(n,f)-radiography as a means to investigate plants for their contamination with natural and technogenic uranium

Abstract

Plants which grow in an area where uranium mining took place have been investigated for their uranium content by applying neutron-fission radiography [(n,f)-radiography]. The uranium was either assimilated by the plant from uranium-bearing soil or deposited at the leaves by uranium-bearing dust particles. Human activities like mining and refinement of uranium ores release technogenic uranium in the environment and increase the concentration of this α-emitting element. The technogenic uranium contributes to radioactive pollution. In addition to the natural amount of uranium in dust, water and the fertile (humus) soil layer, the technogenic uranium may increase the effect of uranium on the human organism. In order to perform efficient radiation protection, one has to obtain knowledge about the sources of radiation. The discovery of open sources which release uranium to the environment is of great importance because of the large biological effect of the α-particles emitted by the uranium. Leaves, roots and soil have been sampled at different locations in the territory of a former uranium ore mine, in the surrounding area and in a forest at the edge of the city of Ronneburg, where a small plot is known for its high natural uranium concentration. The plastic foil “Lavsan” was used as track detector, and the irradiation was performed with a fluence of 10 16 neutrons cm −2. (n,f)-radiography applied to plants yields information about the presence of local α-emitting sources of uranium and their location. The density of the fission fragment tracks enables the estimation of the uranium concentration.