Separation of Strontium from Other Fission Products in High Level Liquid Waste by TODGA

Abstract

Large amounts of high level liquid waste (HLLW) has been generated from the reprocessing of spent nuclear fuel employing the PUREX process. It contains complex composition including various fission products (FPs), corrosion products and minor actinides (MAs). Some of these nuclides, such as strontium-90 (90Sr), can be used in military and medical fields and have commercial value. The separation of strontium is not only about to develop the value of HLLW but also reduce the radioactivity of the liquid waste for disposal. Separating of Sr from other elements including Ln, Y, Cs, Ru, Fe, Mo, Zr, etc. is essential to obtain available strontium products. In this work, N,N,N′,N′-Tetraoctyldiglycolamide (TODGA) was used for the purpose focusing on removing fission products and corrosion products other than Sr. Firstly, 0.05 mol/L TODGA was used as extractant to separate Sr from Ln, Zr and Y, by which process Ln, Zr and Y were extracted to the organic phase and Sr entered the raffinate. Meanwhile, Ru, Fe and Cs were in the aqueous phase together with Sr. 0.2 mol/L TODGA was further used to contact with the raffinate, by which Sr was extracted and Ru, Fe and Cs were still in the aqueous phase being separated. After the Sr was stripped from the organic phase, Sr product was obtained. The separation method has been verified with non-radioactive simulated HLLW and radioactive genuine HLLW as feed liquid, proving its reliability.