近地面强中子源辐射环境场分布的蒙特卡罗计算

Monte Carlo Calculation for the Field Distributionof Radiation Environment of Near Ground Strong Neutron Source

针对强中子源在地面附近大气中形成的辐射场,研究地面介质对中子辐射场的影响,采用蒙特卡罗方法,模拟计算了不同高度单能中子源在地面高度1 m处形成的中子组织剂量分布。研究结果表明:与自由大气模型相比,由于地面介质的存在,在近源区中子组织剂量因地面反射而增强,在远源区,地面的屏蔽对中子组织剂量起削弱作用;针对某个探测点,存在一个最大剂量源高,并给出了最大剂量源高随水平投影距的变化关系拟合关系式,分布中子源算例表明,该拟合关系式具有一定的通用性。

The radiation environment field formed by a strong neutron source in the atmosphere near the ground will be affected by the ground.To study the effect of the ground on the neutron radiation field,The Monte Carlo method is used to simulate and calculate the distribution of neutron dose formed by single energy neutron sources over the ground height of 1 meter.The results show that compared with the non-ground homogeneous atmosphere model,the neutron tissue dose in the near region is enhanced by the ground reflection,while the shielding of the ground weakens the neutron tissue dose in the far region away from the neutron source.For a detection point,there is a source height crossponding to the maximum dose,and a fitting relationship between the source height and the horizontal projection distance is provided.The distributed neutron source example shows that this fitting relationship has a certain degree of universality.