(A) study on the prediction of tritium behavior in rice plant after a short-term exposure of HTO

Abstract

In many Asian countries including Korea, rice is a very important food crop. Its grain is consumed by humans and its straw is used to feed animals. In Korea, there are four CANDU type reactors that release relatively large amounts of tritium into the environment. Since 1997, KAERI (Korea Atomic Energy Research Institute) has carried out the experimental studies to obtain domestic data for various parameters concerning the direct contamination of plant. In this study, the behavior of tritium in the rice plant is predicted and compared to the measurement performed at KAERI. Using the conceptual model of the soil-plant-atmosphere tritiated water transport system which was suggested by Charles E. Murphy, tritium concentrations in the soil and in the leaves relative to time were derived. For the effect of tritium concentration in the soil, the tritium concentrations in leaves are described by a double exponential model. On the other hand if the tritium concentration in the soil is disregarded, the tritium concentration in leaves is described by a single exponential term as explained in other models (e.g. Belot’s or STAR-H3 model). Also concentration of organically bound tritium in leaves is predicted, conformed, and compared to the measurements. These results can be used to predict the tritium concentration in the rice plant at a field around the site and corresponding the ingestion dose following the release of tritium to the environment.