[en] The mass limit of plutonium fixed at 370 g by the safety rules has been exceeded of 2 g because of a plutonium sampling not taken into account (inconsistency in the accompanying document) the operators operators waited to raise the inconsistency to take it into account. If the margins of safety were important to avoid a criticality accident it appears two significant dysfunctions: imperfect knowledge of the software of fissile matter management. This system does not deliver a warning message of exceeding the limit of 370 g. contrary to what the operator thought and the introduction of matter without immediate updating of this software, without procedure adapted to this particular situation. This significant incident highlights the necessity of corrective actions implementation to strengthen the prevention of criticality risks. (N.C.)