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

2. 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

3. 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 Rev. 2 documents bounding value of 15g/FA

4. 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

5. 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

6. 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 Revision 2 results (15 g/FA) applicable to all plants
Support risk informed closure methods (Option 3)
Assist in closure process

7. 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)

8. 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 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

9. 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

10. 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

11. 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

12. Pressurized Water Reactor Owners Group
Additional Support for Issue Closure
PWROG support for alternative closure options
SECY 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

13. 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

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

15. 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

16. 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

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