Development of new technology using nuclear reactor for the research of agricultural environment and expanding of its use

In the previous year, rare metals present in soils were examined with high accuracy by radioactivation analysis method using data analyzer and so this study aimed to investigate an analyzing method for rare metals in plants based on the previous data. Standard plant samples such as tea leaf, tomato, apple, etc., of which metal concentration has been known were used as the subjects. After ashing, the samples were exposed to neutron irradiation for 20 min and γ-ray spectrometry was performed after 1, 2, 4 weeks and 3 months. The contents of rare metals in plants were smaller than those in soils but those were found measurable after an appropriate cooling period. In addition, non-destructive measuring method for abundant elements such as Si, Fe, etc. was investigated with many kinds of soils by prompt γ-ray analysis and highly accurate analysis became able by correcting the values using Ti as an internal standard. The relationship between the water-elution rates for heavy metals and the duration of neutron irradiation was investigated and the rate was found to be affected by the irradiation time and the characteristics of organic substances in the soil. (M.N.)