Multi-coated dispersion fuel element with high safety characteristic and complex structure and preparation method of multi-coated dispersion fuel element

The invention discloses a high-safety-characteristic complex-structure multi-coated dispersion fuel element and a preparation method thereof. The fuel element comprises TRISO particles, a SiC component for the fuel element and a packaging cover plate. The TRISO particles are of a multi-layer coating structure and sequentially comprise a fuel core, a loose pyrolytic carbon layer, a compact pyrolytic carbon layer and a SiC layer from inside to outside, the size of the fuel core is 500-800 microns, and the SiC component is provided with porous channels; and filling the TRISO particles into the porous channels of the SiC component to form a fuel element substrate, densifying the substrate by adopting chemical vapor infiltration, and packaging and connecting the densified substrate by adopting a packaging cover plate to obtain the multi-coated dispersion fuel element with the complex structure. The proportion of TRISO particles in the fuel element is increased by adopting the modes of filling, chemical vapor infil