JP2006225239A - Apparatus for manufacturing ammonium diuranate particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for manufacturing ammonium diuranate particles, in which highly concentrated uranium can be used as a raw material and with which the ammonium diuranate particles each having high sphericity can be obtained. <P>SOLUTION: The apparatus 1 for manufacturing the ammonium diuranate particles has a dropping device 2 for dropping a raw liquid containing uranyl nitrate, and a reaction tank 3 equipped with a reaction tank main body 4 for accommodating an aqueous ammonia solution which reacts with the raw liquid containing uranyl nitrate being dropped and a circulation flow passage position setting means 5 for changing the position of the circulation zone wherein the aqueous ammonia solution in the reaction tank main body 4 is circulated from a lower part to an upper part. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an apparatus for producing ammonium heavy uranate particles, and more particularly, heavy uranium that can handle highly enriched uranium as a raw material and produce ammonium heavy uranate particles having good sphericity. The present invention relates to an ammonium acid particle production apparatus.

  According to Non-Patent Documents 1 to 5, HTGR fuel is generally manufactured through the following steps. First, uranium oxide powder is dissolved in nitric acid to form a uranyl nitrate solution. Next, pure water, a thickener and the like are added to the uranyl nitrate solution and stirred to obtain a uranyl nitrate-containing stock solution. The prepared uranyl nitrate-containing stock solution is cooled to a predetermined temperature, adjusted to a 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. The surface of the droplet is gelled by the ammonia gas, thereby preventing deformation when reaching the surface of the aqueous ammonia solution. Uranyl nitrate in the aqueous ammonia solution sufficiently reacts with ammonia to form ammonium heavy uranate particles (hereinafter sometimes abbreviated as “ADU particles”).

  The ammonium deuterated uranium particles are dried and then roasted in the atmosphere to contain more oxygen than uranium dioxide, resulting in uranium oxide having an oxygen: uranium molar ratio greater than 2, eg, uranium trioxide, Reduction and sintering result in high-density ceramic-like uranium dioxide particles. The uranium dioxide particles are sieved, that is, classified to obtain fuel nuclei having a predetermined particle size.

The fuel nuclei are loaded onto a fluidized bed, and coating is performed by thermally decomposing the coating gas. The coating layer is formed by coating the first layer, the second layer, the third layer, and the fourth layer from the fuel core surface. In the case of the first layer of low density carbon, it is obtained by pyrolyzing acetylene (C ₂ H ₂ ) at about 1400 ° C. In the case of the high density pyrolytic carbon of the second layer and the fourth layer, it is obtained by pyrolyzing propylene (C ₃ H ₆ ) at about 1400 ° C. In the case of SiC of the third layer, it is obtained by thermally decomposing methyltrichlorosilane (CH ₃ SiCl ₃ ) at about 1600 ° C.

  In general fuel compacts, the coated fuel particles obtained as described above are pressed or molded into a hollow cylindrical shape or cylindrical shape together with a graphite matrix material made of graphite powder, binder, etc., and then fired. Obtained.

S. Kato "Fabrication of HTTR First Loading fuel", IAEA-TECCDOC-1210, 187 (2001) N. Kitamura "Present status of initial core fuel fabrication for the HTTR" IAEA-TECCDOC-988, 373 (1997) Kimio Hayashi, “High Temperature Engineering Test Reactor Design Policy, Manufacturability and Comprehensive Soundness Evaluation” JAERI-M 89-162 (1989) Kazuo Tsuji, “Development of Advanced Technology for HTGR Fuel Production” JAERI-Research 98-070 (1998) Hasegawa Masayoshi, Mishima Yoshimi supervision "Reactor Material Handbook", published on October 31, 1977, pages 221-247, Nikkan Kogyo Shimbun

  On the other hand, when manufacturing nuclear fuel using nuclear fuel materials such as uranium, as a method to prevent criticality accidents, in general, the "mass limit" that the amount of uranium handled is less than the critical mass, and the amount of uranium is Regardless of the shape and dimensions that do not cause criticality, the “shape restriction” handles uranium.

  In the case of “mass restriction”, the maximum handling amount for uranium having a concentration of 10% or less is 9.6 kg, and the maximum handling amount for uranium having a concentration of 20% or less is 4.0 kg. Therefore, the batch size in each manufacturing process needs to be below these values. Further, from the viewpoint of safety, considering the case of double loading by mistake, the batch size in each manufacturing process needs to be 1/2 or less of these values. Therefore, the productivity of nuclear fuel deteriorates and it cannot be said that it is suitable as a criticality management method for mass production facilities.

  On the other hand, in the case of “shape restriction”, the size defined by the enrichment and shape of uranium varies. For example, the size of the storage facility for uranium with a concentration of 10% or less, when the storage facility is cylindrical, the diameter of the cylinder is 19.8 cm or less, and the storage facility is flat, The thickness of the flat plate is 8.3 cm or less.

  In addition, the size of the storage facility for uranium with a concentration of 20% or less is when the shape of the storage facility is a cylindrical shape, the diameter of the cylinder is 17.4 cm or less, and the shape of the storage facility is a flat plate shape, The thickness of the flat plate is 6.7 cm or less.

  Since there is no limit to the amount of uranium handled in these storage facilities, “shape limitation” is preferable as a criticality management method for mass production facilities. However, as described above, since the dimensional limit value in the “shape limit” becomes smaller as the uranium becomes highly enriched, the facility for manufacturing the fuel core must be an elongated cylindrical shape or a thin flat plate shape. Absent.

  For example, in the step of dropping the prepared uranyl nitrate-containing stock solution into an aqueous ammonia solution, ammonia and uranyl nitrate sufficiently react in the aqueous ammonia solution to generate ADU particles. Here, the generated ADU particles are deformed because the ADU particles are stacked on the upper side. Therefore, there is a problem that the sphericity of ADU particles is deteriorated.

  In order to solve the problem that the sphericity of the ADU particles deteriorates, the ADU particles are caused to flow in the aqueous ammonia solution by generating an upward flow from the lower side to the upper side in the aqueous ammonia solution. Techniques have been proposed to prevent them from overlapping each other.

  In particular, when highly enriched uranium is used as a raw material, the storage equipment must be in the shape of an elongated cylinder or a thin flat plate, so it is necessary to make the ADU particles flow by strengthening the upward flow. However, by making the upward flow too strong, an excessive force is applied to the ADU particles and the ADU particles are deformed. Therefore, there is still a problem that the sphericity due to the deformation of the ADU particles is deteriorated.

  The present invention eliminates such conventional problems, can handle highly enriched uranium as a raw material, and can produce ammonium heavy uranate particles having good sphericity. It is an object of the present invention to provide a particle manufacturing apparatus.

As means for solving the problems,
Claim 1 includes: a dropping device that drops a uranyl nitrate-containing stock solution containing uranyl nitrate; a reaction tank body that contains an aqueous ammonia solution that reacts with the dropped uranyl nitrate-containing stock solution; and an ammonia aqueous solution in the reaction tank body. An apparatus for producing ammonium heavy uranate particles, comprising a reaction tank having a circulation channel position setting means for changing the position of a circulation region circulated from below to above,
According to a second aspect of the present invention, the circulation channel position setting means is provided below the bottom of the reaction vessel main body, and is provided and supplied at a supply port for supplying an aqueous ammonia solution and above the bottom of the reaction vessel main body. A plurality of outlets for discharging the aqueous ammonia solution from the reaction vessel body, a pipe connected between the supply port and the plurality of outlets, a pump connected to the pipe for flowing the aqueous ammonia solution, and the pipe The apparatus for producing ammonium biuranate particles according to claim 1, further comprising switching means for switching the aqueous ammonia solution to flow between the supply port and one discharge port.
According to a third aspect of the present invention, the pipe includes a main pipe connected to the supply port, to which the pump is connected, and a plurality of sub pipes branched from each discharge port to the main pipe and connected. The means is provided in the section of the main pipe between the sub pipe side switching valve provided in each of the plurality of sub pipes, and the predetermined sub pipe connected to the main pipe and the sub pipe adjacent to the sub pipe. The apparatus for producing ammonium heavy uranate particles according to claim 2, further comprising a main pipe side switching valve.

  According to the present invention, first, a uranyl nitrate-containing stock solution is dropped into a reaction tank body containing an aqueous ammonia solution. The dropped uranyl nitrate-containing stock solution reacts with ammonia while descending the aqueous ammonia solution. At this time, it changes from the outer surface of the droplet to ammonium heavy uranate. Here, inside the reaction tank main body, the position of the circulation region is changed by the circulation channel position setting means. By changing the position of the circulation region, the droplet gently descends in the region where no circulation flow is generated, and the droplet reacts with the aqueous ammonia solution. The reacted droplet becomes ammonium deuterated uranate particles. In addition, since only the minimum necessary region where the ammonium heavy uranate particles are present can be selectively flowed, deformation of the ammonium heavy uranate particles during flow can be suppressed. Therefore, it is possible to produce ammonium biuranate particles having good sphericity. In addition, since the ammonium heavy uranate particles in the reaction vessel main body can be sufficiently flowed, it can be applied even when the reaction vessel main body has an elongated cylindrical shape, for example, when a highly concentrated uranium is used as a raw material. Is possible. Therefore, highly enriched uranium can be handled as a raw material.

  Moreover, according to this invention, the aqueous ammonia solution discharged | emitted from the discharge port flows the inside of piping with a pump. Then, the switching means switches so that the aqueous ammonia solution flows between the supply port and one discharge port. Here, if one discharge port is switched to another discharge port, the position of the circulation region through which the aqueous ammonia solution circulates changes. Therefore, the position of the circulation area can be changed.

Furthermore, according to the present invention, each sub piping side switching valve and the main piping side switching valve,
Select the main pipe and sub pipe through which the aqueous ammonia solution flows. Therefore, since the main pipe is connected to the supply port and the sub-pipe is connected to the discharge port, the aqueous ammonia solution can be switched between the supply port and one discharge port.

  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]
The ADU particle manufacturing apparatus 1 includes a dropping device 2 and a reaction tank 3 provided below the dropping device 2.

[Drip device]
The dropping device 2 is a device that drops a uranyl nitrate-containing stock solution containing uranyl nitrate into the reaction tank 3. The dripping device 2 has a nozzle. The nozzles only have to have a predetermined inner diameter. When the uranyl nitrate-containing stock solution is dropped, illustration is omitted, but each nozzle is dropped and / or dropped in the uranyl nitrate-containing stock solution. The uranyl nitrate-containing stock solution is dropped by oscillating in a direction orthogonal to.

  The arrangement of the dropping device 2 is not particularly limited as long as it can be dropped into the reaction tank 3, but for example, it is preferably arranged on the central axis X of the reaction tank 3. In this way, the ADU particles formed by the dripped uranyl nitrate-containing stock solution are less likely to collide with the reaction vessel 3, and deformation of the ADU particles can be reduced.

[Reaction tank]
The reaction tank 3 includes a reaction tank body 4 and a circulation channel position setting means 5.

  The reaction tank main body 4 contains an aqueous ammonia solution that reacts with the dripped uranyl nitrate-containing stock solution. Examples of the cross-sectional shape of the reaction tank body 4 include a polygonal shape, a circular shape, and an elliptical shape. In addition, although illustration is abbreviate | omitted, the reaction tank main body 4 opens only only the part corresponding to the location where the dripping apparatus 2 is arrange | positioned, and it is preferable that it is formed in the airtight shape. In this way, fluctuations in concentration due to vaporization of the ammonia aqueous solution to be stored can be suppressed.

  The bottom 4A of the reaction tank main body is preferably formed so as to decrease in diameter as it goes downward. An extraction pipe 4B provided in the dropping direction and an extraction valve 4C provided in the extraction pipe 4B are provided below the reaction tank main body bottom 4A.

  The circulation channel position setting means 5 changes the position of the circulation region formed by circulating the aqueous ammonia solution in the reaction tank body 4 from below to above. The circulation flow path position setting unit 5 includes a supply port 6, a plurality of discharge ports 7, a pipe 8, a pump 9, and a switching unit 10.

  The supply port 6 is provided below the reaction tank main body bottom 4A and supplies an aqueous ammonia solution. Specifically, the supply port 6 is provided in the extraction pipe 4B between the reaction tank main body bottom 4A and the extraction valve 4C.

  The plurality of discharge ports 7 are provided above the reaction tank main body bottom 4 </ b> A, and discharge the supplied aqueous ammonia solution from the reaction tank main body 4. The plurality of discharge ports 7 are respectively formed on the side wall surface of the reaction tank body 4 at different positions in the height direction. In addition, the some discharge port 7 is discharge port 7A, 7B, 7C, 7D, and 7E, respectively from the lower side.

  The plurality of discharge ports 7 need not be formed so as to open in the same direction with respect to the supply port 6. For example, the plurality of discharge ports 7 are formed at symmetrical positions with respect to the supply port 6 across the central axis X of the reaction tank body 4, and the plurality of discharge ports 7 are in the opposite direction to the supply port 6. It may be formed so as to open.

  The pipe 8 includes a main pipe 81 connected to the supply port 6 and connected to the pump 9, and a plurality of sub pipes 82 branched and connected from the discharge ports 7 to the main pipe 81. . In addition, the some sub piping 82 is sub piping 82A, 82B, 82C, 82D, and 82E in an order from the lower side.

  The pump 9 is connected to the pipe 8, specifically to the main pipe 81, and causes the aqueous ammonia solution to flow.

  The switching means 10 is provided in the pipe 8 and switches so that the aqueous ammonia solution flows between the supply port 6 and one discharge port 7 (any one of the discharge ports 7A to 7E).

  The switching means 10 includes a sub piping side switching valve 11 and a main piping side switching valve 12. The sub piping side switching valve 11 is provided in each of the plurality of sub pipings 82. Specifically, the auxiliary piping side switching valve 11 is provided as the auxiliary piping side switching valves 11A, 11B, 11C, 11D, and 11E for the plurality of auxiliary piping 82A, 82B, 82C, 82D, and 82E, respectively. ing.

  The main pipe side switching valve 12 is provided in each section of the main pipe between the predetermined sub pipe connected to the main pipe 81 and the sub pipe adjacent to the sub pipe.

  Specifically, a main pipe side switching valve 12A is provided in a section of the main pipe 81 between the sub pipe 82A and the sub pipe 82B. Further, a main pipe side switching valve 12B is provided in a section of the main pipe 81 between the sub pipe 82B and the sub pipe 82C. Further, a main pipe side switching valve 12C is provided in a section of the main pipe 81 between the sub pipe 82C and the sub pipe 82D. A main pipe side switching valve 12D is provided in a section of the main pipe 81 between the sub pipe 82D and the sub pipe 82E.

[Usage method and operation / effect of ADU particle production equipment]
The usage method and operation of the above ADU particle production apparatus will be described below. The uranyl nitrate-containing stock solution used when producing ADU particles with the ADU particle production apparatus of the present invention is obtained by adding a water-soluble polymer to uranyl nitrate obtained by mixing uranium oxide and nitric acid, and then adding pure water. It is prepared by adjusting the viscosity by adding.

  Examples of the uranium oxide include uranium dioxide, uranium trioxide, and triuranium octoxide, and uranium trioxide is particularly preferable.

  Examples of the water-soluble polymer include polyvinyl alcohol (hereinafter abbreviated as PVA), synthetic polymers such as sodium polyacrylate and polyethylene oxide, cellulose polymers such as carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, and ethyl cellulose, soluble starch, And starch-based polymers such as carboxymethyl starch, water-soluble natural polymers such as dextrin, and galactan.

  One of these various water-soluble polymers may be used alone, or two or more thereof may be used in combination. Among these, the synthetic polymer is preferable as the water-soluble polymer, and polyvinyl alcohol is particularly preferable.

  First, a predetermined concentration and a predetermined amount of aqueous ammonia solution are accommodated in the reaction tank body 4. Next, a predetermined uranyl nitrate-containing stock solution is circulated through the dropping device 2, and droplets of the uranyl nitrate-containing stock solution are dropped from the dropping device 2.

  Although illustration is omitted, ammonia gas may be appropriately sprayed on each dropped droplet. In this way, gelation proceeds on the surface of the droplet, and deformation of the droplet when colliding with the ammonia aqueous solution surface can be suppressed.

  Thereafter, each droplet settles in the aqueous ammonia solution in the reaction vessel body 4 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.

  In this reaction, ammonia is consumed by the reaction in the aqueous ammonia solution, so that the ammonia concentration varies depending on a portion of the reaction tank body 4. Here, the circulation region where the aqueous ammonia solution is circulated in the dropping direction is set by the circulation channel position setting means 5 to, for example, a portion where the ammonium deuterated uranate particles generated by the reaction hardly exist.

  Here, when the circulation region is set to a portion where, for example, the ammonium deuterated uranate particles produced by the reaction hardly exist, the aqueous ammonia solution supplied from the supply port 6 flows in the pipe 8 by the pump 9. To do. Then, the switching means 10 switches so that the aqueous ammonia solution flows between the supply port 6 and one discharge port 7 (any one of 7A to 7E). Here, if one discharge port 7 (any one of 7A to 7E) is switched to another discharge port 7 (any one of 7A to 7E), the position of the circulation region through which the aqueous ammonia solution circulates changes. It will be. Therefore, the position of the circulation area can be changed.

  Specifically, immediately after the start of dropping, an aqueous ammonia solution is circulated between the supply port 6 and the discharge port 7A. At this time, the auxiliary piping side switching valve 11A is opened, and the other auxiliary piping side switching valves 11B to 11E are closed. Moreover, the main piping side switching valves 12A to 12D are closed.

  In this state, the pump 9 causes the aqueous ammonia solution to flow through the supply port 6, the reaction tank main body bottom 4 </ b> A, the auxiliary pipe 82 </ b> A, the main pipe 81, and the pump 9 (see the arrow in FIG. 1). Therefore, the region where the aqueous ammonia solution flows becomes a circulation region. In this case, in the reaction tank main body 4, no circulating flow is generated in the portion above the discharge port 7A. In the portion above the discharge port 7A, the droplet of the uranyl nitrate-containing stock solution is in the reaction, but the influence of the flow can be reduced.

  The dropping of the uranyl nitrate-containing stock solution proceeds and the generated ADU particles are deposited up to the vicinity of the discharge port 7A. In this case, an aqueous ammonia solution is circulated between the supply port 6 and the discharge port 7B. At this time, the auxiliary piping side switching valve 11B is opened, and the other auxiliary piping side switching valves 11A, 11C to 11E are closed. Further, the main piping side switching valve 12A is opened, and the other main piping side switching valves 12B to 12D are closed.

  In this state, the aqueous ammonia solution flows through the supply port 6, the reaction vessel main body bottom 4 </ b> A, the auxiliary pipe 82 </ b> B, the main pipe 81, and the pump 9 by the pump 9. In this case, in the reaction tank main body 4, no circulating flow is generated in the portion above the discharge port 7B. In the upper part of the discharge port 7B, the droplet of the uranyl nitrate-containing stock solution is in the reaction, but the influence of the flow can be reduced.

  Further, the dropping of the uranyl nitrate-containing stock solution proceeds, and the generated ADU particles are deposited up to the vicinity of the discharge port 7B. In this case, an aqueous ammonia solution is circulated between the supply port 6 and the discharge port 7C. At this time, the auxiliary piping side switching valve 11C is opened, and the other auxiliary piping side switching valves 11A, 11B, 11D, and 11E are closed. Further, the main pipe side switching valves 12A and 12B are opened, and the other main pipe side switching valves 12C and 12D are closed.

  In this state, the aqueous ammonia solution flows through the supply port 6, the reaction vessel main body bottom 4 </ b> A, the auxiliary pipe 82 </ b> C, the main pipe 81, and the pump 9 by the pump 9. In this case, in the reaction tank main body 4, no circulating flow is generated in the portion above the discharge port 7C. In the upper part of the discharge port 7C, the droplet of the uranyl nitrate-containing stock solution is reacting, but the influence of the flow can be reduced.

  By repeating the operation as described above, the position of the circulation region can be changed.

  As described above, since the aqueous ammonia solution circulates in the circulation region, the lower ADU particles are not deformed by the weight of the upper ADU particles. In addition, since the uniform ammonia concentration is maintained, the reaction proceeds uniformly, so that ammonium deuterated uranate particles having good sphericity can be produced.

  In addition, since there is almost no part of the ammonium heavy uranate particles, circulation is not performed, so that excessive force due to the circulation flow is not applied to the falling soft heavy ammonium uranate particles, and the ADU particles are deformed. Nor. Therefore, ADU particles having good sphericity can be produced. In addition, since the ADU particles in the reaction vessel main body 4 can be sufficiently flowed, the reaction vessel main body 4 as in the present embodiment has an elongated cylindrical shape, for example, in the case of using highly enriched uranium as a raw material. Even so, it can be applied. Therefore, highly enriched uranium can be handled as a raw material.

  The reaction proceeds after a predetermined time, and the ADU particles deposited on the bottom 4A of the reaction tank main body are discharged to the outside of the reaction tank main body 4 through the extraction pipe 4B by opening the extraction valve 4C.

  In addition, the ADU particles discharged to the outside of the reaction vessel main body 4 are washed and dried, and then are baked, reduced, and sintered under predetermined conditions to become uranium dioxide particles.

  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.

FIG. 1 is a schematic view showing an apparatus for producing ammonium heavy uranate particles according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ADU particle manufacturing apparatus 2 Dripping apparatus 3 Reaction tank 4 Reaction tank main body 4A Reaction tank main body bottom part 4B Extraction piping 4C Extraction valve 5 Circulation flow path position setting means 6 Supply port 7 (7A-7E) Discharge port 8 Piping 81 Main piping 82 (82A to 82E) Sub piping 9 Pump 10 Switching means 11 (11A to 11E) Sub piping side switching valve 12 (12A to 12D) Main piping side switching valve

Claims (3)

  A dropping device for dropping a uranyl nitrate-containing stock solution containing uranyl nitrate, a reaction tank main body containing an aqueous ammonia solution that reacts with the dropped uranyl nitrate-containing stock solution, and an aqueous ammonia solution in the reaction tank body circulated from below to above An apparatus for producing ammonium heavy uranate particles, comprising: a reaction tank having a circulation channel position setting means for changing the position of the circulation region.   The circulation channel position setting means is provided below the bottom of the reaction vessel main body, and is provided with a supply port for supplying an aqueous ammonia solution and an upper side of the bottom of the reaction vessel main body, and reacts the supplied aqueous ammonia solution. A plurality of outlets for discharging from the tank body, a pipe connected between the supply port and the plurality of outlets, a pump connected to the pipe and flowing an aqueous ammonia solution, and provided in the pipe, The apparatus for producing ammonium heavy uranate particles according to claim 1, further comprising switching means for switching so that the aqueous ammonia solution flows between the supply port and one discharge port. The pipe is connected to the supply port, and includes a main pipe to which the pump is connected, and a plurality of sub pipes branched from each discharge port and connected to the main pipe.
The switching means is provided in a section of a main pipe between a sub pipe side switching valve provided in each of a plurality of sub pipes, a predetermined sub pipe connected to the main pipe, and a sub pipe adjacent to the sub pipe. The apparatus for producing ammonium heavy uranate particles according to claim 2, comprising a main pipe side switching valve provided respectively.

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