Recent development and validation of physical models in the computer code INTRA

The INTRA code is specified by the ITER Joint Central Team and the European Community as a reference code for safety analyses of Tokamak type fusion reactors. The code simulates pressure transients and chemical reactions within the vacuum vessel and surrounding compartments resulting from system failure due to equipment malfunctions. During the last year considerable extensions and improvements to INTRA have been made. Models for simulation of counter-current flow of gases in a flow junction and for internal heat generation sources, such as decay heat within heat slabs, surface heat loads and heating or cooling devices, have been implemented. Applications and validations against different experiments, such as ICE and LOVA tests, have been carried out as part of these developments. The results show that INTRA, with the new models, has a reasonable agreement with the experimental results and it has improved its capability to predict pressure, temperature and flow transients but some improvements are still necessary.