Daigo Tsuru

R&D of a Li2TiO3 pebble bed for a test blanket module in JAEA

At JAEA, a test blanket module (TBM) with a water-cooled solid breeder is being developed. This paper presents recent achievements of research activities for the TBM, particularly addressing the pebble bed of the tritium breeder materials and tritium behaviour. For the breeder material, the chemical stability of Li2TiO3 was improved using Li2O additives. To analyse the pebble bed behaviour, thermomechanical properties of the Li2TiO3 pebble bed were assessed experimentally. To verify the pebble beds nuclear properties, the activation foil method was proposed and a preliminary experiment was conducted. To reduce the tritium permeation, the chemical densified coating method was developed and the coating was attached to F82H steel. For tritium behaviour, the tritium recovery system was modified in consideration of the design change of the TBM.

Achievements in the development of the Water Cooled Solid Breeder Test Blanket Module of Japan to the milestones for installation in ITER

As the primary candidate of ITER Test Blanket Module (TBM) to be tested under the leadership of Japan, a water cooled solid breeder (WCSB) TBM is being developed. This paper shows the recent achievements towards the milestones of ITER TBMs prior to the installation, which consist of design integration in ITER, module qualification and safety assessment. With respect to the design integration, targeting the detailed design final report in 2012, structure designs of the WCSB TBM and the interfacing components (common frame and backside shielding) that are placed in a test port of ITER and the layout of the cooling system are presented. As for the module qualification, a real-scale first wall mock-up fabricated by using the hot isostatic pressing method by structural material of reduced activation martensitic ferritic steel, F82H, and flow and irradiation test of the mock-up are presented. As for safety milestones, the contents of the preliminary safety report in 2008 consisting of source term identification, failure mode and effect analysis (FMEA) and identification of postulated initiating events (PIEs) and safety analyses are presented.

Evaluation of Strength on Dissimilar Metal Joints for ITER First Wall Components

The first wall (FW) of ITER blanket includes beryllium (Be) armor tiles joined to CuCrZr heat sink with stainless steel cooling tube and backing plate in order to improve plasma performance and reduce thermal stress. Therefore dissimilar materials joints are indispensable for fabricating the high heat flux components. Since these joints must withstand thermal and mechanical loads caused by the plasma and electromagnetic force, it is important to evaluate the strength and thermal fatigue life of dissimilar materials joints. When the dissimilar materials joints are subjected by external force and thermal loading, the stress of the joint may indicate singularity at the interface edge. Since the stress singularity may lower the strength of joints, the singularity is evaluated numerically for the various materials combinations and joint configuration to be used in high heat flux components of fusion reactors in this investigation. Moreover, tensile test and elasto-plastic FEM analysis are performed to investigate the fracture behavior of Be/Cu alloy and stainless steel/ Cu alloy obtained the FW mock-up. The results reveal two singular solutions of type rpj −1 for a half-plane bonded to a quarter-plane joint and the singularity is larger than that of a bonded quarter-planes joint. From the viewpoint of stress singularity, the configuration of bonded quarter-planes joint is better than the half-plane bonded to a quarter-plane joint. The singularity for W/Cu alloy combination is large compared to other combination of materials. Especially the singularity of stainless steel/ Cu alloy is very small. Tensile specimen of Be/CuCrZr joint fractured at the bonding interface due to the stress singularity. For the stainless steel/ Cu alloy, however, the specimens fractured at the Cu alloy region apart from the interface.Copyright

Overview of the R&D Activities of Water Cooled Ceramic Breeder Blanket

This paper overviews the R&D activity of Water Cooled Ceramic Breeder (WCCB) Blanket in Japan. Japan is performing R&D of WCCB Blanket as the primary candidate of the breeding blanket for the fusion DEMO reactor. Regarding the development of blanket module fabrication technology, a real scale First Wall (FW) was fabricated using Reduced Activation Ferritic Martensitic Steel (RAFMS) F82H. Using fabricated FW mockup, thermo-hydraulic performance and high heat flux tests were successfully performed with the heat flux equivalent to ITER TBM condition, 0.5 MW/m2 , 80 cycles with the coolant condition as DEMO, 15 MPa 300 °C. Also, real scale Side Wall (SW) and real scale breeder pebble bed structure have been successfully fabricated. Furthermore, assembling of the real scale FW plate mockup and SW plate mockup was successfully performed. Development of major key technologies for the WCCB TBM structure fabrication has been progress toward the establishment of fabrication technology of WCCB TBM.Copyright