Imaging apparatus and method for monitoring radiation within a closed structure

An observation instrument for observing the inside of a thick-walled radiation shielded cell, wherein the instrument is arranged to be capable of extending inside a cavity passing through a wall of the cell, the instrument comprising two separate modules:

• a first module of the instrument comprising:
• a biological protection shield;
• a gamma ray detector for measuring gamma rays emitted in zones situated in the cell;
• and
• a travel mechanism for moving the detector between a retracted position in which the detector is retracted into the cavity and a deployed position for observing the inside of the cell, the travel mechanism being coupled to the detector and including an actuator for causing the detector to move between the retracted position and the deployed position;
• and
• a second module of the instrument comprising a dome that is substantially transparent to rays or radiation and that is arranged to be capable of sliding in the cavity, which dome is capable of receiving the detector therein when the detector is in the deployed position for observation;
• each of the two modules including a mutual bearing face, the two modules being capable of being put into mutual contact via their respective mutual bearing faces when the modules are engaged in the cavity,
• the detector being arranged between the dome and the shield and being secured to the shield via the travel mechanism,
• the dome being provided at a first end of the instrument,
• the actuator causing the detector to move between the retracted position away from the dome and the deployed position in which the detector extends inside the dome,
• the travel mechanism being arranged between the dome and the shield, and
• the dome being separate from the detector, from the travel mechanism, and from the shield of the instrument.