Evaluation of Nuclear Heat and Dose Rate for JT-60SU

Neutronics investigation has been made for the JT-60SU. Under the neutron production rate of l×l020n/s due to D-T operation, peak nuclear heating rate in a superconducting magnet (SCM) winding pack is 0.19 mW/cm2 at the inboard on the mid-plane, and that at the outboard near the NBI duct is 0.27 mW/cm3. These values satisfy the design limit of 0.2 mW/cm3 in inboard SCM winding pack and that of 1 mW/cm3 in the outboard SCM near the duct, respectively. The dose rate in one month after shutdown of 8000 s operation in the cryostat near the NBI duct is obtained ~10 μSv/h. The dose rate in the cryostat in one month after shutdown satisfies the design target of 20 μ Sv/h. Consequently, total shield thickness of the vacuum vessel in inboard and outboard, and additional shielding in the present design is expected to be enough.