Fuel pellet with continuous phase structure and preparation method of fuel pellet

Abstract

The invention discloses a fuel pellet with a continuous phase structure and a preparation method of the fuel pellet. The preparation method comprises the following steps: S1, spheroidizing UO2 particles; S2, adding additive powder into the spheroidized UO2 particles, and mixing the additive powder and the spheroidized UO2 particles in a rolling manner to uniformly cover the surfaces of the UO2 particles with the additive powder; and S3, performing discharge plasma sintering on the mixed UO2 particles and additive powder to allow the additive powder to form continuous meshed thermal conductancechannels distributed between the UO2 particles, thereby preparing the fuel pellet with the continuous phase structure. In the preparation method disclosed by the invention, the surfaces of the spheroidized UO2 particles are coated with the additive powder at first, and then the discharge plasma sintering is performed, so that the continuous meshed phase structure can be formed in the fuel pelletto reduce the preparation difficulty, and then the thermal conductivity and the comprehensive performance of the fuel pellet are improved, the sintering time is shortened, and the sintering efficiencyis improved.

Description

technical field [0001] The invention relates to the technical field of nuclear fuel, in particular to a fuel pellet with a continuous phase structure and a preparation method thereof. Background technique [0002] After the Fukushima nuclear accident in Japan, countries around the world began to pay close attention to the safety of nuclear fuel elements. Accident tolerant fuel (ATF for short) is a new generation fuel concept proposed to improve the fault tolerance performance of reactors under severe accident conditions. The application of accident-tolerant fuel will fundamentally improve the resistance of newly-built nuclear power plants to severe accidents, and effectively improve the safety and economy of nuclear power. [0003] Uranium dioxide nuclear fuel is a traditional commercial nuclear reactor fuel with excellent high temperature stability and radiation stability. However, the thermal conductivity of uranium dioxide is low, and the thermal conductivity will decre...

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Problems solved by technology

[0006] 1. The high melting point of nuclear fuel is high, and the sintering temperature of liquid phase sintering is usually higher than the melting point of low-melting components or eutectics, so the sintering temperature of liquid phase sintering is usually above 2400K. Excessively high sintering temperature makes the pellets unstable at high temperature Increased resistance, increased sintering defects;

[0007] 2. In order to obtain dense pellets, the sintering time is usually more than 10 hours, and the sintering period is long;

[0008] 3. Some toxic additives are easy to volatilize at high temperature, difficult to collect, and easy to cause environmental pollution

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