分子动力学模拟压水反应堆中联氨对水的影响

本文采用分子动力学方法模拟在常温常压下(1 atm,298 K)和在压水堆环境下(155 atm,626 K),水分子数为256,联氨(N₂H₄)分子数为0,25,50,75等不同数目时,水和联氨粒子系统的动力性质和微观结构.同时探讨了联氨分子的引入对水中溶解氧的影响.从模拟结果可知,在常温常压下,当联氨的分子数为0,25,50,75时,粒子系统的均方位移会随联氨分子数的增加而增加;联氨分子数为0与为25,50,75比较时会少一个数量级;压水堆环境下,联氨分子数 关键词： 分子动力学 压水堆 联氨

Molecular dynamics simulation for the impact of hydrazine on the water of pressurized water reactors

In this paper, we used molecular dynamics to simulate dynamic properties and micro-structure of the water-hydrazine particle system under various conditions:chamber condition of 1 atm, 298 K; pressurized water reactor (PWR) environment of 155 atm, 626 K; with number of water molecules of 256, numbers of hydrazine (N₂H₄) molecules of 0, 25, 50 and 75. And we have also explored the impact on the dissolved oxygen in water when hydrazine molecule is added to the system. The simulation results show that in the chamber ambient, when the number of molecules of hydrazine varies from 0 to 25, 50 and 75, the mean square displacement (MSD) in the particle system will increase with the number of particles of the hydrazine. The MSD for hydrazine molecule of number 0 will be ten less than that of 25, 50 and 75. Under the PWR environment, with hydrazine molecule number of 50, the MSD is about 4 times higher than that in chamber ambient. At the same time, under such condition, the MSD of particle system does not increase with the number of hydrazine molecules. The MSD with hydrazine molecule of 50 is higher than its counterpart with the number of molecules of 25 or 75. In addition, the micro-structure of particle systems, from the perspective of the radial distribution functions (RDF), will increase with the increase of concentration of hydrazine in chamber ambient. This conclusion goes along with the fact that hydrazine is easy to react with water to generate hydrazine hydrate. While in the pressurized water reactor environment, the radial distributions of the water with the number of hydrazine molecules of 25, 50 and 0 will have no big change. But the radial distributions with the number of hydrazine molecules of 75 increase significantly. It can be seen from simulation data that hydrazine added to PWR significantly inhibits the dissolved oxygen in water, but the inhibition does not increase in proportion to the increase of the concentration of hydrazine. This phenomenon and its causes are revealed comprehensively in this paper.