[en] For the D₂O moderated reactors, the explosive rupture of a power channel pressure tube is one of the hypothetical accidents which are to be considered for the full assessment of the system safety. The purpose of this paper is to give a coherent presentation of the main aspects and problems encountered in the evaluation of the consequences of this hypothetical accident. The explosive rupture of the pressure tube is assumed to be due to the fast propagation of a longitudinal crack of critical length. This very unlikely rupture mechanism is by far the most dangerous conceivable. For the case of the CIRENE reactor, on the basis of a wide set of burst tests, it can be concluded that even in the most severe accident conceivable, pressure tube rupture propagation from one power channel to the adjacent one is very unlikely, the peak transverse force due to explosion being limited to approximately 100 N/mm channel height at most, and lasting only a few ms. In addition, the dynamic loads in core structures caused by the pressure peaks in the D₂O tank, do not produce any relevant damage to the main structural functions. (Auth.)