Safety analyses of pressurized water reactors and boiling water reactors in the event of small-break loss-of-coolant accidents strongly depend on leakage rate predictions using two-phase critical flow models. The paper aims to revise the critical flow criterion and consider the nonequilibrium phenomena of critical flows in constructing a modified two-phase critical flow model. The model predictions exhibit strong similarities with the experimental values, with prediction deviations of 14.4% for mass fluxes and 19.3% for outlet pressure. The compiled code, according to the proposed model, can be exploited in pressure pipeline designs, providing the theoretical basis for leak-before-break analyses.