ON THE DETERMINATION OF LOW PU CONTENT IN THE ENVIRONMENT

The method of Pu-239 minor content determination in the soil, water, a ir, living species is developed. It is based on chemical extraction of plutonium from the specimens. The Pu-236 alpha-active tracer was used to control the chemical yield of Pu from samples. The layers with Pu were put in contact with polyterephtalate and irradiated with thermal neutron fluences approximately 10(15) cm-2 together with calibrated U and P ethalons. The Pu content in soils from North Ukraina region was 310(-12) - 1.210(-13) g/g. To check the possible Th-U minor admixtures of U and Th in Pu fractions, the control experiments with 23 MeV gamm a-rays were carried out. It provides an upper limit of admixture of th ese nuclei at the level of less-than-or-equal-to 10(8) per sample.