雑固体廃棄物をプラズマ溶融して製作した溶融固化体の化学的安定性

Chemical stability of solidified products made from incombustible wastes by plasma melting

亀尾 裕 ; 原賀 智子   ; 中塩 信行; 星 亜紀子 ; 中島 幹雄

Kameo, Yutaka; Haraga, Tomoko; Nakashio, Nobuyuki; Hoshi, Akiko; Nakashima, Mikio

低レベル放射性廃棄物をプラズマ溶融して製作した溶融固化体の化学的安定性を調べるため、MCC-3S試験法に準拠した溶出試験を行い、溶融固化体の主要成分(Na, Al, Si, Ca, Fe)と放射性核種(Co, Cs, Eu)の溶出率(NL)を測定した。溶融固化体の化学組成がNLに与える影響について調べた結果、溶融固化体のNLに対するFeO濃度の影響はあまり大きくなく、CaOとSiOの重量比で表される塩基度に大きく依存することがわかった。塩基度が0.8以下溶融固化体の場合、logNLは塩基度と直線関係にあるため、溶融固化体の化学組成を調べることによりNLを推定することが可能であると考えられる。

In order to investigate chemical stability of solidified products made from Low Level Radioactive Wastes (LLW) by plasma melting, a leaching test based on the MCC (Material Characterization Center)-3S Agitated Powder Leach Test Method was performed to determine Normalized Elemental Mass Loss (NL) of both main components (Na, Al, Si, Ca, and Fe) of the solidified product and radioactive tracers (Co, Cs, and Eu) incorporated into it. The results of leaching test indicated that NLi value was greatly affected by basicity defined as weight ratio of CaO to SiO in the solidified product, while effect of FeO concentration on NL value was small. In the case of basicity less than 0.8, logarithm of NL linearly increased with the basicity, implying that NL value can be estimated by chemical composition of the solidified products.