Chromium-doped UO is a widely-studied near-term deployable accident-tolerant fuel concept because it results in a dense, large-grain structure that increases the fuel resistance to densification, swelling, and fission gas release. A new charged-interstitial mechanism was recently proposed to describe the behavior of dopants like chromium in sintered UO₂. Based on that mechanism, manganese was suggested as an even stronger dopant than chromium. In the current work we use mesoscale sintering simulations in an effort to validate the new mechanism. We compare the relative behavior of Cr-doped and undoped UO₂ against experimental data in the literature. We also make predictions of the relative behavior of Mn-doped UO₂. Simulations are done using the phase field-based grand potential sintering model.

Dopants have two effects on sintered UO₂. They marginally increase the densification rate and greatly increase the average grain size. Both of these effects are individually tested in small-scale simulations. Then large 3D sintering simulations are used to test the combined behavior of both effects. The results for the densification rate simulations are consistent with experiments for Cr-doped fuels. However, the grain growth rates are lower than what is found in the literature for Cr-doped fuels.

掺杂铬的UO是一种经过广泛研究的近期可部署的耐事故燃料概念，因为它产生了致密的大颗粒结构，提高了燃料对致密化，膨胀和裂变气体释放的抵抗力。最近提出了一种新的带电填隙机制，以描述诸如UO ₂烧结态的掺杂剂的行为。基于这种机理，锰被认为是比铬更强的掺杂剂。在当前的工作中，我们使用中尺度烧结模拟来验证新机制。我们比较了Cr掺杂和未掺杂UO ₂的相对行为与文献中的实验数据。我们还预测了Mn掺杂UO ₂的相对行为。使用基于相场的大势烧结模型进行仿真。

掺杂剂对烧结的UO ₂有两种作用。它们略微增加了致密化率，并大大增加了平均晶粒尺寸。这两种效果均在小规模仿真中进行了单独测试。然后使用大型3D烧结模拟来测试两种效果的组合行为。致密化速率模拟的结果与掺铬燃料的实验一致。但是，晶粒生长速度低于文献中掺铬燃料的生长速度。