[en] An empirical correlation has been developed for predicting departure from nucleate boiling (DNB) using data for an axially heat flux distribution. This correlation is recommended for use in predicting the DNB heat flux in a nuclear research reactor fuel coolant channel (annuli) or any rectangular channel. In this paper, an investigation was carried out on identify the important parameters affecting DNB heat flux in annuli and rectangular channels, focusing on the effects of channel operation conditions (inlet temperature, pressure, coolant volume flow rate). The predicted DNB results for nuclear reactor fuel coolant channel results have been compared and agree closely with the exiting international DNB heat flux data.(author)