Preparation method of dispersion fuel pellet with high uranium loading capacity

Abstract

The invention discloses a preparation method of a dispersion fuel pellet with high uranium loading capacity, which comprises the steps of firstly adopting means such as pelleting, self-grinding balling and rolling coating to realize the balling of a uranium-based fuel and the coating with a reinforcing phase, then performing high temperature plasma sintering on a coated ball to obtain the uranium-based fuel pellet; forming a large amount of pores in a core pellet of the fuel by utilizing the volatilization of a pore-forming agent under high temperature, then promoting the low-temperature rapiddensification sintering of the reinforcing phase by combining the high temperature plasma sintering technology and a sintering aid, thus obtaining the dispersion fuel pellet with high uranium loadingcapacity, wherein the dispersion fuel pellet has a special core-shell structure in which the compact reinforcing phase coats the porous fuel core pellet, and the special core-shell structure is loosein the interior and compact in the exterior. The method has the advantages that the preparation is simple and the preparation cost is low, can be used for the scale production of the uranium-based fuel pellet; the uranium-based fuel pellet prepared by the method has the advantages of high thermal conductivity, high safety, high uranium loading capacity and high economy.

Description

technical field [0001] The invention relates to a preparation method of high uranium loading dispersed fuel pellets. Background technique [0002] Uranium dioxide (UO 2 ) has the advantages of low neutron capture cross section, radiation stability, high melting point, good corrosion resistance to coolant water, and good compatibility with cladding materials, and is the most widely used nuclear fuel material in the nuclear industry . However, its thermal conductivity is the lowest among all nuclear fuel materials (metal type, carbide, nitride). Thermal conductivity is one of the most important thermophysical properties of nuclear fuel, which directly determines the performance of the fuel system in the nuclear reactor. The lower the thermal conductivity of the fuel pellets, the higher the temperature of the fuel assembly during reactor operation. Under the irradiation environment, the thermal stress and the release of fission gas in the pellets will also increase, which wil...

AI Technical Summary

Problems solved by technology

The lower the thermal conductivity of the fuel pellets, the higher the temperature of the fuel assembly during reactor operation. Under the irradiation environment, the thermal stress and the release of fission gas in the pellets will also increase, which will lead to deformation and cracking of the pellets, shortening the fuel consumption. Component life

In addition, the lower the thermal conductivity of the fuel pellets, the higher the energy storage of the fuel system, which will greatly reduce the safety margin of the reactor operation, especially in the event of a loss of coolant accident (Loss Of Coolant Accident, LOCA) , the energy stored in the fuel system cannot be released quickly, which will directly lead to a sharp rise in the temperature of the fuel system, creep and collapse of the pellets, meltdown of the core, and exposure of radioactive substances. If it is not effectively controlled, it will cause a serious nuclear accident

After the Fukushima nuclear accident in Japan, people began to realize that the defect of traditional uranium dioxide with low thermal conductivity has become a major safety hazard affecting the operation of nuclear power plants (R.O.Meyer, Nucl.Technol., 2006,155:293)