Separation system for HLLW by using CMPO impregnated silica adsorbent

The process concept of separation system of high-level radioactive liquid waste (HLLW) using an octylphenyl-N,N-diisobutylcarbomoyl phosphine oxide impregnated silica adsorbent (CMPO-adsorbent) was designed for separation of Cs and Sr. The process consists of two separation steps. Each step is composed of three CMPO-adsorbent columns, and the adsorbents are used in rotation for separation of HLLW. That is, the system has six columns. Uranium and Zirconium inhibit the adsorption of minor actinoids (MA) and lanthanoids. Therefore, the adsorption and removal of U and Zr from the HLLW occur in the 1st step. Adsorbed U and Zr are eluted using citric acid. The HLLW from the 1st step is sent to the 2nd step to adsorb MA, lanthanoids and other transition metals. MA and lanthanoids are eluted using 0.01 mol/dm³ HNO₃, and Mo is recovered by using oxalic acid. The process required a large amount of citric acid and oxalic acid, but these eluents can be reused, therefore the amounts of spent acids are reduced. The column adopted a cartridge form in consideration of the exchange of adsorbent. The bed volume of the adsorbent is 0.67 m ³/column. The size of separation plant has 60 m length, 80 m breadth and 36 m height.