Preparation method of thorium-uranium mixed oxide ceramic microspheres

A technology of mixed oxides and ceramic microspheres, which is used in the manufacture of reactors, nuclear power generation, climate sustainability, etc. smooth surface effect

Active Publication Date: 2013-06-19
NUCLEAR POWER INSTITUTE OF CHINA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method is conducive to the preparation of (Th,U)O2 microspheres with good surface quality, but this sol preparation method is prone to precipitation when the uranium content is high
Shigeru YAMAGISHI of the Japan Atomic Energy Research Institute and H. Tel of the School of Atomic Energy Sciences of Ege University in Turkey wrote "Production of (Th, U)O2 Microspheres with Uranium Content of 0~35% by Sol-Gel Process Using CCl4 as Gelation Media” and Journal of Nuclear Materials 256 (1998) Neutralization of thorium-uranium with aqueous ammonia is described in "Investigation of production conditions of ThO2-UO3 microspheres via the sol-gel process for pellet type fuels" on 18-24 ThO2-UO3 sol was obtained by mixing nitrate solution, and gel microspheres were prepared by external gelation method, but the preparation method of this sol was complicated and difficult to control

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0033] Step 1 Sol preparation process ： Take acid-deficient uranyl nitrate solution ([U]=630g / l, NO 3 — / U molar ratio = 1.80) 39.3ml, add thorium nitrate (Th(NO 3 ) 4 4H 2 O) 6.4g (Th / (Th+U)=0.1); after the thorium nitrate is dissolved, add deionized water to a solution volume of 50ml; cool the mixed solution to 0°C-5°C, slowly add 9.0g Urea and 21.0g HMTA (Urea, HMTA / U molar ratio = 1.3), stirring while adding, to obtain a uniform and transparent sol;

[0034] Step 2 Dispersion gelling process ： Disperse the obtained sol with a dispersing head with a pore size of 0.2mm, and the dispersed sol is dropped into the 2-ethylhexanol gelling medium at 60°C to prepare wet gel microspheres;

[0035] Step three washing process ： The gel microspheres were washed 4 times with 0.5mol / l ammonia water containing 50vol% ethanol for 20min each time,

[0036] Step 4 Drying and calcination process ： Add 1000ml of water into the drying calciner, and then put the washed gel balls into th...

Embodiment 2

[0039] Step 1 Sol preparation process ： Take acid-deficient uranyl nitrate solution ([U]=610g / l, NO 3 — / U molar ratio = 1.60) 31.5ml, add thorium nitrate (Th(NO 3 ) 4 4H 2 O) 19.1g (Th / (Th+U)=0.3), after the thorium nitrate is dissolved, add deionized water until the volume of the solution is 50ml, then cool the mixed solution to 0°C-5°C, slowly add 10.4g Urea and 29.9 g HMTA (Urea / (U+Th) molar ratio = 1.5, HMTA / (U+Th) molar ratio = 1.85), stirring while adding, to obtain a uniform and transparent sol;

[0040] Step 2 Dispersion gelling process ： Disperse the obtained sol with a dispersing head with a pore size of 0.2mm, and the dispersed sol drops into the 2-ethylhexanol gelling medium at 75°C to prepare wet gel microspheres;

[0041] Step three washing process ： The gel microspheres were washed 3 times with 0.5 mol / l ammonia water containing 50vol% ethanol for 40 min each time;

[0042] Step 4 Drying and calcination process ： Add 1500ml of water into the drying cal...

Embodiment 3

[0045] Step 1 Sol preparation process ： Take acid-deficient uranyl nitrate solution ([U]=620g / l, NO 3 — / U molar ratio = 1.50) 22.1ml, add thorium nitrate (Th(NO 3 ) 4 4H 2 O) 31.9g (Th / (Th+U)=0.5), after the thorium nitrate is dissolved, add deionized water to a solution volume of 50ml, cool the mixed solution to 0°C-5°C, slowly add 12.5g Urea and 35.6g HMTA ( / (U+Th) molar ratio = 1.8, Urea, HMTA / (U+Th) molar ratio = 2.2), stirring while adding, to obtain a uniform and transparent sol;

[0046] Step 2 Dispersion and gelation process: Disperse the obtained sol with a dispersing head with a pore size of 0.2mm, and drop the sol formed by sol dispersion into the 2-ethylhexanol gelation medium at 95°C to prepare wet gel microspheres;

[0047] Step three washing process ： The gel microspheres were washed 4 times with 0.5mol / l ammonia water containing 50vol% ethanol, 50min each time;

[0048] Step 4 Drying and calcination process ： Add 2000 ℃ of water into the drying calcine...

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Abstract

The invention belongs to a preparation method of nuclear fuel, and concretely relates to a preparation method of thorium-uranium mixed oxide ceramic microspheres. The method uses an internal gelation method, and comprises using an acid-lacking uranyl nitrate solution and thorium nitrate as raw materials, preparing sol, dispersing gelling, washing, drying, calcining and reduction sintering to prepare ThO2-UO2 microspheres with a diameter of 0.05-0.20 mm. The ThO2-UO2 microspheres has outstanding advantages of smooth surface, good sphericity, compact inside, uniformly distributed thorium, and a density being greater than 96.8% TD; and the method is simple, and can prepare the thorium-uranium mixed oxide ceramic microspheres with different thorium contents.

Description

technical field [0001] The invention belongs to a method for manufacturing nuclear fuel, in particular to a method for preparing thorium-uranium mixed oxide ceramic microspheres. Background technique [0002] Since the neutron absorption cross section of thorium fuel is three times that of uranium fuel, the conversion efficiency of thorium in thermal neutron piles is higher than that of uranium fuel. 238 U high, while uranium fuel is added 232 Th, which is equivalent to adding burnable poison, can load more fuel under the same stack control level, thereby prolonging the life of the core. The use of thorium fuel can also flatten the radial power distribution of the core, thus making the reactivity control easy. Therefore, using (Th,U)O 2 Ceramic fuel is one of the effective ways to prolong the life of reactor core. [0003] For the preparation of thorium-uranium mixed oxide ceramic microspheres, the sol-gel method is mainly used abroad. The early preparation of thorium-u...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G21C21/02C04B35/01C04B35/624
CPCY02E30/30
Inventor 尹荣才刘小龙左国平卢长先
Owner NUCLEAR POWER INSTITUTE OF CHINA
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