Abstract The design and deployment of integrated modular water reactors (IMRs) and evolutionary reactors whose operations are based on passive systems are on the rise. The natural circulation (NC) based passive systems being adopted rely on natural convection, buoyancy driven-flow and vapour condensation. In this work, a numerical approach that can determine the required conditions for establishing this widely applied thermal hydraulic phenomenon in simple turbulent two phase nuclear passive system is presented. Through the method, other relevant thermal-hydraulic parameters which are of interest in safety and reliability analyses of such NC-based systems can also be obtained. The case of the System-integrated Modular Advanced ReacTor (SMART) based on the method was demonstrated. Furthermore, the validity of the approach was proven using the test data and simulation results of a NC-based experimental facility. The method is simple and easy to apply to NC-based systems of similar configurations.

中文翻译：

---

估算简单核被动系统中自然循环条件的数值方法

摘要 基于无源系统运行的集成模块化水反应堆 (IMR) 和演化反应堆的设计和部署正在兴起。采用的基于自然循环 (NC) 的被动系统依赖于自然对流、浮力驱动流和蒸汽冷凝。在这项工作中，提出了一种数值方法，该方法可以确定在简单的湍流两相核被动系统中建立这种广泛应用的热水力现象所需的条件。通过该方法，还可以获得在此类基于 NC 的系统的安全性和可靠性分析中感兴趣的其他相关热工水力参数。展示了基于该方法的系统集成模块化高级反应堆（SMART）的案例。此外，使用基于 NC 的实验设施的测试数据和模拟结果证明了该方法的有效性。该方法简单且易于应用于类似配置的基于 NC 的系统。