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Yin, X.; Koma, Yoshikazu; Inaba, Yusuke*; Takeshita, Kenji*
no journal, ,
The decontamination and volume reduction of Cs contaminated soil by efficient Cs removal remains a great challenge after the Fukushima Daiichi Nuclear Power Station accident. In present work, we studied the selective removal of Cs from the clay soils by treating with hydrothermal cations in a column system. The results will inspire new insights for treatment of post-accident soils in Fukushima.
Mishima, Ria; Tachioka, Sotaro*; Inaba, Yusuke*; Harigai, Miki*; Matsumura, Tatsuro; Watanabe, Shinta*; Onoe, Jun*; Nakase, Masahiko*; Takeshita, Kenji*
no journal, ,
In Japan, the final disposal of high level liquid waste (HLLW) will be done after vitrification into borosilicate glass and then disposed into deep underground. In this vitrification process, there are some concerns. The first concern is precipitation of platinum group metals (PGMs) in the melter due to their low solubility into borosilicate glass. The second concern is the formation of yellow phase caused by Mo content. The final concern is the generation of huge number of vitrified glasses and the requirement of wide space needed for final disposal. Among many kinds of extractants and adsorbents for separation of such metal ions, metal hexacyanoferrate (HCFs) were reported to have an ability to adsorb PGMs. The objective of this study is to elucidate the adsorption behavior of aluminum hexacyanoferrate (AlHCF) for various metal ions and understand the relation between elution and adsorption. The effect of synthetic and workup conditions on PGM and Mo adsorption from simulated HLLW (sHLLW) was surveyed. Also, the relationship between adsorption of metal ions and elution of the AlHCF was studied. The synthesized AlHCF showed adsorption performance for PGMs and Mo in simulated HLLW. As a result of an adsorption test with a Pd single component solution to investigate the adsorption mechanism, the eluted element ratio was Fe:Al = 1:4 in the Pd adsorption test. However, the element ratio was Fe:Al = 3:4 in the original AlHCF. Therefore, it was suggested the existence of not only Pd adsorption, but also resorption and stabilization mechanisms.
Matsumura, Tatsuro; Ban, Yasutoshi; Suzuki, Hideya; Tsubata, Yasuhiro; Hotoku, Shinobu; Tsutsui, Nao; Toigawa, Tomohiro
no journal, ,
To minimize the radioactive waste from nuclear fuel cycle, we have conducted research and development of the new reprocessing and MA separation process, SELECT process (Solvent Extraction from Liquid-waste using Extractants of CHON-type for Transmutation), using innovative extractants. The extractants for each solvent extraction processes were developed in JAEA. The extractants for reprocessing process are monoamides as alternative extractants for TBP. For MA+RE recovery process, we developed TDdDGA which has very high performance to recover of MA from high level waste. HONTA and ADAAM were developed for MA/RE separation process and Am/Cm separation process respectively. All of the extractants consist of C, H, O, and N elements, and can be decomposed to gases by incineration. The demonstration tests using genuine spent fuel and high level liquid waste of the SELECT process have been conducted. Uranium solution and U+Pu mixed solution were separated from spent fuel, and MA, americium and curium, were recovered and separated from HLW effectively. The details of the extraction tests for each separation processes will be presented in correspond presentations in this conference.