Radiological risk assessment of outdoor 222Rn and 220Rn around rare earth element and uranium mines from northern Vietnam

Abstract

Abstract The outdoor 222Rn and 220Rn concentrations at 320 sampling points at 1 m above the ground in different sites surrounding rare earth element (REE) and uranium mines from northern Vietnam were measured using the RAD7. Results showed that 222Rn concentrations were always higher than 220Rn concentrations with large variation ranges from 25.7 to 573 Bq m−3 and from 18.5 to 385 Bq m−3, respectively. The high correlation between 220Rn and 228Ra concentrations in surface soil of the studied sites were observed. The highest 220Rn and 222Rn concentrations are found at the sampling points of the REE NX-Lai Chau site. The 220Rn and 222Rn activities surrounding the REE mines were found to be higher than those surrounding the uranium mines. The average annual committed effective doses originated from the inhalation of 220Rn and 222Rn outdoor concentrations is about five times higher than the worldwide average value.