JP4321859B2 - HTGR fuel particle manufacturing apparatus and method - Google Patents

Description

  The present invention relates to an apparatus and a method for manufacturing fuel particles for coated fuel particles that constitute, for example, a fuel loaded in a HTGR.

  High temperature gas reactors have inherent safety by using a gas coolant that does not cause chemical reactions even at high temperatures, such as helium, which is formed of graphite with a large heat capacity and good high temperature integrity. It is a high-temperature reactor that can extract gas coolant with a high outlet temperature, and the high-temperature heat of about 900 ° C can be used not only for power generation but also for hydrogen production and chemical plants. To do.

  In such a high temperature gas furnace, a graphite molded article in which granular fuel is embedded is used as a fuel element. This fuel is usually coated fuel particles formed by forming a plurality of coating layers on the outer surface of fuel particles having a diameter of about 350 to 650 μm obtained by sintering uranium dioxide into a ceramic form.

For example, a low density pyrolytic carbon layer having a density of about 1 g / cm ³ is formed as the first coating layer, a high density pyrolytic carbon layer having a density of about 1.8 g / cm ³ is formed as the second coating layer, A total of four coating layers, in which a silicon carbide (SiC) layer having a density of about 3.2 g / cm ³ is formed as the ^three coating layers, and a high-density pyrolytic carbon layer having a density of about 1.8 g / cm ³ is formed as the fourth coating layer. What has been applied is common.

  The first coating layer has both a function as a gas stopper for the gaseous fission product and a function as a buffer part for absorbing deformation of the fuel particles. The second coating layer has a function of holding gaseous fission products, and the third coating layer has a function of holding solid fission products, and is a main strength member of the coating layer. The fourth coating layer has a function as a protective layer of the third coating layer as well as the function of holding the gaseous fission product similar to the second coating layer.

  The diameter of a typical coated fuel particle as described above is about 500-1000 μm. The coated fuel particles are dispersed in a graphite base material and formed into a compact fuel compact shape. Further, a fixed amount of the compact is put into a graphite tube, and the fuel rod is plugged up and down. Finally, the fuel rod is inserted into a plurality of insertion holes of the hexagonal column type graphite block, and a large number of the hexagonal column type graphite blocks are stacked in a honeycomb array to constitute a core.

  In addition, in the production of fuel particles that are formed as coating fuel particles by forming a coating layer, an external gelation method that obtains gel-like particles by vibration dropping is used as a method capable of mass formation (for example, patents). Reference 1).

  Specifically, first, a powder of uranium oxide is dissolved in nitric acid to obtain a uranyl nitrate stock solution, and pure water and additives are added to the uranyl nitrate stock solution and stirred to obtain a dripping stock solution. The additive is a thickening agent that causes the dripped uranyl nitrate droplet to become spherical due to its surface tension during dropping, and at the same time is added to cause the stock solution to gel by contact with ammonium. Examples thereof include polyvinyl alcohol resins, resins having a property of gelation under alkaline conditions, polyethylene glycol, and metroses.

  The dropping stock solution prepared as described above is cooled to a predetermined temperature, adjusted in viscosity, and then dropped into an aqueous ammonia solution by vibrating a small-diameter dropping nozzle. The undiluted solution that has entered the aqueous ammonia solution as droplets is allowed to react sufficiently with the ammonia uranyl nitrate, and at the same time the additive is gelled to form gel-like particles containing ammonium heavy uranate (ADU).

  In addition to the above external gelation method, ADU gel particles can also be obtained by an internal gelation method. In this internal gelation method, an ammonia donor such as hexamethylenetetramine, that is, a chemical substance that decomposes by heating to generate ammonia is added to the dropping stock solution, and the stock solution is heated to about 100 ° C. paraffin. By dropping it into a liquid tank of oil, silicon oil or the like, a gelation reaction is caused from the inside of the liquid droplet by heating in the liquid tank to form gel particles.

  The ADU gel particles obtained by the gelation method as described above are roasted in the atmosphere, removed moisture and additives to become uranium trioxide particles, and further reduced and sintered to obtain high-density ceramics. Spherical fuel particles made of uranium dioxide.

Furthermore, as a manufacturing process of the coated fuel particles using the fuel particles, there is a method in which the fuel particles are loaded on a fluidized bed and coated by thermally decomposing the coating gas. For example, in the case of the low-density carbon layer of the first coating layer, acetylene (C ₂ H ₂ ) is thermally decomposed at about 1400 ° C., and the high-density pyrolytic carbon layer of the second and fourth coating layers. Is carried out by thermally decomposing propylene (C ₃ H ₆ ) at about 1400 ° C. In the case of the SiC layer of the third coating layer, methyltrichlorosilane (CH ₃ SiCl ₃ ) is thermally decomposed and coated at about 1600 ° C.

  A general fuel compact is obtained by press-molding or molding coated fuel particles into a hollow cylindrical shape or a cylindrical shape together with a graphite matrix material made of graphite powder, a binder, and the like, and then firing.

JP-A-9-127291 (FIG. 7)

  However, in the fuel particle manufacturing method using the external gelation method or the internal gelation method by vibration dropping as described above, the dripping stock solution is dropped at the time of a liquid surface collision when dropped into an aqueous ammonia solution or paraffin oil. Most of the liquid droplets were deformed by the impact, resulting in gelled particles in the deformed state. As a result, only fuel particles with poor sphericity were obtained.

  Therefore, as a means to prevent such deformation, the concentration of the uranyl nitrate solution is adjusted to give strength to withstand the impact when colliding with the ammonia aqueous solution surface, or the dropping distance to the ammonia aqueous solution surface is reduced to reduce the impact. It was considered to reduce the force and to reduce the droplet diameter.

  However, even when the concentration of the uranyl nitrate solution is adjusted, the strength to completely resist the impact at the time of dropping cannot be obtained, and a perfect spherical shape cannot be maintained, and the sphericity is not so good. Only material was obtained.

  In addition, when the distance between the ammonia aqueous solution surface and the dropping start position is shortened, it is due to the surface tension during dropping that the droplet is originally made spherical, so that the droplet has a good sphericity. However, even if it is not possible to secure the necessary falling distance and the impact of landing can be reduced, a substance with a very high sphericity cannot be obtained as a result. Furthermore, when the dropping device is close to the ammonia generation source, a gelation reaction of the stock solution may occur inside the device, and the dropping may be hindered.

  In addition, the method of dropping the droplets with a small droplet diameter has no problem as long as the target fuel particle size is commensurate with it, but it cannot be applied otherwise. As described above, it has been difficult to obtain fuel particles with good sphericity by the conventional external gelation method.

  In view of the above problems, the object of the present invention is that the formation of ADU gel particles using the external gelation method or the internal gelation method is unlikely to cause deformation of the droplet at the time of collision with the drop liquid surface. An object of the present invention is to provide an apparatus and a method for producing fuel particles for a HTGR capable of producing fuel particles with good sphericity.

In order to achieve the above object, an apparatus for producing fuel particles for a HTGR according to the invention described in claim 1 is prepared from an aqueous solution containing an additive that undergoes a gelling reaction upon contact with ammonia, and a uranyl nitrate solution. For a high temperature gas furnace comprising: a dropping means for dropping a dropping stock solution from a nozzle; and a liquid tank for receiving the droplets dropped from the nozzle to cause the gelation reaction and gelling the droplets In the fuel particle manufacturing apparatus,
A droplet surface gelling means for bringing ammonia into contact with the droplet in the middle of a dropping path until the droplet dropped from the nozzle reaches the liquid level of the liquid tank ;
The droplet surface gelling means includes:
An ammonia injection nozzle mechanism that sprays ammonia from a substantially horizontal direction on a falling droplet;
An exhaust mechanism that is provided at an opposed position across the drop path of the droplet with respect to the ammonia injection nozzle, and exhausts an ammonia stream that is injected from the ammonia injection nozzle and exceeds the drop path;
An air curtain-like ammonia flow is forcibly formed between the ammonia injection nozzle and the exhaust mechanism immediately above the upper surface opening of the liquid tank .

Method for producing a high-temperature gas reactor fuel particles according to the invention of claim 2 are those in the manufacturing apparatus of HTGR Fuel particles according to claim 1, wherein the liquid tank houses aqueous ammonia It is.

The method for producing fuel particles for a HTGR according to the invention described in claim 3 is the method for producing fuel particles for a HTGR according to claim 2 , wherein the ammonia provided on the ammonia aqueous solution surface of the liquid tank. The ammonia injection nozzle mechanism and the exhaust mechanism are further disposed above the ammonia filling region.

A high temperature gas reactor fuel particle manufacturing apparatus according to a fourth aspect of the present invention is the high temperature gas reactor fuel particle manufacturing apparatus according to the first aspect , wherein the dripping stock solution generates an ammonia donor by heating. In addition, the liquid tank contains a heating liquid heated to a predetermined temperature.

The method for producing fuel particles for a HTGR according to claim 5 is a stock solution preparation for obtaining a drop stock solution prepared from an aqueous solution containing an additive that undergoes a gelation reaction upon contact with ammonia and a uranyl nitrate solution. A droplet forming step of dropping the stock solution from a nozzle toward a lower liquid tank to form spherical droplets of the dripped stock solution, and gelling the droplet in the liquid tank to form a gel-like heavy uranium In a method for producing fuel particles for a HTGR comprising a solidification step for forming ammonium acid particles,
For the spherical liquid droplets formed in the liquid droplet forming step, the liquid droplet surface gelation step is brought into contact with ammonia before reaching the liquid surface of the liquid tank,
The droplet surface gelation step includes a step of spraying ammonia from an ammonia injection nozzle to a droplet that is falling and a step of sucking an ammonia air stream that has passed the drop route from an exhaust mechanism at a position opposite to the drop route. The air curtain-like ammonia flow is forcibly formed between the injection nozzle and the exhaust mechanism immediately above the upper surface opening of the liquid tank .

The method for producing fuel particles for a HTGR according to claim 6 is the method for producing fuel particles for a HTGR according to claim 5 , wherein the droplet surface gelation step is performed by spraying the ammonia. The method further includes a step of passing the ammonia-filled region later.

  According to the production apparatus of the present invention, a droplet in which a dropping stock solution containing an additive as a gelling aid and a uranyl nitrate solution is dropped from the nozzle of the dropping means causes a gelation reaction in the dropping stock solution to form a droplet. Since the liquid droplet surface gelling means for bringing ammonia into contact with the droplet in the middle of the dropping path until reaching the liquid surface of the liquid tank for gel particle formation, the droplet is brought into contact with the aqueous ammonia surface by the means. Since the gelation reaction is advanced by contact with ammonia from the surface until reaching the point, a gel layer is formed on the outer surface of the droplet, and the true spherical shape of the droplet is fixed to some extent by this gel layer. Therefore, deformation of the droplets can be suppressed even by impact at the time of collision with the liquid surface, and the true spherical shape can be maintained and the liquid tank can be entered while the gelling reaction is completed in the liquid tank. It becomes an effective gel-like ammonium heavy uranate particle (ADU gel particle), and has an effect that fuel particles finally obtained can have a good sphericity.

  Further, according to the production method of the present invention, spherical droplets formed in a droplet forming step of dropping a dropping stock solution containing an additive as a gelling aid and a uranyl nitrate solution from a nozzle toward a lower liquid tank. On the other hand, since the droplet surface gelation step is performed to contact the ammonia before reaching the liquid level of the liquid tank, the liquid is brought into contact with the ammonia until the liquid level of the liquid tank is reached in the step. Since the gelation reaction can proceed from the surface to the droplet to form a gel layer on the outer surface, the true spherical shape of the droplet can be fixed to some extent by this gel layer. Therefore, when the liquid collides with the liquid surface, the deformation due to the impact of the droplets is suppressed and the spherical shape is maintained and the liquid tank enters the liquid tank. As a result, fuel particles having a good sphericity can be produced.

  In the method for producing fuel particles for a HTGR according to the present invention, a dripping stock solution prepared from an aqueous solution containing an additive that undergoes a gelation reaction upon contact with ammonia and a uranyl nitrate solution in a stock solution preparation step is used as a droplet. In the forming process, it drops from the nozzle toward the lower liquid tank to form spherical droplets of the stock solution. As the droplet surface gelation process, before reaching the liquid level of the liquid tank with respect to the spherical droplets Since the spherical droplets are brought into contact with ammonia, the gelation reaction proceeds on the surface by contact with the ammonia, and a gel layer is formed on the outer surface of the droplets.

  Therefore, since the formed gel layer fixes the spherical shape close to the true sphere of the droplet as the outer shell, the droplet remains in the spherical shape and the liquid does not deform due to the impact at the collision with the liquid surface. In the liquid in the tank, in the coagulation process, in the case of the external gelation method, in the liquid tank containing the aqueous ammonia solution, and in the case of the internal gelation method, the dripping stock solution contains an ammonia donor. For example, in a liquid bath of paraffin oil or silicon oil heated to about 100 ° C., gelled ammonium heavy uranate particles (hereinafter referred to as ADU gel particles) that are completely gelated to the center of the droplet and have a good sphericity. Will be formed). Fuel particles with good sphericity are produced from the ADU gel particles with good sphericity obtained in this manner through a predetermined process such as a subsequent heat treatment step.

  In addition, droplets whose spherical shape is fixed by the outer surface gel layer as the outer shell before reaching the liquid level of the liquid tank as described above settles in the liquid tank more quickly than if they landed as liquid droplets. Therefore, even if a large number of droplets are dropped into the aqueous ammonia solution one after another by vibration dripping, even if the droplets are in contact with each other, it is difficult to bond with each other. The amount of particles is reduced, and as a result, ADU gel particles having a uniform particle size can be obtained.

  In addition, as a droplet surface gelatinization process, the method of spraying ammonia with respect to the droplet which is falling, for example is mentioned as a suitable method which contacts ammonia to the whole surface of a droplet efficiently in a short time.

  In addition, the longer the contact time of ammonia with the falling droplet, the more reliable the formation of the gel layer on the outer surface of the droplet, and the thicker the gel layer, the stronger the outer shell, Since the effect of maintaining a true spherical shape becomes higher with respect to the impact at the time of collision with the ammonia aqueous solution surface, in addition to the above-described ammonia spraying, if a step of passing the ammonia-filled region is further provided, the liquid will be more liquid. It is desirable that the true spherical shape of the droplet is fixed.

  As a manufacturing apparatus capable of realizing the above manufacturing method, a dropping stock solution prepared from an aqueous solution containing an additive that undergoes a gelation reaction upon contact with ammonia and a uranyl nitrate solution is placed on the liquid tank in a dropping means. Droplet surface gelling means for dropping ammonia from the positioned nozzle to the liquid tank and bringing the droplet into contact with ammonia in the middle of the dropping path until the liquid droplet dropped from the nozzle reaches the liquid level of the liquid tank; Just do it. It should be noted that the ammonia contact start position on the droplet by the droplet surface gelling means is a position that can secure a drop distance at which a true sphere is sufficiently formed by the surface tension of the droplet dropped from the nozzle means.

  In this apparatus, the liquid droplet dropped from the nozzle of the dropping means was brought into contact with ammonia before colliding with the liquid surface in the liquid tank, and the gelation reaction proceeded on the surface to form a gel layer on the outer surface. It will be a thing. That is, since the true spherical shape of the droplet is fixed with the gel layer as an outer shell, the true spherical shape is maintained without being deformed by an impact at the time of collision with the liquid surface in the liquid tank. You can sink into the tank.

  Therefore, the liquid droplet undergoes a gelation reaction to the center in the liquid tank, and when completed, it becomes an ADU gel particle with good sphericity. Since it is gelled, ADU gel particles having a uniform particle size can be obtained without bonding droplets. That is, fuel particles finally obtained from such ADU gel particles having good sphericity and uniform particle size also have good sphericity and uniform particle size.

  In the case of the external gelation method, the present invention contains an aqueous ammonia solution in the liquid tank, and in the case of the internal gelation method, oil for heating is contained in the liquid tank and dropped. In any case, the difference is that an ammonia donor that generates ammonia by heating is further added to the stock solution.

  The droplet surface gelling means of the present apparatus can be widely used as long as it has a mechanism for bringing ammonia into contact with the falling droplet. For example, if an ammonia injection nozzle mechanism that blows ammonia from a substantially horizontal direction to a falling droplet is provided, the entire surface of the droplet can be formed with a simple configuration of injecting ammonia from a nozzle at a predetermined position. Ammonia can be contacted.

  In addition, the longer the contact time of ammonia with the falling droplet, the more reliable the formation of the gel layer on the outer surface of the droplet, and the thicker the gel layer, the stronger the outer shell, The effect of maintaining a true spherical shape becomes higher with respect to the impact at the time of collision with the liquid level in the liquid tank. Therefore, in addition to the above-described ammonia spraying by the ammonia injection nozzle mechanism, if a contact area with ammonia is further provided in the lower droplet drop area, the true spherical shape of the droplet is more reliably fixed. .

  For example, in the case of the external gelation method, an aqueous ammonia solution is stored in the liquid tank, but if the ammonia-filled region is provided on the surface of the aqueous ammonia solution, the droplets after the ammonia is sprayed are It passes through the ammonia atmosphere until it reaches the ammonia aqueous solution surface after entering the tank. That is, in this configuration, it is possible to secure a further ammonia contact time of the droplets with a simple configuration in which the same liquid tank for storing the aqueous ammonia solution is used without providing a separate facility.

  When forming an ammonia-filled region on the surface of the aqueous ammonia solution at the top of the liquid tank in this way, the liquid tank has a portion other than the top opening for receiving the falling droplets so as to contain ammonia as much as possible. Is preferably closed.

  In addition, the ammonia injection nozzle mechanism has a position of the dropping device and the ammonia injection nozzle so that ammonia injected from the nozzle does not enter the dropping device and gel the stock solution in the device. It is desirable to restrict the movement of ammonia to the dropping device side by setting the relationship or adjusting the atmosphere.

  For example, an exhaust mechanism that sucks an ammonia stream that has been jetted from the ammonia jet nozzle and has passed through the drop path to a position opposite to the ammonia jet nozzle across the drop path to discharge it to a predetermined area outside the apparatus The structure which further provides is mentioned. Since the ammonia flow is forcibly formed in an air curtain between the ammonia injection nozzle and the exhaust mechanism, the air curtain is formed directly above the opening of the liquid tank above the ammonia filling region. If the predetermined components of the device are arranged in such a way, the ammonia injected from the ammonia injection nozzle can be prevented from moving to the dropping device side, and at the same time, the air can be sealed in the ammonia-filled area above the liquid tank by the air curtain. An effect is also obtained.

  Further, in the aqueous ammonia solution in the liquid tank, ammonia is consumed and the concentration thereof decreases as the ADU gel particle generation reaction proceeds. As described above, an ammonia-filled region is provided in the upper part of the liquid tank. If so, ammonia is replenished from the surface of the aqueous ammonia solution that is the contact surface with the region, so that no trouble is caused in the reaction even if a large number of droplets are successively dropped by vibration dropping.

  The ADU gel particles obtained by the apparatus configuration as described above are fuel particles having a good sphericity and a uniform particle diameter through a heat treatment apparatus section corresponding to a predetermined process such as subsequent drying, roasting, and sintering. It becomes.

  FIG. 1 shows a schematic configuration of an ADU gel particle production unit using an external gelation method as an apparatus for producing fuel particles for a HTGR according to an embodiment of the present invention. The production unit is mainly supplied with a dropping stock solution prepared by adjusting a liquid tank 6 containing an aqueous ammonia solution 7, an aqueous solution containing an additive that undergoes a gelation reaction upon contact with ammonia, and a uranyl nitrate solution. A source T1 and a vibration dropping device 1 for dropping the dropping stock solution from the supply source T1 to the liquid tank from the vibration nozzle 2 positioned above the liquid tank 6 are provided.

  The vibration dripping device 1 has a pump for controlling the flow rate of the dripping stock solution supplied from the supply source T1 and a vibration mechanism that vibrates the nozzle 2, and the vibration frequency determined in advance according to a desired droplet diameter. An oscillator that oscillates in (1), an amplifier that increases the frequency of the oscillator, and a vibrator that receives the vibration amplified by the amplifier and vibrates the nozzle.

  Further, in the present manufacturing department, as the droplet surface gelling means, the ammonia injection nozzle mechanism 3 that sprays ammonia from the substantially horizontal direction on the liquid tank 6 on the liquid tank 6 and the ammonia aqueous solution surface above the liquid tank 6. And an ammonia-filled region 8 provided on the surface. The liquid tank 6 is in a closed state except for the opening 9 for receiving the droplets, and secures the ammonia-filled region 8. In this embodiment, ammonia is supplied from the same supply source T2 to the ammonia filling region 8 and the ammonia injection nozzle mechanism 3 in the liquid tank 6.

  Further, in this manufacturing unit, the ammonia flow jetted from the nozzle of the mechanism and sucked over the droplet dropping path is exhausted at a position opposed to the ammonia jet nozzle mechanism 3 across the droplet dropping path. By providing the exhaust mechanism 5 to be formed, an ammonia air curtain 4 is formed immediately above the opening 9 of the liquid tank 6, and after injection, the ammonia enters the vibration dropping device 1 to gel the stock solution and drop it. While avoiding the problem which inhibits a process, it shall contain the ammonia of the ammonia filling area | region 8 coming out of the liquid tank 6. FIG.

  In the ADU gel particle manufacturing unit having the above-described configuration, the droplet 10 that has been dropped from the vibrating nozzle 2 and has fallen into a spherical shape due to its surface tension is added to the ammonia injection nozzle mechanism before entering the opening 9 of the liquid tank 6. Ammonia sprayed from No. 3 is sprayed, a gelling reaction occurs on the droplet surface, a gel layer is formed on the outer surface, and then enters the liquid tank 6 through the opening 9 until reaching the ammonia aqueous solution surface. In the meantime, it passes through the full region 8, during which the gelation reaction further proceeds on the surface of the droplet, and the gel layer as the outer shell is strengthened.

  Thus, the droplet 10 having the outer shell of the gel layer formed on its outer surface has a fixed spherical shape, and hardly deforms even when it collides with the ammonia aqueous solution surface. While maintaining a good spherical shape, the solution settles in the aqueous ammonia solution 7, and gelled ADU particles are obtained when the gelation reaction to the center progresses and is completed.

  Since the droplet 10 having the outer shell of the surface gel layer thus formed settles in the aqueous ammonia solution more quickly than the case where the droplet does not have the outer shell, it is difficult for the droplets to contact each other. Even if a large number of droplets 10 enter the aqueous ammonia solution 7 one after another by vibration dropping and the droplets come into contact with each other, they can be bonded to each other independently due to the presence of their outer shells (gel layers). Instead, the resulting ADU gel particles have good sphericity and uniform particle size.

  An example in which ADU gel particles are actually formed by the manufacturing unit of FIG. 1 described above will be described below. First, a dropping stock solution was prepared from a polyvinyl alcohol solution and an uranyl nitrate solution as additives.

  In the present embodiment, a nozzle having a nozzle diameter of about 2 mm was used as the vibrating nozzle 2 and the stock solution was dropped by vibrating the nozzle at a frequency of about 90 Hz. The ammonia spraying position by the ammonia injection nozzle mechanism 3 was set approximately 40 mm below the lower end of the nozzle 2 to ensure a sufficient distance for the falling droplet 10 to be spherical. Furthermore, the distance from the opening 9 of the liquid tank 6 to the ammonia aqueous solution surface, that is, the distance of the ammonia filling region 8 was set to about 300 mm.

  The stock solution was dropped under the above conditions. By this dropping, a droplet having a diameter of approximately 0.07 mm is obtained. As described above, after dropping, the spherical droplet 10 is sprayed with ammonia by the ammonia injection nozzle mechanism 3, then enters the liquid tank 6 through the opening 9, passes through the ammonia-filled region 8, and then ammonia. It settles in the aqueous solution 7. ADU gel particles were obtained by immersing these droplets 10 in a liquid bath as they were for at least a predetermined coagulation time required for completing the gelation reaction.

  Here, as a comparative example of the present embodiment, the stock solution was dropped under the same conditions as in the present embodiment, except that ammonia was not sprayed from the ammonia injection nozzle mechanism 3 of the manufacturing unit and ammonia was removed from the ammonia filling region 8. The conventional type ADU gel particles were obtained.

  As a result of obtaining the sphericity of each ADU particle, the conventional type comparative example was about 1.2, whereas the ADU particle obtained in this example was about 1.08. It became clear that the sphericity was greatly improved. Accordingly, the fuel particles obtained from the ADU gel particles having a good sphericity through a predetermined heat treatment step also have a better sphericity than the conventional one.

  Moreover, although the case where the external gelation method was used was demonstrated in the above Example, this invention is similarly effective when the internal gelation method is used. In the case of the internal gelation method, an ammonia donor such as hexamethylenetetramine is further added to the dropping stock solution adjusted by the dropping stock supply source T1, and ammonia is thermally decomposed in the liquid tank 6 to generate ammonia. The ADU gel particle manufacturing unit can be configured by containing paraffin oil or the like heated to a high temperature that can be damped.

  Also in this case, the droplet 10 containing the ammonia donor dropped from the vibrating nozzle 2 by the droplet surface gelling means constituted by the ammonia injection nozzle mechanism 3 and the exhaust mechanism 5 disposed above the liquid tank 6 Before reaching the oil liquid level in the liquid tank, a gelling reaction occurs from the surface by spraying ammonia, and an outer shell of the gel layer is formed on the outer surface, and its spherical shape is fixed. Therefore, the liquid droplet hardly settles even when it collides with the oil level in the liquid tank, and settles in the oil while maintaining a spherical shape with good sphericity, and is heated and heated inside the liquid droplet. Ammonia is generated and the gelation reaction proceeds from the center, and when the gelation reaction is completed, gel-like ADU particles with good sphericity can be obtained.

  The setting of conditions such as dropping, ammonia spraying position, ammonia aqueous solution surface position of the liquid tank, dropping frequency, temperature, time, etc. in the present invention is not limited to those shown in the above-mentioned examples, and the additive used What is necessary is just to select suitably according to a kind, density | concentration, a desired particle size, quantity, etc. Moreover, although the case where the vibration dropping method was used was shown in the said Example, this invention is not limited to this, For example, the case where a natural dropping method etc. are used is also effective.

It is a schematic block diagram explaining the ADU gel particle manufacturing part of the manufacturing apparatus of the fuel particle for high temperature gas reactors by one Example to this invention.

Explanation of symbols

1: Vibrating dripping device 2: Vibrating nozzle 3: Ammonia injection nozzle mechanism 4: Air curtain 5: Exhaust mechanism 6: Liquid tank 7: Aqueous ammonia solution 8: Ammonia filling area 9: Opening 10: Droplet T1: Dropping stock solution supply source T2: Ammonia supply source

Claims (6)

Dropping means for dropping a dropping stock solution prepared from an aqueous solution containing an additive that undergoes a gelling reaction upon contact with ammonia and a uranyl nitrate solution from a nozzle, and the gelation reaction upon receiving a droplet dropped from the nozzle In the apparatus for producing fuel particles for a HTGR equipped with a liquid tank for generating droplets into gel particles,
A droplet surface gelling means for bringing ammonia into contact with the droplet in the middle of a dropping path until the droplet dropped from the nozzle reaches the liquid level of the liquid tank ;
The droplet surface gelling means includes:
An ammonia injection nozzle mechanism that sprays ammonia from a substantially horizontal direction on a falling droplet;
An exhaust mechanism that is provided at an opposed position across the drop path of the droplet with respect to the ammonia injection nozzle, and exhausts an ammonia stream that is injected from the ammonia injection nozzle and exceeds the drop path;
An apparatus for producing fuel particles for a HTGR, wherein an air curtain-like ammonia flow is forcibly formed between an ammonia injection nozzle and an exhaust mechanism immediately above the upper surface opening of the liquid tank . The apparatus for producing fuel particles for a HTGR according to claim 1 , wherein the liquid tank contains an aqueous ammonia solution. Further comprising ammonia fill area provided on an aqueous ammonia solution surface of the liquid tank, the ammonia injection nozzle mechanism and the exhaust mechanism, to claim 2, characterized in that disposed above the ammonia filling region An apparatus for producing fuel particles for a HTGR as described. The dripping stock solution further includes an ammonia donor that generates ammonia by heating, and the liquid tank contains a heating liquid heated to a predetermined temperature. Item 2. The apparatus for producing fuel particles for a HTGR according to Item 1 . A stock solution preparation step for obtaining a drop stock solution prepared from an aqueous solution containing an additive that undergoes a gelation reaction upon contact with ammonia and a uranyl nitrate solution, and dropping the stock solution from a nozzle toward a lower liquid tank to drop the stock solution Production of fuel particles for a high temperature gas reactor comprising a droplet forming step for forming a spherical droplet of a stock solution and a solidification step for gelling the droplet in the liquid tank to form gel-like ammonium uranate particles. In the method
For the spherical liquid droplets formed in the liquid droplet forming step, the liquid droplet surface gelation step is brought into contact with ammonia before reaching the liquid surface of the liquid tank,
The droplet surface gelation step includes a step of spraying ammonia from an ammonia injection nozzle to a droplet that is falling and a step of sucking an ammonia air stream that has passed the drop route from an exhaust mechanism at a position opposite to the drop route. 8. The fuel particle for a HTGR according to claim 7, wherein an ammonia flow in the form of an air curtain is forcibly formed between the injection nozzle and the exhaust mechanism immediately above the upper surface opening of the liquid tank. Manufacturing method. The method for producing fuel particles for a HTGR according to claim 5 , wherein the droplet surface gelation step further includes a step of passing the ammonia-filled region after the ammonia is sprayed.

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