Investigation and improvement of the radiation tolerance of a teleoperated manipulator-equipped vehicle to be used in radioactive environments

Investigations have been carried out in order to assess and to improve the radiation tolerance of a remote controlled, manipulator-equipped vehicle. Operating in radiative environments, these robots have to withstand total dose stresses up to several 10 kGy. The complexity of tasks these vehicles have to perform makes it necessary to supply them with extensive electronic systems on board. Thus, it has to be taken into account, that semiconductor electronic devices are highly sensitive to ionizing radiation. An approach to rise the radiation tolerance level of such a robot is described. It's electronic system has been analyzed and then the whole robot has been exposed to Co/sub 60/ radiation to identify the weakest radiation tolerance of it's different electronic components. This way failures within the onboard electronic systems could be determined, that would have remained unidentified if only isolated electronic subsystems would have been irradiated. Once the sensitive components were identified, measures have been taken to improve their radiation tolerance. To verify the radiation hardening, the modified systems were submitted to further radiation tests and modified again according to the test results. Within this iterative approach it is possible to raise the radiation tolerance level of the vehicle to 15 kGy in the case all power subsystems are modified as demonstrated during this investigation. Even in the case that only two types of power subsystems are modified to radiation hardness, the radiation tolerance of the vehicle can be raised to 2.7 kGy, which is about three times the initial value.