[en] The effect of the appendages of LWR and CANDU fuel bundle on CHF are reviewed from the published papers and presented the influence mechanisms of those appendages on CHF. And the CHF experimental works have performed for two series of CANFLEX bundles with and without buttons with a modelling fluid as refrigerant R-134a and uniform heat flux condition. From the experiments, the effects of buttons of CANFLEX bundle on CHF and Critical Channel Power (CCP) were evaluated. The results show that the buttons enhance CCP as well as CHF. The CHF enhancement ratio due to the presence of buttons are increasing as increasing dryout quality for all flow conditions and increasing mass flux only for high pressure conditions and CHF enhancement ratio due to mixing devices of spacer grid for a LWR fuel assembly is not always the same trend for some LWR's. From this study, the button design was evaluated as an appropriate one under the CANDU operating conditions because most CHF flow conditions for CANDU fuel bundle belong to high dryout quality conditions. (author). 33 refs., 11 figs