JP4334366B2 - Ammonium uranate particle production equipment - Google Patents

Description

  The present invention relates to an apparatus for producing ammonium heavy uranate particles.

  A fuel for a HTGR is generally manufactured through the following processes. First, uranium oxide powder is dissolved in nitric acid to obtain a uranyl nitrate stock solution. Next, pure water, a thickener and the like are added to the uranyl nitrate stock solution and stirred to obtain a dropping stock solution. The prepared dropping undiluted solution is cooled to a predetermined temperature to adjust the viscosity, and then dropped into an aqueous ammonia solution using a small-diameter dropping nozzle.

  The droplets dropped on the aqueous ammonia solution are sprayed with ammonia gas before reaching the surface of the aqueous ammonia solution. Due to the ammonia gas, the surface of the droplet is gelled, whereby deformation of the gelled droplet is prevented when the falling droplet collides with the surface of the aqueous ammonia solution. In addition, the gelled droplet may be hereinafter referred to as “gelled droplet”. The gelled droplets in the aqueous ammonia solution become ammonium heavy uranate particles (hereinafter sometimes abbreviated as “ADU particles”) by the reaction of uranyl nitrate existing in the ammonia with ammonia.

  The ADU particles are dried and then roasted in the air to become uranium trioxide particles. Furthermore, the uranium trioxide particles are reduced and sintered to become high-density uranium dioxide particles. The uranium dioxide particles are screened, that is, classified to obtain fuel core fine particles having a predetermined particle size.

  The fuel core particles are loaded onto the fluidized bed, and the gas for forming the coating layer is pyrolyzed to form a coating layer composed of a plurality of layers on the surface of the fuel core particles. The first layer in the coating layer is formed of low density pyrolytic carbon produced by pyrolyzing acetylene at about 1400 ° C. In addition, the second layer and the fourth layer in the coating layer are formed of high-density pyrolytic carbon generated by pyrolyzing propylene at about 1400 ° C. Further, the third layer in the coating layer is formed by thermally decomposing methyltrichlorosilane at about 1600 ° C.

  After the coating layer is formed, the HTGR fuel is molded as a general fuel compact. This fuel compact is obtained by press-molding or molding a high-temperature gas reactor fuel into a hollow cylindrical shape together with a graphite matrix material made of graphite powder, a binder, etc. (see Non-Patent Document 1). .

Reactor Material Handbook, p221-p247, published October 31, 1977, published by Nikkan Kogyo Shimbun

  Conventionally, equipment having one jet outlet for jetting ammonia gas is used for a plurality of dropping nozzles. When equipment having one ejection port for ejecting ammonia gas is used in this way, the flow rate of ammonia gas with respect to droplets dropped from a plurality of dropping nozzles is not uniform, and each droplet comes into contact with each other. The flow rate of ammonia gas is different. For this reason, there is a problem that the surface of the produced ammonium heavy uranate particles has, for example, a rippled pattern, which affects the sphericity of the uranium dioxide particles obtained in a later step. .

  The present invention provides an ammonium heavy uranate particle production apparatus capable of solving such conventional problems and producing ammonium heavy uranate particles for obtaining uranium dioxide particles having good sphericity. Let it be an issue.

Means for solving the problems include a precipitation tank for storing an aqueous ammonia solution, a plurality of dropping nozzles for dropping a uranyl nitrate-containing stock solution into the aqueous ammonia solution stored in the precipitation tank, and the plurality of dropping nozzles, respectively. A heavy uranic acid comprising a plurality of ammonia gas jetting means having a plurality of ammonia gas jetting ports capable of jetting ammonia gas toward each of the dropping paths in which droplets of the uranyl nitrate-containing undiluted solution dropped are dropped It is an ammonium particle manufacturing apparatus.

In a preferred embodiment of the ammonium heavy uranate particle production apparatus according to the present invention, the height from the tip of the dropping nozzle to the upper end of the ammonia gas outlet is 10 to 40 mm, the dropping path and the ammonia gas outlet In a preferred embodiment of the ammonium heavy uranate particle production apparatus according to the present invention, the distance to the tip is 3 to 15 mm, the flow rate of ammonia gas ejected from the ammonia gas ejection port is 3 to 25 L / min, and And an ammonia gas suction means for sucking the ammonia gas ejected from the ammonia gas ejection means, the ammonia gas suction means being on the opposite side of the ammonia gas ejection means with the drop path of the droplet in the middle It is provided in the position.

  In a preferred aspect of the apparatus for producing ammonium deuterated uranium particles according to the present invention, the ammonia gas ejection means has a plurality of ammonia gas ejection ports capable of ejecting ammonia gas toward the dropping path of the droplet, The flow rate of the ammonia gas ejected from the plurality of ammonia gas ejection ports can be adjusted.

(1) According to the present invention, ammonia gas is ejected from the ammonia gas ejection means to a series of droplets of the uranyl nitrate-containing stock solution that are respectively dropped from a plurality of dropping nozzles. Ammonia gas is uniformly ejected, and the generated ADU particles do not exhibit a rippled pattern, so that uranium dioxide particles with good sphericity can be obtained.

(2) According to the present invention, the ammonia gas suction means sucks the ejected ammonia gas, thereby increasing the directivity of the ejected ammonia gas flow, and the plurality of ammonia gas flows affect each other. Since it is less applied, the ADU particles that are further generated do not exhibit a rippled pattern.

(3) According to the present invention, the plurality of ammonia gas ejection ports can adjust the ejection flow rate of ammonia gas so that the ammonia gas ejection state can be kept constant even when the pressure loss of ammonia gas differs. Can keep.

  Hereinafter, an ammonium heavy uranate particle manufacturing apparatus (hereinafter, also referred to as “ADU particle manufacturing apparatus”) according to an embodiment of the present invention will be described with reference to FIG. However, the ADU particle manufacturing apparatus illustrated in FIG. 1 is an example of the present invention, and the ADU particle manufacturing apparatus according to the present invention is not limited to the ADU particle manufacturing apparatus illustrated in FIG.

[ADU particle production equipment]
As shown in FIG. 1, the ADU particle manufacturing apparatus 1 is provided between a precipitation tank 2, a plurality of dropping nozzles 3 provided above the precipitation tank 2, and the precipitation tank 2 and the dropping nozzle 3. A plurality of ammonia gas ejection means 4 and a plurality of ammonia gas suction means 5 are provided.

[Settling tank]
The precipitation tank 2 is a tank that stores an aqueous ammonia solution and reacts uranyl nitrate and ammonia in droplets falling from the dropping nozzle 3 to form ammonium heavy uranate particles. The sedimentation tank 2 has a cylindrical shape with an upper part opened and a lower part closed. In addition, although not shown, a discharge port for discharging the generated ammonium heavy uranate particles (hereinafter sometimes abbreviated as “ADU particles”) is provided at the lower portion of the precipitation tank 2. The discharge port is also provided with a circulation flow forming means capable of ejecting ammonia gas into the ammonia aqueous solution in the precipitation tank 2 to form an upper and lower circulation flow in the ammonia aqueous solution.

  In addition, an ammonia gas supply means 21 for filling the precipitation tank 2 with ammonia gas is provided outside the precipitation tank 2. The ammonia gas supply means 21 is connected to an ammonia gas supply port 22 formed on the side wall of the precipitation tank 2 and fills the ammonia gas in the precipitation tank 2 on the liquid surface of the aqueous ammonia solution. The ammonia gas supply port 22 is formed at a position higher than the liquid level of the aqueous ammonia solution to be stored.

[Drip nozzle]
The dropping nozzle 3 drops a uranyl nitrate-containing stock solution (hereinafter sometimes abbreviated as “dropping stock solution”) into the aqueous ammonia solution stored in the settling tank 2 and is arranged in a row at a constant interval. Is provided. The plurality of dropping nozzles 3 only have to have a predetermined inner diameter. When dropping the dropping stock solution, although not shown, each dropping nozzle is connected to the dropping stock solution in the dropping direction and / or Alternatively, the dropping stock solution is dropped by vibrating in a direction orthogonal to the dropping direction. In addition, this dripping nozzle 3 is connected to a dripping stock solution storage tank (not shown) that stores the dripping stock solution via a pipe, and the dripping stock solution is supplied from this dripping stock solution storage tank. . In the example shown in FIG. 1, the plurality of dropping nozzles 3 are arranged in a line in the horizontal direction. However, in the present invention, even if the dropping nozzles are arranged in a plurality of horizontal lines, The drop nozzles may be arranged in a circle.

[Ammonia gas ejection means]
The ammonia gas ejection means 4 is provided above the opening of the sedimentation tank 2 and at a position that does not close the opening. Specifically, as shown in FIG. 2, the ammonia gas jetting unit 4 is configured so that each of the dropping liquid drops dropped from the plurality of dropping nozzles 3 is directed toward a dropping path X where the drops are dropped. It suffices if the ammonia gas can be ejected, and a plurality of circular ammonia gas ejection ports 41 capable of ejecting the ammonia gas are provided on the dropping paths X of the droplets. That is, the ammonia gas ejection port 41 is provided for each dropping path X of the dropped particles formed by each of the plurality of dropping nozzles 3. The ammonia gas is supplied from the ammonia gas supply means 21 to the ammonia gas ejection means 4.

  The ejection direction of the ammonia gas ejected from the ammonia gas ejection port 41 and the dropping path X are preferably orthogonal. In this way, ammonia gas can be sprayed evenly on the surface of each droplet.

  In a specific mode as shown in FIG. 2, as an example, the inner diameter D1 of the plurality of ammonia gas ejection ports 41 is 1 to 17 mm. Here, if the inner diameter D1 is less than 1 mm, ammonia gas may be sprayed only on a part of the droplet. If the inner diameter D1 exceeds 17 mm, ammonia gas is sprayed simultaneously on the adjacent droplets, and as a result, the spraying of ammonia gas on the droplets may be uneven.

  Moreover, in the specific mode as shown in FIG. 2, as an example, the height H <b> 1 from the tip of the dropping nozzle 3 to the upper end of the ammonia gas outlet 41 is 10 to 40 mm. Here, if the height H1 is less than 10 mm, the time for spraying ammonia gas on the droplets is too short, and the spraying of ammonia gas on the droplets may be insufficient. When the height H1 exceeds 40 mm, the time for spraying ammonia gas on the droplets becomes long and the spraying of ammonia gas may become excessive.

  Further, in a specific mode as shown in FIG. 2, as an example, a distance L1 between the dropping path X and the tip of the ammonia gas jet port 41 is 3 to 15 mm. Here, when the distance L1 is less than 3 mm, adhesion of droplets may occur at the ammonia gas ejection port 41 itself. When the distance L1 exceeds 15 mm, the ejected ammonia gas includes ambient air, and it may not be possible to secure a sufficient ammonia gas concentration to spray the droplets.

  The plurality of ammonia gas ejection ports 41 can adjust the ejection flow rate of ammonia gas. Specifically, as shown in FIG. 3, a flow meter 43 is connected to a pipe 42 for supplying ammonia gas to each of the ammonia gas ejection ports 41, and a valve 44 connected to the pipe 42 is operated to thereby operate the flow meter 43. The flow rate of ammonia gas is adjusted by observing

  When the inner diameter D1, the height H1, and the distance L1 are within the above ranges, the flow rate at the flow meter 43 when the ammonia gas is ejected from the ammonia gas ejection port 41 is 3 to 25 L / min. preferable. If the flow rate when jetting ammonia gas is less than 3 L / min, there is a possibility that droplets with poor formation of a film containing ammonium heavy uranate may be formed, and the flow rate when jetting ammonia gas. However, if it exceeds 25 L / min, the free fall of the droplets may be hindered by the flow of ammonia gas.

[Ammonia gas suction means]
The ammonia gas suction means 5 is provided above the opening of the sedimentation tank 2 and at a position that does not close the opening. More specifically, as shown in FIG. 2, the ammonia gas suction means 5 is provided at a position opposite to the dropping gas path X with respect to the ammonia gas ejection means 4, and sucks the ejected ammonia gas.

  The distance L2 between the dropping path X and the tip of the ammonia gas suction means 5 may be a distance that does not interfere with the droplets and the ammonia gas suction means 5.

  When the ammonia gas suction means 5 is arranged in this way, ammonia flowing smoothly from the ammonia gas ejection means 4 to the ammonia gas suction means 5 without causing the ammonia gas flow ejected from the ammonia gas ejection means 4 to stay. A gas stream can be formed.

  The ammonia gas suction means 5 only needs to be formed so as not to generate a turbulent flow in the air flow of the ammonia gas crossing the dropping process X of the falling droplets and to form a smooth air flow of the ammonia gas. .

  Therefore, in the embodiment shown in FIG. 2, the ammonia gas suction means 5 is provided with an ammonia gas suction port (not shown) that opens facing the ammonia gas jet port 41 for each ammonia gas jet port 41. ing.

  With such an ammonia gas suction means 5, an undisturbed ammonia gas stream is formed between the ammonia gas jet port 41 and the ammonia gas suction port facing the ammonia gas jet port 41. Well formed. And when a droplet falls in the ammonia gas stream that flows without being disturbed in this way, the ammonia gas stream flows so as to wrap up the entire droplet that passes through the ammonia gas stream, so that uniform heavy uranium on the surface of the droplet A film containing ammonium acid is formed and gelled droplets are formed.

[Usage method and operation of ADU particle production equipment]
The usage method and operation of the above ADU particle production apparatus will be described below. First, an ammonia aqueous solution having a predetermined concentration and a predetermined amount is stored in the precipitation tank 2. On the other hand, the ammonia gas supply means 21 is operated to fill the precipitation tank 2 with a predetermined concentration and a predetermined amount of ammonia gas.

  Next, a predetermined dropping stock solution is circulated through the dropping nozzle 3, and droplets of the dropping stock solution are dropped from the plurality of dropping nozzles 3. Each dropped droplet falls on the dropping path X. On the other hand, ammonia gas is ejected from the ammonia gas ejection port 41 of the ammonia gas ejection means 4 to each of the dropping paths X through which the droplets pass by free fall. The ammonia gas ejected from the ammonia gas ejection port 41 is sprayed equally to each droplet, and gelation proceeds on the surface of each droplet.

  Then, the ammonia gas suction means 5 sucks the ejected ammonia gas. The ammonia gas suction means 5 sucks the ejected ammonia gas, thereby increasing the directivity of the gas flow of the ejected ammonia gas and reducing the influence of the plurality of ammonia gas flows on each other.

  Further, each droplet sprayed with ammonia gas falls from the opening of the precipitation tank 2 into the precipitation tank 2. Here, the part above the ammonia aqueous solution liquid level inside the precipitation tank 2 is in a state where ammonia gas is filled. When the inside of the sedimentation tank 2 falls, each droplet absorbs ammonia gas from a portion filled with ammonia gas. Due to the absorption of the ammonia gas, the surface of each droplet is further gelled.

  Thereafter, each droplet settles in the aqueous ammonia solution in the precipitation tank 2, and further absorbs ammonia from the aqueous ammonia solution. Each droplet is gelled not only on the surface but also on the inside, and the reaction proceeds to ADU particles.

  After a predetermined time, the reaction proceeds and the ADU particles precipitated in the lower part of the precipitation tank 2 are discharged to the outside of the precipitation tank 2 from the discharge port of the precipitation tank 2 (not shown).

  The ADU particles discharged to the outside of the precipitation tank 2 are dried, and then are baked, reduced, and sintered under predetermined conditions to become uranium dioxide particles.

According to this embodiment as described above, the following effects are obtained.
(1) Ammonia gas is ejected from the ammonia gas ejecting means 4 onto each droplet path X of the droplets, respectively, from each of the plurality of droplet nozzles 3 so that it is uniform for each droplet. As a result, ammonia gas is jetted out, and the generated ADU particles do not exhibit a rippled pattern, so that uranium dioxide particles with good sphericity can be obtained.

(2) Since the ammonia gas suction means 5 sucks the ejected ammonia gas, the directivity of the gas flow of the ejected ammonia gas is increased, and the plurality of ammonia gas gas flows are less likely to affect each other. Therefore, the ADU particles that are further generated do not exhibit a rippled pattern.

(3) The ammonia gas ejection port 41 can adjust the ejection flow rate of the ammonia gas, so that the ammonia gas ejection state can be kept constant even when the pressure loss of the ammonia gas is different.

  It should be noted that the present invention is not limited to the above-described embodiment, and modifications and improvements within a scope that can achieve the object of the present invention are included in the present invention.

  In the above-described embodiment, for example, the ammonia gas ejection means 4 has a plurality of circular ammonia gas ejection ports 41. However, the present invention is not limited to this, and as shown in FIG. It is good also as the slit-shaped ammonia gas ejection port 41A long in the dripping path X direction of each drop.

  In addition, the specific structure, shape, and the like when carrying out the present invention may be other structures as long as the object of the present invention can be achieved.

FIG. 1 is a schematic view showing an ADU particle production apparatus according to the present invention. FIG. 2 is an enlarged perspective view of the ammonia gas ejection means and the ammonia gas suction means. FIG. 3 is a schematic view showing the ammonia gas ejection means. FIG. 4 is a schematic view showing a modification of the ammonia gas ejection means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ADU particle manufacturing apparatus 2 Settling tank 3 Dripping nozzle 4 Ammonia gas ejection means 5 Ammonia gas suction means 21 Ammonia gas supply means 22 Ammonia gas supply port 41 Ammonia gas ejection port 42 Piping 44 Valve | bulb 41A Ammonia gas ejection port X Drip path

Claims (4)

A precipitation tank for storing an aqueous ammonia solution;
A plurality of dropping nozzles for dropping a uranyl nitrate-containing stock solution into the aqueous ammonia solution stored in the settling tank;
An ammonia gas ejection means having a plurality of ammonia gas ejection ports capable of ejecting ammonia gas toward each of the dropping paths in which droplets of the uranyl nitrate-containing stock solution dropped from each of the plurality of dropping nozzles fall. An apparatus for producing ammonium heavy uranate particles. The height from the tip of the dropping nozzle to the upper end of the ammonia gas outlet is 10 to 40 mm, the distance between the dropping path and the ammonia gas outlet is 3 to 15 mm, and from the ammonia gas outlet The apparatus for producing ammonium heavy uranate particles according to claim 1, wherein the flow rate of the ammonia gas to be ejected is 3 to 25 L / min . Comprising ammonia gas suction means for sucking ammonia gas ejected from the ammonia gas ejection means,
3. The ammonium heavy uranate particles according to claim 1, wherein the ammonia gas suction means is provided at a position opposite to the ammonia gas ejection means with the drop path of the droplet as an inside. Manufacturing equipment. The ammonia gas ejection means has a plurality of ammonia gas ejection ports capable of ejecting ammonia gas toward the dropping path of the droplets, and is capable of adjusting the flow rate of the ammonia gas ejected from the plurality of ammonia gas ejection ports. The apparatus for producing ammonium heavy uranate particles according to any one of claims 1 to 3, wherein the apparatus is one.

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