報告書番号

T97061

タイトル（和文）

長半減期核種の乾式分離技術の開発混合溶融塩からのアクチニド元素の分離・回収実証試験

タイトル（英文）

DEVELOPMENT OF PYROMETALLURGICAL PARTITIONING TECHNOLOGY OF LONG-LIVED NUCLIDES -DEMONSTRATIONAL EXPERIMENTS ON SEPARATION AND RECOVERY OF ACTINIDE ELEMENTS FROM MIXED MOLTEN SALT-

概要 （図表や脚注は「報告書全文」に掲載しております）

軽水炉使用済燃料の再処理により生ずる高レベル廃液からウラン，ＴＲＵを乾式法で分離すると高温冶金分離工程の成立性確認のため，実規模（１トンの使用済燃料から生ずる高レベル廃液量を５００リットルと仮定し，これを１バッチで処理する場合に相当）の１／６０００及び１／２０００スケールの前処理工程後の想定混合溶融塩からアクチニド元素を分離・回収する試験を実施した。その結果，目標以上の純度でアクチニド元素が回収できた。また，１／６０００スケール試験では廃棄物側に移行したＴＲＵ量は総検出量の０．６２％以下であり，９９％以上の回収が確証された。また，１／２０００スケール試験では１％を越えるＴＲＵが廃棄物側に移行したが，これは必要回数の抽出を行わなかったためである。これにより，ＴＲＵを９９％以上回収し，混入する不純物量を回収ＴＲＵの重量以下にするという，当所の乾式分離の目標を達成できることが確認できた。

概要 （英文）

DEMONSTRATIONAL EXPERIMENTS ON THE SEPARATION AND RECOVERY OF ACTINIDE ELEMENTS FROM MIXED MOLTEN SALT CONTAINING NOBLE METAL, ALKALINE EARTH, AND RARE-EARTH ELEMENTS (RES) WERE CONDUCTED AT BOTH 1/6000 AND 1/2000 OF INDUSTRIAL SCALE. THE EXPERIMENTS INVOLVED TWO REDUCTIVE EXTRACTIONS, ELECTROREFINING, MULTISTAGE EXTRACTIONS USING BISMUTH AS A SOLVENT, AND ELECTRORECOVERY OF TRANSURANIC ELEMENTS (TRUS). THE ELECTROREFINING PROCESS YIELDED CATHODE DEPOSITS WITH ACTINIDE PURITIES GREATER THAN 99 WT.% OF THE DEPOSITED METAL. THE MULTISTAGE EXTRACTION PROCESSES ALSO YIELDED PRODUCTS WITH TRU/RE WEIGHT RATIOS OF 2.45 AND 3.21, COMPARED TO THE TARGET OF 1.0. OVERALL CARRYOVERS OF TRUS TO THE WASTE PRODUCT IN THE 1/6000-SCALE EXPERIMENT WERE LESS THAN0.62% OF FINALLY DETECTED TRUS, COMPARED TO THE TARGET OF 1.0%. THOUGHTHE FINAL MASS BALANCES OF TRUS RANGED BETWEEN 65% AND 74% IN THIS EXPERIMENT, THE MISSING AMOUNTS WERE ASSUMED TO HAVE REMAINED IN THE SYSTEM AND TO BE RECOVERABLE. ACCORDINGLY, RECOVERY OF MORE THAN 99% OF TRUSWAS DEMONSTRATED. THOUGH OVERALL CARRYOVERS OF TRUS TO THE WASTE PRODUCT IN THE 1/2000-SCALE EXPERIMENT RANGED BETWEEN 1.5% AND 3.2%, THIS WAS DUE TO SAMPLE ANALYSIS FAILURE, AND THE VALUES WOULD HAVE BEEN LESS THAN 1.0% HAD SAMPLE ANALYSIS BEEN AVAILABLE TO GUIDE THE OPERATION OF THE MULTISTAGE EXTRACTION PROCESS. THE CUMULATIVE RESULTS OF THESE EXPERIMENTS DEMONSTRATE THAT CRIEPI S PYROPARTITIONING PROCESS WILL MEET THEPROCESS GOALS FOR ACTINIDE SEPARATION AND PRODUCT PURITY.

報告者

キーワード