Reaction kinetics of ferrous sulfamate under irradiation using time-resolved electron pulse radiolysis

This study investigated the kinetics of ferrous sulfamate, Fe(NH₂SO₃)₂, reacting with key radical species generated during used nuclear fuel (UNF) reprocessing. Using time-resolved electron pulse radiolysis, second-order rate coefficients were determined for the reactions of Fe(NH₂SO₃)₂ with the hydrogen atom (H˙), hydroxyl (˙OH) radical, nitrate (NO₃˙) radical, and oxygen radical anion (O˙^-). The results indicate that Fe(NH₂SO₃)₂ behaves similarly to other dilute solutions of ferrous ions, with no unique protective effects attributable to the presence of sulfamate anions at millimolar concentrations. The rate coefficient for the reaction of Fe²⁺ and NO₃˙ was found to be (2.31 ± 0.07) × 10⁹ M^-1 s^-1, significantly higher than previously reported values. The rate for the reaction of Fe²⁺ with ˙OH was (2.59 ± 0.10) × 10⁸ M^-1 s^-1, aligning with literature findings for ferrous sulfate. These results underscore the importance of ferrous ion reactivity in the degradation of Fe(NH₂SO₃)₂ under UNF reprocessing conditions and highlight the need for further research to assess its long-term stability and effectiveness.