脉冲中子-裂变中子探测铀黄饼的MCNP模拟

The Monte Carlo N particle transport code simulation of pulsed neutron-fission neutron uranium yellowcake exploration

利用MCNP程序模拟研究脉冲中子-裂变中子探测铀黄饼,采用脉冲式中子源,利用氦三管中子探测器记录裂变中子,得到铀黄饼中的铀含量信息。通过对14 MeV脉冲中子源和产生的裂变中子在不同铀含量模型中的输运计算,分析了裂变中子与铀含量的关系。结果表明:利用裂变超热中子衰减时间谱,可以确定铀黄饼中的铀含量;通过对热中子衰减时间谱进行校正,可以提高铀黄饼中铀含量计算结果的准确度。

The Monte Carlo N particle transport code （ MCNP ） is used to simulate how to explore the uranium yel-lowcake by using the pulsed neutron-fission neutron （ PNFN） method. In order to obtain uranium yellowcake quan-titation, pulsed neutron source was used, prompt fission neutrons were detected by using the neutron detector. Un-der the condition of different uranium quantitation models, the transport of the 14 MeV pulsed neutron source and the released fission neutron were calculated. On the basis of these, the relationship between fission neutron and ura-nium quantitation was studied. The results show that using the epithermal neutron time decay spectrum, the urani-um yellowcake quantitation can be determined; the precision of the uranium yellowcake quantitation could be in-creased by the correction of thermal neutron time decay spectrum.