分子动力学模拟压水反应堆中氢气对水的影响

通过分子动力学方法模拟了在常温常压下(1 atm, 298 K)和在压水堆环境下(155 atm, 626 K), 水分子数为256, 氢分子数为0, 25, 50, 75和100等不同数目时, 粒子系统的动力学性质和微观结构, 分析了不同氢气对水中溶解氧的影响. 从模拟结果可知, 在常温常压和压水堆环境下, 当氢粒子数分别为0, 25, 50, 75和100时, 粒子系统的均方位移会随氢分子数增加而增加, 并且常温常压下的增长幅度远小于压水堆环境下的增长幅度, 如压水堆环境下氢分子数为75时系统的均方位移约是常温常压下氢分子数为75时系统的均方位移的6.02倍, 比压水堆环境下氢分子数0时系统的均方位移增加了131.88%. 此外, 粒子系统的微观结构, 从径向分布函数看, 在常温常压下随着氢分子数目的增加而小幅度增加, 这与常温常压下因氢气溶解在水中增大了氧离子周围的粒子密度相符合. 而在压水堆环境下, 氢分子数为75, 50, 25与为0时的水比较, 其径向分布均不会有太大的变化, 而分子数为100时会出现明显增加, 与为0时的水比较其径向分布增加了22.00%. 模拟结果表明, 往压水堆中的水加入氢气能明显地抑制水中的溶解氧.

Molecular dynamics simulation for the effect of hydrogen on the water of pressurized water reactors

In this paper, molecular dynamics is used to simulate dynamic properties and micro-structure of the water-hydrogen particle system under various conditions: 1 atm, 293 K; pressurized water reactor (PWR) environment of 155 atm, 626 K; the number of water molecules of 256, numbers of hydrogen (H₂) molecules of 0, 25, 50, 75 and 100, and the mean square displacement (MSD) in the particle system increases with the number of particles of the hydrogen increasing. Under the PWR environment, with hydrogen molecule number being 75, the MSD is about 6 times higher than that in chamber ambient. At the same time, under such a condition, the MSD of particle system increases 131.8829% higher than that in the case of the number being 0. In addition, the micro-structure of particle systems, from the view of the radial distribution functions (RDF), increase with the increase of concentration of hydrogen in chamber ambient, which coincides with the fact that the hydrogen dissolution in water increases the particle density around oxygen ions at nomal temperature and normal pressure. While in the PWR environment, the radial distributions of the water with the numbers of hydrogen molecules of 75, 50, 25 and 0 have no big change, but the radial distribution with the number of hydrogen molecules of 100 increases significantly and it is 22.0048% higher than that in the case of the number being 0. It can be seen from simulation data that hydrogen added to PWR significantly inhibits the oxygen dissolution in water. This phenomenon and its cause are revealed comprehensively in this paper.