FINITE-ELEMENT ANALYSIS OF TWO-PHASE FLOWS.

Safety studies for liquid cooled reactors address the questions raised by postulated failures of the cooling system. It is of importance to predict the time history of the depressurization that follows a loss of coolant accident to guarantee the integrity of the overall system. In this report the sudden depressurization of a straight pipe filled with heated and compressed water is investigated. This investigation represents the first attempt to employ a direct stiffness finite-element approach to the solution of the depressurization of a straight pipe. The MARC Nonlinear Finite Element Analysis program provided the necessary software capabilities. Two analyses were performed. In the second, allowance was made for non-equilibrium flow. The prehistory results obtained with this approach confirm previously obtained analytical and experimental results.