Am-Be中子源屏蔽优化设计的蒙特卡罗模拟研究  

Monte Carlo simulation on optimal design of neutron shielding for Am-Be source

作　　者：吴赫 张锋[1] 李亚芬 韩忠悦 顾明翔 

机构地区：[1]中国石油大学(华东)地球科学与技术学院,山东青岛266580

出　　处：《辐射防护》2017年第2期94-99,共6页Radiation Protection

基　　金：国家自然科学基金资助项目(No.41374125;41574119);国家重大油气专项(No.2011ZX0520-002);中央高校基本科研业务费专项资金资助(14CX05011A;15CX06008A)

摘　　要：用低密度富氢材料作为^(241)Am-Be中子源防护罐屏蔽材料,防护罐尺寸大,屏蔽效率低,不利于现场测井作业。利用蒙特卡罗模拟方法,分别计算多种屏蔽材料对中子的慢化效果,优化设计了中子屏蔽效果好、相对轻便的防护罐。模拟结果得到:针对石油测井常用的18 Ci^(241)Am-Be中子源屏蔽罐,内层选用钨作为高能快中子的慢化层,厚度取13 cm;外层选用硼聚乙烯作为较低能量快中子慢化和热中子吸收层,厚度取18 cm。防护罐整体尺寸为?62 cm×62 cm,体积0.187 m^3,质量430 kg,比传统石蜡罐直径和重量约小一半,屏蔽罐外辐射剂量率小于0.025 m Sv·h^(-1),符合辐射防护标准要求。Hydrogen-rich material is currently used as shielding material in the conventional container of^241Am-Be neutron source,which causes the protective bucket large size,low efficiency and difficult to transport to well logging field. In this work,two different shielding materials are determined. And Monte Carlo simulation method is employed to optimize the thickness and combination mode of that filling material. Results show that the optimal volume and weight of protective tank is 0. 187 m^3 and 430 kg,respectively. Particularly,13 centimeters thick tungsten is select as the inner shielding layer and 18 cm thick boron polyethylene is chosen for thermal neutron-absorbent as the outer layer,and the radiation levels of concerned location is evaluated using MCNP code. It can be conclude that the dose rate of the outside is less than 0. 025 mSv·h^-1,which meet the requirement of relevant standards.

关 键 词：^241Am-Be中子源 屏蔽 优化设计 MCNP 钨 硼聚乙烯 

分 类 号：O571.53[理学—粒子物理与原子核物理]