A Monte-Carlo benchmark of TRIPOLI-4 and MCNP on ITER neutronics

Radiation protection and shielding studies are often based on the extensive use of 3D Monte-Carlo neutron and photon transport simulations. ITER organization hence recommends the use of MCNP-5 code (version 1.60), in association with the FENDL-2.1 neutron cross section data library, specifically dedicated to fusion applications. The MCNP reference model of the ITER tokamak, the 'C-lite', is being continuously developed and improved. This article proposes to develop an alternative model, equivalent to the 'C-lite', but for the Monte-Carlo code TRIPOLI4. A benchmark study is defined to test this new model. Since one of the most critical areas for ITER neutron transport analysis concerns the assessment of radiation levels and Shutdown Dose Rates (SDDR) behind the Equatorial Port Plugs (EPP), the benchmark is conducted to compare the neutron flux through the EPP. This problem is quite challenging with regard to the complex geometry and considering the important neutron flux attenuation ranging from 10¹⁴ down to 10⁸ n/cm²/s. Such code-to-code comparison provides independent validation of the Monte-Carlo simulations, improving the confidence in neutron transport simulation results. (authors)