微型中子源反应堆中子谱参数测量

Measurement of Neutron Spectrum Parameters of Miniature Neutron Source Reactor

以Au、Zr和Fe为活化探测器,采用裸探测器法测量中国原子能科学研究院微型中子源反应堆的中子谱参数f、α、fF和φth。内辐照座的α、f和fF分别为-0.007±0.003、20.8±0.4、5.5±0.2。该方法对φth的测量结果与4πβ-γ符合法的一致,相对偏差小于2%。与SLOWPOKE相比,微堆有较高的α、fF值。与已有测量数据的比较表明,微堆中子谱在很长一个时期内是稳定的,利用微堆作为中子源的k0法中子活化分析不需中子注量率监测器,且比较器一经照射和测量后,可用于其后较长时间内所有分析的计算标准。

The neutron spectrum parameters of the miniature neutron source reactor （MNSR） in China Institute of Atomic Energy were measured by bare monitor method using Au, Zr and Fe as monitors. The measured values of α （a parameter accounting for the non-ideality of the 1/E epithermal neutron fluence rate distribution）, f （thermal / epithermal neutron fluence rate） and fF （thermal / fast neutron fluence rate） in the inner irradiation site are -0. 007±0. 003, 20.8±0.4, and 5.5±0.2, respectively. The value of φth measured by this method is agreed with that measured by 4πβ-γmethod within 2%. Compared with SLOWPOKE, MNSR had higher values of a and fF. The comparison with the previous measurements indicates that MNSR has a quite constant neutron spectrum. The fluence rate monitors are not needed when k0-NAA is performed by using MNSR as neutron source, and with occasional check, the comparator data from one measurement may be used as a standard for subsequent analyses over a period of time.