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Evolution of Shielding Computations for the ITER Upper ECH Launcher

A. Serikov, U. Fischer, D. Grosse, P. Spaeh, D. Strauss

Nuclear Technology / Volume 175 / Number 1 / July 2011 / Pages 238-250

Technical Paper / Special Issue on the 16th Biennial Topical Meeting of the Radiation Protection and Shielding Division / Photon and Neutron Transport and Shielding (DETERMINISTIC or Mc)

This paper presents an overview of the evolution of the radiation shielding calculations for the ITER upper port electron cyclotron heating (ECH) launcher performed over the last 6 yr at Karlsruhe Institute of Technology (KIT). The current advances at KIT in the development of the McCad program as an interface between a computer-aided-design (CAD) system and the Monte Carlo radiation transport codes Monte Carlo N-Particle (MCNP) Version 5 (MCNP5) and TRIPOLI-4 enable a substantial increase of neutronic calculation efficiency for the development of nuclear systems design. This work provides new results in the application of calculation techniques enhanced with the CAD-based radiation transport capabilities of McCad and with the inherent features of MCNP5 such as its variance-reduction techniques (VRTs) and mesh tallies. High-resolution mapping of the helium production distribution in the ITER location that was supposed to be rewelded was accomplished using the MCNP mesh tally. This mapping is important because the reweldability of irradiated steel is limited by the content of helium generated. In the ITER heterogeneous models with the possibility of radiation streaming effects resulting in hot spots, the need to obtain excellent results closely related to the original CAD model is an additional reason to use McCAD. The statistical errors associated with the mesh tally results were reduced by applying VRTs and by taking advantage of the MCNP5 message passing interface parallel computations on the JUROPA High Performance Computer for Fusion operated in the Juelich Supercomputer Centre at Forschungszentrum Juelich. The shielding calculations were supplemented with activation analyses of the ECH launcher irradiated materials performed by the FISPACT-2005 inventory code. The French system of radioactive waste (RW) management adopted by ITER was applied to the classification of the launcher's steel irradiated during the 20-yr Modified Design Requirements and Guidelines Level 1 (M-DRG1) ITER operational scenario. The masses of the launcher's different parts have been estimated in terms of the RW types.

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