DYNAMIC - a one-dimensional reactor dynamics code for calculating fast transients in power reactors

The computer code DYNAMIC calculates time-dependent power density distributions in axial or radial direction for a one-dimensional reactor model. The neutron flux is described with the aid of the improved quasistatic method. For one or more representative coolant channels consisting of a fuel rod and the surrounding coolant temperature and density distributions and other thermal quantities of interest for safety considerations are determined. Allowing coolant boiling, the two-phase flow is treated as a homogeneous mixture. Feedback is taken into account using the dependence of neutron cross sections on densities and temperatures. On the basis of a hypothetical accident calculated according to the one-dimensional and the point model, the importance of space-dependent effects in investigating fast transients is demonstrated. (author)