Uranium nitride-silicide advanced nuclear fuel: higher efficiency and greater safety

Abstract

As part of Accident Tolerant Fuel initiative for light water reactors, uranium silicide and silicidenitride are being considered as fuels that can be combined with a more robust cladding such as a ferritic (FeCrAl) alloy. Although these materials have been studied in the past, uncertainties remain concerning the fundamental behaviour of these systems. In this study, four compositions between U 3 Si 5 and USi 2 were fabricated by arc-melting. Additionally, in an effort to understand the UN-U 3 Si 2 fuel system, an unidentified U-Si-N ternary was observed in samples fabricated by arc-melting U 3 Si 2 in the presence of varied concentrations of N 2 in Ar. The analyses of compositions prepared to investigate these systems include structural characterisation using X-ray diffraction and compositional analysis employing scanning electron microscopy with energy dispersive spectrometry. Initial values of the Gibbs energy parameters via the CALPHAD (CALculation of PHAse Diagrams) method have been developed for the ternary phases observed upon U 3 Si 2 -FeCrAl interactions.

Electronic structure comparisons of isostructural early d- and f-block metal(iii) bis(cyclopentadienyl) silanide complexes

“…[3][4][5] In comparison, f-block silicon chemistry is less well developed but shows promise, 6 with lanthanide (Ln) silicides used to fortify low-alloy steels, 7 Ln silanide catalysts employed in unsaturated hydrocarbon polymerisations, 8,9 and actinide (An) silicides showing potential for use as high-density nuclear fuels. [10][11][12][13] Given that the physicochemical properties of the f-elements have been exploited in numerous technologies, 14,15 it follows that a deeper understanding of f-block silicon chemistry could lead to new applications that complement d-block silicon analogues.…”

“…The greater covalency of 5f 3 U(III) vs. 4f 3 Nd(III) is found by comparison of their EPR and electronic absorption spectra and magnetic measurements, with calculations indicating that uranium 5f orbitals have weak π-bonding interactions with both the silanide and Cp′′ ligands, in addition to weak δantibonding with Cp′′.well developed but shows promise, 6 with lanthanide (Ln) silicides used to fortify low-alloy steels, 7 Ln silanide catalysts employed in unsaturated hydrocarbon polymerisations, 8,9 and actinide (An) silicides showing potential for use as high-density nuclear fuels. [10][11][12][13] Given that the physicochemical properties of the f-elements have been exploited in numerous technologies, 14,15 it follows that a deeper understanding of f-block silicon chemistry could lead to new applications that complement d-block silicon analogues. f-Block silicon chemistry has continued to slowly develop and now includes multiple examples of cyclopentadienyl (Cp)-supported M-Si bonds.…”

f-Element silicon and heavy tetrel chemistry

“…U 3 Si 2 , USi 2 ) as alternatives to conventional UO 2 fuel due to an increase in uranium density and a larger thermal conductivity in the former materials, potentially allowing prolonged generation of energy from nuclear fuels. [31][32][33] Given historical experimental and computational limitations, early reports of f-element silicon chemistry lack in-depth analysis of the bonding and properties of the M-Si linkage compared to what can be done now; a higher level of analysis has only started to be practicable recently and these fundamental studies are the necessary rst step for this eld to develop further. The increasing rate of development in felement silicon chemistry in the last two decades has provided the motivation for this perspective; the heavier tetrels are discussed herein to inspire the future development of the felement chemistry of these elements also, but silicon remains the focus.…”

Understanding the interface interaction between U3Si2 fuel and SiC cladding

“…Materials. The U 3 Si 2 material for the current effort was prepared from depleted uranium (Los Alamos National Laboratory, 99.98%) and elemental silicon (Sigma Aldrich, 99.99%) by arc-melting 26 . Arc-melting was conducted inside a glovebox maintained at an oxygen and H 2 O level <0.1 ppm.…”