Activated corrosion products in ITER first wall and shielding blanket heat transfer system

Corrosion and erosion phenomena play an important role in mobilising activated materials in fusion machines. This paper deals with the assessment of the activated corrosion products (ACPs) related to the primary heat transfer system (PHTS) of the first wall/shielding blanket (FW/SB) of the ITER plant. BCPs could be a cause for concern in terms of occupational radiation exposure (ORE) in maintenance scenarios. They could also be relevant in the case of severe accidents, such as ex-vessel LOCAs. The assessment mainly refers to the TAC-4 design developed for ITER. The mobilisation of the activated material has been estimated with the qualified CEA code PACTOLE. It considers ail the chemical and physical phenomena responsible for corrosion, activation and transport of corrosion products in cooling loops. The XSDNRPM-S code is used for neutronic calculations; the ANITA-2 code for activation calculations. The results obtained show the improvement gained, in terms of corrosion and radioactive inventory reduction, by avoiding the use of the boron as additive. Results obtained point out the impact of the main water chemistry parameters (e.g. water temperature and pH) on ACP production, transport and deposition. A parametric comparison has been carried out considering the coolant flowing during dwell periods, two different in-vessel FW/SB AISI 316L compositions and two fluences: 0.3 and 3 MW/spl middot/y/m/sup 2/.