热管反应堆多物理耦合平台初步研究

Preliminary Research on a Multi-Physics Coupling Platform for Heat Pipe Reactors

为实现高精度、高置信度的核能系统先进数值模拟技术,探究核能系统内部真实的物理过程,本文开发了中子物理-固体导热-应力分析的三维高精度核热固多物理耦合计算平台MPCH,可开展核反应堆的中子输运、热扩散和热膨胀的多物理耦合计算。该程序基于Picard迭代的外耦合框架,整合了开源蒙特卡罗程序OpenMC、有限元程序Nektar++和SfePy。本文以新型空间热管反应堆KRUSTY为对象,在核热固耦合的计算框架下对其进行计算分析。多物理耦合计算结果表明,该耦合平台能够有效预测KRUSTY反应堆的有效增殖因子变化、功率分布、温度分布及热膨胀现象;在4 kW的堆芯热功率下,全堆局部温差为21.6K,热应力导致的形变率为2.47%,核热固耦合的作用会使堆芯的温度分布更加均匀。该多物理耦合计算程序的设计对新堆设计、研发和校核具有重要作用。

In order to achieve high-precision and high-fidelity numerical simulations of nuclear energy system and to explore the true physical process therein, a coupled three-dimensional high-fidelity calculation platform named MPCH for neutronics/thermal-conduction/stress-analysis calculation has been developed in this work. Therefore, MPCH can be used to perform a series of multi-physics coupled calculation of neutron transport, thermal conduction and thermal expansion. MPCH is constructed based on Picard iteration by integrating open-source codes: OpenMC, Nektar++ and SfePy. In this paper, the new space heat pipe reactor KRUSTY is calculated and analyzed under MPCH. The calculation results of multi-physics coupling show that MPCH can effectively predict the effective multiplication factor change, power distribution, temperature distribution and thermal expansion of the KRUSTY reactor. At the power of 4 kW, the local temperature difference of the whole reactor is 21.6 K. The thermal stress leads to the deformation rate of 2.47%. Moreover, the effect of neutronics/thermal-conduction/stress-analysis coupling tends to make a more uniform temperature distribution of the core. This multi-physical coupling calculation program plays an important role in the design, development and verification of new reactors.