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Uranium dioxide-based fuel pellet with adjustable thermal expansion coefficient and enhanced thermal conductivity, and preparation method thereof

A technology of thermal expansion coefficient and uranium dioxide, which is applied in the field of reactor fission materials, can solve the problems of mismatching thermal expansion coefficient, affecting the stable service of fuel pellets, residual thermal stress, etc., so as to delay the air gap closing time, reduce residual thermal stress, The effect of simple method

Active Publication Date: 2020-05-12
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

In the prior art, adding Mo alone to uranium dioxide can achieve the effect of enhancing thermal conductivity, but due to the mismatch of thermal expansion coefficient, residual thermal stress will be generated during the preparation process, which may affect the fuel pellets in the stack. stable service in

Method used

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  • Uranium dioxide-based fuel pellet with adjustable thermal expansion coefficient and enhanced thermal conductivity, and preparation method thereof
  • Uranium dioxide-based fuel pellet with adjustable thermal expansion coefficient and enhanced thermal conductivity, and preparation method thereof

Examples

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Embodiment 1

[0027] This embodiment discloses a uranium dioxide-based fuel pellet with adjustable coefficient of thermal expansion and enhanced thermal conductivity of the present invention, specifically:

[0028] 1) Add uranium dioxide raw material powder, metal beryllium powder and molybdenum powder in a volume ratio of 75:10:15 to a nylon tank for wet mixing, wherein the grinding medium is absolute ethanol, the wet mixing time is 24 hours, and the rotation speed is 120r / min; then vacuum dry to get evenly mixed UO 2 - Be-Mo blanks.

[0029] 2) The UO obtained in step 1 2 - Be-Mo blanks are put into graphite molds for densification by spark plasma sintering, the sintering atmosphere is vacuum, the sintering temperature is 900°C, the heating rate is 50°C / min, the holding time is 30min, and the pressure is 80MPa, The vacuum degree is 0.5Pa, and then the film is removed and the size is processed.

[0030] After determination, the thermal conductivity of the sample prepared in this embodim...

Embodiment 2

[0032] This embodiment discloses a uranium dioxide-based fuel pellet with adjustable coefficient of thermal expansion and enhanced thermal conductivity of the present invention, specifically:

[0033] 1) Add uranium dioxide microspheres, metal beryllium powder and molybdenum powder into a nylon tank in a volume ratio of 85:5:10, and dry mix. The mixing method with beryllium powder and molybdenum powder is dry mixing without adding any Grinding media and balls, the dry mixing time is 0.5h, and the rotation speed is 300r / min. Get a homogeneously mixed UO 2 - Be-Mo blanks.

[0034] 2) The UO obtained in step 1 2 - Be-Mo blanks are put into graphite molds for densification by spark plasma sintering, the sintering atmosphere is vacuum, the sintering temperature is 1250°C, the heating rate is 300°C / min, the holding time is 2min, and the pressure is 30MPa, The vacuum degree is 20Pa, and then the film is released. Dimensions can be processed, the microstructure such as figure 1 s...

Embodiment 3

[0037] This embodiment discloses a uranium dioxide-based fuel pellet with adjustable coefficient of thermal expansion and enhanced thermal conductivity of the present invention, specifically:

[0038]1) Add uranium dioxide raw material powder, metal beryllium powder and molybdenum powder in a volume ratio of 90:2:8, add them to a nylon tank, and wet mix them. The grinding medium is absolute ethanol. The wet mixing time is 15 hours, and the rotation speed is 220r / min; then vacuum dry to get evenly mixed UO 2 - Be-Mo blanks.

[0039] 2) The UO obtained in step 1 2 - Be-Mo billets are put into a hot-pressing mold for hot-pressing sintering, the sintering atmosphere is argon, the sintering temperature is 1280°C, the heating rate is 50°C / min, the holding time is 0.5h, and the pressure is 50MPa. Then remove the film and size processing.

[0040] After determination, the thermal conductivity of the sample prepared in this embodiment is more than 180% (800-1000° C.) of the thermal ...

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Abstract

The invention discloses a uranium dioxide-based fuel pellet with an adjustable thermal expansion coefficient and enhanced thermal conductivity, and a preparation method thereof. According to the preparation method, metal beryllium (Be) with high thermal conductivity and high thermal expansion coefficient and metal molybdenum (Mo) with high thermal conductivity and a low thermal expansion coefficient are added into a uranium dioxide pellet matrix, the component ratio of Be / Mo is regulated and controlled, the densified fuel pellet is sintered at a high temperature, so that the thermal conductivity of the uranium dioxide fuel pellet is enhanced, the thermal expansion coefficient of the uranium dioxide pellet is adjusted, the residual thermal stress of the fuel pellet is reduced, and the service cycle of the fuel pellet is prolonged so as to meet the harsh reactor work design requirements of the cladding-pellet fuel element under the normal work condition and the accident work condition ofthe reactor, improve the safety and the economy of the existing commercial pressurized water reactor, effectively delay the closing time of the air gap between the cladding and the fuel pellet underthe accident condition and delay the mechanical interaction between the fuel and the cladding to substantially improve the safety margin of the reactor under the accident condition.

Description

technical field [0001] The invention belongs to the field of reactor fission materials, and in particular relates to a uranium dioxide-based fuel pellet with an adjustable coefficient of thermal expansion and enhanced thermal conductivity and a preparation method thereof. Background technique [0002] The sudden occurrence of the Fukushima nuclear power plant accident in Japan in March 2011 made the active commercial nuclear reactor fuel element UO 2 The reliability of -Zr safety has been seriously questioned. Under the new trend of rapid development of nuclear energy and higher intrinsic safety requirements, UO 2 -Zr fuel elements can no longer meet the requirements of higher intrinsic safety of nuclear energy and the development of multi-application reactor types in the future. The sudden occurrence of the Fukushima catastrophic nuclear power accident exposed the disadvantage of the low thermal conductivity of the existing uranium dioxide fuel, that is, the hidden danger...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G21C21/02C22C29/12C22C1/05C22C1/10B22F1/00B22F3/14B22F3/105
CPCG21C21/02C22C29/12C22C1/051B22F3/14B22F3/105B22F2003/1051B22F2999/00B22F1/052B22F2201/11Y02E30/30
Inventor 程亮张鹏程严彪杰王志毅高瑞杨振亮李冰清褚明福钟毅王昀黄奇奇
Owner MATERIAL INST OF CHINA ACADEMY OF ENG PHYSICS
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