JP2006300766A - Method and apparatus for weighing raw material particle for use in molding fuel compact - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and apparatus for weighing raw material particles for use in molding fuel compact which satisfies accurate weighing, speedy weighing, lowering difficulty of weighing and reduction of weighing cost. <P>SOLUTION: A technology for weighing raw material particles applied in molding process of a fuel compact including nuclear fuel material among processes for manufacturing fuel for high-temperature gas-cooled reactors is provided. It weighs raw material particle 11 of a fuel compact and has the following steps. At first, the raw material particle 11 is measured in volume. Then, the raw material particle 11 after measuring volume is weighed. For the weighing raw material particle 11, actual weighed value and a target weighing value of a fuel compact are compared in calculation, the difference of the actual weighed value from the target weighing value is counted to the number of raw material particle 11 and raw material particle 11 of necessary quantity for resolving the difference is supplied to the weighing raw material particle by the number. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a weighing technique attached to a fuel compact molding process (press molding process) in a fuel manufacturing process including nuclear fuel material for a HTGR. More specifically, the present invention relates to a raw material particle for a fuel compact in a short time. It relates to a method and an apparatus for weighing.

  As is well known for high-temperature gas reactors, the core structure (including fuel) is composed of graphite with a large heat capacity and good high-temperature soundness, and an inert gas such as He gas that does not cause a chemical reaction even at high temperatures is used as a cooling gas. Used. By doing so, the inherent safety is increased, and the He gas having a high outlet temperature can be taken out. The high heat of about 900 ° C. obtained from this HTGR enables heat utilization in a wide range of fields including power generation, hydrogen production, chemical plants, and others.

  Regarding the fuel of the HTGR, the following can be said with reference to the following Patent Documents 1 and 2, Non-Patent Document 1, and the like. The coated fuel particles having a diameter of 500 to 1000 μm are obtained by coating four layers on the outer peripheral surface of a fuel nucleus (diameter 350 to 650 μm) made of an oxide of nuclear fuel material. A coating layer of coated fuel particles, the first coating layer made of low-density carbon having both a gas reservoir function for accumulating gaseous fission products FP and a buffer function for absorbing fuel nuclear swelling It is. The second coating layer made of high-density carbon has a holding function for gaseous FP, and the third coating layer made of silicon carbide SiC has a holding function for solid FP. The fourth coating layer made of high-density carbon similar to the second coating layer has a function of retaining the solid FP and also has a protective function for the third coating layer. In addition to these, a fuel compact is obtained by mixing coated fuel particles with graphite powder and molding and sintering into a fixed shape, and a fuel rod is obtained by sealing a fixed quantity of fuel compact in a graphite tube. Eventually, a high-temperature gas reactor fuel is obtained by loading a predetermined number of fuel rods into the insertion ports of the graphite block.

  Generally, the fuel for the HTGR is manufactured as follows. In the initial step of creating fuel nuclei, uranyl nitrate stock solution is dropped into an ammonia solution to form ammonium heavy uranate particles, and the particles are dried and then oxidized, reduced, and sintered. When coating the fuel nuclei with the first coating layer to the fourth coating layer to produce coated fuel particles, each layer is formed by introducing the fuel nuclei into the high-temperature fluidized bed and carrying out the CVD method. In an example of making a fuel compact, a predetermined amount of coated fuel particles is formed into a predetermined shape together with a graphite matrix material (graphite powder + binder, etc.) and sintered. In another example of making a fuel compact, coated fuel particles are coated with a graphite matrix material to form overcoat particles, a predetermined amount of overcoat particles are formed into a predetermined shape together with the graphite matrix material, and then sintered. . In the step of making the fuel rod, the fuel compact may be enclosed in the graphite tube. The fuel in the HTGR is completed by loading the thus obtained fuel rods into the insertion ports of the graphite block.

  The above-mentioned coated fuel particles have a diameter in the range of 500 to 1500 μm, and in the case of overcoat particles having an overcoat layer formed thereon, the diameter is in the range of 1000 to 3000 μm. For such particles, those having an overcoat layer are referred to as overcoat particles, but in a broad sense, overcoat particles are also included in the category of coated fuel particles. Therefore, in the following, the overcoat particles are also simply referred to as coated fuel particles.

When producing a fuel compact in the production of fuel in a HTGR, as described above, the molding process is carried out using coated fuel particles as a raw material. In that case, a high-quality fuel compact can be obtained by accurately weighing the raw material particles per one fuel compact, which leads to an improvement in the quality of the final product. Incidentally, in the conventional method, this weighing is carried out using an electromagnetic micro-feeder, a pre-made weighing device, a pre-made weighing container, etc. disclosed in Non-Patent Document 2 below and others. The embodiment in that case will be further described. The electromagnetic microfeeder quantitatively feeds the raw material particles into the weighing container on the weighing instrument from the vibration supply section having a cross-sectional groove shape inclined downward with an appropriate gradient, and supplies it to the weighing instrument. Measure.
Japanese Patent Laid-Open No. 06-265669 JP 07-218674 A Atomica Encyclopedia ATMICA [Search on the Internet on December 7, 2004] <URL: http://www-atm.jst.go.jp/atomica/03030301_1.html> Electromagnetic microfeeder MF-1 type (manufactured by Tsutsui Rika Instruments Co., Ltd .: Tokyo) [Search on the Internet on February 22, 2005] <URL: http://www.funtaitokogyo.co.jp/rasinban/tt/ tt-5.html>

  When weighing raw material particles for one fuel compact by the conventional method as described above, depending on the width, gradient (downward tilt angle), frequency, etc. of the vibration supply unit in the electromagnetic microfeeder, Raw material particle supply speed and weighing time are determined. In the case of the conventional method, since the supply speed of the raw material particles is low, it takes a long time to finish weighing, and several minutes are required to weigh several tens of grams of raw material particles with a precision of two decimal places. End up. Of course, when the supply speed of the raw material particles is increased by adjusting the vibration supply unit of the electromagnetic microfeeder or changing the specifications, the holding time can be shortened. But this comes with a tedious adjustment. If the feed rate of the raw material particles is excessively increased so as to give priority to shortening the weighing time, the measurement system becomes unstable or disturbance occurs, resulting in a decrease in weighing accuracy.

  In view of such technical problems, the present invention intends to provide a weighing method and a weighing apparatus that can satisfy high-precision weighing, high-speed weighing, reduction in weighing difficulty, reduction in weighing cost, and the like.

  The method for weighing raw material particles for compact fuel molding according to claim 1 of the present invention is characterized by the following problem solving means in order to achieve the intended purpose. That is, the weighing method according to claim 1 is a raw material particle weighing technique carried out in a process for forming a fuel compact including a nuclear fuel substance in a process for producing a high temperature gas reactor fuel. In the method for weighing per fuel compact, first weigh the raw material particles, then weigh the raw material particles after volumetric measurement, and then weigh the actual measured weight for one fuel compact for the raw material particles in the weighing And the target weighing value are compared and the difference between the actual weighing value and the target weighing value is converted into the number of raw material particles, and the number of raw material particles necessary for eliminating the difference is counted in the raw material particles in the weighing. It is characterized by being supplied in units.

  The method for weighing raw material particles for compact fuel molding according to claim 2 of the present invention is the method according to claim 1, wherein raw material particles having an average diameter of 0.5 to 3 mm and an average sphericity of 1.2 or less are used. It is characterized by weighing.

  The method for weighing fuel compact molding raw material particles according to claim 3 of the present invention is the method according to claim 1 or 2, wherein the raw material particles having a weight per particle of 0.002 to 0.01 g are weighed. It is characterized by.

  The method for weighing fuel compact molding raw material particles according to claim 4 of the present invention is characterized in that, in the method according to any one of claims 1 to 3, the target weighing value is in the range of 0.001 to 100 g. To do.

  The fuel compact molding raw material particle weighing device according to claim 5 of the present invention is characterized by the following problem solving means in order to achieve the intended purpose. That is, the weighing apparatus according to claim 5 is a raw material particle weighing technique performed in a forming step of a fuel compact including a nuclear fuel substance in a process for producing a fuel for a HTGR. In an apparatus for weighing per fuel compact, a volume measuring container for volumetric measurement of raw material particles, a weighing device for weighing the volumetric raw material particles, and one fuel compact for the raw material particles being weighed Means for comparing and calculating the actual measurement value and the target measurement value to convert the difference between the actual measurement value and the target measurement value into the number of raw material particles, and additional raw material particles for the raw material particles in the measurement And a particle supply machine for supplying in units.

The method for weighing the fuel compact molding raw material particles according to the present invention has the following effects. (1) Since the raw material particles calculated in number units are supplied to the volumetric raw material particles to reach the target weighing value, the weighing of raw material particles for compact fuel molding satisfies high weighing accuracy of two decimal places or less. Can be made.
(2) Volumetric measurement and replenishment of raw material particles can be completed in about 1 minute. Therefore, the speed of the weighing of the raw material particles for compact molding can be increased so as to surpass the prior art.
(3) It is only necessary to replenish a very small amount of raw material particles with respect to the volumetric raw material particles to be weighed close to the target weighing value, and there is no need for highly difficult adjustments. This can be done easily even with the required weighing.
(4) For weighing, it is only necessary to have a volumetric container, weighing device, particle supply machine, etc., and expensive equipment such as an electromagnetic microfeeder is not required. In addition, particle supply machines consume much less power than electromagnetic microfeeders. Therefore, with regard to the weighing of the fuel compact molding raw material particles, the initial cost and the running cost can be suppressed and the weighing cost can be reduced.

  The fuel compact molding material particle weighing device according to the present invention has the following effects. (5) Since it is equipped with a volumetric container, weighing device, raw material particle number conversion means, particle supply machine, etc., while ensuring high-precision weighing, high-speed weighing, reduced weighing difficulty, reduced weighing costs, etc. This is a useful and useful apparatus for carrying out the method of the present invention.

  Embodiments of the fuel compact molding raw material particles to be handled in the present invention and the fuel compact molding raw material particle weighing apparatus according to the present invention will be described in advance with reference to the accompanying drawings.

  In FIG. 1 to FIG. 4, the raw material particles 11 described first are composed of the above-described coated fuel particles. The raw material particles 11 include coated fuel particles having no overcoat layer and coated fuel particles having an overcoat layer. This will be described in detail with reference to FIG. 4. The raw material particles 11 without the overcoat layer are formed on the outer peripheral surface of the fuel core (core) 12 with the first coating layer 13, the second coating layer 14, the third coating layer 15, and the first coating layer. The raw material particles 11 having the four coating layers 16 and the like and having the overcoat layer further include a graphite matrix material layer 17 on the fourth coating layer 16.

The fuel core 12 made of an oxide of nuclear fuel material is made of uranium dioxide sintered in a ceramic form and having a diameter of 350 to 650 μm. The first coating layer 13 formed on the outer peripheral surface of the fuel core 12 is made of low density carbon (low density pyrolytic carbon), and has a thickness of 30 to 150 μm and a density of 0.8 to 1.2 g / cm ³ . The first coating layer 13 has a gas storage function for storing gaseous fission products (FP) and a buffer function for absorbing fuel nuclear swelling. The second coating layer 14 formed on the first coating layer 13 is made of high-density carbon (high-density pyrolytic carbon), and has a thickness of 20 to 50 μm and a density of 1.6 to 2.0 g / cm ³ . The second coating layer 14 has a function of holding a gaseous FP. The third coating layer 15 formed on the second coating layer 14 is made of silicon carbide (SiC), and has a thickness of 20 to 50 μm and a density of 3.0 to 3.2 g / cm ³ . The third coating layer 15 is a main strength assurance layer and also has a holding function for the solid FP. The 4th coating layer 16 formed on the 3rd coating layer 15 consists of high density carbon (high density pyrolytic carbon) similar to the 2nd coating layer 14, thickness 20-80 micrometers, density 1.6-2. 0.0 g / cm ³ . The fourth coating layer 16 has a function of retaining the solid FP and also has a protection function for the third coating layer 15. As shown in the illustrated example, the coated fuel particles having no overcoat layer are formed by finishing the coating layer with the fourth coating layer 16. In this case, the particle diameter (outer diameter) is in the range of 500 to 1500 μm (0.5 to 1.5 mm), and has a diameter of 1200 μm (1.2 mm) as an example. As the coated fuel particles without the overcoat layer, there is one in which a fifth coating layer made of a pyrolytic carbon layer is formed on the fourth coating layer 16. The carbon layer for the fifth coating layer does not need to have a high density. The graphite matrix material layer 17 formed on the outer peripheral surface of the fourth coating layer 16 (or the fifth coating layer) is made of a rolling granulated material of the graphite matrix material. In this case, the graphite matrix material is obtained by uniformly kneading a graphite powder with a binder. The graphite matrix material layer 17 has a thickness in the range of 20 to 400 μm. A coating layer having such a graphite matrix material layer 17 as a coating layer is a coated fuel particle having an overcoat layer. The particle diameter (outer diameter) in this case is in the range of 1000 to 3000 μm (1 to 3 mm), and has a diameter of 1300 μm (1.3 mm) as an example. The raw material particles 11 also have an average sphericity of 1.2 or less.

When the average diameter of the raw material particles 11 is D1 (mm), the average volume V1 (cm ³ ) is represented by the following formula (1).
V1 = (4 / 3π) × (D1 / 20) ³ (1)

  In FIG. 1, a measuring container 21 for primarily measuring raw material particles 11 is made of an arbitrary material selected from metal, reinforced resin, and a composite material thereof. In particular, it is made of a material having a small coefficient of thermal expansion and a large mechanical property (strength). The weighing container 21 has a cylindrical shape with a bottom in the illustrated example which is only an example, but it may be a rectangular tube with a bottom.

The volume V2 (cm ³ ) of the measuring container 21 is set based on the following formula (2) when the average weight of the raw material particles 11 is W1 (g) and the target weighing value is W2 (g).
V2 = (W2 / W1) × (V1) × (100-3.2) (2)
“3.2” in the equation (2) is calculated by assuming that the filling rate error of the raw material particles 11 into the measuring container 21 is 2% at the maximum.

  The weighing device 31 illustrated in FIG. 1 is an electronic balance having a high resolution excellent in responsiveness, temperature characteristics, and impact resistance. The weighing device 31 has many functions such as piece counting, check weighing,% weighing, unit conversion (factor calculation) function, general statistical data processing, filter measurement, and others. The weighing device 31 is also equipped with a computer 32 for recording, storing, processing and inputting / outputting various data obtained by these functions, and a control signal calculated by the computer 32 will be described later. Can be output to the particle supply machine 41. Incidentally, the computer 32 compares the actual measured value of one fuel compact with the target measured value for the raw material particle 11 weighed by the weighing device 31 by an arithmetic circuit, and calculates the difference between the measured measured value and the target measured value as the raw material particle. Is converted into the number of particles and input to a particle supply machine 41 described later.

  In FIG. 1, a weighing container 33 mounted on a weighing device 31 is used for receiving raw material particles 11 that are primarily weighed by the weighing container 21 and raw material particles 11 that are sent from the particle supply machine 41 that will be described later. Is. The weighing container 33 is made of the same material as the weighing container 21. In terms of the relationship between the weighing device 31 and the weighing container 33, when weighing the raw material particles 11, the weighing device 31 does not include the weight of the weighing container 33 and weighs only the net amount of the raw material particles 11 and displays it. Or output.

  The particle supply machine 41 illustrated in FIGS. 1 to 3 includes a base 42, a support base 43, a bearing 44, a rotating disk 45, a particle loading guide member 51, a particle supply guide member 54, an electric motor 61, and a rotation. It comprises a controller 64 and others.

  In the above description, the support base 43 for supporting the turntable 45 via the bearing 44 is assembled on the base 42 as shown in FIG. Of these, the base 42 and the support base 43 are made of metal, synthetic resin, wood, a composite material thereof, or the like having an appropriate mechanical strength, and the bearing 44 is made of a known material.

  The disc-shaped rotating disk 45 apparent in FIGS. 2 and 3 has a large number of recesses 46 arranged at equal intervals in the circumferential direction along the outer periphery of the surface and also has a shaft 47 protruding from the center of the back surface. The concave part 46 of the turntable 45 may be any of spherical, conical, pyramidal, cylindrical, and prismatic dents as long as one raw material particle 11 can be fitted. . In the case of the illustrated example, a spherical recess 46 is employed. The turntable 45 having such a recess 46 is rotatably supported on the support base 43 by the bearing 44 that holds the shaft 47 inclined. That is, the turntable 45 is rotatably supported in a posture inclined backward to 15 to 30 degrees, specifically about 20 degrees. Regarding the relationship between the depth of the concave portion 46 and the raw material particles 11, the raw material particles 11 fitted in the concave portion 46 protrude out of the concave portion 46 at a portion slightly larger than half of the particles. However, since the turntable 45 is in an inclined state, the raw material particles 11 usually do not escape from the recess 46 or fall off.

  The guide member 51 for loading particles and the guide member 54 for supplying particles illustrated in FIGS. 2 and 3 are as follows. One guide member 51 is a long tubular or groove-shaped member. The guide member 51 has a particle inlet (not shown) on the proximal end side and an open particle outlet 52 on the distal end side. Further, a small protruding piece 53 as shown in FIG. 3 is formed at the lower part of the particle outlet 52 of the one guide member 51 for particle delivery. The other guide member 54 is also a long tubular or grooved member. The guide member 54 has an open particle inlet 55 on the proximal end side and an open particle outlet 57 on the distal end side. Further, a small projecting piece 56 as shown in FIG. 3 is formed for receiving particles under the particle inlet 55 of the other guide member 54. These guide members 51 and 54 are also made of any material such as metal, synthetic resin, or composite material thereof. Among them, the guide members 51 and 54 made of synthetic resin have flexibility.

  As is apparent from FIG. 2, the particle loading guide member 51 and the particle supply guide member 54 are arranged on the surface side of the rotating disk 45. In the illustrated example, which is only a specific example, the particle loading guide member 51 is disposed close to one side of the surface of the rotating disk in the downward gradient with the particle outlet 52 side as the lower level. At the same time, it is supported by a supporting means (not shown) while maintaining such posture and position. The particle outlet 52 and the protruding piece 53 of the guide member 51 arranged in this way come to be separated from the respective concave portions 46 of the turntable 45 at a fixed position during rotation. The particle supply guide member 54 is also arranged in a descending gradient with the particle outlet 57 side as the lower side, the particle inlet 55 side being disposed close to the other side of the surface of the rotating disk, and supporting such a posture and position, not shown. Supported by means. Accordingly, the particle inlet 55 and the protruding piece 56 of the guide member 54 are also separated from the respective concave portions 46 of the rotating disk 45 at a fixed position during rotation. In addition, the base end side (particle inlet side not shown) of the particle loading guide member 51 has a particle feeding system (not shown) for causing the raw material particles 11 in a row to enter the guide member 51 one after another. Have been contacted. Further, the particle outlet 57 side of the particle supply guide member 54 reaches the weighing container 33 on the weighing device 31 as shown in FIG.

  The electric motor 61 shown in FIG. 3 is for applying a rotational force to the turntable 45. Therefore, the electric motor 61 mounted on the support base 43 has a drive shaft 62 connected to the shaft 47 of the turntable 45 via a coupling 63. The electric motor 61 further includes a stepping motor (pulse motor) or a servo motor that can set the rotation amount per step to 15 degrees, for example, and adjust the rotation amount. The electric rotation controller 64 connected to the electric motor 61 is for instructing the electric motor 61 to output a step when receiving a control signal from the computer 32 on the weighing device 31 side.

  Next, an embodiment in which the above-described means is used for the weighing method of the fuel compact molding raw material particles according to the present invention will be described below.

  In FIG. 1, the raw material particles 11 are weighed in the first stage. At this time, since the volume of the measuring container 21 is V2, the predetermined amount of the raw material particles 11 is put into the measuring container 21 based on this. The means for putting the raw material particles 11 into the measuring container 21 may be either manual, semi-automatic or fully automatic. For example, when performing a mechanical operation such as semi-automatic or fully automatic, a known measuring hopper is used. What is necessary is just to supply a fixed amount of the raw material particles 11 into the container 21.

  In FIG. 1, in the next stage, the raw material particles 11 after the volume measurement are weighed. At this time, the raw material particles 11 in the weighing container 21 are transferred into the weighing container 33 on the weighing device 31. More specifically, after the weighing container 21 placed on the turntable or the conveyor is transported to a predetermined position, the raw material particles 11 in the weighing container 21 are transferred into the weighing container 33 by grasping it with a robot band. Or, it may be held by a movable robot band and the raw material particles 11 may be transferred into the weighing container 33 in the same manner as described above. When the raw material particles 11 after volumetric measurement are transferred into the weighing container 33 in this way, the weighing device 31 weighs them.

At this stage, the weighing device 31 weighs the raw material particles 11 after volumetric measurement, so that the current weighing value is slightly below the target weighing value W2 as shown in the equation (2). Therefore, a shortage of raw material particles 11 must be added to the weighing container 33. The addition of the raw material particles 11 is performed in units of number, so that the raw material particles 11 in the weighing reach the target weighing value W2. Incidentally, the number W4 (number) of the raw material particles 11 to be added is obtained by the following equation (3) when the weight in the current weighing (the weight of the raw material particles 11 after the volume measurement) is W3 (g).
W4 (pieces) = (W2-W3) / W1 (3)

  When the weighing device 31 is weighing the raw material particles 11 after volumetric measurement, the computer 32 performs an electrical or electronic calculation based on the above equation (3), and the raw material particles 11 that are insufficient with respect to the target weighing value W2. , That is, the number of raw material particles 11 to be added. The number signal of the raw material particles 11 obtained here and a signal prompting the addition thereof, that is, a control signal are transmitted from the computer 32 to the rotation controller 64 of the particle supply machine 41.

  Upon receiving the control signal, the rotation controller 64 of the particle supply machine 41 rotates the electric motor 61 by a predetermined step based on the control signal. For example, when only 50 raw material particles 11 need be added to the weighing container 33 on the weighing device 31, the electric motor 61 is operated for 50 steps, and the rotating disk 45 is rotated intermittently or continuously for 50 steps.

  Referring to FIG. 2, raw material particles 11 are loaded in each of the recesses 46 in the substantially upper half area of the surface of the turntable 45. The raw material particles 11 in the recess 46 located at the lowermost left side in the upper half region of the rotating disk face the particle inlet 55 of the particle supply guide member 54. Accordingly, when the turntable 45 is rotated one step in the counterclockwise direction of FIG. 2, the lowermost raw material particle 11 on the left side enters the particle supply guide member 54 from the particle inlet 55, and the particle is lowered while gravity falling there. It falls into the weighing container 33 from the outlet 57. When the turntable 45 rotates the next step in the counterclockwise direction of FIG. 2, the next raw material particle 11 on the turntable 45 matches the particle inlet 55 and falls into the weighing container 33 in the same manner as described above. . In the subsequent step rotation, the raw material particles 11 at predetermined positions on the rotating disk 45 are successively dropped into the weighing container 33 in the same manner as described above. In FIG. 2, on the right side of the turntable 45 when the raw material particles 11 are added in this way, empty concave portions 46 in the substantially lower half area of the surface are successively raised along with the step rotation. Is separated from the particle outlet 52 of the particle loading guide member 51. When the empty concave portion 46 matches the particle outlet 52 of the particle loading guide member 51, the raw material particles 11 in the guide member 51 are transferred from the particle outlet 52 to the empty concave portion 46. Therefore, each empty recess 46 is loaded with the raw material particles 11 each time it coincides with the particle outlet 52 of the particle loading guide member 51.

  Thus, when a predetermined number of raw material particles 11 are added into the weighing container 33, the weighing device 31 can visually and / or audibly detect that the raw material particles 11 in the weighing have reached the target weighing value W2. To inform. The target weighing value W2 when weighing the fuel compact molding raw material particles by such means is in the range of approximately 100 g. Incidentally, when the “target weighing value W2 = several tens of grams” and “weighing accuracy = two digits or less of the decimal point” are realized by means of the present invention, the time required for this is less than half that of the prior art.

  The raw material particles 11 precisely weighed by the means of the present invention are pressed or molded into a hollow cylindrical shape. A sintered compact of the molded product becomes a fuel compact, and a fuel rod is obtained by putting a certain amount of fuel compact in a graphite tube and sealing the top and bottom with end plugs. As a final product, a fuel in the high temperature gas furnace is obtained by loading a predetermined number of fuel rods into the insertion ports of the hexagonal columnar graphite block.

  The method of the present invention and the device of the present invention have high weighing accuracy, short weighing time, and low initial cost and running cost, so that the industrial applicability is high.

1 is a perspective view schematically showing an embodiment of a method and a device of the present invention. It is a front view of the particle supply machine employ | adopted by one Embodiment of this invention method and this invention apparatus. FIG. 3 is a side view of the particle supply machine shown in FIG. 2. It is sectional drawing which showed an example of the raw material particle handled with this invention method and this invention apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Raw material particle | grains 12 Fuel nucleus 13 1st coating layer 14 2nd coating layer 15 3rd coating layer 16 4th coating layer 17 Graphite matrix material layer 21 Measuring container 31 Weighing apparatus 32 Computer 33 Weighing container 41 Particle supply machine 45 Turntable 46 Recess 47 Shaft 51 Guide member for loading particles 52 Particle outlet 53 Protruding piece 54 Guide member for supplying particle 55 Particle inlet 56 Protruding piece 57 Particle outlet 61 Electric motor 62 Motor drive shaft 64 Rotation controller

Claims (5)

  In a method for weighing raw material particles carried out in a fuel compact forming step including a nuclear fuel material in a process for producing a fuel for a HTGR, the raw material particles are weighed per fuel compact. First, volumetrically measure the raw material particles, then weigh the volumetric raw material particles, and then compare the actual measured value for one fuel compact with the target measured value for the raw material particles being weighed. A fuel compact characterized by converting the difference between the actual measurement value and the target measurement value into the number of raw material particles, and supplying the required amount of raw material particles to the raw material particles in the weighing unit in order to eliminate the difference Method of weighing raw material particles for molding.   2. The method for weighing fuel compact molding raw material particles according to claim 1, wherein raw material particles having an average diameter of 0.5 to 3 mm and an average sphericity of 1.2 or less are weighed.   3. The method for weighing fuel compact molding raw material particles according to claim 1, wherein raw material particles having a weight per particle of 0.002 to 0.01 g are weighed.   The method for weighing fuel compact molding raw material particles according to any one of claims 1 to 3, wherein the target weighing value is in the range of 0.001 to 100 g.   In an apparatus for weighing raw material particles carried out in a process for forming a fuel compact containing a nuclear fuel material in a process for producing a fuel for a HTGR, the raw material particles are weighed per one fuel compact. Volumetric container for volumetric measurement of raw material particles, weighing device for weighing raw material particles after volumetric measurement, and comparison between the actual measured value for one fuel compact and the target measured value for the raw material particles in the weighing Means for calculating and converting the difference between the actual measurement value and the target measurement value into the number of raw material particles, and a particle supply machine for supplying additional raw material particles in units of the raw material particles in the weighing An apparatus for weighing raw material particles for compact fuel molding, comprising:

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