T. Hernandez

Radiation enhanced degradation of aluminium mirrors for remote handling and diagnostics applications: Effect of humidity

Abstract High quality mirrors will be required for different diagnostic and remote handling systems in International Thermonuclear Experimental Reactor (ITER). The possibility of radiation enhanced surface degradation has been assessed. Unprotected Duralumin discs and high quality SiO overcoated aluminium on Pyrex mirrors have been irradiated with 60 Co gamma rays at 12 Gy/s up to 50 MGy. Irradiations from 303 to 523 K have been performed in air and nitrogen. It has been observed that humidity is a key factor in the degradation process and produces severe corrosion on the aluminium mirror surface even with SiO overcoating. SEM and XPS analysis of chemical species formed on the surface indicate that the degradation produces aluminium hydroxide compounds, and the corrosion corresponds to a filiform mechanism.

Overview of the HCPB Research Activities in EUROfusion

In the framework of the EUROfusion’s Power Plant Physics and Technology, the working package breeding blanket (BB) aims at investigating four different BB concepts for an EU demonstration fusion reactor (DEMO). One of these concepts is the helium-cooled pebble bed (HCPB) BB, which is based on the use of pebble beds of lithiated ternary compounds and Be or beryllides as tritium breeder and multiplier materials, respectively, EUROFER97 as structural steel and He as coolant. This paper aims at giving an overview of the EU HCPB BB Research and Development (R&D) being developed at KIT, in collaboration with Wigner-RCP, BUTE-INT, and CIEMAT. The paper gives an outline of the HCPB BB design evolution, state-of-the-art basic functionalities, requirements and performances, and the associated R&D activities in the areas of design, functional materials, manufacturing, and testing. In addition, attention is given also to the activities dedicated to the development of heat transfer augmentation techniques for the first wall and the corresponding testing. Due to their nature as design drivers, a brief overview in the R&D of key HCPB interfacing areas is given as well, namely, the tritium extraction and recovery system, the primary heat transfer and power conversion systems, and safety topics, as well as some specific activities regarding the integration of in-vessel systems through the BB. As concluding remarks, an outline of the standing challenges and future R&D plans is summarized.