Preliminary design of ITER component cooling water system and heat rejection system

Being an experimental facility, the entire fusion power of ITER Tokamak needs to be rejected to the atmosphere with the help of Cooling Water System. The heat generated in the Tokamak is 847 MW whereas that of auxiliary heating systems and supporting systems is approximately 300 MW. The heat generated in the Tokamak is transferred through Tokamak Cooling Water System (TCWS) to Component Cooling Water System (CCWS) and then to the Heat Rejection System (HRS). The HRS which acts as the heat sink finally rejects the heat to the atmosphere. As ITER Tokamak will operate in a cyclical manner during various scenarios, the real challenge lies in providing an optimized HRS design which can accommodate the short duration pulses, when the incoming heat is approximately 1150 MW and also the comparatively longer dwell periods, when heat input is a small fraction of that. A significant challenge in the design of CCWS is that the system must remove the intermittent pulse-triggered heat loads along with the normal continuous auxiliary systems heat loads, while maintaining stable cooling water temperatures, pressures and flows through the Tokamak and the components of plant auxiliary systems. This paper describes the optimized CCWS design which meets the system requirements and seamlessly transfers the heat generated in the Tokamak, components of auxiliary and supporting systems to HRS. This paper also highlights the challenges encountered during the preliminary design and describes the development of a viable optimized HRS design solution which is capable of rejecting the heat to the atmosphere and maintaining the basin temperature within prescribed limit.