Effect of Alpha Radiolysis of Water on CANDU Fuel Oxidation

Abstract

The oxidation of CANDU fuel (UO₂) by the products of alpha radiolysis of water has been investigated using X-ray Photoelectron Spectroscopy and electrochemical techniques. Experiments with H₂O₂ and O₂, two of the oxidants formed during radiolysis of water, show that the rate of oxidation of UO₂ by H₂O₂ is almost 200 times faster than by dissolved O₂. Possible reaction paths of oxidation of CANDU fuel by these oxidants are discussed. The oxidation of UO₂ by the products of direct alpha radiolysis of water, formed by an alpha flux comparable with that expected at the fuel surface at the estimated time of waste container failure, causes very little oxidative dissolution of UO₂ fuel.