Radiation levels in the ITER tokamak complex during and after plasma operation

Extensive neutronics and 3-D activation simulations were carried out to assess the levels of radiation throughout the ITER tokamak complex. The simulated radiation sources included D-T fusion neutrons exiting the cryostat and gamma rays arising from the activation of cooling water, activated pipe chases and cask transfers. Resultant biological dose rates, dose rates to silicon and particle fluxes, for both neutrons and gamma rays, have been calculated. Results of on-load simulations of activated water show photon biological dose rates approaching 3.2 kSv/h near the upper cooling pipes, and dose rates on the B2 level of the tokamak complex are typically of the order of 0.1 μSv/h or less inside the diagnostics and tritium handling buildings. On-load neutron dose rates are calculated to be less than 1 Sv/h inside the port cells. The dose rate resulting from activated steel pipe chases, 10⁶ s after shutdown was typically a few μSv/h. Simulations of integrated dose to electronics for multiple divertor cask transfers show a dose to silicon inside the north-east electronics cubicle of 9.8 × 10^-5 Gy and inside the tritium handling building is shown to be of the order of 1 × 10^-7 Gy.