Activation analysis and radwaste assessment of CFETR

Abstract

The materials in the fusion system will be activated by the neutrons generated from D-T fusion reactions, causing the material with activity and decay heat at a variety level among the system. Predicting the amount of radwaste produced in the Chinese Fusion Engineering Testing Reactor (CFETR) and the time-evolution feature of the radwaste is of great importance to the minimization of waste and determine the management strategy. The purpose of this paper is to minimize the quality and quantity of the activated solid waste as low as reasonably achievable via source control, recycling and reuse, clearance, optimization of the management at the designing phase of CFETR. A detailed 3D model for CFETR is created to calculate the neutron spectra and fluxes of all non-void cells of the model. The inventory calculation for each cell with the given irradiation scenario and the cooling scheme was then carried out with FISPACT-II. The extensive calculation, data analysis, and post-processing are performed using a data processing code to calculate the component averaged activation responses and the waste classifications. The results suggest that the in-vessel materials exposed to high level neutron fluxes can hardly meet the clearance and low-level waste requirements, but they can be recycled with an advanced remote handling system shortly after shutdown or a conservative remote handling system after temporary storage within 100 years. The vacuum vessel, port plug, cryostat, and coils can be recycled with a conservative remote handling system with temporary storage. Especially, the port plug, cryostat, and central solenoid are clearable with temporary storage of 100 years. The influence of the operation time of in-vessel components on the radwaste severity and quantity is also evaluated. The severity of the radwaste increases when the operation time increases from 1000 to 3000 MWY, then decreasing with operation times longer than 3000 MWY. The detailed operation plan should be determined with comprehensive consideration of the important factors, including the influence on the radwaste severity. The allowed impurity level is also estimated, finding that the Uranium in the breeding zone and the SS316L used in divertor should be blamed for the intermediate-level waste production of blanket and divertor.