The study the present paper deals with has been developed in the framework of the Safety and Environmental Assessment of Fusion Power Long Term Programme (SEAL), continuing the past SEAFP study, promoted by the Commission of the European Union.

The aim of the present work is to analyse the corrosion induced by cooling water and the subsequent phenomena (dissolution of deposits, precipitation of soluble products, migration and deposition of activated particles along the cooling circuits) and to evaluate the activated corrosion product (ACP) distribution among the different regions of the cooling system. The ACP distribution will be used for the assessment of Occupational Radiation Exposure (ORE) that is involved in the working activities at the primary cooling system (PCS) of the SEAFP Alternative Plant Model (APM). ACPs could be a cause for concern in terms of occupational radiation exposure in maintenance scenarios, being responsible for about 90% of ORE in nuclear fission power plants. They could also be considerable for fusion devices in the case of severe accidents, such as ex-vessel LOCAs. The production due to neutron bombardment, corrosion/erosion, transport and deposition of the ACPs inside the PCS tubes and components have been estimated with the qualified and validated CEA code PACTOLE. It considers all the chemical and physical phenomena responsible for corrosion, activation and transport of corrosion products in cooling loops. The SEAFP-APM cooling system analysed has been a 1/8 cooling loop of the FW/Blanket. The thermofluidodynamic conditions inside the cooling loop, the water chemistry, the neutron fluxes and the operation scenario have been considered for the ACP assessment.

The results presented here are new and very significant because the ACP evaluation by PACTOLE carried out so far for the ITER project has been only referred to a pulsed fusion device, while the SEAFP reactor project considers steady state operation and a primary cooling system similar to a PWR one. The influence of the different design and operation parameters, like material selection, water chemistry etc., are discussed. The results obtained are extensively used to evaluate the occupational radiation exposure ORE. The related results are discussed and presented in another paper prepared by the same authors for this Topical Meeting.