Neutronic analysis of the ITER Equatorial Port Plug 1

Abstract The ITER Equatorial Port 1 will host the following diagnostic systems: the Radial Neutron Camera (RNC), the High Resolution Neutron Spectrometer (HRNS), the Gamma Ray Spectrometer, the Hard X-Rays Monitor, the Pressure Gauges, the Bolometers, the Equatorial Visible/Infrared Wide Angle Viewing System (WAVS), the Neutron Flux Monitor (NFM), the Motional Stark Effect (MSE) system and the Divertor Impurity Monitor (DIM). These diagnostics are integrated inside the Port Plug, a water-cooled stainless steel support structure, which also includes Diagnostic Shielding Modules, designed to provide enough radiation shielding capabilities, to protect the diagnostic systems and to reduce the dose level in the Port Interspace. A new concept for the design of the Port Plug is under consideration: it is based on the installation of the diagnostics inside vertical drawers, completely independent from each other, that are inserted in the Port Plug structure through guiding rails. The paper presents the results of three-dimensional neutronic analyses performed with MCNP5 Monte Carlo code in support of the Port Plug design and integration. The reference ITER MCNP 40° model “Alite” has been updated including the details of the drawers and three diagnostics. Nuclear heating radial profiles have been produced for different toroidal and poloidal positions to be used as input for thermal and thermo-mechanical analyses. 3-D Neutron flux maps have been calculated in order to assess the effect of radiation streaming through all gaps (between the drawers, around the Port Plug and along the diagnostic penetrations) and to provide an estimate of the shielding effectiveness of the new Port Plug concept.