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Based on the design requirements of the first stage of the China Fusion Engineering Test Reactor (CFETR), the activation performance calculation and analysis of the components in the dual function lead-lithium blanket were performed using a neutron transport design and safety evaluation software system (SuperMC) with the fusion evaluation database JEFF3.2. A coupled burnup and transportation calculation method was used to calculate the radioactivity, residual decay heat, dose rate, and potential biological hazards of each component in the equatorial surface of the fusion reactor at different times after shutdown. The waste disposal problem of the tritium breeding blanket after the decommissioning of the fusion reactor was analyzed according to the relevant nuclear waste disposal standards in the safety and environment assessment of fusion power strategy. Results of the analysis show that under the condition of normal operation of 200 MW for 10 years, all components of the breeding blanket in the CFETR can satisfy simple recycling standards and meet the requirements of the first stage of CFETR radioactive waste treatment after 50 a of cooling.

BackgroundTraditional shielding X/γ ray materials are generally lead or lead containing materials, which have the disadvantages of high toxicity, heavy weight, difficult molding and high price. Polymer composite materials are considered to be new materials that can effectively protect against nuclear radiation in the future. Epoxy resin (EP) as a base material has many advantages, such as corrosion resistance, good mechanical properties, strong wear resistance, excellent insulation, and stronger radiation resistance, while rare earth materials have a better shielding effect on γ-rays in the 20~88 keV energy region, and can make up for the weak absorption zone of lead.PurposeThis study aims to verify the shielding performance of nano Yttrium trioxide/epoxy resin composites (Y2O3/EP) against X/γ rays.MethodsFirst of all, Y2O3/epoxy resin radiation protection materials with different yttrium oxide contents were prepared by filling Y2O3 into EP. Then, the positron lifetime spectrum analysis combined with X-ray diffraction (XRD), scanning electron microscopy (SEM) and other methods were employed to study the microstructure of the material whilst the thermogravimetric analysis and differential scanning calorimeter (DSC) were applied to analyzing the thermal stability of the material, and Vickers hardness tester and universal tensile machine were used to test the mechanical properties of the material. Finally, the Monte Carlo N Particle Transport Code (MCNP) was applied to the simulation calculation of the radiation protection performance of the these samples.ResultsTesting results show that Y2O3 filled with epoxy resin can improve the thermal stability, hardness and Young's modulus of the composite material, but reduce the tensile strength. In the X/γ ray energy range of 20~1 332 keV, the shielding effect of 40% Y2O3/EP composite is 2%~10% of that of pure Pb under the same material thickness, and the shielding effect of 40% Y2O3/EP composite is 15%~66% of that of pure Pb under the same mass.ConclusionsAlthough the shielding effect of Y2O3/EP composite is worse than that of pure lead, it can meet the shielding requirements at X/γ low-energy radiation region with capability to replace lead or lead containing materials as radiation shielding materials.

BackgroundChina Dual Functional Lithium-Lead (DFLL) blanket is designed by the Institute of Nuclear Energy Safety Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences for fusion reactor. Since the designs of fusion reactor tritium breeding blankets are highly depended on neutronics calculation, nuclear data and simulation software used for DFLL cladding design is needed to be verified.PurposeThis study aims to evaluate the feasibility of nuclear data and code in DFLL cladding design by neutronics experiments.MethodsFirst of all, a DFLL mock-up was built and a series of neutronics experiments were performed on the D-T Fusion Neutron Generator. Then, a combination of Nb activated foil with reaction channel 93Nb(n,2n)92mNb and 238U fission chamber was chosen in this experiment for neutron yield measurement and relative neutron source intensity monitoring respectively. The Li2CO3 pellets and activation foils were used to measure the tritium production rates (TPR) and the multi-threshold reaction rates at different depths in the DFLL mock-up respectively. Finally, the measured TPR and reaction rates of the activation foils were compared with Monte Carlo simulation results coupled with JEFF3.2 nuclear data library.ResultsThe comparison results show that measurement uncertainty of neutron source intensity is within 4.2%, and the ratios of calculation results to experimental data (C/E) are 1.0~1.07 on TPRs and 0.77~1.1 on reaction rates.ConclusionsThe obtained results indicate that the tritium breeding ratio in neutronics design can be accurately evaluated.