Activation of the Concrete in the Bio Shield of ITER

Calculations of neutron spectra in different parts of the tokamak building of ITER are performed. A computational geometry model of the tokamak building is prepared using MCNP-4C. The model includes adequate material composition and geometry description of the main parts of the tokamak for PPCS plant model A [1]: toroidal field coils, vacuum vessel, shield, blanket structure, first wall, divertor, 14.1 MeV neutron source. The design and the dimensions of the bio shield are taken from the current ITER design [2]. MCNP calculations of the neutron spectra in the bio shield (concrete) of ITER are performed, using the neutron spectra in TF coils calculated at UKAEA [1] as external neutron source. The neutron spectra in the concrete calculated by MCNP are used as input data in the code EASY99 for estimations of the activation of the concrete in the bio shield around the tokamak. The time evolutions of the maximum (in the bio shield floor) and minimum (in the bio shield side walls) specific activity (Bq/kg) and dose rate (Sv/h.) of the main dominant nuclides in the concrete are evaluated and compared for 3 different concrete types, used as biological shield in the PWR and BR3 reactors. [1]. R.Pampin-Garcia and M.J.Loughlin, "Neutronic and Activation Calculations for PPCS Plant Model A". PPCS/UKAEA/PPCS4D2-3, May 2002. Euratom/UKAEA Fusion Association, Culham Science Centra, Abigdon, Oxfordshire OX14 3DB, UK. Power Plant Conceptual Study, Stage 3. [2]. DDD 6.2 SiteLayout and Buildings – Introduction