Dynoboss: a computer code for the nonlinear dynamics of boiling water nuclear reactors

The DYNOBOSS code can be used for the analysis of instabilities in boiling systems in general and BWR in particular. The DYNOBOSS code combines models BWR thermal-hydraulics and neutronics. The thermal-hydraulics model includes a multi-parallel channel core model and models of other major components of the BWR recirculation loop. The modeling of two-phase flows utilizes the drift-flux formulation and include such important factors as subcooled boiling, heated wall dynamics and others. The steady-state operating conditions are obtained coupling the loop thermal-hydraulics with a two-dimensional model of core neutronics. The results have showed that the DYNOBOSS code properly predicts the onset and propagation of unstable oscillations in BWR