Yuanzineng kexue jishu (Apr 2023)
Simulation Analysis on Influence of Bottom Structure Design on Electromagnetic Field of Cold Crucible for Vitrification
Abstract
As the last step of the nuclear fuel cycle, nuclear waste reprocessing is essential to the safe utilization and sustainable development of the nuclear industry and nuclear energy. Vitrification is currently internationally recognized as the best solution for the treatment of high-level radioactive waste, and it is also the only high-level waste disposal method that realizes engineering applications. The cold crucible induction melting (CCIM) vitrification technology is one of the key research directions of high-level waste liquid vitrification technologies. As an important part of the cold crucible, the bottom affects the magnetic permeability, sealing, strength and leakage process of the cold crucible. In order to improve the pouring efficiency during cold crucible melting process, the magnetic induction intensity near the discharge port needs to be enhanced. The effects of the design of the crucible bottom on the magnetic induction intensity and electromagnetic loss inside the cold crucible were studied. The 3D electromagnetic induction models of cold crucibles with different bottom structures were established by using the AC/DC module of COMSOL Multiphysics software. The simulation results show that changing the number of slits has little effect neither on the magnetic field inside the crucible, nor on the magnetic field and the electromagnetic loss at the bottom of the crucible. The slit width of crucible bottom increasing from 5 mm to 20 mm, the magnetic flux density inside the crucible increases by about 4%, and the electromagnetic loss of the glass melt domain in the crucible increases by about 1.7 kW (the proportion increased by about 6%). Increasing the length of the slits from 90 mm to 115 mm, the magnetic flux density near the center of the crucible bottom increases by 0.1-1.25 mT, and the electromagnetic loss of the glass melt near the bottom increases by 1.6% (about 0.4 kW). Accordingly, the magnetic permeability and the heating efficiency of the cold crucible can be improved by increasing the slit width. The magnetic induction intensity near the discharge port can be improved by increasing the length of the slits, thereby improving the leakage efficiency. In practical applications, it is not only necessary to improve the heating efficiency of the cold crucible, but also to avoid the leakage of the glass melt at the bottom of the cold crucible during the melting process. Therefore, the structural design of the cold crucible bottom needs to comprehensively consider factors such as the magnetic permeability, the heating efficiency, the strength of the crucible and the processing of water-cooled components inside the slits.
