Method of dissolving spent nuclear fuel

Purpose: To inhibit corrosion of the stainless-steel dissolving machine, eliminate insoluble hull and simplify separation and recovery of vaporized constituents, when spent fuel is dissolved by using nitric acid. Method: NOx gas is forcibly added to the spent nuclear fuel when the fuel is dissolved by using nitric acid. In case the concentration of nitric acid is too high, dissolution rate is high but the corrosion rate of the dissolving machine also become much higher. NOx gases containing NO, NO2, N2O4, N2O3, O2, N2 are forcibly supplied to the vapor-phase section in the dissolving machine. Greater effects can be obtained by blowing the gas directly into the solution so as to contribute the suppression of corrosion potential, the inhibition of RuO4, the oxidization by NOx and the simplified recovery of iodine in the vapor phase through the reduction of (IO3)-1 into I2. (Yoshino, Y.)