Doryokuro Kakunenryo Kaihatsu Jigyodan

Kazuhiro Kawamura

Masayuki Yoneya

Takeshi Takahashi

Shin-ichiro Torata

Kenichi Sasage

A method of vitrifying a high-level radioactive liquid waste comprising removing a precipitate composed mainly of Mo and Zr from the high-level liquid waste, mixing the resulting high-level liquid waste with a raw glass material having a chemical composition wherein the B.sub.2 O.sub.3 /SiO.sub.2, ZnO/Li.sub.2 O and Al.sub.2 O.sub.3 /Li.sub.2 O ratios are at least 0.41, at least 1.00 and at least 2.58, respectively, and melt-solidifying the mixture to thereby form a vitrified waste. By using such a raw glass material, there can be obtained a vitrifled waste having the waste content of about 45% by oxide weight in which the same leaching rate as that of a conventional vitrified waste having the waste content of 25% by oxide weight is ensured without suffering from yellow phase separation.

Method of vitrifying high-level radioactive liquid waste

A method of recovering volatile ruthenium, which is separated and formed by constant potential electrolysis from high-level radioactive liquid waste discharged from the reprocessing step of spent nuclear fuel by purex process, in the form of stable solid. The method comprises electrolyzing at a constant potential a high-level radioactive liquid waste from which palladium has substantially been removed in advance, thereby vaporizing ruthenium, bringing the vaporized ruthenium into contact with an aqueous solution of formic acid to precipitate ruthenium oxide, and separating the precipitate from the aqueous solution of formic acid.

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Ibaraki, Japan

Kazuhiro Kawamura