Advances in the synthesis of uranium diboride

Fabio Martini1

Antoine Claisse2, Mattias Puide2, Iuliia Ipatova3,1, William E. Lee1, Simon C. Middleburgh1

1Bangor University, Bangor, UK; 2Westinghouse AB, Västerås, Sweden; 3University of Birmingham


Uranium diboride (UB2) is a promising material to be used in advanced technology fuel (ATF) concepts. Uranium diboride has a higher thermal conductivity and a higher uranium density than uranium dioxide (UO2). The neutron transparency of UB2 can be adjusted by tuning the isotope ratio between 10B and 11B, therefore allowing to obtain a fuel material with intrinsic burnable absorber characteristics, providing operational flexibility.
However, an industrially scalable synthesis route for UB2 was first proposed only in 2020 in a joint effort between the University of Manchester and Bangor University. The synthesis consists of the boro/carbothermal reduction of UO2 with carbon (C) and boron carbide (B4C) and mirrors one of the routes by which zirconium diboride (ZrB2) can be prepared from zirconium dioxide (ZrO2).
According to a thermodynamic model of the reaction system, which correctly predicted the conditions for the formation of UB2, the reaction was conjectured to proceed through a uranium tetraboride (UB4) intermediate. The conjecture was corroborated by the presence of UB4 as an impurity in the final product, detected via XRD analysis.
In this work, the reaction model is further validated by preparing and isolating UB4 and making it react again to obtain UB2. A wider understanding of the thermochemistry of the reaction system allows for better optimization of the synthesis and the sintering of UB2.

Event Timeslots (1)

Tuesday – 14th September 2021
Fabio Martini