Conceptual Design of Tokamak High Power Reactor (A-SSTR2)

Based on the last decade of JAERI reactor design studies, an advanced commercial reactor concept (A-SSTR2) that meets both economical and environmental requirements has been proposed. The A-SSTR2 is a compact power reactor (Rp = 6.2 m, ap = 1.5 m, Ip = 12 MA) with a high fusion power (Pf = 4 GW) and a net thermal efficiency of 51%. The machine configuration is simplified by eliminating the center solenoid (CS) coil system. An SiC/SiC composite for the blanket structure material, helium gas cooling with a pressure of 10 MPa and an outlet temperature of 900°C, and TiH2 for the bulk shield material are introduced. For the toroidal field (TF) coil, a high temperature (TC) superconducting wire made of bismuth with a maximum field of 23 T and a critical current density of 1,000 A/mm2 at a temperature of 20 K is applied. In spite of the CS-less configuration, a computer simulation gives satisfactory plasma equilibria, plasma initiation process, and current ramp-up scenario. The current rampup time is about 22 hours. The MHD stabilities for the ballooning mode and the ideal low n kink-modes are confirmed. The stabilization of n = 1 and n = 2 kink modes requires a shell position closer than 1.4 times and 1.2 times the plasma minor radius, respectively. With regard to the divertor thermal condition, it was found that a neon gas-seeded divertor plasma with a fraction of ˜ 2.5% gives a thermal load reduction at the divertor plate from 460 MW to 100 MW and a plasma temperature drop at the divertor plate from 200 eV to 20 ˜ 30 eV. By increasing the shield thickness by about 15 cm, the total radwaste is dramatically reduced. The radwaste percentage relative to the total waste is reduced from 92 wt.% to 17 wt.%.