水蒸気と酸化ホウ素を用いた塩化物の酸化物への転換 乾式再処理から発生する塩廃棄物の処理への適応

Conversion of Alkali Metallic Chloride to Oxide using Water Vapor and Boron Oxide; Application of Treatment of Molten Salt Waste from Dry Reprocessing

佐藤 史紀 ; 明珍 宗孝; 照沼 仁*; 新井 修*

Sato, Fuminori; Myochin, Munetaka; Terunuma, Hitoshi*; Arai, Osamu*

乾式再処理より発生する廃溶融塩をガラス固化するための前処理として、水蒸気と酸化ホウ素(B2O3)を用いた塩化物の酸化物への転換処理を検討した。熱力学計算コードを用いた事前検討を行った後、NaCl-2CsCl共晶塩を用いた試験を行い、本手法で塩化物を酸化物へ転換できることを確認した。

Out-of-pile experiments on the release of fission products (FPs) under transient heating conditions were carried out for mixed oxide fuels. The fuels used in the experiments, the plutonium content of which was 30wt%, were irradiated up to 65 GWd/t in the experimental fast reactor JOYO. The experiments consisted of two runs, FP-1 and FP-2. In FP-1, the fuel sample was first heated to 2,000C and then up to 3,000C. The holding time was 30 min at each temperature. In FP-2, the terminal temperatures were 1,500C and 2,500C, and the holding time was 30 min in the same manner. The release of Cs, a volatile FP, was detected as soon as the fuel sample was heated up. The release rate, after peaking in several minutes, decreased gradually via a diffusion process in the fuel matrix. The "gross" diffusion coefficient agreed well with the data reported in other experiments using LWR fuels. The release fractions were identical in both experiments, namely Cs 100%, Sb 100%, Ru 10%, Ce 0% and Eu 0%.