A chamber for reacting exothermic material is disclosed, the chamber comprising a multilevel structure including at least: a receptacle for storing the material, corresponding to a lower level; a median level comprising a reactive load containing at least one alkaline-earth carbonate, so as to absorb heat emitted during the oxidation reaction of the material, the alkaline-earth carbonate decomposing under the effect of the heat in an endothermic reaction; an upper level comprising a cover. Optionally, the material stored is a carbide of plutonium and/or uranium.