Unified software development approach for the safety-critical ITER maintenance devices

The RH devices used for ITER divertor maintenance are movers or manipulators composed of electro-hydraulic and electrical actuators. Such devices are CMM, CTM and WHMAN to assist CMM and CTM. These devices execute complex and safety-critical operations while supporting ITER reactor elements weighting several tons. Despite the differences in the load capacity and functionality, the control system of these devices can be categorized as position servo control or force servo control. In this paper we propose the use of unified software development approach currently developed and demonstrated at the DTP2. This new approach takes into account the ITER RH requirements for all maintenance devices, not only the water-hydraulic maintenance devices. The need for extensive software verification and validation utilizing international standards for safety-critical systems is addressed. This applies both to control software architecture and user interface design. In principle, we propose that all ITER maintenance devices are developed and tested with the common software architecture and user interface. This makes it possible to reuse generic software modules that are well documented and tested, resulting decreased verification and validation period and development cost. Utilising this approach also improves reliability and safety of the maintenance operations.