DISPOSITIF DE DEPLACEMENT D'UNE GRAPPE DE CRAYONS DE COMMANDE DE REACTEUR NUCLEAIRE

A device for moving a cluster of nuclear reactor control elements, more especially usable for changing the moderation rate of a nuclear reactor, comprising a vertical shaft having nippers cooperating with grabs integral with sub-clusters. Each grab comprises resilient fingers engageable with the nippers and lockable by snap fitting on the fixed upper structure. Each nipper is formed so as to engage resilient fingers and unlock them from the upper structure when the nipper is raised above the position which causes locking of the grab on the structure. A fixed lower structure is provided for causing forced disengagement of the nipper when this latter is lowered beyond the rest position of the grab on this structure. Raising of the nipper then drives the grab by simple bearing force.