COSTAX-BOIL, Transient Dynamic Analysis of BWR and PWR in Axial Geometry

1 - Nature of physical problem solved: Transient analysis of BWR are performed in the time domain. The code couples the two velocity groups neutron diffusion kinetic calculations (up to 10 delayed neutron groups) in one dimension (axial) with the heat conduction equations in the fuel rods and a two phase flow dynamics calculation for the typical coolant channel. The program is intended for the analysis of intermediate accidents or severe operational transients in which a detailed spatial representation is essential. 2 - Method of solution: Doppler and void reactivity feedback are accounted for pointwise. A flexible input allows representation of reactivity transients, flow recirculation, or inlet enthalpy transients, or an arbitrary mixture of them, including control rod bank movement. No pressure variation is possible in the present version