中子多重性钚-铀部件质量测量系统及实验进展

Neutron multiplicity assay device and experiment progress on Pu-U components

为了对核弹头中拆卸下来的和处于库房存储状态的核部件的质量进行无损测量,搭建了一个由32根3 He正比计数管和方型高密度聚乙烯慢化腔体构成的中子多重性探测器,采用8通道电子学处理器件进行中子脉冲信号分析,基于5组252 Cf中子源对中子多重性探测器进行标定,验证了自主开发的标定算法,获取了系统标定参数。分别对6个武器级罐装钚部件,7个罐装铀部件进行中子多重性实验测量,实验分析结果显示:基于点模型修正后的钚部件中子多重性质量测量值与标称值偏差小于1.5%,基于双Am-Li源标定曲线法的铀部件质量测量偏差小于5%。

To verify nuclear components dismantled from a nuclear warhead or stored in a nuclear facility,a neutron multiplicity counter with 32 ^3 He tubes and high density polythene cavity was built.Eight channel circuits were used to process the signals from3 He tubes.Five^ 252 Cf neutron sources were used to calibrate parameters of the counter.To improve the mass assay accuracy,analysis algorithm for weighted point model and double Am-Li neutron sources neutron multiplicity counting were studied.The neutron multiplicity distribution for six weapon-grade plutonium components and seven highly enriched uranium components were measured with the neutron multiplicity counter,assay results show that the mass assay bias is below 1.3%for plutonium components with the weighted neutron multiplicity model,while the value is below 5%for uranium components with calibration curve method.