Radiological Characteristics of the Plant Species Taken from the Checking Area within 30 Km Influence Zone of the Volgodonsk Nuclear Plant.
Andrej Pronin and Tamara Abramova. Rostov State Univ, Bolschaya Sadovaya,105, Rostov -on- Don, Russia
Due to the startup of the Volgodonsk nuclear plant in 2001 there has appeared the necessity to monitor the local environment and its alteration. Within 30 km observation zone we have initiated ecological and radiological monitoring works which will be continuing for the whole period of the plant operation up to its decommissioning. To exercise the monitoring based on the natural-landscape geographical zonation method with the account of topographic and soil data we have determined the checking areas, which lie in different distances from the nuclear plant. We have been collecting annual samples of the same steppe zone plant species to detect the content of the following radionuclides in them: U-235, U-238, Th-234 (63), Th-234 (93), Ra-226, Pb-210, Th-224, Am-241, Cs-137, K-40. We have not detected a distinct dependence between certain isotopes content and the plant species: in the plants of the same species the quantity of the specific isotope can be more than double. It may be the result of extremely uneven radionuclides spread on the area of the 30 km Volgodonsk nuclear plant influence zone. To evaluate the radionuclides transfer from soil into plants we have determined the coefficient of isotopes biological absorption. We have ascertained that for the majority of the isotopes the coefficient of isotopes biological absorption is higher than 1 and for only U-224 it is lower than 1 in the majority of the samples. The radionuclides income into plants also depends on the content of N, P, K, Mg, Al, Br, Fe, Sr in the land mass. Mathematically true relationship of U-238 on N (r = 0,43), Cs-137 on Al (r = 0,59), etc. assumes that the value of the biological absorption of macro- and microelements as well as their relationship can be used to evaluate the radiation load on biocenosis.