Application Of Thermal Stratification Models For AP1000 Accident Analysis

Passive containment cooling system as a part of the passive engineered safety features, its reliability directly affect the "inherent safety of the reactor". So the reliability analysis of it have a great significance, and passive containment cooling system (PCCS) crevasse spray problems directly affect the reliability of the containment vessel, passive containment heat transfer capability is the bottleneck of power reactor safety. We focus the parameter is the last nuclear power plant security barrier bearing capacity which is benefit for the design of CAP 1400 and CAP 1700.After the accident condition,if we can predict exactly the distribution of the concentration and temperature in the containment vessel, it is very important to the optimization of the reactor design and accident analysis.Currently the reactor industry more professional software mainly used lumped parameter method software such as WGOTHIC, TRAC MELCOR.The conservative solution software can only get close value.Finite element analysis software drawbacks is that require huge grid.This one-dimensional model is more advantageous than commercial 3D software. Heat transfer formula is given by Westinghouse.Programs utilizing Westinghouse given evaporation and condensation formula binding Peterson theory developed AP1000 containment model thermal-hydraulics in accident conditions.It uses a simplified one-dimensional model calculation and improves accuracy.The characteristics of this program is no need to divide complex meshing and can quickly calculate the fluid temperature and the concentration distribution.And this program is designed for AP1000 and CAP 1400 containment specially which have very strong pertinence.This paper also develop a steam injection thermal process which aim at a small size of containment experiment to validate program.Finally, on the basis of the original program, the modification of input conditions to the transient mass energy release parameters had been done.We study the distribution of containment temperature, pressure, etc with the use of small passive containment steam jet stream experiments.By analyzing the results of experiments and procedures we come to the conclusion:Procedures for safe upper housing space simulation is better, but the lower space temperature difference.The reason is that the program may not take into account the wall jet and radiation heat transfer.Finally, with CAP 1400 MSLB and LOCA accident, the new program calculate the results compared with WGOTHIC to verify procedures transient mass and energy release model one dimensional model. Through multiple sets of comparative data to fully explain the significance of mixing and thermal stratification on containment thermal-hydraulic analysis.