Calculation Of Thermohydraulic Response And Hydrodynamic Behavior Of Pressure-suppressed Containment

Marine floating nuclear power can provide clean energy for marine resources development,which is of strategic importance.The pressure-suppressed containment has the advantages of small size and compact structure of nuclear power plant,which is an important reference for the design of marine floating nuclear power plants.China’s research on the simulation of pressure-suppressed containment is relatively insufficient.In addition,the hydrodynamic load generated by the hydrodynamic behavior of the suppression system under accident conditions has an important impact on the pressure-bearing capacity of the containment boundary,and there is a lack of research on this part in China:A simulation modeling scenario based on the MELCOR program is first performed for a pressure-suppressed containment,focusing on the effect of droplet distribution in mass energy release on atmospheric pressure and containment temperature under reference accident conditions.Emphasis is placed on the effects of the MELCOR droplet drop model,droplet suspension model,and gas mixture density in the containment on the calculation of short-term pressure in the containment.The results show that the density of the gas mixture in the envelope affects the maximum pressure in the envelope,that the higher the gas density,the slower the release of the containment pressure,and that the choice of the droplet suspension model and the increase of the fog density can lead to more conservative results.On this basis,simulation modeling of a small pressure-suppressing containment test device is performed to investigate the effect of different structural parameters on the pressure-suppressing effect.The calculation results show that the reduction of the free volume of the containment vessel can increase the pressure suppressing effect;the gas to water ratio of the suppressing basin on the system response,too low or too high basin water volume fraction will weaken the role of the suppressing basin;the immersion depth of the suppression tube on the pressure suppression effect of the suppression basin has no significant impact;the outlet area of the suppression tube and the peak pressure inside the shell are negatively related,when the area increases to some extent,the pressure suppression effect does not change.When the area increases to some extent,the pressure suppression effect does not change significantly.The influence of each factor on the maximum pressure of the containment is in decreasing order: the cross-sectional area of the pressure suppression tube,the gas/water ratio of the pressure suppression pool,the free volume of the containment,and the immersion depth of the pressure suppression tube.To compensate for the inability of the MELCOR program in calculating the hydrodynamic behavior of the pressure suppression system to simulate the inertial effect of the water column in the pressure suppression tube and the expansion of the pool caused by rising air bubbles,Pravin Sawant’s basic numerical model of the ABWR type containment was used to numerically model the MARK II type containment,respectively to establish the pressure suppression tube release model and the expansion model.