Quick Look Report on EU Fact Finding Trip

1. Quick Look Report on EU Fact Finding Trip S.J. Zinkle1, R.J. Kurtz2, and A.F. Rowcliffe3 1Oak Ridge National Laboratory 2Pacific Northwest National Laboratory 3ORNL Consultant TBM Conference Call October 27, 2005

2. Trip Objectives and Topics of Discussion • Status of the EU and US TBM programs. • Ferritic steel fabrication and joining options (HIPping, diffusion bonding, TIG and EB welding, NDE). • Development of structural design criteria. • Research on compatibility and tritium management: Pb/Li- ferritic steel, and tritium permeation barrier methodology. • Ceramic breeder fabrication, pebble bed deformation mechanics and feasibility of accommodating multiple breeding unit cells in one TBM. • Instrumentation and diagnostics for TBM performance monitoring. • Component qualification: • Irradiation effects testing • TBM mock-up fabrication • Integrated loop tests • High heat flux tests

3. Facilities Visited • October 17: Forschungszentrum Karlsruhe (Boccaccini, Meyder, Neuberger, Kamlah, Knitter, Moeslang) • October 18: EFDA - Garching (Laesser, Diegele, Poitevin, Zmitko) • October 19: ITER International Team - Garching (Barabash) • October 20: ENEA-Brasimone (Benamati, Dell’Orco, Tincani, Aiello)

4. Presentations Obtained - I • FZK: • Boccaccini - “Programme and Strategy” • Boccaccini - “EU DEMO Blankets and Their Test in ITER” • Meyder - “Design of HCPB TBM and Integration” (in German) • Neuberger - “TBM Integration” • Gan, Kamlah - “Thermomechanical Modeling of Ceramic Breeder and Beryllium Pebble Beds” • Knitter - “Ceramic Breeder Fabrication Techniques” (N/A) • EFDA: • Diegele - “Overview on EU ITER TBM Concepts and Strategy + Status of Materials Development” • Diegele - “R&D Program on Design Rules” • Zmitko - “Compatibility and Tritium Management Activities” • Poitevin - “TBM Box Manufacturing Technologies Development” • ITER International Team: • Barabash - “Materials for ITER”

5. Presentations Obtained - II • ENEA: • Dell’Orco - “HCBP TBM R&D at Brasimone” (N/A) • Aiello - “HCLL TBM R&D at Brasimone” (N/A) • Tours of HCBP and HCLL TBM Testing Facilities

6. Major Findings - I • The EU database on radiation effects in Eurofer is lacking data in the 500-550°C range at ITER relevant dose. There is interest in a collaborative program to utilize HFIR to meet this need. • The physical and mechanical properties for Eurofer are contained in Appendix A of the ITER Structural Design Criteria. The contents of this Appendix are not currently available outside of the EU and this situation is not likely to change until the full ITER agreement is signed. • At least four approaches have been tried to fabricate the FW, grid and cooling plate components while maintaining dimensional tolerances on the square and rectangular section cooling channels. Sufficient progress has been made to allow sub-components fabrication for initial loop testing, but further development is needed before proceeding to full TBM mock-ups. • Difficult challenges include: • Bend transition from first wall to side wall. • Defining the assembly sequence of the full TBM. • Performing the required heat treatments at each stage to guarantee the Eurofer structure is in the required microstructural condition.

7. Major Findings - II • Integration of a TBM into ITER will require remote orbital welding of 11 piping connections. Due to limited working space for remote welding, it is probably not possible to install different unit cells and provide separate purge gas systems. The information gained from testing alternative unit cell designs and the subsequent post-operational inspection, examination and analysis would greatly outweigh this potential disadvantage. • A major welding program is ongoing for TBM assembly. The program includes EB, laser and TIG welding to produce ~25 different types of joints in combination with a range of NDE techniques. Evaluation of the irradiation performance of the full range of welds and post-weld heat treatments is included (significant effects found at ~2 dpa). • The current ITER structural design criteria are formulated for low temperature operating conditions; however, TBMs will operate in a temperature regime where thermal creep of Eurofer is not negligible and creep/fatigue interactions may be important. • A viable strategy for the assessment of the high-temperature behavior of various types of joints envisaged for TBMs has not been formulated. Specimens for assessing the effects of irradiation on the behavior of joints must be designed to reflect the loading conditions expected for TBMs.

8. Potential US/EU TBM Materials R&D Collaborations (October 2005) - I • Development of improved structural design criteria and structural stress analysis methods including flaw tolerance (NDE detection limits) and lifetime analyses [FZK, EFDA]. • Development of standardized test methods for evaluating the integrity and mechanical properties of materials, including dissimilar metal joints, creep-fatigue, etc. [EFDA, IEA]. • Development of the materials data base (unirradiated and irradiated properties) on Eurofer base metal at 500-550°C and joints [FZK, EFDA]. • Advanced characterization techniques for evaluating HIP fabricated structures (NDE and destructive techniques) [EFDA]. • Development of in-situ diagnostics for TBMs beyond simple temperature and coolant flow measurements [FZK, EFDA].

9. Potential US/EU TBM Materials R&D Collaborations (October 2005) - II • Development of adherent corrosion-resistant oxide films on structural materials such as superalloys, some of which may serve as tritium permeation barriers in piping and ancillary equipment [EFDA]. • Investigation of Pb-Li compatibility and ferritic/martensitic steel/Pb-Li stress corrosion cracking issues [EFDA]. • Assessment of alternative mockup fabrication techniques [FZK, ENEA]. • SiC composite fabrication techniques, physical and mechanical properties [EFDA]. • Joining techniques for Be/ferritic steel and Be/W (divertor applications) [FZK]. • Characterization of as-fabricated ceramic breeder pellets and investigation of ceramic pebble bed thermomechanics [FZK].

10. ITER Machine Materials Issues - I • Evolving designs and developments in fabrication technologies generate requirements for additional structural materials performance data. • Cu-Cr-Zr alloy irradiation data needs: • Irradiation creep, fracture toughness, creep/fatigue interaction, influence of product form and behavior of cast material. • Ni-Al Bronze (pins, pads) • Strength, fracture toughness at 0.01dpa, 150-300°C • Ti-6Al-4V (flexible coupling) • Tensile ,fracture properties at 0.1 dpa, 150-200°C • XM-19 Steel (high strength pins) • Tensile, fracture properties at 1.0dpa,100°C • Cu-Ni-Be (compression washer in flexible cartridge) • Mechanical behavior at 0.2-0.4dpa, 150-300°C • Boron-doped 304SS (VV neutron absorber) • Dimensional stability, tensile, fracture properties at 0.01 dpa, 100°C

11. ITER Machine Materials Issues - II • For 316LN the basic data base is complete except for weld performance data under review by CEA. • Alternatives to wrought products require additional irradiation performance data. • Cast 316LN proposed by the US for shield module. • Powder HIP 316LN proposed by EU for FW application. • Cu-Cr-Zr/SS bonded joints for FW, divertor and for TBMs. • Design rules for performance of joints. • Standardization of mechanical testing methods. • Design of irradiation testing specimens. • Acceptance criteria for manufactured joints. • Irradiation performance database for final fabrication technologies.