Transient response of VHTR compartment system following depressurization accident

This study aims to develop an analytical method for evaluating the pressure-temperature response of HTGR containment system provided with multiple compartments following depressurization accident. Estimation of peak pressures in the Compartments where Pipe Rupture is postulated (hereafter referred to as CPR) depends much on the method to simulate the mixing of discharged helium and air in CPRs. So, in this paper, the authors introduce an analytical model which is considered to be adequately conservative in estimating the peak pressures in CPRs. Calculated pressure transients for each postulated accident, based on the first conceptual design of VHTR, are presented with the results of sensitivity analyses. It is concluded that the peak pressures in CPRs due to the maximum pipe ruptures can be suppressed below the allowable limits by providing suitable pressure relief devices. (author)