The analytical tools, which are fuel rod computer codes, that Quantum Technologies AB use and develop, contain models of several of the phenomena that are acting on the nuclear fuel (cladding temperature, fission gas driven pressure, strain and stress in the cladding, rod rupture, etc.) and how the separate effects interact in the complex integrated manner. The codes are under constant development and need to be compared with actual tests. In this report simulations of three tests in Halden (IFA-650.2,3 and 4) are described.
Although it is difficult to model complex accident scenarios, the results obtained by Quantum Technologies AB show that it can be achieved. The codes and models can reasonably calculate cladding temperature, strain and diameter increase as a function of time, and finally estimate the position of cladding rupture.