Study of the elaboration of U3O8 by the Modified Direct Denitration process (MDD)

Messaoud Bennemla; Toufik Semaoune; Yasmina Hammache; Sihem Ouatas; Fatima Lekouara; Meriem Chabane Sari; Dallal Chebouki

doi:10.57056/ajet.v8i2.129

Authors

Messaoud Bennemla Department of uranium oxides, Draria Nuclear Research Centers, Bp 43 Sébala-Draria, Algiers, Algeria
Toufik Semaoune Draria Nuclear Research Centers, Bp 43 Sébala-Draria, Algiers, Algeria
Yasmina Hammache Draria Nuclear Research Centers, Bp 43 Sébala-Draria, Algiers, Algeria
Sihem Ouatas Draria Nuclear Research Centers, Bp 43 Sébala-Draria, Algiers, Algeria
Fatima Lekouara Draria Nuclear Research Centers, Bp 43 Sébala-Draria, Algiers, Algeria
Meriem Chabane Sari Draria Nuclear Research Centers, Bp 43 Sébala-Draria, Algiers, Algeria
Dallal Chebouki Draria Nuclear Research Centers, Bp 43 Sébala-Draria, Algiers, Algeria

DOI:

https://doi.org/10.57056/ajet.v8i2.129

Keywords:

Modified direct denitration process, Uranyl Nitrate (UNH), Uranium trioxide, Triuranium octoxide

Abstract

In the nuclear industry, uranium trioxide (UO₃) is considered an intermediate in the preparation of uranium metal or uranium dioxide (UO₂), which are the two most widely used nuclear fuels. Several processes have been described for transforming solutions of uranyl nitrate UO₂(NO₃)₂ into uranium trioxide. Among these processes, Modified Direct Denitration (MDD) has been implemented to prepare Uranium trioxide with high reactivity. This process consists of adding ammonium nitrate to a pure uranyl nitrate solution to form the double salt (NH₄)₂UO₂(NO₃)₄.2H₂O which decomposes by calcination to produce a UO₃ powder. The objective of this work is to study, first, the thermal decomposition of double salt (NH₄)₂UO₂(NO₃)4.2H₂O in nitrogen atmosphere by thermogravimetry in order to determine the formation temperatures of the different phases and second, the determination of the optimal parameters (time and temperature) to prepare stable triuranium octoxide (U₃O₈) using muffle furnace. As results, the MDD product obtained is an orange colored and free flowing UO₃ powder, having a surface area in the target range [5-12 m²/g]. In addition, by calcination of UO₃ powder at 650°C for one hour, U₃O₈ oxide is obtained. The identification of the latter by the O/U ratio gave a value of 2.65, which is in the range [2.6-2.66]. This suggests that the oxide produced under these conditions is β-U₃O₈.

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