Reactions of hypobromite with neptunium(IV) and plutonium(IV) in alkali solutions

Neptunium(VII) is formed in deaerated 0.8-16 M NaOH containing 5 x 10(-3) M Np(OH)(4) suspension and hypobromite ion. In 0.5-8 M NaOH containing 5 x 10(-3) M Pu(OH)(4), under the action of hypobromite Pu(VI) is accumulated both in solution and in the precipitate, and in 12-14 M NaOH Pu(VII) is formed. The rate of all the reaction stages increases with increasing oxidant and alkali concentrations and with temperature. Probable mechanism of reactions is considered.