高纯热中子束装置及设计

A facility for producing high purity thermal neutron beam and its design

在10MW重水反应堆水平孔道建成了液氮冷却单晶硅的高纯热中子束装置。在液氮温度下,热中子注量率是1.3×10~7、镉比30000。本文详细地描述了中子准直器的设计原理,并导出了计算公式。在束张角相同时,锥形准直器的中子注量率是直管准直器的1-4倍。本文也计算了经50cm单晶硅的热中子谱及热中子和快中子透射率同单晶硅长度的关系。理论和实验符合。

The facility has been set up on the 10 MW heavy water reactor in the Institute of Atomic Energy. A 50 cm long single crystal silicon cooled by liquid nitrogen is used for improving the quality of thermal column. At 77K, the neutron flux is 1.3×107, Cd-ratio is 30000 and×-dose in the beam is 1.935 ×10-8C/kg·s.The calculation of the neutron collimetor is given in detail. Neutron flux for a conical collimator is 1-4 times more than that for a straight collimator with the same angle converging. The relations of flux and angular divergence with the shape of collimator are described.