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Journal Articles

Consideration on modeling of Nb sorption onto clay minerals

Yamaguchi, Tetsuji; Ohira, Saki; Hemmi, Ko; Barr, L.; Shimada, Asako; Maeda, Toshikatsu; Iida, Yoshihisa

Radiochimica Acta, 108(11), p.873 - 877, 2020/11

 Times Cited Count:0 Percentile:0.01(Chemistry, Inorganic & Nuclear)

Journal Articles

Sorption behavior of thorium onto montmorillonite and illite

Iida, Yoshihisa; Barr, L.; Yamaguchi, Tetsuji; Hemmi, Ko

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 23(1), p.3 - 8, 2016/06

Thorium (Th)-229 is one of the important radionuclides for the performance assessment calculations for high-level radioactive waste repositories. The sorption behavior of Th onto montmorillonite and illite were investigated by batch sorption experiments. Experiments were carried out under variable pH and carbonate concentrations. The sorbability of montmorillonite was higher than that of illite. Distribution coefficients, $$K_{rm d}$$ (m$$^{3}$$ kg$$^{-1}$$), decreased with increased carbonate concentrations and showed the minimal value at around pH 10. The sorption behaviors of Th were analyzed by the non-electrostatic surface complex model with PHREEQC computer program. The model calculations were able to explain the experimental results reasonably well. The decreases of $$K_{rm d}$$ was likely due to the stabilization of aqueous species by hydroxo-carbonate complexations in the solutions.

Oral presentation

Radiolytic degradation of high density polyethylene used for storage of water treatment waste from Fukushima Daiichi NPS

Barr, L.; Idesaki, Akira*; Taguchi, Mitsumasa*; Yamaguchi, Tetsuji

no journal, , 

Water treatment waste from the ALPS system at Fukushima Daiichi Nuclear Power Station is stored in high density polyethylene containers. During the storage period radiation leads to degradation of the polymer properties. This study investigated the extent and rate of polymer degradation induced by radiation. The irradiation conditions were altered to represent the storage environment and the composition of the waste produced by the ALPS system. Increasing the irradiation temperature changes the rate of diffusion of reactive species and leads to greater oxidative degradation of the polymer. More aromatic antioxidants provide greater protection against radiation compared with aliphatic additives. Irradiation in water rather than air limits the availability of oxygen and reduces the degree of oxidative degradation. Increasing the pH of the aqueous phase results in an increase in tensile strength of the polymer than irradiation in deionised water, which is attributed to the increased formation of double bonds and crosslinks following hydrogen extraction by the reactive water radiolysis products. The results of the study show the importance of the specific environment and conditions of irradiation and highlight the different degradation pathways that containers will be subjected to throughout their operational lifetime.

Oral presentation

Effect of atmosphere on degradation of polyethylene under $$gamma$$-ray irradiation

Idesaki, Akira*; Barr, L.; Taguchi, Mitsumasa*; Yamaguchi, Tetsuji

no journal, , 

Because 1F water treatment secondary waste slurry is stored in a high-performance polyethylene container, it is necessary to understand radiation degradation of polyethylene. In particular, this study was conducted because there is no knowledge about the influence of water or slurry. Stress cracking properties, one of the indicators of degradation of polyethylene, were different in air and in water (and in slurry). This difference was considered together with the results of other characteristic tests. In addition, it was revealed that degradation is effectively suppressed in any environment by containing an antioxidant in polyethylene.

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