Tungsten boride shields in a spherical tokamak fusion power plant
Tungsten boride shields in a spherical tokamak fusion power plant
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球形托卡马克聚变发电厂中的硼化钨屏蔽
DOI：
10.1088/1741-4326/ac09ce
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发表时间：
2021
期刊：
影响因子：
3.3
通讯作者：
S. Humphry
中科院分区：
文献类型：
--
作者：
C. Windsor;J. Astbury;J. Davidson;Charles J.R. McFadzean;J. Morgan;C. Wilson;S. Humphry
利用MCNP程序模拟了球形托卡马克聚变反应堆中心高温超导体（HTS）堆芯的屏蔽性能。目标是尽量减少能量沉积到冷却的高温超导堆芯中，并通过限制中子和伽马通量将高温超导辐射损伤保持在可接受的水平。所比较的屏蔽材料为W2B、WB、W2B5和WB4以及反应烧结硼化物B0.329C0.074Cr0.024Fe0.274W0.299、单片W和WC。考虑了253到670毫米之间的五种屏蔽厚度，对应于1400到2200毫米之间的等离子体主半径。与单片w相比，W2B5给出了最有利的结果，在中子通量和伽马能量沉积方面减少了约10或更大的系数。这些结果与层状水冷屏蔽进行了比较，得出的结果是，使用慢化硼的单片屏蔽提供了相当的中子通量和功率沉积，并且（在W2B5的情况下）甚至更好的性能。从反应堆安全的角度来看，由于与氧的放射性活化有关的风险，没有水冷却剂的良好性能具有优势。硼化物屏蔽层的10B同位素浓度考虑在0% ~ 100%之间。自然生成的20%馏分的能量沉积比0%馏分的能量沉积要低得多，但在40%以上，改善程度基本达到饱和。讨论了候选材料的热物理性质，特别是热应变。据我们所知，W2B5的性能是其他单片屏蔽材料无法比拟的。部分原因是它的三角晶体结构使它的原子密度比其他硼化物高。也有人认为，它的高性能取决于它有足够高的10B含量，以保持一个恒定的中子能谱穿过屏蔽。
The favourable properties of tungsten borides for shielding the central high temperature superconductor (HTS) core of a spherical tokamak fusion power plant are modelled using the MCNP code. The objectives are to minimize the power deposition into the cooled HTS core, and to keep HTS radiation damage to acceptable levels by limiting the neutron and gamma fluxes. The shield materials compared are W2B, WB, W2B5 and WB4 along with a reactively sintered boride B0.329C0.074Cr0.024Fe0.274W0.299, monolithic W and WC. Five shield thicknesses between 253 and 670 mm were considered, corresponding to plasma major radii between 1400 and 2200 mm. W2B5 gave the most favourable results with a factor of ∼10 or greater reduction in neutron flux and gamma energy deposition as compared to monolithic W. These results are compared with layered water-cooled shields, giving the result that the monolithic shields, with moderating boron, gave comparable neutron flux and power deposition, and (in the case of W2B5) even better performance. Good performance without water-coolant has advantages from a reactor safety perspective due to the risks associated with radio-activation of oxygen. 10B isotope concentrations between 0% and 100% are considered for the boride shields. The naturally occurring 20% fraction gave much lower energy depositions than the 0% fraction, but the improvement largely saturated beyond 40%. Thermophysical properties of the candidate materials are discussed, in particular the thermal strain. To our knowledge, the performance of W2B5 is unrivalled by other monolithic shielding materials. This is partly as its trigonal crystal structure gives it higher atomic density compared with other borides. It is also suggested that its high performance depends on it having just high enough 10B content to maintain a constant neutron energy spectrum across the shield.