基于CFD的安全壳局部隔间非能动氢气复合器布置方案研究

非能动氢气复合器用于压水堆核电厂严重事故条件下安全壳内氢气的消除。通过计算流体力学(CFD)方法能够给出事故条件下非能动氢气复合器周围三维流场和温度场的分布。基于CFD程序根据非能动氢气复合器消氢公式，计算非能动氢气复合器进出口的气体流量和气体组分，并作为非能动氢气复合器的边界条件，开展三维空间内非能动氢气复合器消氢速率和氢气分布情况研究。结果表明：简化的非能动氢气复合器模拟方案能很好地模拟非能动氢气复合器样机的消氢效果；对安全壳内局部隔间开展非能动氢气复合器消氢效果研究发现，在相同环境条件下，非能动氢气复合器布置在较高位置与布置在较低位置相比，布置在较高位置时，非能动氢气复合器具有更高的消氢速率，隔间整体氢气浓度较低，但是非能动氢气复合器布置在较高位置时出现隔间底部局部氢气聚集的情况。

Layout Optimization of Passive Autocatalytic Recombiner in Local Compartment of Containment Base on CFD

During severe accidents in pressurized water reactor (PWR) nuclear power plant, a large amount of hydrogen is produced due to zirconium water reaction, which seriously threatens the safety of the reactor. Passive autocatalytic recombiner and hydrogen igniter are effective prevention and mitigation measures to reduce the hydrogen risk in containment for PWR nuclear power plant. At present, passive autocatalytic recombiners or hydrogen igniters are arranged at different locations in the containment. In the study of hydrogen elimination effect in containment, lumped parameter program or theoretical calculation method are often used. However, lumped parameter program is difficult to give the effect of hydrogen distribution. With the development of computer technology, computational fluid dynamics (CFD) method has been more and more applied in the field of nuclear power safety. CFD code can also be used to simulate the hydrogen distribution and evaluate the effect of passive autocatalytic recombiners in different compartments during severe accidents. For each passive autocatalytic recombiner supplier will provide the hydrogen elimination rate formula of the passive autocatalytic recombiner, there are different methods to simulate the passive autocatalytic recombiners in containment, such as, by modeling the structure of passive autocatalytic recombiners in detail and choose the complex chemical reaction model, the actual reaction process inside the passive autocatalytic recombiner can be simulated. Or the hydrogen elimination rate is calculated through the experimental formula provided by the supplier, and the source term of each component in the species functions is modified. In this paper, a novel and simplified CFD simulation method was applied to model the hydrogen elimination effect of passive autocatalytic recombiner prototype, to be specific, passive autocatalytic recombiner was treated as black box, the flow rate and composition of gas at the inlet and outlet of passive autocatalytic recombiner were set as boundary conditions. Then the method was used to simulate and optimize the layout of passive autocatalytic recombiners in local compartment of nuclear power plants, the conclusions show that the validation of the simplified simulation scheme of passive autocatalytic recombiners is verified, and the calculated hydrogen elimination result can fit well with the experiment data. The hydrogen elimination rate of passive autocatalytic recombiner at a higher position is larger than that at a lower position, and the overall hydrogen concentration in the compartment is lower. However, the phenomenon of local hydrogen accumulation at the bottom of the compartment may happen if passive autocatalytic recombiner is set at a higher position.