(150b) The Heat Rejection System of the Iter Reactor

ITER will be the largest fusion experimental reactor in the world designed to reach the first plasma at mid of 2018. ITER is being designed to demonstrate the technological feasibility of the nuclear fusion energy conversion, at plant scale, from high temperature Deuterium-Tritium plasma using the TOKAMAK magnetic confinement arrangement and with a power amplification at least of 10.

The ITER design experience, the effort in developing the leading-edge technologies and the knowhow acquired during its operation will guide the realization a proper long-term R&D fusion programme. ITER will bridge the gap between Nuclear Fusion and the large scale commercial production of electricity at competitive cost with other sources by 2045.

ITER will have a large Vacuum Vessel that hosts the Plasma facing components. These components include the Blanket and the Divertor that will operate at temperatures, heat loads and neutron flux higher than that of reached in a nuclear fission power plant reactor.

Among others, one of the main critical issues of the ITER reactor is the transfer of the heat generated in the Plasma, during the D-T reaction, through the Tokamak Cooling Water System (TCWS), to the intermediated closed loop Component Cooling Water System (CCWS) and then, via the open loop Heat Rejection System (HRS) to the environment. The HRS also absorbs heat through the CCWS from other non nuclear systems like the Chilled Water System (CHWS), the Cryogenic System, the Steady State Electrical Power Network (SSEPN) and other auxiliary systems. The HRS rejects to the environment all the heats from the ITER components (nuclear and non nuclear) with the only exception the Vacuum Vessel whose heat are released via a separate primary heat transfer system to the air coolers. The HRS is based on a Cooling Towers System (CTS) designed to release to the environment up to 450 MW whilst the total peak value produced during the DT pulse is about 1270 MW (35% of duty cycle).The CTS requires both high make up water and blowdown flow rates, which in turn demand stringent water chemistry control to limit the possible loop contamination.

This paper describes the main design modifications and optimizations recently introduced with a closed intermediate CCWS and an open HRS system.

The main benefit are the minimization of the capital and operating costs, the optimization of the piping layout, the introduction of a second containment barrier to the gaseous and liquid radwaste releases and the relevant minimization of the impact to the environment.