Development and testing of methods for extracting and conditioning accident elimination sorbents in the basements of the Fukushima Daiichi NPP

The present study aimed to select a method for extracting and conditioning sorbents located in the basements of the Fukushima Daiichi NPP (Japan) after the accident elimination. FSUE “RADON” conducted tests of two schemes for extracting and hydraulically unloading sorbents using a pump: directly into a filter trap or a dispenser with pulp overflow into the basement, followed by the transportation of thickened sorbents from the dispenser to the filter trap. The filter trap filling time, which is controlled by the passage of sorbent particles through the inspection window of the flange at the outlet of the flow, does not exceed 1.5 h at a filling degree of more than 95%. The recommended post-treatment mode includes rinsing with water to a chloride ion concentration of less than 30 mg/dm³, dehydration with compressed air, and holding for draining the remaining liquid with periodic pumping.