article posted 6 April 2016
Hirohide Kofuji has been engaged in the investigation of nuclear fuel cycle system properties, development of pyrochemical reprocessing technologies and recently a new technology research for high level waste treatment generated from pyrochemical and advanced PUREX reprocessing. He is a doctor of engineering of the Japan Atomic Energy Agency.
Vitrification properties of MA adsorbents
Hirohide KOFUJI*, Sou WATANABE, Ichiro GOTO, Akio ORIUCHI, Masayuki TAKEUCHI, Hidekazu KOBAYASHI & Kenichi SASAGE
Japan Atomic Energy Agency, 4-33 Muramatsu, Tokai, Naka-gun, Ibaraki-pref., Japan
In order to develop a technology to reduce environmental footprint by the high level radioactive waste, the separation procedure of minor actinide (MA) which has been generated from uranium and plutonium recovery process of reprocessing has been investigated. Extraction chromatography has been thought to be suitable for MA separation from the view point of waste management because porous silica particle would be used as a carrier of extractant in the chromatographic column.
Examined extractants such as CMPO (n-octyl(phenyl)-N,N-diisobutyl carbamoylmethylphosphine oxide) and HDEHP (di-(2-ethylhexyl)phosphoric acid) are candidate for the recovery or mutual separation of rare earth and MA elements and they are also used by the solvent extraction procedure.
In the extraction chromatography method, such extractants are impregnated into a copolymer of styrene-divinylbenzene which is coated on the surface of porous silica particles and is filled up in the chromatographic column for the elements separation operation. Spent column medium adsorbing some rare earth element (a part of fission product elements) could be thought to be used as the raw materials of vitrified high level waste form, the final waste volume are therefore expected to be much reduced.
The view point of this study is that glass materials containing extractant constituent elements can be vitrified or not having sufficient properties as the waste form. In this presentation, results of vitrification test would be introduced using simulated high radioactive liquid waste composition. As the primitive studies, possibility of vitrification was examined by XRD, degradation products of the extractants were analyzed by TPD/MS (Temperature Programmed Desorption/Mass Spectrometry and chemical durability of the glass samples would be evaluated by the normalized element mass loss estimated by MCC-1 (Material Characterization Center-1) reaching test.