Transfer Coefficients of ¹³⁷Cs via the Forage-Cow-Milk Pathway in Aomori-Prefecture of Japan

Abstract

The transfer of radiocesium to foodstuff of cattle is very serious, because it contributes significantly to internal exposure resulting from the intake of ¹³⁷Cs through the feed-cow-milk pathway. The transfer coefficient from feed to milk (F_m) is widely used to predict the dose to man from the radioactivity released to the biosphere. A commercial fuel reprocessing plant is under construction in Rokkasho-mura/Aomori Prefecture, the northeastern district of Japan. To figure out F_m under conventional farming conditions, therefore, transfer of ¹³⁷Cs into cattle was studied experimentally using ¹³⁷Cs deposited in the environment in cooperation with two daily farms in this region. Transfer factors for ¹³⁷Cs from feed to cow's milk have been obtained from data acquired from biweekly routine monitoring program under the two dissimilar farming conditions. The one dairy farm condition is mainly composed of high hay ration and the other is high concentrate ration. As a result of the experiments, ¹³⁷Cs activity of milk correlated significantly with that of feed. The mean transfer coefficients of ¹³⁷Cs to milk were calculated to be 0.0037 and 0.0063 (d/l), respectively.