“Ion sputtering – thermal separation” technology for spent nuclear fuel processing

Abstract

The purpose of this work is to develop a new technology for spent nuclear fuel (SNF) processing, aimed at effective solution of the problem – creation of a closed nuclear fuel cycle. We offer “dry” technology “Ion sputtering - thermal separation” (IS-TS) for a spent nuclear fuel processing with its separation into elemental components by differentiation them due to individual variations in the saturated vapor temperature. Separation is provided through SNF tablets sputtering-evaporation at the high-pressure microplasma discharge (pressure about 1 atm.) in an inert gas (e.g., argon) flow with the following separation into elemental components along the diffusion tube sections maintained at the specified temperature levels. According to IS-TS technology, at the current density of 5 A/cm2 and voltage of 600 V, mass processing rate of SNF is estimated 0,01 g/sec or ∼1 kg/day. Accounting of additional effect of thermal tablet evaporation further increase processing rate value. In this way, a single block of 100 discharge-diffusion tubes, operating in parallel, is estimated to recover 30 ton of SNF per year. The microplasma high-pressure discharge in an inert gas environment used in IS-TS technology is also applied for decontamination of irradiated reactor graphite and internal surfaces of metal structures of the primary circuit of NPU.