Economic Considerations of Commercial Tokamak Options

Abstract

Systems studies have been performed to assess commercial tokamak options. Super conducting, as well as normal, magnet coils in either first or second stability regimes have been considered. A spherical torus (ST), as well as an elongated tokamak (ET), is included in the study. The cost of electricity (COE) is selected as the figure of merit, and beta and first-wall neutron wall loads are selected to represent the physics and technology charac teristics of various options. The results indicate that an economical optimum for tokamaks is predicted to require a beta of around 10%, as predicted to be achieved in the second sta bility regime, and a wall load of about 5 MW/m 2 , which is assumed to be optimum tech nologically. This tokamak h expected to be competitive with fission plants if efficient, noninductive current drive is developed. However, if this regime cannot be attained, all other tokamaks operating in the first stability regime, including spherical torus and elongated tokamak and assuming a limiting wall load of 5 MW/m 2 , will compete with one another with a COE of about SO mill/kWh. This is 40% higher than the COE for the optimum reactor in the second stability regime with fast-wave current drive. The above conclusions pertain to a 1200-MW(e) net electric power plant. A comparison was also made between ST, ET, and superconducting magnets in the second stability regime with fast-wave current drive at 60C MW(e). The result indicates that the COE of an ET or ST device operating with the same technology requirement (wall load) as a superconducting magnet tokamak is about the same as the COE of a superconducting magnet tokamak in the second stability regime. Therefore, a device like ST or ET appears to look more attrac tive in lower ratings than 1200 MW(e).

Analyzing thermal creep strain of a tokamak first-wall steel

“…Table I gives the composition of HT-9 steel, which would probably bethe material of choice for the first wall of a commercial reactor, and has thus attracted considerable research and development attention. 3--6 It should be pOinted out that as far as the design of the first wall for a long service lifetime is concerned, thermal creep deformation is not as important a consideration as other potential failure modes, such as neutron irradiation (inreactor) creep deformation, creep-fatigue interaction, thermal shock or embritValue Equation 2 Equation 3 Equation 4 1.503 x 10--3 1. 073 x 10--2 2.231 X 10--3 3.229 X 10--' In the literature of constitutive equations for the thermal creep deformation of materials, two basic approaches have been taken: phenomenological modeling7 and extraction from experimental data of the values of the coefficients of empirical relations 8 or those with a fundamental base.…”