Experimental lithium-lead module for neutronics studies of fusion blankets

In a (D,T) type fusion machine, about 80% of the fusion energy is transported by neutrons outside the reactor's core and deposited in the blanket, an assembly of materials surrounding the machine. Tritium breeders, such as lithium and lithium-lead (LiPb) eutectic alloys, mainly dictate the design of fusion blankets. Neutronics studies, on blanket module assemblies, form an initial step towards real construction of one or another blanket. Within the framework of this dissertation, different blanket elements: first wall/structural material, tritium breeder etc., and leading fusion blanket concepts are briefly reviewed. Lithium-lead eutectic is of particular interest since the neutron multiplication takes place in the breeder, where tritium is produced. Therefore, one-dimensional optimization calculations were performed to study the use of Li17Pb83, with natural lithium abundance. Generally, this breeder is used with very high Li6 enrichment. It was found that it would be difficult to design compact blankets and to achieve reasonable tritium production, with Li17Pb83 eutectic having natural lithium isotopic composition. Either the breeder should be highly enriched in Li6 or another enriched lithium zone should follow. This study, however, led to the design and construction of the Experimental Lithium-Lead Module (EL2M). The EL2M was also used for International Comparison on Measuring Techniques of Tritium Production Rate (TPR) for Fusion Neutronics Experiments, a program initiated by JAERI (Japan Atomic Energy Research Institute) in which eight international research institutions joined. (author) figs., tabs., 124 refs