Abstract: A process for producing a strong, adherent protective layer on copper parts, with a high rate of covering of the substrate, by passivating anodization, characterized in that the copper parts are immersed in a liquid KF, 2HF bath and subjected to anodic current of low surface-related density which is less than 0.1 A/dm.sup.2, which current may be continuous or intermittent.

Abstract: A process is disclosed for producing sintered mixed metal oxide nuclear f pellets containing UO.sub.2 and the oxide of at least one other fissionable or rare earth element M, the pellets being directly soluble in nitric acid without nitric acid additive or prior treatment of the pellets. The process comprises the steps of mixing together nitrate solutions of the elements, concentrating the mixture of solutions, thermally denitrating the concentrated nitrate mixture without additives, to obtain an intermediate mixed oxide powder, calcining the intermediate mixed oxide powder, reducing the calcined mixture, stabilizing the uranium oxide UO.sub.2 in the reduced oxide mixture, shaping and pressing the resulting stabilized, reduced oxide mixture to obtain pellets of green material, sintering the pellets of green material and grinding the sintered pellets.