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Numerical Analysis of Dryout Phenomena in Light Water-Cooled Nuclear Reactors using Particle Method

轻型水冷核反应堆干涸现象的粒子法数值分析

基本信息

批准号：
14380232
负责人：
OKA Yoshiaki
金额：
$ 9.15万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

In Boiling Water Reactors (BWRs), annular mist flow appears in the upper part of the core. Dryout is a limiting condition of thermalhydraulic design. It is important to analyze dry out accurately for the reactor design and safety. Moving Particle Semi-implicit (MPS) method has been developed by the present researchers. The MPS method does not need meshes, so that droplet separation and merging are easily analyzed. In the present study, direct simulation of dry out was carried out using the MPS method.Dryout phenomenon consists of the deposition process where droplets are absorbed by the liquid film flowing on the fuel reds, and the entrainment process where droples are released from the liquid film. First, single droplet behavior in the deposition process was analyzed by the MPS method. When the droplet diameter is small or the impact velocity is slow, the droplet is totally absorbed by the liquid film. When the droplet diameter is large or the impact velocity is high, the droplet impact disturbs the liquid film and new droplets are generated. This new droplets (re-entrainment) cannot be neglected in the Boiling Water Reactor (BWR) conditions.A particle-mesh hybrid method was developed based on the finite volume method and the particle method (MPS method). Gas-liquid two-phase flow can be analyzed efficiently using the hybrid method. A low-Reynolds number k-ε model was incorporated into this hybrid method. Simulation of liquid film flow and instability on the fuel rods in BWR cores using the hybrid method.In this study, numerical methods have been developed to analyze the basic processes in the dryout phenomenon m the BWR conditions. Anew knowledge about the re-entrainment process was also obtained.

在沸水堆（BWR）中，环形雾流出现在堆芯上部。干涸是热工水力设计的一个限制条件。准确分析干化对反应堆的设计和安全运行具有重要意义。移动粒子半隐式（MPS）方法是近年来发展起来的一种新方法。MPS方法不需要网格，因此容易分析液滴分离和合并。本文采用MPS方法对干熄过程进行了直接模拟，干熄现象包括液滴被在燃料红上流动的液膜吸收的沉积过程和液滴从液膜中释放的卷吸过程。首先，用MPS方法分析了沉积过程中单个液滴的行为。当液滴直径较小或撞击速度较慢时，液滴完全被液膜吸收。当液滴直径大或冲击速度高时，液滴冲击扰动液膜并产生新的液滴。在有限体积法和颗粒法（MPS法）的基础上，发展了一种颗粒-网格混合方法，并对该方法进行了数值模拟。混合方法可以有效地分析气液两相流。该混合方法采用了低雷诺数k-ε模型。用混合方法模拟沸水堆堆芯燃料棒上的液膜流动和不稳定性本文发展了数值方法来分析沸水堆工况下燃料棒干涸现象的基本过程。对二次夹带过程也有了新的认识。