Reduction of uranium (Ⅵ to Ⅳ) by hydrogenation using Adams' catalyst

摘要

Plutonium uranium reduction extraction using U(Ⅳ) as universal reductant for Pu partitioning is the only technology practiced internationally to recover U and Pu from spent nuclear fuels. Uranous requirement of Indian reprocessing plants is met by the electrolytic reduction of uranyl nitrate with 50-60% conversion. Though the current requirement can be met with this method, it increases the load on uranium purification cycle. In addition, it is a batch process with slow kinetics. In order to achieve higher conversion of uranyl nitrate to uranous nitrate, catalytic reduction method using hydrogen in presence of Adams' catalyst (PtO_2) was tried. Parametric studies have been performed in an autoclave to evaluate the effect of U(Ⅵ) concentration, the role of hydrazine nitrate and pressure. It is observed that kinetics is improved at higher pressures. The studies revealed that near total conversion of uranium from (Ⅵ to Ⅳ) can be achieved by the catalytic reduction route.