Modelling of two-phase flow under accidental conditions fusion codes benchmark

The scope of this benchmark is to assess the capabilities of the best estim ate thermal hydraulic codes to simulate the main physical phenomena occurri ng during an in-vessel break transient within a water-cooled fusion-type re actor: pressurisation of a volume at low initial pressure, critical flow, c ounter pressure effect, relief into an expansion volume. The results, which are given by the code are of the same order of magnitude. Discrepancies ar e observed which are mainly due to the different ways the codes simulate th e break mass flow rate and the pressurisation of the vacuum vessel. (C) 200 1 Elsevier Science B.V. All rights reserved.