Radioiodine (¹³¹I) and radiocesium (¹³⁴Cs and ¹³⁷Cs) uptake through the above ground parts and transfer to the bulb of tulip (Tulipa gesneriana L.) was measured in April 2011, one month after the heavy depositions of radioactive materials. Plant samples were collected from a flower garden of J Village on April 20 and 28, 2011. Each sampled above ground parts was equally divided into two portions and one portion was washed with detergent including surfactant to remove dust from the surface and the other portion was unwashed as a control. The average retention factor after washing (activity concentration ratios after and before washing) for radioiodine and radiocesium were 0.97 and 0.58, which means more radioiodine was fixed on the plant surface. Activity of one sampled tulip bulb was measured and the concentration ratios between the bulb to the directly contaminated above ground parts were 0.03 for ¹³¹I and 0.47 for radiocesium. It was clear that radiocesium was more mobile than iodine in the plant.

The temporal variations of compressive strength and flowability (slump-flow), and the adsorption behaviors of Co, Sr, and Cs for fly ash-based geopolymers, were investigated for immobilization of radioactive wastes. The geopolymer samples were prepared by using 1–5 M NaOH solution and cured at ambient temperature. The strength and flow were related to the amount and concentration of NaOH solution. The trends were discussed with the amount of heat generated at an early stage of curation. In addition, the geopolymers adsorbed Co equivalent to cements, Sr and Cs more than cements. The trends of absorption were related to the pH of leachates and the magnitude of x-ray diffraction (XRD) peaks of materials which possess larger distribution coefficients. We considered the possibilities to improve performance and to resolve problems in workability for actual use for immobilization of radioactive wastes according to the results of the present work.