Computer Modelling of Alpha Radiolysis of Aqueous Solutions in Contact with Used U02 Fuel

Abstract

A computer program, MAKSIMA-CHEMIST, has been used to qualitatively model the concentration-time behaviour of radical and molecular species and, in particular, oxidizing species generated by alpha radiolysis of an aqueous solution in contact with the surface of used CANDU U0₂ fuel. The computer results predict that ~10^-5 mol*L^-1 H₂ would suppress the formation of O₂ and H₂O₂ provided that no O₂ was initially present in solution. The model also predicts that Fe²⁺ would control the continued accumulation of O₂ and H₂O₂. Preliminary results from electrochemical experiments using an alpha source and a U0₂ electrode indicate that H₂ lowers the electrode potential below that in the absence of H₂ but the potential is still oxidizing. When Fe²⁺ is present in solution, reducing potentials are maintained.