Nuclear Safety Related Analyses of the ITER Quasi- Optical ECH Launcher A. Serikov, U. Fischer, D. Grosse, R. Heidinger, P. Spaeh, D. Strauss Association FZK-EURATOM, Forschungszentrum Karlsruhe, P.O. Box 3640, D-76021 Karlsruhe, Germany, serikov@inr.fzk.de Abstract—Nuclear safety related analyses were performed for the Quasi-Optical (QO) design of the Electron Cyclotron Heating (ECH) launcher installed in the ITER upper port. The critical nuclear responses, effecting nuclear safety of the launcher and nearby components, were calculated using the MCNP5 3D radiation transport code. The CAD interface programme McCad was applied for the conversion of the CAD model into MCNP geometry description. The radiation effects of the launcher’s halved internal shield were estimated on the Chemical Vapor Deposit (CVD) diamond windows, vacuum vessel, and Toroidal Field Coils (TFC). It was revealed that the nuclear safety requirements were satisfied. ITER ECH launcher; Monte Carlo MCNP code; fusion neutronic modeling; McCad conversion tool; nuclear safety I. INTRODUCTION Because of the radiological inventory (tritium and nuclear waste), ITER is considered in France as a nuclear facility. And one of the objectives of ITER is the demonstration of its radiological and environmental safety as the substantial advantage of nuclear fusion power. Such advantages will be fulfilled in ITER by satisfying safety requirements established by the licensing regulations of the French authority [1]. The identified nuclear safety requirements imposed on the Electron Cyclotron Heating (ECH) launcher as an ITER upper port functional part were analysed. Some of the considered requirements are specific for the ECH launcher, such as neutron loads on the window tritium barrier and the front steering mirrors; others are attributed to the whole ITER machine, as radiation shielding requirements, shutdown dose rate and aspects of radioactive waste management. The ECH launcher will be installed in the ITER upper port to control the Magneto-Hydro-Dynamic (MHD) instabilities in the ITER plasma by means of injection of mm-wave beams directed to the plasma magnetic surfaces [2]. The launcher must have an opening to plasma volume with 14 MeV neutron D-T source, shown in Figs. 1 and 2, leading to possible extensive radiation streaming along the waveguide channels. As the launcher open channels penetrate the blanket and Vacuum Vessel (VV), tritium safety must be guaranteed. The tritium containment of the launcher assumes two independent barriers consisting of Chemical Vapor Deposit (CVD) diamond windows and safety isolation valves, shown in Fig.1. The adopted ECH launcher design features front steering mirrors, depicted in Fig.2, which are placed near the opening and directly exposed to plasma neutrons. The radiation shielding of the launcher has the greatest consequences for its operation and the operation of nearby ITER components, such as VV, and the Toroidal and Poloidal Field Coils’ (TFC and PFC) superconducting magnets, after its operation - affecting personnel access to the maintenance area of CVD windows at its back-end, and even after its dismantle - having an influence on radwaste management. II. METHODOLOGICAL APPROACH The methodology of the performed nuclear safety related analyses comprises state-of-the-art computational codes, nuclear libraries, tools, and interfaces. Dedicated computation schemes were applied for the neutronic 3D models generation from a Computer Aided Design (CAD) system, radiation transport, and activation analyses. The modeling of neutron transport processes in fusion application like ITER could harness the Monte Carlo (MC) method’s potential, because the MC method describes particle histories in the geometry model without any simplifications, and it gives continuous energy representation of the particle interactions with matter. These interactions follow the nuclear laws with pointwise dependencies of nuclear cross-sections contained in nuclear data libraries. For ITER nuclear analyses, the FENDL-2.1 neutron library was applied. A. CAD to MCNP conversion by McCad Usually, the initial modeling of fusion devices is performed in CAD systems with explicit 3D geometry imaging [3]. There are mainly two approaches to make CAD models available for MC particle transport codes: either to use an interface programme for conversion of the CAD geometry description into a representation suitable for the MC transport code, as implemented at FZK, Karlsruhe/Germany with the McCad interface code, which has been used for several fusion applications [4], or to directly link a CAD geometry engine to a MC code, as done in the DAG-MCNPX code developed by University of Wisconsin, Madison/USA [3]. Currently [4], McCad allows the bidirectional conversion of 3D neutronics models between a CAD system and the MC radiation transport code MCNP5 [5]. The design of the ECH launcher mm-wave beam-line system is being developed by Plasma Physics Research Centre (CRPP) Lausanne, Switzerland. The structural and integrated design is elaborated at FZK. The main shielding parts of the launcher are depicted in Fig. 1, in which a scheme of the conversion process from the CAD (CATIA) model of the 978-1-4244-2636-2/09/$25.00 ©2009 IEEE