Radiation shield analyses in support of the FS design for the ITER ECRH launcher

This paper is devoted to the radiation shield analyses for the front steering (FS) design of the electron cyclotron resonance heating (ECRH) launcher installed in the ITER upper port. The neutron fluxes, nuclear heat density, helium production, and neutron displacements rate have been calculated by Monte Carlo N-Particle (MCNP) transport code. Three-dimensional MCNP models of the FS ECRH launcher have been produced with high accuracy directly from the CAD geometry models by means of the McCad interface programme. A shielding analysis has been performed to estimate the material composition and optimum length required for the launcher's internal shield. Neutron streaming calculations have been done using the MCNP point detectors method. Variance reductions in nuclear responses of particles track-length estimations were achieved by the optimized weight windows, particles splitting, and Russian roulette techniques. Nuclear design parameters of the FS ECRH launcher have been evaluated by the neutronics analyses with dedicated computational procedures. The analyses show that safety issues and radiation shielding requirements in the FS design are fully satisfied to radiation design limits specified for ITER project.