CAJ | 학술논문

目的研究裂变中子谱照射中国参考人单位中子注量在血液中产生的24Na比活度AB/φ,并分析实验场所地板、墙壁和天花板等的散射中子对测量结果的影响.方法利用强度约3×108中子/s的252Cf中子源对中国参考人模体进行照射.模体躯干尺寸按中国参考人制作,外壳由4 mm有机玻璃制成,内有人体组织当量液,主要元素的重量比为H∶N∶O∶C=10.6∶2.5∶63.2∶23.7,密度1.007g/cm3(20℃).中子源到模体长轴的照射距离d(m)分别为1.1、2.1、3.1和4.1.中子源和模体的剑突部位离地面1.6 m.结果单位中子注量照射在模体内产生的24Na平均比活度与照射距离有关,根据实验结果推导出的AB/Φ的最大值(AB/ΦM)约为1.85×10-7Bq·cm2·g-1.结论 AB/ΦM相当于252Cf中子谱平行射线照射的情况,这一数据比文献报道的BOMAB模体的实验结果大3%.实验表明,在照射场所的地面、墙壁散射中子对24Na比活度有显著的贡献,但对入射中子的剂量贡献却相对较小.因此,在实际的中子照射事故中,利用血液24Na比活度估算受照者的中子剂量时,事故场所散射中子的贡献将导致过高估计中子剂量,需要进行修正.
목적 연구렬변중자보조사중국삼고인단위중자주량재혈액중산생적24Na비활도AB/φ,병분석실험장소지판、장벽화천화판등적산사중자대측량결과적영향.방법 이용강도약3×108중자/s적252Cf중자원대중국삼고인모체진행조사.모체구간척촌안중국삼고인제작,외각유4 mm유궤파리제성,내유인체조직당량액,주요원소적중량비위H∶N∶O∶C=10.6∶2.5∶63.2∶23.7,밀도1.007g/cm3(20℃).중자원도모체장축적조사거리d(m)분별위1.1、2.1、3.1화4.1.중자원화모체적검돌부위리지면1.6 m.결과 단위중자주량조사재모체내산생적24Na평균비활도여조사거리유관,근거실험결과추도출적AB/Φ적최대치(AB/ΦM)약위1.85×10-7Bq·cm2·g-1.결론 AB/ΦM상당우252Cf중자보평행사선조사적정황,저일수거비문헌보도적BOMAB모체적실험결과대3%.실험표명,재조사장소적지면、장벽산사중자대24Na비활도유현저적공헌,단대입사중자적제량공헌각상대교소.인차,재실제적중자조사사고중,이용혈액24Na비활도고산수조자적중자제량시,사고장소산사중자적공헌장도치과고고계중자제량,수요진행수정.
Objective To investigate the specific activity of 24Na per unit neutron fluence,AB/Φ,in blood produced for Chinese reference man irratiaded by 252Cf neutron source,and to analyze the effects of scattering neutrons from ground,wall,and ceiling in irradiation site on it.MethodsA 252Cf neutron source of 3 × 108 n/s and the anthropomorphic phantom were used for experiments.The phantom was made from 4 mm thick of outer covering by perspex and the liquid tissue-equivalent substitute in it.The data of phantom dimensions fit into Chinese reference man.The weight ratios of H,N,O and C in substitute equal from source to long axis of phantom were 1.1,2.1,3.1 and 4.1 m,respectively.Both the neutron source and the position of xiphisternum of the phantom were 1.6 m above the floor.ResultsThe average specific activity of 24Na per unit neutron fluence was related to the irradiation-distances,d,and its The AB/ΦM corresponds to that of phantom irradiated by plane-parallel beams,and the value is about more 3% than that by BOMAB phantom reported in literature.It has shown that floor-( wall-)scattered neutrons in irradiation site have significant contribution to the specific activity of 24Na ,but they contributed relatively little to the induced neutron doses.Consequently,using the specific activity of 24 Na for assessing accidental neutron doses received by an individual,the contribution of scattered neutrons in accident site will lead dose to be overestimated,and need to be correct.