Plutonium and Americium Alpha Radiolysis of Nitric Acid Solutions

The yield of HNO 2, as a function of absorbed dose and HNO 3 concentration, from the α-radiolysis of aerated HNO 3 solutions containing plutonium or americium has been investigated. There are significant differences in the yields measured from solutions of the two different radionuclides. For 0.1 mol dm –3 HNO 3 solutions, the radiolytic yield of HNO 2 produced by americium α-decay is below the detection limit, whereas for plutonium α-decay the yield is considerably greater than that found previously for γ-radiolysis. The differences between the solutions of the two radionuclides are a consequence of redox reactions involving plutonium and the products of aqueous HNO 3 radiolysis, in particular H 2 O 2 and HNO 2 and its precursors. This radiation chemical behavior is HNO 3 concentration dependent with the differences between plutonium and americium α-radiolysis decreasing with increasing HNO 3 concentration. This change may be interpreted as a combination of α-radiolysis direct effects and acidity influencing the plutonium oxidation state distribution, which in turn affects the radiation chemistry of the system.