Plutonium isotopes and 137Cs in Dolon settlement near the Semipalatinsk Nuclear Test Site. About 50 years after the first nuclear weapon testing

Recent controversies concerning the radiation doses for populations living in the village of Dolon due to the nuclear explosions carried out at the Semipalatinsk Nuclear Test Site (SNTS) have encouraged us to evaluate in more detail the levels and distributions of residual long-lived radionuclides 137Cs and Pu isotopes (238Pu, 239,240Pu) in soils within the village. Soil core samples up to a depth of about 30 cm and/or 100 cm were collected at 25 sites and subjected to analysis of 137Cs and Pu isotopes. The inventories of 137Cs and 239,240Pu were found to be in the wide range of 790-10,310 and 530-14,320 Bq/m2, respectively. Sequential leaching of Pu from the soil showed that more than ca. 80% of the 239,240Pu was not leached by hot digestion with conc. HNO3 + H2O2, indicating the presence of Pu associated with fused silicates. Further, the presence of hot-particles from the Pu contaminants by a-track radiography technique using CR-39 polycarbonate was confirmed in the soil, even at present, after about 50 years from the first nuclear weapon testing. (author)