I-129 AND I-127 IN ENVIRONMENTAL-SAMPLES COLLECTED FROM TOKAIMURA IBARAKI, JAPAN

Concentrations of **1**2**9I and **1**2**7I in water, soil, pine needle and algae samples collected in the vicinity of the nuclear fuel reprocessing plant in Tokaimura/Ibaraki, and from other areas of Japan, were determined by radiochemical neutron activation analysis. Compared with background levels of **1**2**9I, higher values were found in the environment near the Tokaimura reprocessing plant. The highest concentrations were found in the surface soil (33 mBq kg** minus **1) and in pine needles (32 mBq kg** minus **1), and the highest **1**2**9I/**1**2**7I ratios were found in pine needles (1. 8 multiplied by 10** minus **5). The **1**2**9I levels in surface soil and pine needles decreased with increasing distance from the reprocessing plant. It was also observed that the **1**2**9I/**1**2**7I ratio (3. 0 multiplied by 10** minus **7) of the surface soil (0-5 cm depth) in Tokaimura was more than 100 times higher than in the soil collected from a depth of 20-25 cm.