DEVELOPMENT OF IN-SITU SYSTEMS FOR (CO2)-C-13 EXPOSURE AND DETERMINATION OF C-13 NET ASSIMILATION RATE OF FRUIT-BEARING SHOOTS AND WHOLE TREE AND CHAMBER FOR PRECISION (CO2)-C-13 EXPOSURE OF YOUNG POTTED TREES

C-14 is the most important radionuclide for assessing exposure dose around the Rokkasho nuclear fuel reprocessing plant, Aomori Prefecture, Japan. A simplified model with ample margins has been used so far for the assessment of the dose derived from C-14. Realistic dose estimate of C-14 using more realistic model is necessary for safety. Apple production is an important core industry in Aomori Prefecture. To construct the dynamic model for apple, using C-13 as a tracer to substitute for C-14, we collected data on C-13 abundance in organs including fruit after (CO2)-C-13 exposure at various fruit growth stages. We developed (CO2)-C-13 exposure systems for three intact fruit-bearing shoots (1), whole mature tree (2) and young potted trees (3). Systems (1) and (2) also can determine net amounts of carbon and C-13 photoassimilated. System (3) is capable of precise feedback control of (CO2)-C-13 and (CO2)-C-12 concentrations based on on-time determination.