WCLL Blanket Module Structure Variation Influence on Neutron Activation Inventories

One of the conceptual designs of the breeder blanket for a European demonstration fusion power station (DEMO) is the water-cooled lithium lead (WCLL) concept. The design development of the WCLL blanket in recent years has undergone the evolution of the neutronics model employing the MCNP code, with key changes in radial lengths and thickness as well as dimensional differences in inner structures such as breeding zone, shielding zones, and manifold. Furthermore, there has also been a significant increase in projected fusion power. Such changes were made with respect to its nuclear, thermohydraulic, and thermomechanical performances. In this paper, neutronic characteristics of WCLL modules were analyzed in terms of fusion power increase and dimensional changes of the blanket geometry presented in DEMO 2014 and 2015 models. For comparison, outboard and inboard blanket modules of the equatorial region were selected. Investigated neutronic characteristics include activity, decay heat, and contact dose rates. The numerical experiment was carried out with MCNP particle transport code and FISPACT/FISPACT-II activation calculation codes with EAF-2010/TENDL-2015 nuclear data libraries.