Mass balance and economic analysis of volume reduction treatment for final disposal of radiocesium-contaminated incineration residues

Abstract

This study evaluates the mass balance and economic feasibility of volume reduction treatment for radiocesium-contaminated incineration residues at the Interim Storage Facility for radioactive waste resulting from the accident at TEPCO’s Fukushima Daiichi Nuclear Power Plant accident in 2011. Operational since March 2020, the Volume Reduction Facility employs thermal melting treatment to concentrate the radiocesium, resulting in the production of 42,000 tons of highly radioactive fly ash. Technologies for further volume reduction of the fly ash have been considered as one possible treatment scenario, but there have been no studies evaluating the optimization of this process. This work focuses on evaluating the feasibility of one promising approach: washing, selective adsorption of radiocesium into an adsorbent, and subsequent adsorbent stabilization. Unit costs were set for each step of the volume reduction process, and mass balance and economic evaluation were conducted. The findings reveal the generation of 390 tons of stabilized waste requring final disposal, along with 10,000 tons of washing residue and 320,000 tons of wastewater. The subtotal cost of fly ash volume reduction was approximately 38 billion yen, with 61% attributed to adsorption treatment. Sensitivity analysis suggested that adsorbents with an adsorption ratio above 5,000 could effectively reduce costs. Notably, the cost of adsorption process significantly influences subtotal costs. These insights enhance understanding of the economic viability and efficiency of volume reduction treatment for radiocesium-contaminated incineration residues, contributing to optimized strategies and technologies for volume reduction prior to final disposal.