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Preparation method of large-grained UO2 (uranium dioxide) fuel pellets with high heat conductivity

A technology of high thermal conductivity and fuel pellets, which is applied in the direction of reactor fuel materials, greenhouse gas reduction, nuclear power generation, etc., can solve problems such as ineffective effects, achieve high temperature stability and radiation resistance, good support and constraints Stabilizes and improves thermal conductivity

Active Publication Date: 2018-04-03
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

The above methods can only improve UO from one aspect 2 The safety performance of fuel pellets cannot be taken into account, or the effect is not obvious

Method used

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Examples

Experimental program
Comparison scheme
Effect test

preparation example Construction

[0026] This embodiment is for traditional UO 2 Due to the low thermal conductivity of fuel pellets and weak fission product holding capacity, a method for preparing uranium dioxide fuel pellets with large grains and high thermal conductivity is provided. 2 Add Cr, Cr to the powder 2 o 3 、Al 2 o 3 , SiO 2 and other grain growth additives to obtain UO with significantly larger size 2 At the same time, BeO, Mo, Cr, W and other thermal conductivity enhancement phases are combined with UO through spheroidization, coating, forming, and sintering techniques. 2 Particles are compounded to obtain thermal conductivity-enhanced large-grain UO2 fuel pellets with a three-dimensional network structure, that is, UO2 fuel pellets are obtained by mixing, pre-pressing, crushing, sieving, and spheroidizing. 2 The UO2-grain growth aid compound pellets that are uniformly mixed with the grain growth aid and have good sphericity, and then use the rolling coating method to uniformly coat the th...

example 1

[0040] Preparation of UO 2 / BeO fuel pellets: UO with a particle size of 100nm 2 Powder is mixed with 2.5wt.% grain growth aid Cr, 0.3wt.% lubricant zinc stearate for 24 hours; 2 The mixture powder with Cr is pressed into UO under the pressure of 400MPa 2 -Cr mixture pre-press; the pre-press is crushed and sieved to obtain UO with a particle size of 50 mesh 2 -Cr composite particles; put the composite particles into spheroidization equipment for grinding and spheroidization for 16 hours to obtain UO with good sphericity 2 -Cr complex pellets.

[0041] Will UO 2 -Cr composite pellets are put into the mixing and coating equipment, adding 10vol.% BeO micropowder of the thermal conductivity enhancement phase with a particle size of 50 μm, and 0.1wt.% lubricant zinc stearate, and mixing and coating for 1 hour to obtain BeO at UO 2 -The surface of the Cr composite ball is coated with a uniform core-shell structure coated ball; the coated ball is put into a powder metallurgy fo...

example 2

[0043] Preparation of UO 2 / Mo fuel pellets: UO with a particle size of 500nm 2 powder with 1wt.% grain growth aid Cr 2 o 3 , 0.1wt.% lubricant Akewax was mixed for 20 hours; the resulting UO 2 with Cr 2 o 3 The mixture powder is pressed into UO under 300MPa pressure 2 -Cr 2 o 3 Mixture pre-press; the pre-press is crushed and sieved to obtain UO with a particle size of 100 mesh 2 -Cr 2 o 3 ; Put the composite particles into the spheroidization equipment for grinding and spheroidizing for 10 hours to obtain UO with good sphericity 2 -Cr 2 o 3 Compound pellets.

[0044] Will UO 2 -Cr 2 o 3 The composite pellets were loaded into the mixing and coating equipment, and 20vol.% of the thermal conductivity enhancing phase Mo powder with a particle size of 10 μm, and 0.25wt.% of the lubricant Ake wax were added, and the mixing and coating was carried out for 2 hours to obtain Mo in UO 2 -Cr 2 o 3 The surface of the composite ball is coated with a uniform core-shell s...

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Abstract

The invention discloses a preparation method of large-grained UO2 (uranium dioxide) fuel pellets with high heat conductivity. The surfaces of UO2-grain growth promoter compound spheres with good sphericity are uniformly coated with heat conductivity enhanced phase powder, coated particles are obtained and subjected to forming and sintering in a high-temperature atmosphere, so that UO2 grains growunder the action of the grain growth promoter, meanwhile, the heat conductivity enhanced phase coating the surfaces of the UO2 particles is intercommunicated after being liquefied at the high temperature, a three-dimensional network structure is formed, and the enhanced phase and a UO2 matrix form special UO2 fuel pellets with the three-dimensional network structure. The enhanced UO2 fuel palletsprepared with the method have the heat conductivity remarkably superior to that of pure UO2, besides, the size of UO2 grains is notably larger than that of conventional UO2 pellets, the high-temperature resistance and the irradiation stability are excellent, and the safety level of a reactor and a fuel system can be remarkably improved.

Description

technical field [0001] The invention relates to a method for preparing uranium dioxide fuel pellets with large crystal grains and high thermal conductivity. Background technique [0002] Uranium dioxide (UO 2 ) is currently the most widely used nuclear fuel material in commercial nuclear reactors. It has high melting point, good high temperature stability, good chemical compatibility with cladding materials and coolants, strong radiation resistance, and the heat of oxygen as a non-fission combination element. Significant advantages such as low neutron capture cross section. However, with the continuous improvement of the nuclear industry's safety requirements for nuclear fuel systems, the problems of low high-temperature thermal conductivity and weak fission product holding capacity have become more and more serious. In accident conditions where coolant is lost, conventional UO 2 The thermal conductivity of the fuel pellets will decline sharply, the temperature of the pel...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G21C3/58
CPCG21C3/58Y02E30/30
Inventor 杨振亮李冰清高瑞贾建平唐浩段丽美刘徐徐钟毅黄奇奇王志毅
Owner MATERIAL INST OF CHINA ACADEMY OF ENG PHYSICS
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