JPS62222195A - Method and device for manufacturing spherical nuclear fuel particle - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method and apparatus for producing spherical nuclear fuel particles. The present invention relates to a method and apparatus for producing nuclear fuel particles.

[Prior art and its issues] A gelation precipitation method has been known as a method for producing spherical nuclear fuel particles. In this method, a thickener is added to an acidic solution of metals such as uranium, thorium, and plutonium (hereinafter sometimes referred to as the stock solution), and this stock solution is mixed with aqueous ammonia stored in a reaction tank for 311 The particles are added dropwise to a liquid medium (hereinafter sometimes referred to as reaction liquid), and while reacting with the reaction liquid, they are allowed to settle in the reaction liquid to obtain spherical particles.

However, in the method described in ``2'', the reaction tank is simply a cylindrical body, and the stock solution is simply dropped into the reaction liquid in the reaction tank, and the stock solution falls and settles in the reaction liquid. The falling speed is fast, and the dropping method of the stock solution causes the reaction to proceed rapidly on the lower surface of the sphere, causing distortion on the upper and lower surfaces of the sphere, making it difficult to obtain spherical particles with satisfactory strength and sphericity. There was a problem.

Therefore, a method that is an improvement on the above method has also been proposed. That is, a method of circulating a reaction liquid to generate convection of particles, a method of blowing air or an inert gas into the reaction liquid to generate convection of particles by bubbles, and thereby controlling the reaction rate of one particle, and This method involves improving the strength, sphericity, etc. of spherical particles to some extent by imparting rotation to the particles.

However, with this type of method, it is difficult to control convection, it is difficult to generate uniform convection over the entire particle, it is therefore difficult to obtain uniform spherical particles over the entire particle, and particles are separated from each other during convection. There were problems such as damage due to collision and loss of strength and α law.

[Purpose of the invention] This invention has been made based on the above-mentioned circumstances.

That is, an object of the present invention is to provide a method and apparatus for producing nuclear fuel particles that can obtain uniform nuclear fuel particles having excellent strength, sphericity, etc., and excellent physical and chemical properties.

[Means for Achieving the Object J] The first aspect of the invention for achieving the above object is characterized in that a nuclear fuel solution is produced by dropping a nuclear fuel solution into a liquid medium housed in a reaction tank having a downwardly inclined plate-shaped body. The second invention is a method for producing spherical nuclear fuel particles in which the dropping method is carried out by rolling and dropping the plate-shaped body, and the gist of the second invention is that the dropping method is performed by rolling and dropping the plate-shaped body. A plate-shaped body inclined toward the center is provided, a liquid medium inlet is provided at the lower part of the reaction tank, a liquid medium outlet is provided at the upper part, a nuclear fuel particle outlet is provided at the bottom of the reaction tank, and the liquid medium is provided at the bottom of the reaction tank. A nuclear fuel solution is introduced from a medium inlet and dropped into a liquid medium stored in a reaction tank, and the nuclear fuel solution is rolled and dropped on the plate-like body to form nuclear fuel particles. This is a spherical nuclear fuel particle manufacturing apparatus characterized in that nuclear fuel particles are taken out from a nuclear fuel particle outlet.

The basic principle of the method and device of the present invention is that a nuclear fuel solution is dropped into a liquid medium, and a tilting plate member provided in the liquid medium is rolled. The principle is to apply rotation to the dropping method to form spherical nuclear fuel particles with high sphericity, uniformity, and poor physical and chemical properties.

Therefore, the method and device R of the present invention can be applied to conventional methods for producing spherical nuclear fuel material by dropping a liquid material containing fuel nuclear material into a liquid medium to form a drip method. .

For example, it can be applied to a method of producing spherical nuclear fuel material by an internal gelation method.

When applied to the internal gelation method, examples of the nuclear fuel solution include a mixed solution of uranyl nitrate and urea, a uranyl nitrate solution, and the like.

However, since the method and apparatus of the present invention are not limited to application to the internal germinating method, the nuclear fuel solution may include a metal acid solution such as plutonium or thorium, an oxide of plutonium or thorium, resorcinol, formaldehyde, etc. A mixed liquid can also be mentioned.

The nuclear fuel solution may contain a thickener, and specific examples of the thickener include hexamethylenetetramine, cellulose compounds, alcohols, glycerin, glycols, and other heterocyclic alcohols TI5.

The nuclear fuel solution is dripped into the liquid medium to form a drip method in the liquid medium.

In the internal gelation method, the liquid medium includes, for example, paraffin oil, ammonia solution, a mixed solution of ammonia, ammonium chloride, and polyethylene glycol, water-soluble carboxylic acid, dicarboxylic acid, oxycarboxylic acid, dioxycarboxylic acid, etc. addition of carvone@-derived compounds.

The downwardly inclined plate-shaped body is disposed such that its upper surface is submerged in the liquid medium so that the nuclear fuel solution rolls and falls.

This plate-shaped body may have any shape as long as it can roll and fall in the dripping method, but it may be formed integrally with a rotatable rotary shaft placed in the center of the reaction tank. Such a rotor, which is preferably a helical rotating hole, can change the falling speed and rolling state of the dripping method by changing the rotational speed or direction of the rotor. The urg can be controlled during contact with the liquid medium, and at the same time the liquid medium is stirred, so when the liquid medium contains a specific component, the concentration can be kept constant and the concentration of the liquid medium can be kept constant. It is.

As the inclined plate-like body, for example, a plurality of plate-like bodies may be provided outside the rotary blade, and the inclination direction of each plate-like body may change in a zigzag manner.

In this case, a gap is provided between the inclined end of each plate-shaped body and the inner wall of the reaction tank, and the dripping method that rolls and falls on the plate-shaped body is applied to the next plate-shaped body located further below from this gap. It is supposed to fall.

When the plate-like bodies are formed in the manner described above, a droplet sphere rolls on a plurality of plate-like bodies, thereby forming spherical particles with high nacreousness.

Spherical nuclear fuel particles produced by the production method and apparatus of the present invention include ammonium deuterate, thorium hydroxide, thorium oxide, plutonium hydroxide, plutonium oxide, and mixtures of one or two or three thereof. Yes, the strength of the outer shell of the particles formed is high,
It has a high degree of nacre.

The spherical particles obtained by the method and mounting of the present invention can be used as oxides, carbides, etc. by operations such as roasting and sintering.

[Example] Hereinafter, an example of the manufacturing apparatus of the present invention will be described together with the method of the present invention with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a reaction tank, and the reaction tank 1 has a substantially cylindrical shape with a funnel-shaped lower part and is made of transparent plastic with an acrylic resin subside. A liquid medium inlet 2 is provided on the lower side wall of the leakage/trough-shaped portion of the reaction tank 1, and a liquid medium outlet 3 is provided on the upper side wall of the reaction tank 1.
A liquid medium is introduced into the reaction tank l from the liquid medium outlet 3.
The liquid medium is allowed to overflow.

In addition, the frontage of section E of reaction tank 1 is blocked by 4 bodies 4,
This lid body 4 is provided with a large number of nuclear fuel solution dripping ports 5 at appropriate intervals, and the bottom of the funnel-shaped portion is provided with a spherical particle outlet 6, which is an abbreviation of the zero reaction tank 1 that can be opened and closed by a valve 7 or the like. 4 bodies 4 in the center! [A rotary shaft 8 is provided which extends downward to an appropriate position in the reaction tank l, and a vertical cross section is provided on the outer periphery of the rotary shaft 8 which can be rotated by an appropriate motor. A spiral rotor blade 9 inclined #2 toward the axis 8 is integrally provided. The edge of this rotary blade 9 extends to the vicinity of the inner wall of the reaction tank 1, and the edge of the rotary blade 9 extends to the vicinity of the inner wall of the reaction tank 1.
It has an i-curved inverted water shape, and the mounting angle to the rotating shaft is 10 to 30 degrees, preferably 13 to 17 degrees. The length of one rotor blade 9 in the lateral direction is also the rotation χ9
The pitch of the rotation axis 8 can be selected arbitrarily.
A shielding plate 10 is provided near the lower end of the shield plate 10 so as to extend laterally from the inner wall. This shielding plate IO not only smoothes the convection of the liquid medium but also has the function of keeping the surface condition of the solution constant.

Next, a method for producing spherical nuclear fuel particles using the above production apparatus will be explained.

First, a liquid medium is introduced into the reaction tank 1 from the liquid medium inlet 2 to fill the inside of the reaction tank 1.Next, the rotating shaft 8 is rotated at a rotation speed commensurate with the reaction speed.Next, the nuclear fuel solution is dropped at an appropriate rate. The nuclear fuel solution is dripped from the nuclear fuel solution dripping port 5. In the dropping method 11 of the nuclear fuel solution, the solution enters the liquid medium and falls onto the surface of the first rotor blade 9, and reacts with the liquid medium while rolling on the upper surface. A constant amount of the liquid medium is supplied and discharged by keeping the liquid medium discharge port 3 open, and in combination with the stirring effect caused by the rotation of the rotary blade 9, the concentration of the liquid medium is kept constant.
1 becomes spherical particles and falls from the bottom end of the rotary blade 9, collects at the bottom of the reaction tank 1, and is ripened.

By controlling the rotational speed of the rotary blade 9 appropriately, the residence time of the dripping method 11 rolling on the rotary blade 9 can be adjusted, and the rolling improves the sphericity of the dripping method 11. At the same time, by adjusting the residence time, it is possible to improve the strength of the outer coating formed on the surface of the dripping sphere II. As a result, uniform spherical nuclear fuel particles with a strong outer shell and high sphericity can be obtained.

Next, FIG. 2 shows another embodiment of the manufacturing apparatus according to the present invention.

In this embodiment, instead of the rotating shaft and spiral rotor of the previous embodiment, a plurality of flat plates 12 extending from the side wall at a slight downward inclination are arranged so that the directions of inclination are alternate. The nuclear fuel solution was placed in a row vertically, and a gap large enough for the dropping method 11 to pass through was provided between the inclined lower end of each flat plate [2] and the inner wall of the reaction tank. It falls along the flat plate 12 while rolling from above to below.

(Example 1) A liquid medium consisting of 9N ammonia, 4N ammonium chloride, and polyethylene glycol was filled into a reaction tank in which the following operations were performed using the production apparatus shown in FIG. 1, and circulated. While rotating the rotor at a speed of 12 times/min, a uranyl nitrate solution (450 gU/liter) was dropped into the liquid medium,
Spherical nuclear fuel particles were obtained by reacting with the liquid medium. The average particle diameter of the obtained spherical particles is 1.8 mm. In addition, the spherical particles obtained by this manufacturing device have 55% less particle damage and poor sphericity than those obtained by conventional methods.
This was a 0% decrease.

Then, when the spherical particles were roasted and sintered at 45Q°C, the breakage rate was 20% lower than that of the conventional method.

[Effects of the Invention] As described above, the present invention can provide a manufacturing method and a manufacturing apparatus that can obtain uniform spherical nuclear fuel particles with high strength, good sphericity, and little breakage.

[Brief explanation of drawings]

FIG. 1 is an explanatory sectional view showing an example of the manufacturing apparatus of the present invention, and FIG. 2 is an explanatory longitudinal sectional view showing another embodiment of the manufacturing apparatus of the invention. l...Reaction tank, 2...Liquid medium inlet, 3...Liquid medium outlet, 5...Nuclear fuel solution dripping [-1, 6...Nuclear fuel particle outlet, 9...Rotation Wings. Figure 1 Figure 2

Claims (8)

[Claims] (1) A spherical nuclear fuel characterized in that a dropping sphere produced by dropping a nuclear fuel solution into a liquid medium housed in a reaction tank having a plate-like body tilted downward is caused to roll and fall on the plate-like body. Method of manufacturing particles. (2) The method for producing spherical nuclear fuel particles according to claim 1, wherein the nuclear fuel solution is a metal acid solution of uranium. (3) The method for producing spherical nuclear fuel particles according to claim 1 or 2, wherein the nuclear fuel solution contains a thickener. (4) The method for producing spherical nuclear fuel particles according to any one of claims 1 to 3, wherein the main component of the liquid medium is ammonia water. (5) The method for producing spherical nuclear fuel particles according to claim 1 or 4, in which the liquid medium is circulated. (6) In the cylindrical reaction tank, a plate-like body is provided that slopes from the inner wall of the reaction tank toward the center, and a liquid medium inlet is provided at the bottom of the reaction tank, and a liquid medium outlet is provided at the top. A nuclear fuel particle outlet is provided at the bottom of the reaction tank, a nuclear fuel solution is introduced from the liquid medium inlet, and is dropped into the liquid medium stored in the reaction tank, and the dropping sphere of the nuclear fuel solution is placed in the plate shape. A spherical nuclear fuel particle production device characterized by forming nuclear fuel particles by rolling and falling on a body, and taking out the obtained nuclear fuel particles from a nuclear fuel particle outlet. (7) The spherical nuclear fuel particles according to claim 6, wherein the plate-shaped body is a spiral rotor blade provided on a rotating shaft extending vertically in the center of the reaction tank. Manufacturing equipment. (8) The apparatus for producing spherical nuclear fuel particles according to claim 7, wherein a plurality of the plate-like bodies are provided so that the inclination direction of each plate-like body changes in a zigzag manner.