In the present work, a numerical study of inward and outward buckling of two successive fuel plates of a typical material testing reactor is investigated using computational fluid dynamics code. Fuel plate buckling results in partial blockage of the hot channel. Both buckling toward the inside and outside are considered. Simulations are conducted for different blockage levels of the nominal flow area, i.e., 0%, 20%, 40%, 50%, 60%, and 70% for inward buckling. Blockage levels of 0%, 20%, 40%, 50%, 60%, 70%, 80%, and 90% are considered for outward buckling. The impact of the flow field redistribution in four successive channels on the cooling capacity of each channel is investigated. The obtained results show that for an inward buckling ratio greater than 50%, critical phenomena will occur that could affect the clad integrity. Moreover, for inward buckling of 70%, the maximum clad temperature in the blocked channel reaches the value associated with the onset of nucleate boiling at the operating pressure. On the other hand, for outward buckling of 90%, critical phenomena that could affect the clad integrity will occur.