EVALUATION OF RADIATION SHIELDING, NUCLEAR HEATING AND DOSE RATE FOR JT-60 SUPERCONDUCTING MODIFICATION
A. MORIOKA, A. SAKASAI, K. MASAKI, S. ISHIDA, N. MIYA, M. MATSUKAWA, A. KAMINAGA AND A. OIKAWA
Japan Atomic Energy Research Institute, Naka Fusion Research Establishment, 801-1 Mukouyama, Naka-machi, Naka-gun, Ibaraki-ken 311-0193, JAPAN
Abstract.
The radiation shielding, nuclear heating and dose rate have been evaluated for JT-60 superconducting modification. The double-walled structure of a vacuum vessel was decided so that the maximum nuclear heating at the inboard side of the superconducting TF coil could be suppressed to be lower than 2.5 mW cm-3. The 316 stainless steel (SS316L) boards outside the vacuum vessel are installed for effective gamma-ray shielding. The dose rate with a reduced activation ferritic steel pedestal for the first wall in the vacuum vessel was estimated. The dose rate with the pedestal in the vacuum vessel reduced by 40 % as compared with the SS316L pedestal. The dose rate outside the cryostat by using the B4C doped concrete was estimated after shutdown of ten years operation.