Operation and shutdown dose rate analysis of CFETR ECRH system

Abstract

Electron Cyclotron Resonance Heating (ECRH) is one of auxiliary heating systems to be installed in CFETR. For heating purpose of ECRH, a penetration space has been designed to transmit the wave to plasma. This will significantly increase the neutrons streaming through the wave channel and result in heavy irradiation of ECRH port structures. For nuclear safety analysis, the irradiation dose during operation of CFETR should be limited according to the regulation of radiological zone. In case of failure, the ECRH is planned to be maintained by workers after shutdown and waiting time of one month until the dose rate decreases to low level of 100 μSv/h. The shielding capabilities of ECRH port has been evaluated in view of dose effect both during operation and after shutdown of CFETR. For that purpose, a 3-D neutronics model has been built to launch the nuclear analysis. The operation dose rate was directly transferred from the neutron and photon flux by using of ICRP-74 flux to dose conversion factors. The shutdown dose rate was obtained with NASCA code system by coupling the Monte Carlo particle transport and FISPACT activation calculation. The obtained operation and shutdown dose data can be provided for the shielding optimization of ECRH wave system.