1. US Breeding Blanket Activities and Plans for Participating in ITER Blanket Test Program
Mohamed A. Abdou
Summary, Approach and Strategy (M. Abdou)
Liquid Breeder Blanket Activities (D. Sze)
Solid Breeder Blanket Activities (A. Ying)
PFC Considerations for TBWG (M. Ulrickson)

2. US Interest in ITER Testing
The US community has a strong interest in participating in ITER Blanket Testing
The US has been a Major Contributor to the ITER testing activities since ITER-CDA. The US contributed substantial efforts on definition of testing parameters, test module design, engineering scaling, test port engineering and remote maintenance, ancillary equipment, etc.
The US community is ready to have strong collaboration on the ITER TBM Program with all the Parties involved

3. US Activities Relevant to ITER TBM Program
Blanket/Chamber Programs
IFE Chamber Program
Materials Program
PFC Program
Safety and Tritium Program
Advanced Design Studies
The current effort, capabilities, and available expertise in these programs are extensive and will enable the US to have a strong ITER TBM Program

4. Current US Blanket/Chamber Activities
APEX
This is a large multi-disciplinary effort that involves 12 US universities and national labs. The APEX effort is aimed at exploration, design, and R&D for INNOVATIVE Blanket/Chamber Concepts with both LIQUID and SOLID Walls.
Liquid Metal MHD
Experiments
3-D Modeling
For both Free Surface and Closed Channel LM concepts. The Free-Surface Effort is aimed at putting a test module in NSTX in 3-5 years. The Closed-Channel effort supports self-cooled (and separately cooled) blankets.

5. Current US Blanket/Chamber Activities (cont’d)
Thermofluids for Low-Conductivity Fluids
Experiments and Modeling
Current focus is on: 1- Methods to enhance heat transfer; 2- MHD effects on heat transfer in turbulent flibe
Solid Breeder R&D
Current focus is on “effective” thermophysical properties, interface conductance, and thermomechanics material interactions for SB blankets with ceramic breeder and beryllium pebble beds

6. Current US Blanket/Chamber Activities (cont’d)
Neutronics
Nuclear Data and Codes for transport, activation, and nuclear responses
Fuel Cycle Modeling
An extensive fuel cycle model has been developed. It is used for the design of tritium systems and the evaluation of tritium self sufficiency requirements.

7. US Plans and Strategy for ITER TBM
Extensive deliberations have occurred in the US fusion community over the past few months about the US strategy and approach to the ITER TBM
Emerging Key Points:
The US will have strong participation
The US will redirect a large part of its blanket program resources to focus on R&D for ITER TBM
The US must rethink its previously preferred two blanket concepts in view of new technical results obtained over the past few years
(cont’d next page)

8. US Plans and Strategy for ITER TBM (cont’d)
There is a need for all ITER Parties to collaborate more, and to possibly consider a more integrated plan among the ITER Parties for carrying out the R&D and construction of the test modules. Among the reasons:
Spirit of “internal collaboration” inherent for the ITER process
Many new technical issues identified for all blanket concepts
Failure to resolve key technical issues, such as tritium permeation barriers and MHD insulators.
The R&D effort and TBM construction and testing will cost much more than previously thought
Funding for fusion in general, and blankets in particular, remains constrained for ALL the Parties involved

9. Emerging View in the US Blanket Community:
What Should the TWO US Blanket Options be for ITER TBM? And How to make the Decision?
Emerging View in the US Blanket Community:
He-cooled Solid Breeder (pebble bed) Blanket with FS
Selected by all parties (EU, J, RF) and has the largest world R&D
US has highly focused R&D in niche areas and rich expertise in underlying technical disciplines
Suggested US Strategy:
Select He/SB/FS as an option but do not have an independent TBM. Rather, plan on unit cell and submodule test articles that focus on particular technical issues of interest to all parties (Strategy will work if collaboration is agreed to by EU, J)
Liquid Breeder Option: ??
ALL Liquid Breeder Options have serious feasibility, “Go-No-Go” issues. To make a prudent decision, the US needs to initiate a 1 to 2 year study supported by highly focused R&D (time schedule is also a problem)

10. Liquid Breeder Blanket Options of Interest to US and Key Feasibility Issues
1. Self-Cooled Li / V
1.A. Li / V was the US choice for a long time. But negative results and lack of progress on serious feasibility issues are ALARMING
MHD Effects
Coating Development, Crack Tolerance
Engineering Design Solutions (that may not require coating)
Corrosion at High Temperature (coupled to coating development)
Tritium Recovery and Control
V Development
2. Lead-Lithium
2.A. He-Cooled Pb-Li with FS
Tritium Permeation (Barrier Development), and Control
Corrosion
2.B. Dual Coolant with He-Cooled First Wall and Self-Cooled –Pb-Li breeding zone with SiC INSERT for electrical/thermal insulation (all structure FS)
SiC insert compatability with Pb-Li (Corrosion temperature limit)
SiC insert performance integrity (cracks in coating of the insert, etc.)
Tritium Permeation and Control

11. Liquid Breeder Blanket Options (cont’d)
3. Molten Salt (Flibe/Flinabe)
3.A. Self-Cooled FLiBe with advanced FS structure
3.B. Self-Cooled FLiNaBe with FS structure
Enhancing heat transfer and MHD effects on heat transfer
Redox, tritium recovery and control

12. Emerging US Plan for ITER TBM Activities (Still in the discussion stage)
Join ITER Test Blanket Working Group (TBWG) (Done)
Initiate Evaluation Study to select Two Blanket options for US ITER TBM (primarily a selection of which liquid breeder option to choose, since there is an agreement on the specifics of the solid breeder option)
Study is to be led by the Chamber/Blanket Community in partnership with Materials, PFC, Safety, and Advanced Design Communities. Study will involve interactions with EU, Japan, RF, S. Korea, and China.
Study must be based on quantitative modeling and R&D data. Strive to eliminate “historical” bias.
Need to make the selection in 1 to 2 years (to meet ITER schedule)
Participation by other ITER Parties is highly encouraged
Initiate R&D and refocus existing activities to address the top-level critical issues that have the highest impact on Selection of Liquid Breeder Option
(e.g., see list given earlier. Examples are MHD insulators, MHD engineering design solutions and experiments, SiC insert corrosion with PbLi, tritium permeation barrier, etc.)

13. Emerging US Plan for ITER TBM Activities (cont’d)
Initiate discussions with other ITER Parties about the strategy for ITER TBM, e.g.,
Focus on 2 blanket options for the World instead of 2 options per party?
Bi-lateral and multi-lateral collaboration on the R&D (as well as construction of the ITER test articles?)
Enhance and focus current international collaborative programs (e.g., JUPITER-II, IEA, etc.) to provide data for ITER Test Module Selection and Development
Concurrently develop engineering scaling and engineering design of test articles in the ITER environment for the Blanket concepts selected for testing in ITER

14. “Informal” Suggestion Division of Responsibilities Among the Parties in the ITER Blanket Test Program
Steps to Arrive at a Practical Division:
Agree on TWO Reference Blanket Concepts to be common for all the parties instead of two blanket concepts per party. (This does not preclude an individual party from pursuing additional blanket concepts if they have enough resources)
Assign one lead party for each reference concept
• Other parties serve in support roles
Agree on a matrix that has two dimensions
A. Test Articles (e.g., One “look-alike,” two “act-alike,” and six submodules for each blanket concept)
B. R&D Tasks: definition and work breakdown structure
Divide the work among the parties by test article and R&D task (based on resources, capabilities, and interests of each party)