[en] Within the context of sodium-cooled fast reactors, the CGEE Alsthom enterprise, under consulting for Novatome, has been engaged with the development of an specific protection system for emergency shutdown situations. System described has been conceived on several stages according to the general organization shown on figure I of the Annex, in such a manner that the exigences and recommendations from the safety regulatory authorities are respected and, at the same time, it is assured a significant reactor operation availability without an spureous rod drop. As an example, a selection of principles, rules and criteria currently applied to the development of a system of this kind is reminded. (J.E. de C.)