Radiation Shielding Analyses for the ITER Upper Port ECRH Launcher

The International Thermonuclear Experimental Reactor (ITER) will use an electron cyclotron resonance heating (ECRH) system in the upper port of the device for plasma stabilization, heating, and current drive by injecting millimeter wave beams into the plasma chamber. The millimeter waves are transmitted to the plasma through long and narrow waveguide channels. The required plasma wall openings could result in enhanced neutron radiation loadings to the ECRH launcher and neighboring reactor components. The analyses aimed at proving that the shielding requirements and all related nuclear design limits specified by ITER can be met for the proposed ECRH launcher design concepts. The nuclear criteria included human safety issues, nuclear waste regulation aspects, and radiation shielding requirements. The proof was conducted by calculating the radiation loads to sensitive components such as the diamond window of the ECRH launcher, the vacuum vessel, and the superconducting magnets and assessing the potential radiation doses to work personnel during shutdown periods. Dedicated computational approaches were developed to handle the related neutron streaming and shielding problems on the basis of threedimensional Monte Carlo calculations by the MCNP code. Suitable MCNP models of the launcher were generated by the automatic conversion of the underlying computer assisted design models using a newly developed interface program. The results of the analyses show that all radiation design limits can be safely met for the considered launcher and shield designs.JRC.F.4-Nuclear Reactor Integrity Assessment and Knowledge Managemen

Neutronic Modeling Challenges for the ITER ECRH Launcher Shielding Design

Comprehensive neutronic analyses are being performed for different variants of the International Thermonuclear Experimental Reactor (ITER) electron cyclotron resonance heating upper launcher under development in the European Union making use of modern computation tools such as the McCad code for geometry conversion and the rigorous two-step (R2S) interface for rigorous shutdown dose rate calculation. There were many reasons for the challenges encountered during the shielding analyses: deep-penetrated radiation transport in the complex geometry of the launcher, frequent need to introduce changes in the three-dimensional MCNP model, and necessity to meet a broad range of nuclear sufficiency requirements specified for ITER. The challenges were successfully addressed and resulted in radiation shielding and nuclear safety support for the current version of the launcher design, which should be workable in ITER. During the process of the launcher design development, a comprehensive knowledge of neutronic characteristics has been gained, and computation methods were matured accordingly.JRC.DG.F.4-Safety of future nuclear reactor