ARIES-ST design point selection

The spherical tokamak (ST) regime of low-aspect-ratio (LAR) tokamak operation has provided an opportunity to consider a 1000-MWe(net) D /T power plant conceptual design, designated ARIES-ST. Physics attributes include high beta ( /50%) together with high bootstrap current contribution ( /95%). Neutral-beam current drive ( /28 MW) supports steady-state operation. The plasma aspect ratio was selected to be A #/1.6 leading to the choice of major plasma toroidal radius, RT /3.2 m and plasma half-width, a /2.0 m. The usual engineering considerations of providing an efficient thermal power cycle (gross efficiency #/45%), while handling first-wall ( /1 MW/m) and divertor-plate ( /5 MW/m) surface heat fluxes, leads to 14-MeV neutron wall loads near 4.1 MW/m (average) and 5.6 MW/m (peak at outboard mid-plane) in a dual (PbLi and He) coolant system. The water-cooled toroidalfield-coil (TFC) centerpost is protected by a 20-cm (inboard) shield that does not breed tritium. Joule dissipation in the TFC system provides the major contribution to the plant recirculating power; specifically, Cu centerpost (222 MW), Al outboard shell (47 MW), Cu leads (27 MW), and power supplies (33 MW). The overall plant recirculating power fraction is an uncomfortable 34%. For a plant capacity factor /76%, consistent with earlier ARIES studies, the COE is projected to be /84 mill/kWe h (1992 constant $), using similar unit-cost assumptions and some passivesafety cost credits. Inclusion of additional credits for advanced, low-unit-cost manufacturing based on plasma spray and related techniques (as applied to the TFC centerpost and outboard TFC shell only) lowers this COE estimate to /79 mill/kWe h. # 2002 Elsevier Science B.V. All rights reserved.