Synthesis of candidate advanced technology fuel: Uranium diboride (UB2) via carbo/borothermic reduction of UO2

Abstract

The synthesis of uranium diboride (UB 2 ) from uranium dioxide (UO 2 ) has been carried out for the first time after a coordinated experimental and theoretical investigation. The reliable conversion of UO 2 to UB 2 is of importance when considering commercially relevant products (e.g. as an advanced technology fuel -ATF), avoiding the use of uranium metal as a reactant. UO 2 was reduced and borated in-situ through careful combination with boron carbide (B 4 C) and graphite (carbo/borothermic reduction). The reaction is observed to only be favourable at low partial pressures of CO, here made possible through use of a vacuum furnace at temperatures up to 1800 • C. At higher partial pressures of CO, the product of the reaction is UB 4 . For phase pure UB 2 , excess B 4 C is required due to the formation of volatile boron oxides that are released from the reaction mixture as is observed when synthesising other borides through similar routes.

Accessible Statistical Regression, Extrapolation and First-Principles Modelling of Nuclear Data for Spent Nuclear Fuel Composition and Decay Heat Calculations in Short-Term Storage and Recycling

“…2,22 The model will continue to be refined over time and any developments in efficacy will be discussed in future publications alongside comparisons with outputs from established fuel performance codes. This model could also be tailored to accident tolerant or advanced technology fuels (ATFs) 29,30,32,33 with alternative ceramics such as borides, 30 carbides, 31 nitrides, 29 and silicides, 32 though this would require accommodation of fuel densities and neutronic behaviour. 33 It may also be possible to model liquid fuel systems as found in molten salt reactors with further adaptions to the model.…”

From caged compounds with isolated U atoms to frustrated magnets with 2- or 3-atom clusters: a review of Al-rich uranium aluminides with transition metals

“…For instance, the addition of approximately 7 -10 wt% of molybdenum to uranium has been intensively studied as a fuel for RTRs due to the high chemical stability of the γ-U(Mo) phase, its stability under irradiation and the increased density of uranium (ρ U ≈ 16-17 g U cm −3 ) (Snelgrove et al 1997, Leenaers et al 2020a. Other materials under consideration include U 3 Si 2 (ρ U ≈ 11.3 g U cm −3 ) (Leenaers et al 2020b), UN (ρ U ≈ 13.5 g U cm −3 ) (Durand andLaudamy 1994, Wallenius 2020), UC (ρ U ≈ 13.0 g U cm −3 ) (Clement Ravi Chandar et al 2020) and UB 2 (ρ U ≈ 11.7 g U cm −3 ) (Turner et al 2020) among others.…”

Self-contained dual-scale composite architectures in spray dried zirconium diboride

“…A candidate composite nuclear fuel concept consists of fissile ceramic microspheres dispersed in a fissile matrix, to boost thermophysical and thermochemical fuel stability during normal operation and in the event of anticipated operational occurrences (AOOs) or design-basis accidents [1], [2]. Ceramic materials like uranium diboride (UB2) [3], uranium silicide (U3Si2) [4] and uranium nitride (UN) [5], [6] are embedded in the parent nuclear fuel, typically uranium oxide (UO2). However, non-fissile ceramics, such as zirconium diboride (ZrB2) are also potential microsphere materials for accident tolerant composite fuels.…”