AbstractA Monte Carlo departure from nucleate boiling ratio (DNBR) limit analysis has recently been performed with a six-channel thermal-hydraulics code model as the tool for DNBR calculations. Compared is the use of the few-channel, fast-running code models with the use of a response surface model as the DNBR calculator. The latter had been used to date for Monte Carlo analyses. The principles of Monte Carlo DNBR limit determination are reviewed to provide the necessary background information.