Abstract

Nuclear thermal propulsion (NTP) provides a consistent source of thrust for long space missions. However, fuel development for NTP reactors is a major technological hurdle. Existing modeling and simulation tools developed by the U.S. Nuclear Engineering Advanced Modeling and Simulation (NEAMS) program for power reactors can be leveraged to help accelerate the fuel development. This work is a preliminary demonstration of the application of NEAMS tools to model NTP fuel. Specifically, the fuel performance tool BISON and the mesoscale reactor materials tool MARMOT are used to develop a multiscale model of thermal transport in a W-UO₂ CERMET fuel element for NTP reactors. Three-dimensional simulations in MARMOT are used to estimate the effective thermal conductivity (ETC) of fresh CERMET fuel at temperatures ranging from 1500 K to 3000 K. The ETC values from MARMOT are then used in BISON simulations that predict the steady-state temperature profile throughout a 61-subchannel hexagonal fuel element. The temperature varies by 83 K throughout the fuel element, with the highest temperature occurring near the outer edges of the element. BISON is also used to show that the temperature profile in prototype fuel elements with fewer subchannels does not vary significantly from that in the 61-subchannel element.

摘要

核热推进 (NTP) 为长期太空任务提供一致的推力源。然而，NTP 反应堆的燃料开发是一个主要的技术障碍。可以利用美国核工程高级建模和仿真 (NEAMS) 计划为动力反应堆开发的现有建模和仿真工具来帮助加速燃料开发。这项工作是应用 NEAMS 工具模拟 NTP 燃料的初步演示。具体而言，燃料性能工具 BISON 和中尺度反应堆材料工具 MARMOT 用于开发 W-UO ₂中热传输的多尺度模型NTP 反应堆的 CERMET 燃料元件。MARMOT 中的三维模拟用于估计新鲜 CERMET 燃料在 1500 K 至 3000 K 温度范围内的有效导热系数 (ETC)。然后将 MARMOT 的 ETC 值用于预测稳态温度分布的 BISON 模拟整个 61 个子通道的六边形燃料元件。整个燃料元件的温度变化为 83 K，最高温度出现在元件的外边缘附近。BISON 还用于表明具有较少子通道的原型燃料元件中的温度分布与 61 子通道元件中的温度分布没有显着差异。