vendors and research labs Utility experts and consultants Independent third party review (I3PR) Coordination with STPNOC RI effort Screen by-pass testing Water chemistry testing LOCA modeling

Pressurized Water Reactor Owners Group In-Vessel Deterministic Program Overview I3PR Bench-top Testing ECCS / LOCA Analysis PIRT (In-vessel fiber /BAP) Program Test Plan Challenge Board Final Test Plan WCAP

Pressurized Water Reactor Owners Group Additional Support for Issue Closure PWROG support for alternative closure options SECY 12-0093 Option 3 “Designed Mitigation” or other approaches Additional support for: NEI submittal template development Operability guidance (Option 1 plants) Defense in depth and mitigating strategies

Pressurized Water Reactor Owners Group Definition of Success In-vessel deterministic program Establish range of options for utilities to determine conditions to satisfy LTCC and minimize overall impact on cost and dose Enhance margins for future design changes and or operability evaluations Industry and NRC alignment Development and execution of alternative closure programs based on industry needs

Pressurized Water Reactor Owners Group Requirements for Success “Work”shop Communication Industry NRC Industry (utility) support for PWROG programs Surveys (get them in)

Pressurized Water Reactor Owners Group Limitations and Constraints PWROG in-vessel deterministic program schedule alignment with Option 2a Option 1 plant submittals contingent upon debris characterization Consistent with WCAP 16793, Revision 2

Pressurized Water Reactor Owners Group Summary Stable resolution of GSI-191 needed Revised PWROG program to address in-vessel fiber in support of utility closeout (Option 2a) Complex phenomena, but program based on ensuring LTCC – range of options PWROG and Tiger Team to support alternative closure options based on utility needs (Option 3) Alignment between industry (PWROG) and NRC is key to success Communications Industry (utility) support for PWROG programs

Pressurized Water Reactor Owners Group Technical Program Details WEC Tim Croyle James Spring Areva Gordon Wissinger