在CARR堆上建立一缓发中子测量系统,用于可裂变核素的鉴别及定量分析。采用3He正比计数管对辐照后的天然铀样品、铀矿样品及浓缩铀样品进行缓发中子测量,并计算系统探测效率、探测限及灵敏度。样品从反应堆辐照后,放到慢化屏蔽体(图1)中测试,中心为铅筒用于吸收样品的γ射线,铅筒外的石蜡作为缓发中子的慢化体,最外层也为石蜡,内外石蜡环间有硼砂、镉箔, A delayed neutron measurement system was set up on the CARR reactor for the identification and quantitative analysis of fissile nuclides. The 3He proportional counter tube was used to measure the delayed neutron measurement of the irradiated natural uranium sample, uranium sample and enriched uranium sample, and the system detection efficiency, detection limit and sensitivity were calculated. Samples were irradiated from the reactor and tested in a moderated shield (Figure 1). The center was a lead tube for absorbing gamma rays from the sample. Paraffin from the lead tube was used as a moderator for slow neutrons. The outermost layer Also paraffin, inside and outside the paraffin ring borax, cadmium foil,