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Method for preparing metal reinforced uranium dioxide nuclear fuel pellet

A uranium dioxide and metal-reinforced technology, which is applied in the direction of reactor fuel materials, nuclear power generation, and reduction of greenhouse gases, can solve problems such as reducing the safety limit of reactors, core block creep, and core meltdown, and achieve good high temperature in the reactor Radiation stability performance, thermal conductivity performance improvement, and the effect of reducing interface thermal resistance

Active Publication Date: 2017-10-17
MATERIAL INST OF CHINA ACADEMY OF ENG PHYSICS +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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)

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment

[0020] The purpose of this embodiment is to solve the problem of low thermal conductivity of UO2 nuclear fuel pellets widely used in existing commercial nuclear reactors, which affects the safety of reactor operation, thereby providing a method for preparing metal-enhanced uranium dioxide nuclear fuel pellets. The preparation method mainly includes two steps. One is to prepare core-shell particles, that is, to use spark plasma sintering (Spark Plasma Sintering, SPS) technology to 2 The powder is pre-fired quickly at low temperature, and UO is obtained after granulation and spheroidization 2 The small balls are physically mixed with metal (one of Mo, Cr, W, etc.) powders, and the metal powders are coated on the surface of UO2 small balls to make core-shell particles of metal-coated uranium dioxide; the second is Preparation of nuclear fuel pellets, i.e. using coating in UO 2 After the metal (one of Mo, Cr, W, etc.) powder on the surface of the ball is liquefied at a high tempe...

example 1

[0022] A method for preparing metal-enhanced uranium dioxide nuclear fuel pellets, comprising the following steps:

[0023] (1) UO with a particle size of 50nm 2 The powder was put into SPS low-temperature calcining special graphite mold, and then placed in SPS sintering furnace for low-temperature rapid pre-sintering. During the low-temperature rapid pre-sintering process, the temperature was raised to 650 °C at a heating rate of 100 °C / min, and then kept for 5 minutes to obtain The density is 5.5g / cm 3 UO 2 pre-sintered billet;

[0024] (2) will UO 2 The calcined billet is crushed and sieved to obtain UO with a particle size of 30 mesh 2 particles, and then the UO 2 Put the particles into the spheroidization equipment for grinding and spheroidization for 3 hours to obtain UO with good sphericity 2 small ball;

[0025] (3) will UO 2 The pellets are loaded into the mixing and coating equipment, and the added particle size is 50 μm and the volume is UO 2 The metal moly...

example 2

[0029] (1) UO with a particle size of 100 μm 2 The powder is put into SPS low-temperature calcining special graphite mold, and then placed in SPS sintering furnace for low-temperature rapid pre-sintering. During the low-temperature rapid pre-sintering process, the temperature is raised to 700 °C at a heating rate of 50 °C / min, and then kept for 1 min. The density is 5.0g / cm 3 UO 2 pre-sintered billet;

[0030] (2) will UO 2 The calcined billet is crushed and sieved to obtain UO with a particle size of 15 mesh 2 particles, and 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;

[0031] (3) will UO 2 The pellets are loaded into the mixing and coating equipment, and the added particle size is 50nm and the volume is UO 2 The metal chromium (Cr) powder of 0.12 times of bead volume carries out mixing coating 2 hours, obtains metal chromium powder in UO 2 The surface ...

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Abstract

The invention discloses a method for preparing metal reinforced uranium dioxide nuclear fuel pellets. The method mainly comprises two steps: firstly, preparing core-shell structure granules, namely performing low-temperature rapid pre-sintering on UO2 powder by using a Spark Plasma Sintering SPS technique, pelletizing, balling to obtain UO2 pellets, performing physical mixing on the UO2 pellets with metal (one of Mo, Cr, W and the like) micro powder to coat surfaces of the UO2 pellets by the metal micro powder, thereby obtaining metal coated uranium dioxide core-shell structure granules; secondly, preparing a nuclear fuel pellets, namely performing high-temperature liquidation on the metal powder on the surfaces of the UO2 pellets, thereby forming a micro cell structure continuous phase similar to a cytomembrane structure around the UO2 pellets, and obtaining the special metal reinforced UO2 nuclear fuel pellets with a UO2 substrate.

Description

technical field [0001] The invention relates to the field of nuclear fuel, in particular to a method for preparing metal-enhanced uranium dioxide nuclear 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 , but 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 ga...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G21C3/64
CPCG21C3/64Y02E30/30
Inventor 杨振亮刘彤李冰清黄华伟高瑞孙茂州贾建平马赵丹丹
Owner MATERIAL INST OF CHINA ACADEMY OF ENG PHYSICS
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