Measuring and Optimizing the Effectiveness of Radiocesium Remediation from Fukushima Soil

The meltdown of the Fukushima Daiichi Nuclear Power Plant in 2011 contaminated soil in a large area surrounding the plant with radiocesium (134Cs & 137Cs). Radiocesium adsorbed very strongly on the vermiculite minerals common to the soil in this region and has proven difficult to remove from the soil. Over the last five years, Dr. Ferreira has developed a remediation method that can successfully remove the radiocesium from Fukushima soil through the combination of ion-exchange and selective precipitation reactions. Previous attempts to quantify the effectiveness of this method were complicated by the fact that the digestion of soil samples for analysis using the Hot Block method yielded questionable data, likely due to incomplete digestion of the soil. A new method for the digestion of Fukushima soils has been developed using an Anton Paar Multiwave Go, which appears to digest the samples more completely. The analysis of cesium concentrations in samples digested using the microwave digestion method using Inductively Coupled Plasma Optical Emission Spectroscopy has resulted in much more precise data sets than previously collected. This higher quality data has allowed us to improve the mass balance of our resulting data (the amount of Cs after the remediation is much closer to the amount of Cs in the soil before it was remediated) and has also allowed us to more accurately compare the relative effectiveness of the four selective precipitation agents being considered for use in the remediation method