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Abstract The optimal radial build and the system parameters of a tokamak fusion system with a normal aspect ratio were found utilizing a tokamak systems analysis coupled with the neutron transport calculation. The optimum build was determined by the requirements on the shielding, the tritium breeding, and the magnetic flux density at the toroidal field (TF) coil. It was shown that for the given fusion power, a thick outboard blanket with a thin inboard blanket allowed for smaller system size. The case with a smaller aspect ratio allowed for a smaller major radius, R 0 and a smaller system size than the case with a larger aspect ratio. With a confinement enhancement factor, H = 1.3, Q >30 was possible for a fusion power larger than 2200 MW for the case with the aspect ratio, A = 3.0; however, Q > 30 was impossible for the case with A = 4.0. The tritium breeding capabilities of the five blanket concepts to be tested as test blanket modules (TBMs) in the International Thermonuclear Experimental Reactor (ITER) were evaluated by varying the blanket thickness and the lithium-6 (Li-6) enrichment. A helium-cooled solid breeder (HCSB) concept showed the best tritium breeding capability while the shielding effect of Pb was noticeable for a helium-cooled lithium lead (HCLL) concept. [ABSTRACT FROM AUTHOR]

Abstract The design of diagnostics system for the Helium Cooled Ceramic Reflector (HCCR) Test Blanket System (TBS) has now progressed from generic approaches to the conceptual design integration phases. It is proposed to monitor the temperature, strain, magnetic field strength and neutron flux in selected positions of the corresponding Test Blanket Module (TBM). The temperature can be measured by thermocouple sensors to be integrated for the first wall and breeding zones of TBM. The strain will be monitored by appropriate gauges on the first wall of TBM. Several magnetic pick-up coils could be installed to measure magnetic field strength inside the TBM structure. For the neutron flux monitoring, pairs of Neutron Activation System (NAS) probes and Micro-Fission Chambers (MFCs) would be installed in the TBM structure. In this paper, a brief description on the proposed diagnostics system as well as the key components is presented, and the integration challenges of HCCR TBS diagnostics system are outlined. [ABSTRACT FROM AUTHOR]

To obtain tritium breeding ratio in tritium breeding blanket experiments, incident neutron flux measurement is essential. To develop high tritium breeding performance, the more precise neutron flux measurement is required. In this work, the Compton suppression gamma ray spectrometer, which can suppress the expected background noise signals from Compton scatterings, is used to detect the gamma rays from neutron activated indium foils for the purpose of reducing the measurement errors in the neutron activation system (NAS). The statistical error of the measured sample activity in the Compton suppressed system is estimated to be about 2.8% from the counting error (1.4%) and the detector efficiency error (2.4%), and the statistical error of the measured sample activity in the non-suppressed system was estimated to be about 4.7% (from the counting error 2.0% and the detector efficiency error 4.3%) in KSTAR experiment. This system can be applied to ITER TBM and future nuclear fusion devices. [ABSTRACT FROM AUTHOR]

Test blanket modules (TBMs) will be installed in the ITER with the aim to investigate the nuclear performance of different breeding blanket designs for fusion power reactors. Here, we present an overview of our ongoing work on three types of neutron flux monitors under development at Karlsruhe Institute of Technology (KIT) for the TBMs. A foil activation system with pneumatic sample transport was constructed by KIT utilizing the intense DT neutron generator of Technical University of Dresden. It is used as a test bench for the development of a neutron activation system for the TBMs. Self-powered neutron detectors (SPNDs) are widely applied in fission reactor monitoring, and the commercially available SPNDs are sensitive to thermal neutrons. We are investigating novel materials for SPND which would be sensitive also to the fast neutron flux expected in the TBMs. Within the I_SMART project, funded by KIC InnoEnergy, KIT is developing an online detector based on silicon carbide electronics for the TBMs. [ABSTRACT FROM PUBLISHER]

Abstract: The first wall of an international thermonuclear experimental reactor (ITER) test blanket module (TBM) is a multilayered component consisting of plasma facing armor and structural materials including the cooling channels. One of the main issues about the R&D on the TBM is to develop the joining technologies for a fabrication of the TBM first wall. The objectives of this study are to optimize the hot isostatic pressing (HIP) conditions and the interlayer combination for the fabrication of beryllium (Be)/ferritic martensitic steel (FMS) joints without a degradation of the mechanical properties of the FMS. Effects of HIP joining conditions including the temperature and interlayer types were investigated. The HIP temperature was selected for the anticipated tempering condition for FMS to avoid a grain coarsening which would deteriorate the mechanical properties of FMS. Several interlayer materials were applied in order to manufacture high strength joints. Be and FMS were joined successfully by the application of a Ti/Cu interlayer and it showed a relatively high bending strength, 257MPa, among the interlayer types studied. The fracture was caused by a delamination of the reaction layer between FMS and the coated interlayer without a plastic deformation. This paper summarizes the results of a Be/FMS joints manufacturing and an investigation of their properties. [Copyright &y& Elsevier]

• EU reference tritium breeding pebbles are produced using a melt-based process. • Process scale-up is underway to ensure the supply for ITER. • Biphasic materials show enhanced mechanical strength and stability. • Design relevant data were summarised in a material property handbook. • Crucial neutron irradiation experiments will complement the material qualification Biphasic ceramic pebbles, consisting of Li 4 SiO 4 and Li 2 TiO 3 , are being developed as the EU reference tritium breeding material for ITER and DEMO. A modified melt-based process for the pebble fabrication was established and optimised with regard to the process stability and yield. In parallel, the properties of pebbles and pebble beds were evaluated in dedicated experiments. These include investigations into e.g. the long-term thermal stability of pebbles, the thermomechanical properties of pebble beds, as well as the compatibility between the ceramics and the structural material. The available data was recently summarised and issued as the Material Property Handbook on Advanced Ceramic Breeders. During the EU DEMO conceptual phase, two main issues are proposed to be pursued in view of ITER. Irradiation campaigns are planned to ensure that the advanced ceramic breeder material is adequately tested and an extensive process scale-up with an increased production rate is foreseen to secure the supply for the ITER test blanket modules. [ABSTRACT FROM AUTHOR]