Life Cycle Assessment for Energy Payback of Spherical Tokamak Reactors

抄録

The energy payback ratio (EPR) is the index evaluating how a power plant produces the higher output energy effectively from the lower input energy. We used the system code and evaluated the EPRs of three reactor models; spherical tokamak (NC-ST), low aspect ratio tokamak reactor (LATR), and standard tokamak reactor (TR). The NC-ST and LATR systems have no center solenoid at the inboard side of plasma. In the case of NC-ST, normal conducting coils (NC) are used for toroidal field system. In LATR and TR superconducting coils (SC) are adopted. After we studied the relationship between the EPR of each fusion reactor and the aspect ratio in the range from 1.2 to 4.0, we evaluated the EPR of three typical models; ARIES-ST like, VECTOR like, and ARIES-RS like. The input parameters of aspect ratio, elongation, and normalized beta are as same as those of each original reactor. It was found that the EPR of LATR is the highest. Since LATR has no power loss due to ohmic-heating of normal conducting coils, the input energy of construction, operation and replacement is the lowest.