Radionuclide contents of leafy vegetables. Their reduction by cooking.

Decontamination ratios of 103Ru 134Cs, and 137Cs were determined for leafy vegetable samples after they were cooked. Samples contaminated with radionuclides from the Soviet Chernobyl reactor accident were obtained in Akita City. The decontamination ratio of the 103Ru content of washed spinach samples to that of similar unwashed samples was 0.83 ± 0.21. The ratio of the 103Ru content of leafy vegetables and edible wild grass samples which were boiled in water to that of similar washed samples was, on the average, 0.72 ± 0.20. The overall decontamination ratio of 103Ru in boiled leafy vegetable samples to unwashed vegetable samples was 0.52 ± 0.20. The decontamination ratios of 134Cs and 137Cs after washing were 0.65 ± 0.42 and 0.64 ± 0.17, respectively. The reduction ratios of 134Cs and 137Cs by boiling were 0.50 0.15 and 0.53 ± 0.13. The overall decontamination ratios were 0.33 ± 0.24 for 134 Cs and 0.34 ± 0.12 for 137Cs. These results indicate that the decontamination ratio of 0.5 which is stipulated by the Nuclear Safety Commission, Japan, is a practical value.