Predictive accuracy of design methods for the relief cross-sections for runaway reactions

On the basis of calculations performed on the results of experiments conduc ted in reactors with volumes up to 10 m(3) for so-called vapour-pressure pr oducing (runaway) reaction systems, it is found that ail simplified or stea dy-state methods regularly afford overdimensioned relief cross-sections. As a consequence, unnecessarily large mass flows leave the reactor to enter t he containment system. A balanced design of both plants components is possi ble only with the aid of transient methods. In the case of gas generating r eactions simplified methods also lead to excessively large pressure relief cross-sections. Design with the aid of a transient method for such a reacti on system is rendered difficult by the fact that a conservative submodel ca nnot be used a priori for description of the expansion behaviour. A paramet ric study is then required.