27th IEEE Symposium on Fusion Engineering

Nuclear and Thermal Analysis of a Reflectometry Diagnostics Concept for DEMO

7 Jun 2017, 11:40

20m

Salon 3

Oral Neutronics and multiphysics simulation W.OA3: Neutronics and Multiphysics Analysis

Speaker

Dr Raul Luís (Instituto dos Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa)

Description

The reflectometry diagnostic (RF) for DEMO is envisaged to provide the 2D electron density profile and to be used as a control diagnostic for the real-time plasma position and shape controller. An initial conceptual study has been done defining the position of the antennas and the routing of the waveguides. In the present design, the integration has been driven by remote handling and blanket interfaces. In order to progress with the system integration, neutronic simulations were performed to find out the cooling requirements. This paper presents the initial nuclear and thermal analyses for the initial design of the reflectometry diagnostic for DEMO. The neutronics simulations were performed using the Monte Carlo simulation program MCNP6 and FENDL 2.1 cross-sections. In a first stage, a CAD model of a 200-mm thick section, divided into 17 sectors (to conform with the blanket configuration) was developed, featuring 40 antennas and the corresponding waveguides. This model was simplified using ANSYS SpaceClaim, to make it suitable for the neutronics simulations, and converted to the MCNP input format using the CAD-based modelling program MCAM. The diagnostics section was then integrated into the 2015 DEMO HCLL MCNP model and filled with the homogeneous breeder blanket mixture used in the HCLL breading blankets. Simulation results show that the nuclear heat loads reach 7 W/cm3 at the surface of the diagnostics section and at the tips of some antennas. Without an active cooling system, the operating temperatures of the components under such heat loads would be well above the acceptable from the thermo-mechanical point of view. The thermal analysis presented in this work provides the temperature distribution in the components when subjected both to neutron/gamma irradiation and thermal radiation from the plasma, after the implementation of a preliminary design of the active cooling system. This analysis, based on the CAD models developed for the neutronics simulations, is performed using the commercial finite element software ANSYS v18 Mechanical. The effects of the operating temperatures on the material properties of the plasma-facing, horn-shaped antennas, as well as the performance of the whole diagnostics system from the neutron shielding point of view, are analysed and discussed in this paper.