Corrosion Radioactive Products in a Primary Cooling System of the ITER Plant: A Preliminary ORE Evaluation

In this paper a preliminary evaluation of the Occupational Radiation Exposure (ORE) of the personnel involved in working activities on sections of the ITER primary cooling systems (PCS) is presented. The analysis has been restricted to the primary cooling circuits of the first wall (FW) and of the shielding blanket (SB). The radioisotopes produced by activation in the pipe's material surfaces are identified using the available works and data, their amount is obtained with suitable computer codes. The calculation is performed using the combination of a 1-D discrete ordinate code and activation codes. The corrosion/erosion problem is faced with two different approaches: a simplified model with steady state conditions and a computer code that evaluates the non-homogeneous distribution of the activated corrosion products (ACP) in the cooling circuit. The ORE is assessed for some working activities considering the direct irradiation from the ACP and the average distance of the workers from the cooling circuit. The results presented in the paper are useful in order to address experiments needed to evaluate the main unknown parameters for the ACP evaluation and then to design the primary cooling circuits. Furthermore the work outlines a methodological procedure and presents some preliminary results for the ORE assessment at the PCS of a fusion plant like ITER.