Treatment of spent salt generated in pyroprocess using zeolite

In the pyrometallurgical reprocessing of metal fuel, it is beneficial to remove fission products (FPs) accumulated in the spent electrorefiner salt so that the amount of salt waste would be reduced by recycling the purified salt. For this purpose, a spent salt treatment process using type-A zeolite is considered to be a promising method. The type-A zeolite has a cation exchange function to capture FP cations in molten salt. Additionally, some kinds of FPs are also absorbed in the cage structure of the zeolite as the form of chlorides. The absorption behavior of cation FPs in LiCl-KCl molten salt has been studied intensively and it was revealed that the cation absorption is expressed by Langmuir type absorption isotherms. Recently, the absorption behavior of iodine has been also examined as a representative of anion FPs in the spent salt. As a challenge to realize both a high decontamination factor and a high throughput at the spent salt treatment process, a zeolite column system is under development. By using an engineering-scale zeolite column apparatus, a demonstration to decontaminate simulating FP represented by cesium was performed, as well as the measurement of the flow rate of the molten salt passing through the columns. (author)