Derivation of Neutron Ambient Dose Using Neutron Monitor in Daejeon

Abstract

The Basic Atomic Energy Research Institute (BAERI) of Hanyang University in Korea constructed a cosmic ray detection system, which is being operated currently. In this study, neutron ambient dose equivalent rate variation from cosmic ray were analyzed under various environmental conditions using the Excel-based Program for calculating Atmospheric Cosmic-ray Spectrum (EXPACS) applying PHITS (Particle and Heavy Ion Transport code System) based Analytical Radiation Model in the Atmosphere (PARMA). Obtained results were compared with previous other studies and confirmed reliable. Measurement from the detection system was used for evaluation of neutron ambient dose equivalent rate at various environmental conditions in Daejeon. Finally, a conversion coefficient defined as the ratio of counts from the neutron monitor to the neutron ambient dose equivalent was obtained considering atmospheric depth, which have a impact on the conversion coefficient derived. The derived formula was polynomial form with r-square adjusted value of 0.9998. This confirms satisfactory accuracy and reliability of the formula and thereby the legitimate methodology introduced for neutron ambient dose equivalent evaluation using neutron monitor in Daejeon.