ITER is an international fusion facility being built in France to demonstrate the scientific and technological feasibility of fusion power. Fusion power at ITER is generated using a Tokamak machine in which burning plasma at temperatures of 150,000,000°C is confined within a vacuum vessel by magnetic fields. The enormous amount of heat generated by the Tokamak and its auxiliary systems is removed by the cooling water systems, consisting of the Tokamak Cooling Water System (TCWS), the Component Cooling Water System (CCWS), the Chilled Water System (CHWS), and the Heat Rejection System (HRS). These systems are designed to remove an initial peak heat load of about 1100MW.

ITER is an experimental facility that will operate in a cyclical fashion. High levels of fusion power will be generated during repeated plasma pulses with specified durations. Heat produced by the fusion reaction will not be used to generate electricity, but will be rejected to the environment.

The cyclical nature of the ITER machine presents distinct challenges to the design of the HRS which must reject normal facility heat loads plus large, intermittent heat loads from Tokamak pulse operations, while maintaining stable and predictable cooling tower basin water temperatures to meet the needs of cooling water system clients. This paper explores these challenges to the HRS design and describes the selected solutions.