Present inventory of Hanford single shell tank waste is about 180,000 tons. More than 70% by weight of the tank waste are non-radioactive sodium nitrate. The paper presents an entirely different approach to pretreatment of Hanford radioactive waste stored in underground tanks. Instead of removing radionuclides, Cs-137 in this case, from the bulk of the waste, this process selectively recovers the non-radioactive sodium salts from the waste by crystallization. It opens up a possible new way of looking at waste pretreatment. The feasibility teat has been done at the facility of Westinghouse Hanford Company. The result shows a potential of reclaim sodium nitrate with a total activity of less than 60 pCi/g. The objective of the research is to develop and demonstrate a scaleable crystallization process to recover sodium nitrate from aluminum and cesium containing mother liquor. Per-pass crystal yields and separation factors as well as the effects of crystal size, slurry density, growth rate and mother liquor concentrations on occlusion and entrainment are studied.