UO₂ Kernel Preparation by M-EG Process and Its Irradiation Test

Kernels of KAERI TRISO fuels are prepared in the following steps: (1) preparation of a raw material solution(UN solution) by UO₃ (or U₃O₈) powder dissolution in the concentrated HNO₃; (2) broth preparation and physical property control by mixing UN, THFA, PVA, and H₂O; (3) preparation of spherical liquid gel droplets and dried-ADU gels in sequence through a reaction between uranyl ions and ammonia ions in a gelation column; (4) ageing, washing, and drying processes of ADU gel using AWD equipment; (5) UO₃ calcination by thermal decomposition of driedADU gel in the air; (6) fabrication of UO₂ kernel by reducing the UO₃ and sintering in the H₂. In this study, improved KAERI processes for UO₂ kernel preparation were presented. ADU gel washing procedure in AWD processes and the heating mode in sintering process were modified and the internal structures of UO₂ kernels are presented as a result.