Method for preparing thorium dioxide pellets

A technology for thorium dioxide and pellets is applied in the field of preparation of thorium dioxide pellets for thorium-based fuel assemblies for nuclear reactors, which can solve the problems of difficulty in preparing thorium dioxide pellets and the like, and achieve good axial uniformity and density. The effect of high and low impurity content

Active Publication Date: 2015-03-25
CHINA NUCLEAR BAOTOU GUANGHUA CHEM IND
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  • Description
  • Claims
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AI Technical Summary

Problems solved by technology

It is difficult to prepare thorium dioxide pellets that meet the index requirements by using this process

Method used

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  • Method for preparing thorium dioxide pellets
  • Method for preparing thorium dioxide pellets

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Experimental program
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Effect test

Embodiment 1

[0040] Step 1: Take 60g of thorium dioxide powder, shape it under a pressure of 50MPa, and press it into a flaky cobalt billet.

[0041] The second step: the flaky cobalt blank obtained in the first step is crushed through a granulator. The granulator uses a stainless steel screen with a pore size of 600 μm, and vibrates in the vibrating sieve machine to screen out particles with a size between 150 and 380 μm.

[0042] Step 3: Put the prepared particles into a cemented carbide mold with a charge of 15g, pressurize the press until the forming pressure is 3000MPa, and press it into a cobalt pellet green body with a diameter of 16.20mm and a height of 19.3mm.

[0043] Step 4: Put the thorium dioxide pellet green body that has passed the surface quality inspection into an argon atmosphere sintering furnace for pellet sintering. The average heating rate is 2.8°C / min, respectively at 500°C and 800°C for 1 hour, the sintering temperature is 1650°C, and the holding time is 4 hours. Co...

Embodiment 2

[0045] Step 1: Take 70g of cobalt powder, shape it under a pressure of 100MPa, and press it into a flake-shaped cobalt billet.

[0046] The second step: crush the flake thorium dioxide blank obtained in the first step through a granulator. The granulator uses a stainless steel screen with a pore size of 600 μm, vibrates in the vibrating sieve machine, and screens out particles with a size between 150 and 380 μm. particles.

[0047] Step 3: Put the obtained particles into a cemented carbide mold with a charge of 22g, pressurize the press until the forming pressure is 400MPa, and press it into a cobalt pellet green body with a diameter of 16.2mm and a height of 20.1mm.

[0048] Step 4: Put the cobalt pellet green body that has passed the surface quality inspection into an argon atmosphere sintering furnace for pellet sintering. The average heating rate is 2.9 / min, respectively at 500°C and 800°C for 1 hour, the sintering temperature is 1700°C, the holding time is 4 hours, cooled ...

Embodiment 3

[0050] Step 1: Take 70g of thorium dioxide powder, shape it under a pressure of 85MPa, and press it into a flaky thorium dioxide billet.

[0051] Step 2: Pass the flake thorium dioxide billet prepared in the first step through a granulator to crush it. The granulator adopts a 600 μm aperture stainless steel screen and vibrates in the vibrating sieve machine to sieve out particles with a size between 150 and 380 μm. particles.

[0052] Step 3: Put the prepared particles into a cemented carbide mold with a charge of 20g, pressurize the press until the forming pressure is 350MPa, and press it into a cobalt pellet green body with a diameter of 16.20mm and a height of 20.0mm.

[0053] Step 4: Put the thorium dioxide pellet green body that has passed the surface quality inspection into an argon atmosphere sintering furnace for pellet sintering. In an argon atmosphere, the average heating rate is 3.2°C / min, respectively at 500°C and 800°C for 1 hour, the sintering temperature is 175...

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Abstract

The invention belongs to the technical field of manufacturing of nuclear fuel elements, and specifically relates to a method for preparing thorium dioxide pellets. The method comprises a powder granulating process: pressing thorium dioxide powder prepared by adopting an oxalate precipitation method and serving as an original raw material into sheets by adopting a compression molding method, crushing in a granulator, screening by a granulator screen, and shaking in a top-knocked sieve shaker to obtain granules for forming the thorium dioxide pellets; a powder molding process: performing die pressing on the granules to obtain a green blank of the pellets; and a pellet sintering process: putting the green blank of the thorium dioxide pellets into a vacuum atmosphere sintering furnace, vacuumizing, washing the furnace, then introducing argon and sintering. The cobalt pellets are prepared by adopting a powder metallurgy process, so that the difficulty of low density of the green blank of the thorium dioxide powder is overcome; and the pellets prepared by the granulating, molding and sintering processes have high density and grain size meeting the index requirements of preparation of fuel elements.

Description

technical field [0001] The invention belongs to the technical field of manufacturing nuclear fuel elements, and in particular relates to a method for preparing thorium dioxide pellets, which is specifically applied to the preparation of thorium dioxide pellets for thorium-based fuel assemblies used in nuclear reactors. Background technique [0002] With the rapid development of nuclear power, it is more and more urgent to find a material that can replace uranium as nuclear fuel. The use of uranium-thorium fuel to replace uranium fuel can effectively alleviate the shortage of uranium resources in my country. In nuclear reactors, thorium dioxide fuel rods are used to replace part of uranium dioxide fuel rods, which can be obtained by thorium absorbing neutrons and multiplying 233 U, 233 U is superior to 235 U 239 Pu's fuel. In the uranium-thorium fuel preparation process, thorium dioxide pellets are the core part of the fuel assembly, and the quality of the pellets direct...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/51C04B35/622
Inventor 任永岗陈连重李爱军杜继军田春雨刘江涛王虹马晓娟郭洪齐永良侯丽楠
Owner CHINA NUCLEAR BAOTOU GUANGHUA CHEM IND
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