Sensor technologies will play a key role in the success of Remote Maintenance (RM) systems for future fusion reactors such as ITER and DEMO. Understanding their limitations and suitability for use in a fusion context is crucial to the operation and maintenance of these reactors. In this paper, we evaluate three key types of sensor which are of particular interest in the robotics field at the moment, namely: colour-depth cameras (such as the Kinect and similar devices), LIDAR (Light Detection And Ranging), and finally mmWave RADAR. Colour-depth cameras are well established for use in mobile robotics applications, and LIDAR has long been used in the automotive and industrial sectors. Sensors based on Millimetre-Wave RADAR are increasingly used for obstacle detection and avoidance due to their small footprint, low weight, lack of moving parts, and the fact they are not typically affected by rain/snow. We evaluate the sensors mainly based on the following criteria: 1) the types of data they provide, 2) the potential environmental resistance of the sensor (gamma radiation), 3) sensitivity to different types of noise, and 4) likelihood of failure. We review the progress in making these three types of sensor capable of operating in Fusion facilities and discuss possible mitigations. We perform an experiment where we investigate the feasibility of using radar to map an indoor scenario, by collecting data from radar, colour-depth camera and LIDAR, simultaneously. We compare the performance between sensors. We concluded that most medium to big metallic surfaces were correctly detected, while most walls and detailed features of typical indoor areas are missed. In summary, radar technology does not seem good enough to map and aid navigation of a mobile robot in an indoor environment on its own but can be used to complement Colour-Depth and LIDAR sensors in Fusion scenarios for redundancy.