Abstract Dynamical behavior of the Brazilian Multipurpose Reactor (RMB) is investigated by using the coupled neutronics and thermal hydraulics code NTHC1, which consists of the neutron point kinetics (NPK) equations with six groups of delayed neutrons, the heat conduction equations in a fuel plate, and the energy transport equation in a coolant subchannel. The Serpent 2 Monte Carlo code is employed to calculate the RMB kinetic parameters of the NPK equations and steady state power distribution. Improved lumped formulations are adopted for heat conduction in the transversal direction of the fuel and cladding, while the fluid energy equation is discretized along the subchannel by finite difference method. The resulting system of ordinary differential equations is solved by numerical method. The NTHC1 code was verified against the IAEA 10 MW MTR benchmark problems, showing good agreement with literature data. The simulation results demonstrated that RMB operates safely under the postulated initiating events (PIE) of loss of flow and reactivity insertion.

中文翻译：

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通过耦合中子学和热工水力代码 NTHC1 对巴西多用途反应堆进行瞬态分析

摘要 巴西多用途反应堆 (RMB) 的动力学行为是利用耦合中子学和热工水力代码 NTHC1 研究的，该代码由六组延迟中子的中子点动力学 (NPK) 方程、燃料板中的热传导方程，以及冷却剂子通道中的能量传输方程。Serpent 2 Monte Carlo代码用于计算NPK方程和稳态功率分布的RMB动力学参数。燃料和包壳横向的热传导采用改进的集总公式，流体能量方程沿子通道采用有限差分法离散化。所得常微分方程组通过数值方法求解。NTHC1 代码针对 IAEA 10 MW MTR 基准问题进行了验证，显示出与文献数据的良好一致性。模拟结果表明，RMB 在假设的起始事件（PIE）的流动损失和反应性插入下安全运行。