Arrangement for checking disengagement between a nuclear reactor control cluster and a drive rod

A control assembly for a nuclear reactor, the control assembly comprising:

• a reactivity control device comprising:
• a control rod cluster extending along an axial direction comprising an upper end which includes an attachment head;
• and
• a drive rod extending along the axial direction, the drive rod comprising an upper end and a lower end located opposite the upper end, the lower end including an attachment device for attaching the drive rod to the attachment head of the control rod cluster, the attachment device being movable between a connection position wherein the drive rod is rigidly attached to the attachment head of the control rod cluster, and a disconnection position wherein the drive rod is separated from the attachment head of the control rod cluster, the drive rod and the attachment device defining a through axial housing forming a sleeve;
• and
• a checking device for checking a separation between the control rod cluster and the drive rod, the checking device is configured to mate with the reactivity control device, the checking device comprising a probe rod received inside the sleeve and mounted free in translation along the axial direction in the sleeve, the probe rod comprising an upper end and a lower end located opposite the upper end, the lower end of the probe rod is arranged to abut against the attachment head of the control rod cluster.