Results are reported on cemented tungsten carbide (cWC) and boride-containing composite materials for the task of shielding the centre column of a superconducting tokamak power plant. The shield is based on five concentric annular shells consisting of cWC and water layers of which the innermost cWC shield can be replaced with boride composites. Sample materials have been fabricated changing the parameters of porosity P, binder alloy fraction fbinder and boron weight fraction fboron. For the fabricated materials, and other hypothetical samples with chosen parameters, Monte Carlo studies are made of: (i) the power deposition into the superconducting core, (ii) the fast neutron and gamma fluxes and (iii) the attenuation coefficients through the shield for the deposited power and neutron and gamma fluxes. It is shown that conventional Co-based cWC binder alloy can be replaced with a Fe–Cr alloy (92 wt.% Fe, 8 wt.% Cr), which has lower activation than cobalt with minor changes in shield performance. Boride-based composite materials have been prepared and shown to give a significant reduction in power deposition and flux, when placed close to the superconducting core. A typical shield of cemented tungsten carbide with 10 wt.% of Fe–8Cr binder and 0.1% porosity has a power reduction half-length of 0.06 m. It is shown that the power deposition increases by 4.3% for every 1% additional porosity, and 1.7% for every 1 wt.% additional binder. Power deposition decreased by 26% for an initial 1 wt.% boron addition, but further increases in fboron showed only a marginal decrease. The dependences of power deposited in the core, the maximum neutron and gamma fluxes on the core surface, and the half attenuation distances through the shield have been fitted to within a fractional percentage error by analytic functions of the porosity, metallic binder alloy and boron weight fractions.
超导托卡马克核聚变发电厂中心柱屏蔽用碳化钨基硬质合金及含硼化物复合材料的研究结果已报道。该屏蔽体由五个同心环形壳层组成，包含碳化钨（cWC）层和水层，其中最内层的碳化钨屏蔽层可用硼化物复合材料替代。通过改变孔隙率P、粘结剂合金分数fbinder和硼重量分数fboron等参数，制备了样品材料。针对所制备的材料以及其他具有选定参数的假设样品，进行了蒙特卡罗研究，内容包括：（i）超导芯中的功率沉积，（ii）快中子通量和伽马通量，以及（iii）穿过屏蔽体时功率沉积、中子通量和伽马通量的衰减系数。结果表明，传统的钴基碳化钨粘结剂合金可用Fe–Cr合金（92 wt.% Fe，8 wt.% Cr）替代，该合金的活化性能低于钴，且屏蔽性能变化很小。已制备了硼化物基复合材料，并证明当置于超导芯附近时，可显著降低功率沉积和通量。一种典型的碳化钨硬质合金屏蔽体，含10 wt.%的Fe–8Cr粘结剂和0.1%的孔隙率，其功率沉积的衰减半厚度为0.06 m。研究表明，孔隙率每增加1%，功率沉积增加4.3%；粘结剂每增加1 wt.%，功率沉积增加1.7%。初始添加1 wt.%的硼可使功率沉积降低26%，但进一步增加硼含量fboron仅带来微小的降低。通过解析函数拟合，功率沉积、芯表面最大中子通量和伽马通量以及穿过屏蔽体的半衰减厚度与孔隙率、金属粘结剂合金和硼重量分数的依赖关系，其拟合误差在分数百分比范围内。