HITEX Process Options for Detritiation of Impurities in the ITER Plasma Exhaust

The High Temperature Isotopic Exchange (HITEX) process has been proposed as a simple and reliable option for detritiating impurities in the ITER plasma exhaust.¹ The process relies on the well known principle of catalytic equilibration, does not involve complicated decomposition reactions, and avoids the formation of tritiated water. The original HITEX process was conceived as a simple batch system which could yield extremely high detritiation factors (∼ 10⁹). However, batch operation (for an ITER scale/impurity feed compositions) necessitates the holdup of tritium inventory (101 gT) equivalent to one batch in the HITEX feed tank. This paper compares batch and once-through HITEX options in light of calculated and experimental results. Tritium inventories, hydrogen swamping rates and Decontamination Factors (DF's) are compared with the objective of optimizing the process configuration for ITER. A promising HITEX configuration for ITER is composed of a once-through first stage which removes the bulk of the tritium in the impurities, followed by a batch-wise second stage which provides a large decontamination factor. Such a hybrid arrangement promises to produce the required DF of 600,000 with a tritium inventory of < 5 g and a hydrogen swamping ratio of about 26:1. The hybrid arrangement is expected to be robust, since it can be built using industrially proven components.