氧化镁中子过滤器研究

核电厂反应堆乏燃料水池格架材料在生产和使用过程中需要对其中子吸收性能进行监测和检测，针对这两方面需求，研制了乏燃料水池格架B₄C_Al材料的中子吸收性能检测设备。为了降低检测过程中超热中子本底的影响，考虑采用氧化镁超热中子过滤器滤除超热中子。对10 和5 cm氧化镁单晶的中子透射率与宏观总截面进行了理论计算，对慢化体表面中子成分进行蒙特卡罗模拟计算并开展实验测量。实验结果表明，10 cm氧化镁对采用8 cm聚乙烯慢化后的252Cf中子源的中子透射率为60.16%，相对镉比值比未加10 cm氧化镁时提高了93.85%，证明常温下采用氧化镁单晶做B₄C_Al检测装置的超热中子过滤器是可行的。

Research on MgO as a Neutron Filter

In response to the need for monitoring and testing of the neutron absorption performance of the spent fuel pool grid material in the nuclear power plant reactor during the production and use process, we have developed the spent fuel pool grid frame B₄C_Al material neutron absorption material detection equipment. In order to reduce the influence of the superthermal neutron background in the detection process, we consider using a magnesium oxide thermal neutron filter to filter out the superthermal neutrons. The neutron transmittance and macroscopic total cross-section of 10 and 5 cm magnesium oxide single crystals were calculated theoretically, and the neutron composition on the surface of the moderator was calculated by Monte Carlo simulation and experimental measurements were carried out. The experimental results show that the neutron transmittance of 10 cm magnesium oxide to the 252Cf neutron source moderated by 8 cm polyethylene is 60.16%, and the relative cadmium ratio is increased by 93.85% compared with that without adding 10 cm of magnesium oxide. At room temperature, magnesium oxide single crystal used as the superthermal neutrons filter of the B₄C_Al detection device is feasible.