Fabio Martini¹

Antoine Claisse², Mattias Puide², Iuliia Ipatova^3,1, William E. Lee¹, Simon C. Middleburgh¹

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

Abstract

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
11:40 am - 12:00 pm
Fabio Martini