Calculation results for the heat transfer crisis conditions during fast transient processes

The impact of axial power distribution, heat transfer across the fuel/cladding gap and various correlations on the calculations of boiling crisis has been studed for transient regimes connected with the reactivity variations. The simulated transient was characterized by the power versus time curve that corresponded to the control rod bundle shot-out at the following core nominal initial parameters: p = 12.3 MPa, T = 270 grad.C, G = 2700 kg/(m2s). Selection of decreased values of the heat transfer coefficient for the gap resulted in an earlier boiling crisis onset or attaining the minimum critical/actual heat flux density ratio. A comparison is made for Osmachkin's and Bezrukov's correlations employment to the critical heat flux density calculations