Radioactive liquid waste treatment at Fukushima Daiichi

The earthquake and tsunami on 11 March 2011 severely damaged the Fukushima Daiichi nuclear plant leading to the most severe nuclear incident since Chernobyl. Ongoing operations to cool the damaged reactors at the site have led to the generation of highly radioactive coolant water. This is currently treated to remove Cs‐137 and Cs‐134 and then passed through a reverse osmosis (RO) unit to reduce the salinity before being cycled back to the reactors. Because only the Cs isotopes are removed, the RO reject water cannot be discharged from the site and this has led to the accumulation of over 200 000 m3 (52 million gallons) of extremely contaminated water which is currently stored on site in tanks. EnergySolutions, in partnership with Toshiba, were contracted to develop a system to reduce 62 isotopes in this waste to allowable levels. This was a significant technical challenge given the high background salt content of the waste‐water, the variation in aqueous chemistry of the radioactive isotopes and the presence of relatively high concentrations of non‐active competing ions (e.g. Ca and Mg) which inhibit the removal of isotopes such as Sr‐89 and Sr‐90.