Preparation of uranium oxide powder for nuclear fuel pellet fabrication with uranium peroxide recovered from uranium oxide scraps by using a carbonate–hydrogen peroxide solution

Abstract

This work studied a way to reclaim uranium from contaminated UO₂ oxide scraps as a sinterable UO₂ powder for UO₂ fuel pellet fabrication, which included a dissolution of the uranium oxide scraps in a carbonate solution with hydrogen peroxide and a UO₄ precipitation step. Dissolution characteristics of reduced and oxidized uranium oxides were evaluated in a carbonate solution with hydrogen peroxide, and the UO₄ precipitation were confirmed by acidification of uranyl peroxo–carbonate complex solution. An agglomerated UO₄ powder obtained by the dissolution and precipitation of uranium in the carbonate solution could not be pulverized into fine UO₂ powder by the OREOX process, because of submicron-sized individual UO₄ particles forming the agglomerated UO₄ precipitate. The UO₂ powder prepared from the UO₄ precipitate could meet the UO₂ powder specifications for UO₂ fuel pellet fabrication by a series of steps such as dehydration of UO₄ precipitate, reduction, and milling. The sinterability of the reclaimed UO₂ powder for fuel pellet fabrication was improved by adding virgin UO₂ powder in the reclaimed UO₂ powder. A process to reclaim the contaminated uranium scraps as UO₂ fuel powder using a carbonate solution was finally suggested.