Joint decontamination - Kyojosen

...The distribution coefficient (a measure of the ease of extraction) is large when the nitric acid concentration is high, but small when the nitric acid concentration is low, (b) in the case of plutonium, the distribution coefficient is large when the atomic valence is tetravalent, but becomes significantly smaller when the atomic valence is trivalent, and (c) in the case of fission products, the distribution coefficient is small. Therefore, the feed is first sent to the first extractor, where it is brought into countercurrent contact with a 30% TBP-dodecane solvent to transfer uranium and plutonium into the solvent phase, and then this solvent is brought into countercurrent contact with nitric acid to expel the accompanying fission products into the aqueous phase (this is called co-decontamination). The solvent is sent to the second extractor, where it is brought into countercurrent contact with a plutonium reducing agent (usually a nitric acid solution of uranium (tetravalent uranium) is used) to reduce the plutonium in the solvent to trivalent, expelling only the plutonium into the aqueous phase. ...

*Some of the terminology that refers to "co-decontamination" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…抽出されやすさの目安)は硝酸濃度が高いと大きいが硝酸濃度が低くなると小さくなる，(b)プルトニウムの場合は原子価が4価のときは分配係数は大きいが3価になると著しく小さくなる，(c)核分裂生成物の場合は分配係数は小さい，という性質がある。そこで，まずフィードを第1の抽出器へ送り，ここで30％TBP‐ドデカン溶媒と向流接触させてウランとプルトニウムを溶媒相中へ移し，次にこの溶媒を硝酸と向流接触させて同伴する核分裂生成物を水相中に追い出す(共除染という)。溶媒は第2の抽出器に送り，プルトニウムの還元剤(通常ウラナス(4価のウラン)硝酸溶液が使用される)と向流接触させて溶媒中のプルトニウムを3価に還元させることによってプルトニウムだけを水相へ追い出す。…

※「共除染」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報