A study of the rapid depressurization of hot water and the dynamics of vapour bubble generation in superheated water

Liquid can be brought to a superheated state by means of very rapid depressurization. Such situations are typical for pipe rupture accidents, which can occur in processing equipment and have to be taken into account, for example, in the design of nuclear power plants with water-cooled reactors. An experimental investigation was carried out using a horizontal pipe attached to a pressure vessel. Rapid depressurization was achieved with the use of a rupture disc assembly. The paper describes the most important test results, a method for calculating the pressure undershoot below the saturation pressure and a simplified model of expansion wave propagation with vapour bubble generation in superheated liquid. On the basis of this model, the density of nucleation sites and the evolution of pressure and void fraction in the two-phase mixture can be estimated.