微型堆辐照座内快中子通量谱的测定

Measurement of fast neutron flux spectrum in irradiation sites of MNSR

用Ａｌ、Ｆｅ、Ｉｎ和Ｎｉ作探测片，用阈探测片活化法测定了中国原子能科学研究院微型堆内、外辐照孔道的快中子通量。用平均截面法求得内外辐照孔道的快中子与热中子通量比（Φｆ／Φｔｈ）分别为０．１９８和０．０７７。用有效阈能法计算了不同能量区间的快中子通量。同时也对四个内辐照管之间及内、外辐照管内径向和轴向快中子通量的不均匀度进行了测定。

The fast neutron flux spectrum has been measured by the activation of the threshold detection foils at the inner and outer irradiation sites of the Miniature Neutron Source Reactor in China Institute of Atomic Energy Five threshold detection foils, i e Al, Fe, In, Ni and Mn were adopted in the experiment The ratios of fast-to-thermal neutron flux for inner and outer irradiation sites were calculated by the method of average cross section, to be 0 198±0 005 and 0 071±0 003, respectively The method of effective threshold energy was used to calculate the neutron flux in different energy ranges The axial and radial inhomogeneities of fast neutron flux for four irradiation sites and the inhomogeneity for different inner irradiation sites were also measured