Low temperature hydrothermal destruction of organics in Hanford tank wastes

The objective of this work is to evaluate and develop a low temperature hydrothermal process (HTP) for the destruction of organics that are present in wastes temporarily stored in underground tanks at the Hanford Site. Organic compounds contribute to tank waste safety issues, such as hydrogen generation. Some organic compounds act as complexants, promoting the solubility of radioactive constituents such as 90Sr and 241Am, which is undesirable for waste pretreatment processing. HTP is a thermal-chemical autogenous processing method that is typically operated between 250 degrees C and 375 degrees C and approximately 200 atm. Testing with simulated tank waste containing a variety of organics has been performed. The distribution of strontium, cesium and bulk metals between the supernatant and solid phases as a function of the total organic content of the waste simulant is presented. Test results using simulant are compared with similar tests conducted using actual radioactive waste