Overview of the ARIES-RS reversed-shear tokamak power plant study

Abstract

The ARIES-RS tokamak is a conceptual, D–T-burning 1000 MWe power plant. As with earlier ARIES design studies, the final design of ARIES-RS was obtained in a self-consistent manner using the best available physics and engineering models. Detailed analyses of individual systems together with system interfaces and interactions were incorporated into the ARIES systems code in order to assure self-consistency and to optimize towards the lowest cost system. The ARIES-RS design operates with a reversed-shear plasma and employs a moderate aspect ratio ( A=4.0). The plasma current is relatively low ( I p=11.32 MA) and bootstrap current fraction is high ( f BC=0.88). Consequently, the auxiliary power required for RF current drive is relatively low (∼80 MW). At the same time, the average toroidal beta is high ( β=5%), providing power densities near practical engineering limits (the peak neutron wall loading is 5.7 MW m −2). The toroidal-field (TF) coil system is designed with relatively `conventional' materials (Nb 3Sn and NbTi conductor with 316SS structures), and is operated at a design limit of ∼16 T at the coil in order to optimize the design point. The ARIES-RS design uses a self-cooled lithium blanket with vanadium alloy as the structural material. The V-alloy has low activation, low afterheat, high temperature capability and can handle high heat flux. A self-cooled liquid lithium blanket is simple, and with the development of an insulating coating, has low operating pressure. Also, this blanket gives excellent neutronics performance. Detailed analysis has been performed to minimize the cost and maximize the performance of the blanket and shield. One of the distinctive features of this design is the integration of the first wall, blanket, parts of the shield, divertor and stability shells into an integral unit within each sector. The maintenance scheme consists of horizontal removal of entire sectors. Prior to the initiation of the ARIES-RS study, a set of top-level requirements and goals for fusion demonstration and commercial power plants was evolved in collaboration with representatives from US electric utilities and from industry. The degree to which ARIES-RS reached these requirements and goals and the necessary trade-offs are described and the high-leverage areas and key R&D items are presented.