EVALUATION OF THE ACTIVATED CORROSION PRODUCT (ACP) AND THEIR DISTRIBUTION IN THE WATER COOLING LOOP OF THE SEAFP PROJECT

The study the present paper deals with has been developed in the frame work of the Safety and Environmental Assessment of Fusion Power Long T erm Programme (SEAL), continuing the past SEAFP study, promoted by the Commission of the European Union. The aim of the present work is to a nalyse the corrosion induced by cooling water and the subsequent pheno mena (dissolution of deposits, precipitation of soluble products, migr ation and deposition of activated particles along the cooling circuits ) and to evaluate the activated corrosion product (ACP) distribution a mong the different regions of the cooling system. The ACP distribution will be used for the assessment of Occupational Radiation Exposure (O RE) 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 ma intenance scenarios, being responsible for about 90% of ORE in nuclear fission power plants. They could also be considerable for fusion devi ces in the case of severe accidents, such as ex-vessel LOCAs. The prod uction due to neutron bombardment, corrosion/erosion, transport and de position of the ACPs inside the PCS tubes and components have been est imated with the qualified and validated CEA code PACTOLE. It considers all the chemical and physical phenomena responsible for corrosion, ac tivation and transport of corrosion products in cooling loops. The SEA FP-APM cooling system analysed has been a 1/8 cooling loop of the FW/B lanket. The thermofluidodynamic conditions inside the cooling loop, th e 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 carrie d out so far for the ITER project has been only referred to a pulsed f usion device, while the SEAFP reactor project considers steady state o peration and a primary cooling system similar to a PWR one. The influe nce of the different design and operation parameters, like material se lection, 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 prep ared by the same authors for this Topical Meeting.