Preparation method of high-safety uranium dioxide nuclear fuel core block

A uranium dioxide, high-safety technology, applied in the field of preparation of high-safety uranium dioxide nuclear fuel pellets, can solve the problems of slow and limited grain growth

Active Publication Date: 2018-06-29
MATERIAL INST OF CHINA ACADEMY OF ENG PHYSICS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, UO 2 The growth of grains at high temperature is very slow. To significantly increase the grain size, the optional grain gro...

Method used

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preparation example Construction

[0023] The method for preparing high-safety uranium dioxide nuclear fuel pellets in this embodiment mainly includes two steps, one is the preparation of core-shell structure particles, and the other is the preparation of nuclear fuel pellets.

[0024] Specifically, step one utilizes the powder metallurgy mold to UO 2 The powder is cold-pressed, and then granulated and spheroidized to obtain UO 2 pellets, and then mixed with grain growth additive micropowder (Al 2 o 3 \Y 2 o 3 、Al 2 o 3 \SiO 2 、Cr 2 o 3 , Cr, etc.) and enhanced phase powder (C f , Graphene, ZrC, SiC w 、SiC f 、SiC p etc.) by physical mixing, the grain growth aid and the reinforcing phase are coated on the UO 2 On the surface of the sphere, core-shell structure particles are obtained, and the specific operation is as follows:

[0025] (1) UO with a particle size of 20nm to 500μm 2 The powder is loaded into a powder metallurgy preforming mold for biaxial compression molding to obtain a density of 5....

example 1

[0034] UO with a particle size of 20nm 2 The powder is loaded into a powder metallurgy preforming mold for biaxial compression molding to obtain a density of 5.5g / cm 3 UO 2 preform; the UO 2 The preform is crushed and sieved to obtain UO with a particle size of 50 mesh 2 particles; then the UO 2 Put the particles into the spheroidization equipment for grinding and spheroidization for 8 hours to obtain UO with good sphericity 2 small ball; the UO 2 Put the pellets into the mixing coating equipment, add 20vol.% grain growth aid Al with a particle size of 100μm 2 o 3 \Y 2 o 3 , where Al 2 o 3 and Y 2 o 3 The mass ratio is 1:1, and 3.5vol.% reinforcement phase C with a particle size of 50μm f ,, mixed and coated for 2 hours to obtain the reinforced phase C f Al 2 o 3 \Y 2 o 3 at UO 2 The surface of the sphere is coated with uniform core-shell structure particle UO 2 @Al 2 o 3 \Y 2 o 3 -C f ;

[0035] Will UO 2 @Al 2 o 3 \Y 2 o 3 -C f The core-shell ...

example 2

[0037] UO with a particle size of 100nm 2 The powder is loaded into a powder metallurgy preforming mold for biaxial compression molding to obtain a density of 5.0g / cm 3 UO 2 preform; the UO 2 The preform is crushed and sieved to obtain UO with a particle size of 10 mesh 2 particles; then the UO 2 Put the particles into the spheroidization equipment for grinding and spheroidization for 2 hours to obtain UO with good sphericity 2 small ball; the UO 2 Put the balls into the mixing coating equipment, add 30vol.% grain growth aid Al with a particle size of 300μm 2 o 3 \SiO 2 , where Al 2 o 3 and SiO 2 The mass ratio is 1:1, and 5vol.% of the reinforcement phase Graphene with a particle size of 100 μm is mixed and coated for 0.5 hours to obtain the reinforcement phase Graphene and the grain growth aid Al 2 o 3 \SiO 2 at UO 2 The surface of the sphere is coated with uniform core-shell structure particle UO 2 @Al 2 o 3 \SiO 2 -Graphene;

[0038] Will UO 2 @Al 2 o ...

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Abstract

The invention discloses a preparation method of a high-safety uranium dioxide nuclear fuel core block. The preparation method comprises the following steps: physically mixing crystallite grain growthauxiliaries, a reinforced phase and uranium dioxide particles, coating the surfaces of the uranium dioxide particles with the crystallite grain growth auxiliaries and the reinforced phase to obtain particles with core-shell structures; sintering the particles with the core-shell structures at a high temperature under micro-oxidation atmosphere, spreading the crystallite grain growth auxiliaries into the uranium dioxide particles and gaps among the particles, dissolving the uranium dioxide particles in the crystallite grain growth auxiliaries, crystallizing and growing, and forming a continuousthree-dimensional net-shaped structure, and dispersing and distributing the reinforcing phase into the crystallite grain growth auxiliaries, thereby obtaining the high-safety uranium dioxide nuclearfuel core block. Dimensions of the uranium dioxide particles are increased through the crystallite grain growth auxiliaries, so that the crystal boundary is reduced, and heat conductivity and stability of the UO2 fuel core block are greatly improved by cooperating with dispersive distribution of the reinforced phase, and therefore, operation economical efficiency and safety level of a reactor anda fuel system are remarkably improved.

Description

technical field [0001] The invention relates to a method for preparing high-safety uranium dioxide nuclear fuel pellets. Background technique [0002] Uranium dioxide (UO 2 ) has the advantages of high melting point, good stability, strong radiation resistance, and low thermal neutron capture cross-section, and is currently the nuclear fuel widely used in light water reactor power stations. But UO 2 There is still a serious defect that the thermal conductivity is low, and the thermal conductivity decreases significantly with increasing temperature, UO 2 The thermal conductivity of the fuel at room temperature and 1000°C is 7.5W / m.k and 2.8W / m.k respectively, which is only one tenth of that of metal uranium. This defect will not only increase the operating temperature of fuel pellets under normal operating conditions and reduce fuel economy, but more importantly, under accident conditions, the temperature at the center of the fuel pellets and the temperature gradient from ...

Claims

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Application Information

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IPC IPC(8): C04B35/80C04B35/50C04B35/63G21C21/10
CPCC04B35/803C04B35/50C04B35/6303C04B2235/3217C04B2235/3225C04B2235/3241C04B2235/3418C04B2235/6567C04B2235/6582G21C21/10Y02E30/30
Inventor 杨振亮李冰清高瑞褚明福唐浩刘徐徐钟毅段丽美黄奇奇王志毅
Owner MATERIAL INST OF CHINA ACADEMY OF ENG PHYSICS
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