Overview of recent nuclear analyses for the Upper ECH launcher in ITER

An overview is given for the analyses of the nuclear physics characteristics in support of the development of the Electron Cyclotron Heating (ECH) launcher installed in the ITER upper port. The launcher's Quasi-Optical (QO) system of millimeter-wave guides represents a pathway for the neutron streaming which results in radiation loads on the launcher internals, mainly on the front steering (FS) mirrors and neighboring ITER components, in particular the vacuum vessel (VV) and the superconducting magnets surrounding the launcher. The radiation transport calculations were performed with the Monte Carlo code MCNP5 employing the recent MCNP geometry model of ITER called Alite and the FENDL-2.1 nuclear data. A dedicated CAD model of the QO ECH launcher, generated with CATIA V5, was converted at FZK into the MCNP5 geometry representation using the McCad conversion tool. The neutron and photon fluxes and critical nuclear responses, such as nuclear heating, neutron damage, and the helium production rate were calculated in the paper and compared with the ITER nuclear design limits. On the basis of the results obtained from the nuclear analyses, it is concluded that the recent design of the QO ECH launcher satisfies the ITER radiation requirements, and thus, from this point of view, can be operated safely.