Simulation of the airborne radioactive substance distribution and monitoring of coolant leakage in a typical Nuclear Reactor Containment

The management of coolant leakage in a Nuclear Reactor Containment is important to ensure the safe operation of a facility and preserve the structural integrity of the containment. This paper conducts the comprehensive analysis using the commercial Computational Fluid Dynamics (CFD) software CFX to assess the concentration distribution and motion of Xe-133 in a typical Nuclear Reactor Containment. Guidelines from the previous studies about the gas distribution in the containment are followed in the simulation. The containment model with detailed internal structure is established and divided into unstructured meshes. Analyses are carried out to quantify the Xe-133 distribution for three cases. These were (1) behavior analysis of Xe-133 for a given short period of time, (2) behavior analysis of Xe-133 for a given long period of time, (3) the effect of various leak rates and leak sources on Xe-133 distribution. The results indicate that the increasing rate of Xe-133 concentration is almost completely proportional to the leak rate of reactor coolant. The varying leak rates and leak sources have no significant impact on homogeneous distribution of leaking radionuclides in containment. The monitor of Xe-133 can ensure timely response to coolant leakage. This paper contributes to a reasonable design of the reactor coolant leakage detection system.