Measurement of reaction rate of actinide in soft neutron field by D_2O moderator for fast transmutation

利用京都大学临界装置（KUCA）对大D_2O反射体反应堆的核特性进行了实验研究。高精度地测量了以下实验数据：Np237在D_2O反射镜中的反应速率分布。不同D_2O反射器堆芯的倍增系数、堆芯和反射器中的中子通量分布。值得注意的是，本实验制备和使用的Np237样品质量大于1mg，具有很高的价值。在使用这些实验数据进行分析研究时，可以得出以下结论：使用JENDL3.2库的MVP代码高估了含有D_2O慢化剂的岩心的倍增因子。对于Np237在D_2O反射镜中的反应速率，MVP和SRAC-CITATION代码的C/E值均约为1.2。

Nuclear characteristics of a reactor with a large D_2O reflector was studied experimentally using the Kyoto University Critical Assembly (KUCA). The following experimental data were measured with high accuracy : reaction rate distributions of Np237 in the D_2O reflector. multiplication factors for cores with various D_2O reflectors, neutron flux distributions in a core and the reflector. It should be noted that Np237 samples prepared and employed in this experiment are very valuable because of the sample mass more than I mg. In the analytical study using these experimental data, the followings can be concluded : the MVP code using JENDL3.2 library overestimates multiplication factor of a core with D_2O moderator. the C/E values of both MVP and the SRAC-CITATION codes are about 1.2 for reaction rate of Np237 in a D_2O reflector.