Dose assessment from activated sodium within a body in criticality accidents
Dose assessment from activated sodium within a body in criticality accidents
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DOI：
10.1093/oxfordjournals.rpd.a006350
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发表时间：
2003-01-01
影响因子：
1
通讯作者：
Yamaguchi, Y
中科院分区：
文献类型：
--
作者：
Takahashi, F;Endo, A;Yamaguchi, Y
一些数据是使用最新的复杂方法得出的，这些方法可以在危急事故中将诱发的Na-24的比活度快速转换为全身的平均剂量。用MCNP-4B程序进行了蒙特卡罗计算，研究了一些含裂变铀的临界系统的中子和伽马射线能谱。通过使用MIRD-5型体模的模拟和计算的能谱，分析了人体吸收剂量和钠的活化与外部辐射的关系。研究发现，诱发的Na-24的中子剂量评估对于医务人员为受害者的治疗提供初步指导将是重要的。然而，入射到人体的中子的能量分布并没有显著影响从Na-24的比活度到人体内诱发的伽马射线剂量的转换。分析阐明了从Na-24比活度到中子剂量的转换依赖于朝着源的方向和人体的大小。对于某些临界组件，在给定比活度为1.4kBq Na~(-24)/g Na~(23)的情况下，根据所获得的数据估算的总剂量范围为33~514 mGy.这项研究建议，应该定义铀溶液和燃料周围材料的大小，以正确估计总剂量，包括来自外部光子的剂量。
Some data were derived using recent sophisticated methods to rapidly convert specific activity of induced Na-24 to average dose over a whole body in criticality accidents. Monte Carlo calculations using the MCNP-4B code were performed to study energy spectra of neutrons and gamma rays for some criticality systems with fissile uranium. Absorbed dose to the human body and the activation of sodium were also analysed against external radiation by simulations using a MIRD-5 type phantom and the calculated energy spectra. It was found that the neutron dose assessment from induced Na-24 would be important to give medical staff initial guidance for treatment of a victim. However, the energy distribution of incident neutrons to the human body did not significantly influence the conversion from the specific activity of Na-24 to dose from gamma rays induced within a body. Analyses were made to clarify the dependence of conversion from Na-24 specific activity to neutron dose on the orientation toward the source and the size of the human body. The total dose estimated based upon the obtained data ranged from 33 mGy to 514 mGy for a given specific activity of 1.4 kBq Na-24 per g Na-23 for some criticality assemblies. This study suggested that the size of uranium solution and material around the fuel should be defined to properly estimate the total dose, including the dose from external photons.