Contribution to the understanding of the radiolysis of water sorbed on plutonium dioxide

In the frame of transportation and middle or long-term storage of plutonium dioxide (PuO2), detailed safety analyses are required. Hydrogen production is one of the main issues. Moreover, previous studies clearly demonstrated that PuO2 has a great affinity for water, and that alpha radiolysis of water sorbed on PuO2 is a major source of hydrogen. The present study focuses on the mechanisms of the alpha radiolysis of water sorbed on plutonium dioxide. The objective of this approach is to determine the rate of hydrogen production according to selected key parameters. In the first part of this evaluation, those parameters are: the relative humidity in the gas phase, the specific surface area of the solid and the dose rate of plutonium. In this paper, after a brief overview of the previous studies, we describe the experimental setup and the choice of parameters. The first experimental results are then discussed. (authors)