A two-compartment model for transport of 131I via the pasture-cow-milk pathway

A two-compartment linear systems model has been developed for predicting the transport of 131I from pasture to milk. The system transfer parameters were determined from previous measurements of concentration of 131I in vegetation, Ksub(v) (pCi.kg-1 dry weight), and in milk, Csub(m) (pCi.l-1) at the Monticello and Dresden nuclear power stations. These measurements indicated that the vegetation was being pulsed in time with deposits of radioactivity as a result of the action of atmospheric wet processes. Model predictions of the ratio of equilibrium values of Csub(m) and Ksub(v) obtained from average model parameter values were 0.19 kg.l-1 for both Monticello and Dresden. This value was higher by factors of 1.5 and 2.8, respectively, than the time-averaged values of the ratio Csub(m)/Ksub(v) previously reported. Data measured under pulsed conditions may be used for assessing long-term releases of radioactivity to the environment provided the data are properly time-averaged. (author)