As built design of the control systems of the ITER full-size beam source SPIDER in the neutral beam test facility - A critical review

SPIDER, ITER's full-size beam source at the Neutral Beam Test Facility (NBTF), has been operational since 2018. SPIDER's mission is to optimize the operation of the beam source in order to reuse SPIDER's experience on MITICA, the full-size prototype of the ITER Neutral Beam Injector, and in the ITER injectors. The exploitation of SPIDER started with short, low-performance pulses lasting up to a few seconds and progressed to obtain long pulses up to 3000 seconds. Furthermore, the integration of plant and diagnostic systems has grown over time. The amount of data collected per pulse provide a measure of evolution: it has gone from a few tens of MB in the first campaign pulses to the current average value of over 130 GB, most of which produced by infrared and visible cameras. From the first operation onwards, the control systems have also evolved, including components and functions initially not foreseen or developed in a preliminary form. This includes the progressive integration of plant and diagnostic systems and of protection and safety functions. The paper initially focuses on the architecture of the SPIDER control systems, i.e. CODAS, the system delivering conventional control and data management, the central interlock system, delivering plant protection, and the central safety system delivering people and environment safety. Since we developed all systems according to the ITER guidelines for implementing control systems, the integrated SPIDER control, interlock and safety systems may provide an interesting example for developers of ITER plant systems. The paper then describes how the top-down definition and implementation of operating states and operational scenarios provides the framework for the integration of control, interlock and safety systems and the basic elements for successful operation. Finally, the paper reports the lessons learned during these years of operation with particular attention to the progressive, continuous evolution and recommissioning of systems.