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論文

Application of phosphate modified CAC for incorporation of simulated secondary aqueous wastes in Fukushima Daiichi NPP, 1; Characterization of solidified cementitious systems with reduced water content

Garcia-Lodeiro, I.*; Lebon, R.*; Machoney, D.*; Zhang, B.*; 入澤啓太; 谷口拓海; 並木仁宏*; 大杉武史; 目黒義弘; 木下肇*

Proceedings of 3rd International Symposium on Cement-based Materials for Nuclear Wastes (NUWCEM 2018) (USB Flash Drive), 4 Pages, 2018/11

Processing of contaminated water from Fukushima Daiichi Nuclear Power Plant (NPP) results in a large amount of radioactive aqueous wastes, with a significant amount of radioactive strontium ( $^{90}$ Sr) and inorganic salts (mainly chlorides). It is challenging to condition these wastes using the conventional cementation because of the significant contamination and associated risk of hydrogen gas generation. The present study investigates the applicability of calcium aluminate cement (CAC) modified with phosphates (CAP) for incorporation of simulated secondary aqueous wastes. The use of CAP system is interesting because it may allow the reduction of water content, and the risk of hydrogen gas generation, since the solidification of this systems does not solely rely on the hydration of clinker phases. CAC and CAP pastes were prepared intermixing with different secondary aqueous wastes (concentrated effluent, iron co-precipitation slurry and carbonate slurry) and cured at either 35 $^{circ}$ C or 90 $^{circ}$ C in open systems for 7 days. Overall, the incorporation of the simulated wastes did not significantly alter the development of CAP or CAC, maintaining the integrity of their microstructure. However, because of the high Cl $^{-}$ content in the simulated wastes, CAC system showed formation of the Friedel's salt (Ca $_{2}$ Al(OH) $_{6}$ Cl(H $_{2}$ O) $_{2}$ ). On the other hand, formation of chlorapatite-type phase was detected in the CAP systems cured at 90 $^{circ}$ C.

口頭

Application of phosphate modified CAC for incorporation of simulated secondary aqueous wastes in Fukushima Daiichi NPP, 2; Leaching test of simulated wasteforms with reduced water content

Garcia-Lodeiro, I.*; 入澤啓太; Lebon, R.*; Mahoney, D.*; Zhang, B.*; 谷口拓海; 並木仁宏*; 大杉武史; 目黒義弘; 木下肇*

no journal, ,

Calcium aluminate cements modified with phosphate (CAP) have been studied as an alternative matrix for the encapsulation of aqueous secondary wastes arising from processing of contaminated waster in Fukushima Daiichi Nuclear Power Plant. The present study focuses on the immobilisation of Sr and the other elements present in the simulated wastes in the CAP cements. As a result, CAP has a great potential as a host matrix for aqueous secondary wastes currently stored in Fukushima. It was possible to incorporate the simulated secondary wastes and form stable solids that can retain Sr under exposure to water.

口頭

Development of solidification techniques with minimised water content for secondary radioactive aqueous wastes in Fukushima, 6; Incorporation of simulated secondary aqueous wastes in CAC and CAP cements

Garca-Lodeiro, I.*; Lebon, R.*; Mahoney, D.*; Zhang, B.*; 入澤啓太; 大杉武史; 中澤修; 木下肇*

no journal, ,

Incorporation of simulated aqueous secondary wastes in CAC and CAP cements was studied. The inclusion of simulated secondary wastes did not disturb the fundamental reaction of the systems, but the significant salt contents resulted in Friedel's salt in CAC and chlorapatite in CAP.

口頭

福島汚染水処理二次廃棄物のための固定化技術の開発,7; 模擬二次廃棄物を含有したCAC固化体及びCAP固化体の浸出試験

Garca-Lodeiro, I.*; Lebon, R.*; Mahoney, D.*; Zhang, B.*; 入澤啓太; 大杉武史; 中澤修; 木下肇*

no journal, ,

福島汚染水処理二次廃棄物を含有したカルシウムアルミネートセメント(CAC)およびそのリン酸セメント(CAP)を高温条件で作製し低含水化させ、その標準浸出試験を実施した。低含水化がCACの浸出挙動に及ぼす影響は少なかったのに対し、CAPにおいては低含水化によりその浸出挙動に有意な変化がみられた。リン酸は特に高温低含水化においてSrを含むアルカリ土類元素の保持に有効であることが示唆された。