Reliability assessment of a charging machine for radioactive waste disposal

The charging machine designed for use in an experimental programme for disposal of vitrified high level radioactive waste canisters in the ASSE salt mine was the subject of a design date reliability assessment. The aim was to allow a judgement of the general reliability and availability of parts of the machine as well as of the system as a whole. The assessment was performed according to the fault tree method. The results are presented in the form of a reliability profile. It was found that those subsystems depending on the hydraulic unit contribute most to the overall failure frequency. No additional weak points were identified. The total failure frequency per year of operating time was estimated to be 29. However, the corresponding availability of the system amounts to more than 95%, thus meeting the requirements for such a machine. (orig.)