Steady state and transient thermal-hydraulic analyses on ITER divertor module

One of the most challenging components of ITER is the divertor devoted at controlling the characteristics of the plasma boundary, exhausting the α particles and reducing the impurities in the plasma. The thermal-hydraulic design of the divertor is particularly, demanding because of the high heat loads and the cooling flow margin in the plasma-facing components (PFCs). The pressure drop is limited by the pumping power and also avoiding the risk of reaching critical heat flux (CHF). Furthermore, for maintenance operation foreseen, each single divertor cassette should be drained and dried before withdrawing it out from the vacuum vessel. To address these requirements, European Fusion Design Agreement (EFDA) has launched a research programme aimed at investigating the theoretical thermal-hydraulic behaviour of the whole divertor cassette, both in the operation and during the water discharge. The study has been carried out with the RELAP5 computer code and the results obtained are herewith presented.