An advanced partitioning process for key elements separation from high level liquid waste

To separate MA (Am, Cm) and some fission product elements (FPs) such as Tc, Pd, Cs and Sr from high level liquid waste (HLLW) systematically, we have been studying an advanced aqueous partitioning process, which uses selective adsorption as the separation method. For this process, we prepared several novel adsorbents which were immobilized in a porous silica/polymer composite support (SiO2-P). Adsorption and separation behavior of various elements was studied experimentally in detail. Small scale separation tests using simulated HLLW solutions were carried out. Pd(II) was strongly adsorbed by the AR-01 anion exchanger and effectively eluted off by using thiourea. Successful separation of Pd(II) from simulated HLLW was achieved. Tc(VII) also exhibited strong adsorption on AR-01 and could be eluted off by using U(IV) as a reductive eluent. Am(III) presented significantly high adsorbability and selectivity onto R-BTP/SiO2-P adsorbents over various FPs including Ln(III). The R-BTP adsorbents were fairly stable in 3 M HNO3, but instable against gamma-irradiation-3M HNO3. An advanced partitioning process consisting of three separation columns for the target elements separation from HLLW was proposed and the obtained experiment results indicated that the proposed process is essentially feasible.