熔融物与混凝土相互作用时熔池内的化学反应研究

Study on the Chemical Reactions in Molten Pool During Molten Core Concrete Interaction

熔融物与混凝土相互作用(MCCI)时释放的裂变产物是压水堆核电厂发生严重事故时主要的二次源项。熔融物侵蚀混凝土时产生的气体和熔渣将进入熔池中与熔融物进行反应,反应得到的易挥发物质将随着气泡离开熔池并在安全壳内形成气溶胶。本文根据化学平衡的假设建立了熔池内的反应模型,并通过反应吉布斯自由能得到平衡常数,进而计算得到熔融物的活度比,最终筛选出熔池内可能存在的118种物质及可能发生的97个化学反应。以上反应模型和筛选方法可用于MCCI时裂变产物释放模型的开发。

Fission products released during the molten core concrete interaction(MCCI)are the main second⁃ary source terms in the case of severe accidents in a PWR nuclear power plant.When the molten material erodes the concrete,the generated gas and salg enter the molten pool and react with molten material.Then the volatile reaction products will leave the molten pool with bubbles and form aerosols in the containment.In this paper,a reaction model in the molten pool is built based on the assumption of chemical equilibrium,in which the equilibrium constant is calculated by reaction Gibbs energy and the activity radios of melt is calculated by the equilibrium constant.Finally,118 possible substances and 97 possible chemical reactions in the molten pool are screened out.The above reaction model and screening method can be used in the development of the fission products release model during MCCI.