Development of advanced blanket materials for a solid breeder blanket of a fusion reactor

Abstract

The design of an advanced solid breeding blanket in a DEMO reactor requires a tritium breeder and a neutron multiplier that can withstand high temperatures and high neutron fluences, and the development of such advanced blanket materials has been carried out by collaboration between JAERI, universities and industries in Japan. The Li2TiO3 pebble fabricated by a wet process is a reference material as a tritium breeder, but its stability at high temperatures has to be improved for its application in a DEMO blanket. One of these improved materials, TiO2-doped Li2TiO3 pebbles, was successfully fabricated and studied. For the advanced neutron multiplier, beryllides that have a high melting point and good chemical stability have been studied. Some characterization of Be12Ti was conducted, and it became clear that it had lower swelling and tritium inventory than beryllium metal. Pebble fabrication study for Be12Ti was also performed and Be12Ti pebbles were successfully fabricated. These activities have shown that there is a bright prospect in realizing a DEMO blanket by the application of TiO2-doped Li2TiO3 and beryllides.

A New Paradigm for Understanding and Enhancing the Critical Heat Flux (CHF) Limit

“…Boiling is a ubiquitous mechanism of heat transfer with numerous applications ranging from small-scale HVAC and refrigeration systems used in most buildings to large boilers in energy and process industries. Due to its unique performance characteristics, boiling has been implemented in extremely demanding applications such as fusion reactors 1 – 3 . The ebullition process in boiling triggers a set of heat and mass transfer events that can generate extremely high local cooling rates 4 – 6 .…”

Recent results on beryllium and beryllides in Japan

“…The problems anticipated in particular are; beryllium metal will react with the structural material in contact, accumulation of a high tritium inventory, and reaction with water vapor in case of loss-of-coolant accident (LOCA) under such environment [3]. In order to minimize these problems, beryllium based intermetallic compounds have drawn an interest in Japan as an alternative to beryllium metal for neutron multiplier [4].…”

Present status of beryllide R&D as neutron multiplier

“…Also, Be 12 Ti has the lowest melting temperature in these candidate materials, suggesting that it is the easiest to fabricate. For these reasons, Be 12 Ti was selected as the first candidate material and R&D has been carried out on this material [6,7].…”