Production of uranium tetrafluoride from the effluent generated in the reconversion via ammonium uranyl carbonate

• Published in: Nuclear engineering and technology Vol. 49; no. 8; pp. 1711 - 1716
• Main Authors: Neto, Joao Batista Silva, de Carvalho, Elita Fontenele Urano, Garcia, Rafael Henrique Lazzari, Saliba-Silva, Adonis Marcelo, Riella, Humberto Gracher, Durazzo, Michelangelo
• Format: Journal Article
• Language: Korean
• Published: 2017
• Subjects: Fuel Fabrication; UF_4; APOFU; Uranium Recovery; Effluent Treatment; Ammonium Bifluoride
• ISSN: 1738-5733; 2234-358X

Uranium tetrafluoride ($UF_4$) is the most used nuclear material for producing metallic uranium by reduction with Ca or Mg. Metallic uranium is a raw material for the manufacture of uranium silicide, $U_3Si_2$, which is the most suitable uranium compound for use as nuclear fuel for research reactors. By contrast, ammonium uranyl carbonate is a traditional uranium compound used for manufacturing uranium dioxide $UO_2$ fuel for nuclear power reactors or $U_3O_8-Al$ dispersion fuel for nuclear research reactors. This work describes a procedure for recovering uranium and ammonium fluoride ($NH_4F$) from a liquid residue generated during the production routine of ammonium uranyl carbonate, ending with $UF_4$ as a final product. The residue, consisting of a solution containing high concentrations of ammonium ($NH_4^+$), fluoride ($F^-$), and carbonate ($CO_3^{2-}$), has significant concentrations of uranium as $UO_2^{2+}$. From this residue, the proposed procedure consists of precipitating ammonium peroxide fluorouranate (APOFU) and $NH_4F$, while recovering the major part of uranium. Further, the remaining solution is concentrated by heating, and ammonium bifluoride ($NH_4HF_2$) is precipitated. As a final step, $NH_4HF_2$ is added to $UO_2$, inducing fluoridation and decomposition, resulting in $UF_4$ with adequate properties for metallic uranium manufacture.