Study of Effects of Atmospheric Humidity on Neutron Transportation and its Dose Field

Accurate calculation of neutron dose in the nuclear radiation field is of great significance to radiation detection, radiation protection, and radiation effect research. The distribution of neutron dose field can be affected by neutron spectrum, air density, and atmospheric humidity. In order to quantitatively investigate the influence of atmospheric humidity on the physical process of neutron transport and the distribution of neutron dose field, the Monte Carlo (MC) simulation model of neutron transport under different humidity conditions is presented in this article, and the parameters of neutron dose at different transport distances under typical humidity conditions for a scenario of an explosion of a nuclear device (ordinary hydrogen bomb) are calculated and analyzed. The quantitative relationship between the neutron dose and atmospheric water content under different mass distances is obtained. Based on this relationship, a fast-parameterized calculation method of neutron dose under different humidity conditions is presented. The relative deviation between the results of fast algorithm and MC simulation is within 8%. The results show that the neutron dose decreases with the increase of atmospheric water content at the same mass distance, and the change of atmospheric humidity can lead to a change of neutron dose up to about 10%–30%. For other types of nuclear devices, in which the source neutrons produced by them are different from that by hydrogen bombs, the influence of atmospheric humidity on the neutron dose field can also be studied by using the method presented here.