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Returning recycling method for MOX fuel pellet with unqualified density

A technology of fuel pellets and recycling methods, applied in the field of nuclear-grade powder metallurgy, which can solve the problems of unqualified MOX fuel pellets, short service life of equipment, introduction of impurities, etc., to meet production efficiency and process stability, and improve sintering The effect of improving activity and specific surface area

Active Publication Date: 2019-06-28
THE 404 COMPANY LIMITED CHINA NAT NUCLEAR
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The purpose of this invention is to provide a method for recycling MOX fuel pellets with unqualified density, which can solve the problems of impurity introduction, powder flying, Problems with short device lifetimes

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0087] The raw material of the present invention is that density value is less than 10.25g / cm 3 , MOX fuel pellets with an impurity content below 300ppm.

[0088] (1) Pellet breaking: Put the MOX fuel pellets with unqualified density into the molybdenum sintering boat. The number of pellets in the boat is controlled at 5 pieces, and then put the sintering boat into the atmosphere control furnace. Evacuate the air pressure in the furnace to 0.01Pa, and feed O at a speed of 1.0L / min. 2 , the air pressure was kept at 5KPa, and the above operation was repeated 3 times. Raise the temperature in the furnace at a rate of 30°C / min, keep it at 400°C for 0.5h, keep the air pressure at 5KPa, and control the gas flow rate at 0.5L / min. After the heat preservation is over, the temperature is lowered to 20°C at a rate of 20°C / min, and the powder is transferred out of the atmosphere controlled furnace. The particle size of the powder is 2.5μm, and the specific surface area is 0.8m 2 / g, t...

Embodiment 2

[0094] The raw material of the present invention is that density value is less than 10.25g / cm 3 , MOX fuel pellets with an impurity content below 300ppm.

[0095] (1) Pellet breaking: put the MOX fuel pellets with unqualified density into the molybdenum sintering boat, the number of pellets in the boat is controlled at 150, and then put the sintering boat into the atmosphere control furnace. Pump the air pressure in the furnace to 1.5Pa, and feed O at a speed of 3.5L / min. 2 , the air pressure was kept at 10KPa, and the above operation was repeated 10 times. The temperature in the furnace was raised at a rate of 7.5°C / min, and kept at 800°C for 8.5 hours, the air pressure was maintained at 7KPa, and the gas flow rate was controlled at 10L / min. After the heat preservation is over, the temperature is lowered to 30°C at a rate of 10°C / min, and the powder is transferred out of the atmosphere controlled furnace. The particle size of the powder is 2.0μm, and the specific surface a...

Embodiment 3

[0101] The raw material of the present invention is that density value is less than 10.25g / cm 3 , MOX fuel pellets with an impurity content below 300ppm.

[0102] (1) Pellet breaking: Put the MOX fuel pellets with unqualified density into the molybdenum sintering boat. The number of pellets in the boat is controlled at 300 pieces, and then put the sintering boat into the atmosphere control furnace. Pump the air pressure in the furnace to 3Pa, and feed O at a speed of 10.0L / min. 2 , the air pressure was kept at 15KPa, and the above operation was repeated 15 times. The temperature in the furnace was raised at a rate of 0.5°C / min, and kept at 1200°C for 12 hours, the air pressure was maintained at 10KPa, and the gas flow rate was controlled at 18L / min. After the heat preservation is over, the temperature is lowered to 40°C at a rate of 1°C / min, and the powder is transferred out of the atmosphere controlled furnace. The powder particle size is 1.0μm, and the specific surface ar...

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Abstract

The invention belongs to the technical field of nuclear grade powder metallurgy and particularly relates to a returning recycling method for an MOX fuel pellet with unqualified density. The process ofthe method comprises the steps of selecting materials, preparing powder, adjusting the oxygen metal proportion of the powder, carrying out passivating treatment on the powder, modifying the powder, and judging whether powder meet the requirement. By utilizing the process, the particle size of a prepared MOX recycled powder product is 0.5-0.9 micron, the specific surface area is 5-15m<2> / g, the tap density is 2.0g / cm<3>-3.0g / cm<3>, the apparent density is 1.8g / cm<3>-2.2g / cm<3>, O / M is 2.0-2.1, and the impurity content is lower than 600ppm; the introduction amount of impurity in the returning recycling process of the pellet is well controlled, the serious powder flying phenomenon is avoided, the specific surface area of the processed powder is remarkably increased, and the sintering activity of the powder is effectively improved.

Description

technical field [0001] The invention belongs to the technical field of nuclear-grade powder metallurgy, and in particular relates to a technology for recycling and reusing unqualified nuclear-grade powder metallurgy products. Background technique [0002] During the development of MOX fuel pellets, due to the unsatisfactory treatment effects of granulation, pressing, sintering and other process steps, the density of some MOX fuel pellet products was unqualified. In order to improve the utilization rate of precious nuclear resources such as uranium and plutonium, and reduce the inventory pressure of unqualified pellets, it is necessary to recycle the MOX fuel pellets with unqualified density. [0003] At present, in the traditional field of powder metallurgy, the method of mechanical crushing is mainly used to deal with the products with unqualified density. This method has the following three disadvantages: 1. The unqualified products will introduce impurities during the cru...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G21F9/30G21F9/28
Inventor 杨廷贵张顺孝朱桐宇张万德郭亮田志强罗超
Owner THE 404 COMPANY LIMITED CHINA NAT NUCLEAR
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