High-density fuels have been proposed as a possible replacement for uranium-dioxide as a fuel for light water reactors (LWRs) due to their increased loading of fissionable material. The objectives of this proposal are (1) to increase reactor cycle length and reactor power, and (2) to offset any neutronic penalty associated with advanced cladding systems. Of the high-density fuels under consideration, there is particular interest in triuranium disilicide (U₃Si₂) due to its increased metal density and favorable thermal properties as compared to UO₂. However, there are concerns regarding the chemical compatibility of U₃Si₂ with water and steam as used for LWR coolant.

This paper summarizes research on fuel-coolant chemical compatibility for UO₂ LWR fuel during a cladding breach and highlights that generally, because of its chemical inertness, UO₂-coolant reactions are of little consequence to reactor operation. However, the volumetric expansion associated with the reaction of UO₂ and oxygen is a concern for possible conditions encountered during air ingress of dry storage. These same concerns arise for U₃Si₂, which exhibits greater volumetric expansion than UO₂ when exposed to water or steam. These reactions ultimately result in increased fuel volume that the cladding must accommodate, as well as additional heat generated as the fuel reacts.

The BISON fuel performance code was used to perform a comparative analysis on the behavior of UO₂ and U₃Si₂ under normal operation. Silicide fuel simulations were then extended to demonstrate how varying thermodynamic and chemical kinetics influence fuel expansion and subsequent cladding performance during a cladding breach. These simulations were further extended to a 3D subsection of a fuel rod to demonstrate the characteristics of the resulting cladding crack.

由于高密度燃料增加了易裂变材料的负荷，因此已提出可以替代二氧化铀作为轻水反应堆（LWR）的燃料。该提议的目标是（1）增加反应堆循环长度和反应堆功率，以及（2）抵消与先进包层系统相关的任何中子损失。在考虑中的高密度燃料中，由于三铀二硅化物（U ₃ Si ₂）与UO ₂相比具有更高的金属密度和良好的热性能，因此引起了人们的特别关注。然而，对于用于LWR冷却剂的U ₃ Si ₂与水和蒸汽的化学相容性存在担忧。

本文总结了在包壳破裂期间对UO ₂ LWR燃料的燃料-冷却剂化学相容性的研究，并着重指出，通常，由于其化学惰性，UO _2-冷却剂反应对反应堆的运行影响不大。然而，与UO ₂和氧气的反应有关的体积膨胀是在干燥存储的空气进入期间遇到的可能条件的关注。对于U ₃ Si ₂也存在同样的问题，当暴露于水或蒸汽时，U ₃ Si _2的体积膨胀比UO _2大。这些反应最终导致包壳必须容纳的燃料量增加，以及燃料反应时产生的额外热量。

使用BISON燃油性能代码对正常运行下UO ₂和U ₃ Si _2的性能进行比较分析。然后扩展了硅化物燃料模拟，以展示在熔覆层破裂期间变化的热力学和化学动力学如何影响燃料膨胀和随后的熔覆性能。这些模拟进一步扩展到了燃料棒的3D子部分，以演示最终熔覆裂纹的特征。