Pilot-Scale Treatment of a Spent Uranium Catalyst Formally Used in the SOHIO Process: Pilot Plant Verification of the SENSEI Process

Approximately 7000 drums of waste uranium catalyst are currently present in Korea and require an appropriate treatment and waste management strategy. Recently, one such process has been developed and has proven successful at both laboratory and bench scales. The success of the process has culminated in its verification at a pilot plant scale. The purpose of this paper is to describe the catalyst treatment process and present results obtained from the pilot plant study that may be applicable to other such wastes. The individual unit technologies have been tested and verified, enabling process scale-up to be successfully proven. The final volume reduction of up to 80% has been confirmed with the successful separation, encapsulation, and immobilization of residue wastes, representing a potential cost saving of US$70 million compared to the direct disposal. The inactive silica component of the waste catalyst was purified and confirmed to be free of uranium. All effluents generated during the process were treated and satisfy the appropriate Korean release criteria. The process employs the concept of Selective Extraction of Nonradioactive Species, Encapsulation, and Immobilization, and is therefore introduced as the SENSEI process.