Integrity Criteria for Models of RBMK Fuel-Channel Pipes under the Conditions of Accidental Heating

Multiparameteric integrity/failure criteria are proposed for models of Zr–2.5% Nb alloy channel pipes under conditions which simulate a disruption of the regular heat-removal regime in RBMK reactors (LOCA, ATWS type accidents). The criteria permit real-time assesssment and prediction of the state of a model of an RBMK channel pipe under the conditions of damaging heating on the basis of the instantaneous values of the pressure in the channel and the rate and character of heating. The criterional relations are constructed on the basis of a numerical simulation of the thermal and strength state of a fragment of a single RMBL channel pipe and the use of experiment-planning methods. The thermomechanical behavior of the model of a channel pipe is calculated using the ATM-TK finite-element code. A comparative analysis of the computational results and the experimental data showed satisfactory agreement between the calculations and experiments.