JP5569834B2 - Method for producing high density, high purity (n, γ) 99Mo - Google Patents

Description

The present invention produces a high-density, high-purity (n, γ) ⁹⁹ Mo by irradiating a molybdenum oxide pellet, a molybdenum oxide pellet produced by this method, and a molybdenum oxide pellet produced by this method in a nuclear reactor. And high density, high purity (n, γ) ⁹⁹ Mo pellets produced by this method.

⁹⁹ Mo is the parent nuclide of ^99m Tc, which is used most in radiopharmaceuticals for medical diagnosis, and is a substance that is always required for daily nuclear medical diagnosis. In Japan, ⁹⁹ Mo is not produced domestically, and the entire supply depends on overseas.

Conventional U (n, fission) ⁹⁹ Mo, which is produced by fission reaction using highly enriched uranium with a concentration of 20% or more as a raw material, has a problem of processing and disposal of fission products produced in large quantities by the nuclear reaction, and the production cost is high. On the other hand, Pu is produced in the manufacturing process because highly enriched uranium is used, and is subject to inspection by IAEA due to concerns about military diversion, which is not desirable from the viewpoint of non-proliferation.

On the other hand, in the case of (n, γ) ⁹⁹ Mo produced by a ⁹⁸ Mo (n, γ) ⁹⁹ Mo nuclear reaction (neutron activation method) using a natural Mo compound as a raw material, the above highly enriched uranium is used. There is no such problem. That is, in the neutron activation method, since ⁹⁸ Mo is neutron-irradiated in a nuclear reactor using low enriched uranium with a enrichment of less than 20%, fission products and Pu are not generated, which is desirable from the viewpoint of nuclear non-proliferation. In order to produce (n, γ) ⁹⁹ Mo, it is necessary to irradiate a solid target (generally MoO ₃ or the like) of a natural Mo compound with a limited volume in the reactor.

Patent Document 1 describes a method for producing molybdenum-99 by neutron irradiation in a nuclear reactor. According to this method, the molybdenum trioxide pellets used were 15 w of ethanol in which 2 w / o (weight per overall: weight percent) camphor was dissolved as a binder (binder) in molybdenum trioxide powder having a high indication purity. / O is added and allowed to stand for 3 to 4 days, after which a certain amount is collected and placed in a mold, and a surface pressure of 980 kg / cm ² is applied to form a pellet. The pellets thus produced are heated and sintered at 600 to 750 ° C. for 90 minutes to remove moisture, ethanol and camphor and increase the hardness.

Japanese Patent Publication No. 60-57040

In order to produce (n, γ) ⁹⁹ Mo, it is necessary to neutron-irradiate a solid target of a natural Mo compound in a nuclear reactor, and in order to efficiently produce ⁹⁹ Mo and increase its production amount It is necessary to increase the amount of molybdenum in the irradiation target material as much as possible. Here, in the production of (n, γ) ⁹⁹ Mo by neutron irradiation in a nuclear reactor, the volume in the nuclear reactor that performs neutron irradiation is limited. It is necessary to increase the density of the irradiation target.

The density of the sintered body sintered by the method described in Patent Document 1 mentioned above is 59% TD (Theoretical Density), which is a ratio to the theoretical value of the sintered density, and is called bulk density. However, the bulk density is not sufficient to efficiently produce ⁹⁹ Mo and increase its production.

In addition, since (n, γ) ⁹⁹ Mo produced by neutron irradiation is activated, when the powder is separated from (n, γ) ⁹⁹ Mo after production, the activated powder is scattered, There is a possibility of polluting the environment, which is not preferable.

As a means for solving the above problems, it is conceivable to use a discharge plasma sintering method. A method for obtaining a sintered body using a discharge plasma is described in many patent documents, and has 0.2 to 0.3 mass% of transition metal carbide fine particles dispersed in Mo. It is known that a molybdenum sintered body sintered by a discharge plasma sintering method having a particle diameter of 10 μm can be obtained. With the spark plasma sintering method having such characteristics, ⁹⁹ Mo is efficiently produced, molybdenum in the irradiation target material is densified in order to increase the production amount, and there is a problem of activated powder peeling. It is considered that an irradiation target that does not occur and suppresses the amount of powder peeling, that is, a molybdenum oxide sintered body can be obtained. However, there has been no report to date that the spark plasma sintering method has been used to form a sintered body of molybdenum oxide.

The inventors of the present application, among various types of pressure sintering for the purpose of obtaining a high-purity molybdenum oxide sintered body suitable for the production of (n, γ) ⁹⁹ Mo by neutron irradiation in a nuclear reactor, We have intensively studied whether the discharge plasma method can be applied.

The present invention has been made in view of the above points, and based on the results of earnest research, without using a binder as shown in Patent Document 1, the molybdenum required for efficient production of ⁹⁹ Mo is obtained. A high-purity molybdenum oxide sintered body that solves the problem of activated powder delamination when densified and activated is obtained by the discharge plasma method and used as a diagnostic radiopharmaceutical by neutron irradiation in a nuclear reactor. The purpose is to produce (n, γ) ⁹⁹ Mo with a short half-life.

The present invention relates to molybdenum oxide sintering manufactured using a discharge plasma sintering method in which a powdered material is charged into a forming die and compressed with a punch to generate a discharge plasma by applying a pulsed current. In a method for producing high purity (n, γ) ⁹⁹ Mo from a body,
Using a high-purity molybdenum oxide material as a powder material, the molybdenum oxide material is sintered by a discharge plasma sintering method to form a 70-98% TD high-purity molybdenum sintered body. high density by irradiation with a molybdenum sintered body in the reactor, high purity (n, gamma) high density and generates a ^{99 Mo,} provides a method of producing high purity (n, γ) ^{99 Mo} To do.

The present invention also sinters the molybdenum oxide material to form a high-density sintered body of 90 to 98% TD, and sinters by a discharge plasma sintering method characterized in that the high density of 70 to 98% TD. A high purity (n, γ) ⁹⁹ Mo is produced by forming a high purity molybdenum sintered body and irradiating the high purity molybdenum sintered body in a nuclear reactor. , Γ) A method for producing ⁹⁹ Mo is provided.

The present invention relates to molybdenum oxide sintering manufactured using a discharge plasma sintering method in which a powdered material is charged into a forming die and compressed with a punch to generate a discharge plasma by applying a pulsed current. In a method for producing high purity (n, γ) ⁹⁹ Mo from a body,
A high-purity molybdenum oxide material is charged into the forming die as a powder material, and a discharge plasma is generated by applying a pulsed current in a compressed state with a low load of 10 to 30 kN at a low temperature of 540 to 640 ° C. The molybdenum oxide powder is sintered by a discharge plasma sintering method to form a high-density, high-purity molybdenum sintered body, and the high-density, high-purity molybdenum sintered body is irradiated in a nuclear reactor to increase the Provided is a method for producing a high density, high purity (n, γ) ⁹⁹ Mo characterized by producing density, high purity (n, γ) ⁹⁹ Mo.

The present invention also provides a method for producing high density, high purity (n, γ) ⁹⁹ Mo, characterized by using molybdenum trioxide or molybdenum dioxide as the molybdenum oxide material.

The present invention also maintains a state of 540 to 640 ° C. and 10 to 30 kN, and performs a sintering process for 4 to 18 minutes for sintering of molybdenum oxide. , Γ) A method for producing ⁹⁹ Mo is provided.

The present invention also provides a method for producing a high density, high purity (n, γ) ⁹⁹ Mo characterized in that molybdenum metal is mixed with a molybdenum oxide material to form a composite molybdenum sintered body.

The present invention also includes a step of forming a large-diameter flat plate-like high-density, high-purity molybdenum sintered body and generating a plurality of molybdenum sintered pellets from the formed large-diameter flat plate-like molybdenum sintered body. A method for producing a high-density, high-purity (n, γ) ⁹⁹ Mo characterized by:

The present invention also provides a high-density, high-purity (n, γ) ⁹⁹ Mo pellet characterized by being produced from a 70-98% TD shaped sintered body sintered by a discharge plasma sintering method. .

The present invention also provides a high-density, high-purity (n, γ) ⁹⁹ Mo pellet characterized by being produced from a molded sintered body of 90 to 98% TD by a discharge plasma sintering method.

According to the present invention, a high-purity molybdenum oxide sintered body (pellet) that can solve the problem of activated powder peeling when activated by applying the discharge plasma method can be molded, and a diagnostic radiopharmaceutical. High purity (n, γ) ⁹⁹ Mo with a short half-life can be produced safely and reliably. Moreover, the high purity (n, gamma) can be produced molybdenum oxide sintered body of high purity to be used to produce the ^{99 Mo.}

  Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a main part of a sintering apparatus used in an embodiment of the present invention.
In FIG. 1, the main part of the sintering apparatus 1 includes a forming die 2, a punch 3 mounted in a recess formed in the upper and lower central portions of the forming die 2, and an outer side of the forming die 2. Are formed from an outer cylinder 4 for instructing from the outside and a pressing base 5 for pressing the upper and lower punches 3 respectively. When referring to the upper punch, the punch 3 is referred to as an upper punch 3A, and when referring to the lower punch, the punch 3 is referred to as a lower punch 3B. Further, when referring to the upper pressing table, the pressing table 5 is referred to as an upper pressing table 5A, and when referring to the lower pressing table, it is referred to as a lower pressing table 5B.

  The molding die 2 is slidable on the inner wall surface 6 of the outer cylinder 4, but is fixed at a predetermined position, and the pressing table 5 is slidable on the inner wall surface 6, but is fixed at a predetermined position. The pressing table 5 is slidable on the inner wall surface 6, and the lower pressing table 5 is set on a support table (not shown).

The upper punch can slide on the inner wall surface of the recess 7 provided in the upper center portion of the molding die 2, and the lower punch can slide on the inner wall surface of the recess 8 provided in the lower center portion of the molding die 2. It contacts the lower end surface of the convex portion of the molding die 2.
A cylindrical space portion 9 communicating with the depressions 7 and 8 is formed by the convex shape portion 10 in the middle center portion of the molding die 2.

  The upper punch 3A includes a pressing punch portion 11 extending in the lower lower punch 3A direction, and the pressing punch portion 11 slides on the inner surface of the space portion 9, that is, the convex-shaped inner surface wall.

  Due to such a shape, the space portion 9 is formed with a molybdenum oxide powder charging portion 12 into which molybdenum oxide powder is charged by the upper punch 3A and the lower punch 3B, and the molybdenum oxide powder 13 is charged therein. .

  A pressing force is applied to the upper pressing table 5A by a pressing machine, that is, a compressor.

  The pressing table 5, the punch 3 and the forming die 2 are made of a conductive material, and the punch 3 is made of a bluffite material. Therefore, electricity can be applied to the molybdenum oxide powder charged in the molybdenum oxide charging portion via the pressing table 5, the punch 3, and the forming die 2. Reference numeral 16 denotes electrical wiring.

As the molybdenum oxide, molybdenum dioxide MoO ₂ and molybdenum trioxide MoO ₃ are selected. The chemical properties of molybdenum dioxide MoO ₂ and molybdenum trioxide MoO ₃ are as follows. Since these molybdenum oxides are used to produce (n, γ) ⁹⁹ Mo as a diagnostic radiopharmaceutical, high purity is required. Therefore, in this embodiment, high-purity molybdenum oxide is formed as high-purity molybdenum trioxide and has an oxidation purity of 99.9% or more, meaning that no new impurities are mixed according to the present invention. When molybdenum raw material is used, its purity should be maintained.
[Molybdenum dioxide; Mo (IV) O ₂ ]
Molecular weight 127.9, tetragonal system; monoclinic system, insoluble in water Mo is generated as an intermediate product when heated in air, but water is passed through red-hot Mo or molybdate and zinc. Reduced by a method that melts. Unlike MoO ₃ below, it does not dissolve in caustic or acid.
[Molybdenum trioxide; Mo (VI) O ₃ ]
Molecular weight 144.0, orthorhombic system, melting point 795 ° C. [sublimation], boiling point 1155 ° C., hardly soluble in water It is the most common oxide of Mo. It is a substance in the final oxidized form obtained when Mo alone or its compound is heated in air or oxygen atmosphere or oxidized with nitric acid. MoO ₃ is a white powder that hardly dissolves in water and has a smooth feeling like talc powder, but when heated, it turns pale yellow and melts at 795 ° C. to become a brown liquid. However, it begins to sublime into white smoke from the temperature near the melting point.

MoO ₃ does not dissolve in ordinary acids except for hydrofluoric acid and concentrated sulfuric acid, but dissolves in weak alkalis such as ammonia water and alkali carbonate aqueous solution and dissolves in molybdate (M ₂ MoO ₄ ). Become.

Thus, the selected high-purity molybdenum dioxide powder or molybdenum trioxide powder is put into the mold (molybdenum oxide charging portion) 12 of the graphite molding die 2 and is sandwiched from above and below by the graphite punch 3. Then, a discharge plasma was generated through an electric current while applying pressure, and a high-density, high-purity powder was sintered.

FIG. 2 shows a sintered high-density, high-purity molybdenum oxide sintered body 20 formed by sintering.
As for the sintering mechanism of the powder body by this method, discharge due to ON-OFF pulse energization occurs between the particles of the molybdenum oxide powder packed in the die, and welding (neck formation) occurs due to vaporization of the particle surface layer. This is because the entire powder body in the die is sintered and formed.

According to this method, it is possible to sinter and form at a temperature lower than the melting point of the molybdenum oxide powder that is the raw material powder, and it is possible to form it at a high density without impairing the physical properties of the raw material powder.
Further, since the sintering can be performed in a short time with a low load, it can be evaluated that the productivity is high.

The characteristics of this method are enumerated as follows.
・ Discharge plasma sintering method ・ No need for binders; high purity and short time production possible ・ High density; conventional 59% TD → This method, for example, 95% TD or more ・ Calculation of firing density is possible; 70 to 98% Controllable within the range of TD (weighting, heating temperature and processing time of discharge plasma sintering process are parameters)
・ Can be manufactured in a short time; conventional 4-5 days → this method; 1 hour (sintering process; for example, 10 minutes)
Low temperature sintering possible: Conventional 720 ° C. → This method; eg 600 ° C.
Low load: Conventional 1 to 8 tons / cm ² → This method, for example, 0.3 tons / cm ²
・ Simple process

FIG. 3 shows molybdenum trioxide pellets as a high-density, high-purity sintered body using the sintering apparatus shown in FIG. 1 for molybdenum trioxide MoO ₃ powder among high-density, high-purity molybdenum oxide powders. The experimental result at the time of shape | molding is shown. The particle size is in the range of 2 to 4 μm and contains 90% or more of molybdenum trioxide MoO ₃ powder.

  FIG. 3A shows the relationship between the heating temperature and the density% when the pressure is 10 kN and the holding time is 10 minutes. When the density is 80 to 95% TD, it can be seen that if the heating temperature is set to 540 ° C. or higher, a temperature within 640 ° C. is sufficient.

  FIG. 3B shows the relationship between the retention time and the density% TD when the pressure is 10 kN and the set temperature is 550 ° C. When the density is 80 to 95% TD, it can be seen that if the holding time is set to 4 minutes or more, a holding time of 18 minutes or less is sufficient. This holding time of 4-18 minutes is a time for the sintering step set for sintering of molybdenum trioxide, and it may be held for longer than this.

FIG. 3C shows the relationship between the pressure kN and the density% TD at a set temperature of 550 ° C. and a holding time of 10 minutes (partially 5 minutes). When the density is 90 to 95%, it can be seen that if the pressure kN is set to 10 kN or more, a pressure within 35 kN is sufficient. Then, according to these data, it can be seen that can form molybdenum trioxide pellets sintered above the high density 95% TD.

  And according to FIG. 3, it becomes possible to control the firing density in the range of 80 to 98% TD, and in this case, it can be seen that the weighting / heating temperature treatment time of the discharge plasma sintering treatment is a parameter. It is also possible to control a lower sintering density.

  Then, considering these data, the following conditions can be set as processing conditions for producing a molybdenum oxide target (size: 20 mmφ, 10 mm thickness).

Die used (made of graphite); od. 50 mmΦx id. 20.5 or
20.0mmΦ
Punch (made of graphite); 20mmΦx 20mmh
[MoO ₃ ] Raw material amount 13.5 to 14.0 g,
Firing temperature 500-600 ° C., temperature holding 5-12 minutes (mainly 10 minutes), weight 6-30 kN (mainly 10 kN), voltage 2.3-2.5 V, current 480-800 A
[MoO ₂ ] Raw material amount 10.2 g, firing temperature 750 to 900 ° C., temperature holding 5 to 10 minutes
Between, weight 10kN, voltage 3.0 ~ 3.2V, current 1200 ~ 1300
A

High density directed to molybdenum trioxide MoO ₃ powder or molybdenum dioxide MoO ₂ powder According to these examples, but so as to obtain a sintered body of high purity molybdenum trioxide MoO ₃ powder or molybdenum dioxide MoO ₂ It is possible to obtain high-density and high-purity sintered pellets by mixing molybdenum metal with powder. For mass production, a large-diameter plate-like high-purity sintered body is formed so as to increase the compression load, and a plurality of (for example, six) sintered pellets are punched out to produce it. Is possible. In other words, it is possible to manufacture a high-purity molybdenum sintered body by using a discharge plasma sintering die having a plurality of large-diameter sintered portions and forming a plurality of molybdenum oxide pellets simultaneously. is there.

From the above results, as typical processing conditions for producing MoO ₃ pellets having a density of 90 to 95% TD (4.2 to 4.5 g / cm ³ ), an effective heating temperature of 600 ° C., a load of 10 kN, heating It is determined that the holding time of about 10 minutes is appropriate, and it can be determined that the sintering density of the MoO ₃ pellets can be arbitrarily controlled in the range of 70 to 95% TD by changing the heating temperature and the heating holding time.

  Thus, using a high-purity molybdenum oxide material as a powder material, the molybdenum oxide material is sintered without using a binder to form a 70-98% TD high-purity sintered body. A discharge plasma sintering method of the material is configured.

  Moreover, the discharge of the molybdenum oxide material which forms a high purity sintered body of 90 to 98% TD by sintering the molybdenum oxide material without using a binder using a high purity molybdenum oxide material as a powder material A plasma sintering method is configured.

  In addition, a high-purity molybdenum oxide material is used as a powder material, and it is charged into a forming die without using a binder. A discharge plasma sintering method of a molybdenum oxide material is formed in which a discharge current is generated by energizing a shaped current, and molybdenum oxide powder is sintered to form a high-purity sintered body.

  A discharge plasma sintering method of molybdenum oxide material using molybdenum trioxide or molybdenum dioxide as the molybdenum oxide material is configured.

  A discharge plasma sintering method of molybdenum oxide material is configured in which the state of 540 to 640 ° C. and 10 to 30 kN is continued and the sintering step of 4 to 18 minutes is performed for sintering of molybdenum oxide.

  Molybdenum oxide pellets obtained by sintering a molybdenum oxide material characterized by obtaining a 70 to 98% TD molded high-purity sintered body by a discharge plasma sintering method are formed.

  Molybdenum oxide pellets obtained by sintering a molybdenum oxide material characterized by obtaining a molded sintered body of 90 to 98% TD by a discharge plasma sintering method are configured.

As described above, a high-purity molybdenum sintered body that generates high-purity (n, γ) ⁹⁹ Mo by irradiation in a nuclear reactor, and this high-purity molybdenum sintered body is converted into a powdery material. As a high-purity molybdenum oxide material, the molybdenum oxide material can be sintered by a discharge plasma sintering method to form a high-density and high-purity material.

FIG. 4 is a diagram showing that the manufactured high-density, high-purity molybdenum sintered body is irradiated in a nuclear reactor. In FIG. 4, a high-density, high-purity sintered molybdenum oxide sintered body 20 is inserted into a core 42 of a nuclear reactor 41 by a pellet holding device 43. By irradiating the inserted molybdenum oxide sintered body in the core 42, high density and high purity (n, γ) ⁹⁹ Mo21 is produced.

The molybdenum oxide pellets thus formed are sealed in a cylinder, inserted into a nuclear reactor, and irradiated to cause a nuclear reaction of (n, γ) ⁹⁹ Mo. This pellet is dissolved to obtain a ⁹⁹ Mo solution, and ^99m Tc (technetium- ^99m ) is extracted from the ⁹⁹ Mo for use in medical diagnosis.

In this way, a high-purity molybdenum oxide material is used as the powder material, and the molybdenum oxide material is sintered by a discharge plasma sintering method to form a high-density, high-purity molybdenum sintered body. High-density, high-purity (n, γ) ⁹⁹ Mo can be produced by irradiating a purity molybdenum sintered body in a nuclear reactor.

  FIG. 5 shows the flow of this embodiment. This example shows an example using molybdenum trioxide powder, but the same applies when using molybdenum dioxide powder.

A high-purity molybdenum trioxide powder MoO ₃ is prepared as a high-purity molybdenum powder (S1), and charged into the forming die shown in FIG. 1 (S2). Pressurization is performed using a molding die and a punch, and the temperature is raised and heated accordingly, and electricity is supplied. Thereby, high-density and high-purity molybdenum trioxide powder is sintered (S3).

  A molybdenum trioxide sintered body (in this example, molybdenum trioxide sintered pellets) is formed (S4) and taken out from the forming die (S5).

A plurality of the produced molybdenum trioxide sintered pellets are juxtaposed and sealed in a cylinder (rabbit) (S6), and irradiated by a nuclear reactor (S7) to produce (n, γ) ⁹⁹ Mo, that is, molybdenum-99. (S8) and take it out (S9).

  In this way, high-density, high-purity molybdenum-99 is produced by irradiating the sintered high-density, high-purity molybdenum oxide pellets in the reactor. This high-density, high-purity molybdenum-99 has a short half-life of 6.01 hours and is a raw material for technetium-99m suitable for use as a diagnostic radiopharmaceutical.

FIG. 6 shows a micrograph (FIG. 6A) showing the state of the MoO ₃ raw material powder and a photograph (FIG. 6B) showing the sintered state of the high-density, high-purity molybdenum sintered pellet. As shown in FIG. 6B, a molybdenum sintered pellet having a high sintering density can be formed by sintering using a discharge plasma sintering method. FIG. 6B shows a sintered state of 88% TD.

  Highly sintered molybdenum pellets can be formed by sintering using the spark plasma sintering method, and even if the sintered density is the same sintered density generated in the conventional method, molybdenum sintered pellets The feature that the amount of powder adhering to the outer surface of the resin can be extremely reduced is obtained. The fact that the amount of powder adhering to the outer surface is extremely small can greatly reduce the amount of contamination of the irradiation atmosphere when irradiated in a nuclear reactor, which is a great merit.

In the conventional MoO ₃ sintered pellets were molded with MoO ₃ sintered pellets and spark plasma sintering of the present embodiment, which has been molded with the compressed powder molding sintering be the same MoO ₃ sintered pellets, spark plasma sintering using, when forming the MoO ₃ sintered pellets, as shown in FIG. 7, the evaporation coagulation, volume diffusion, surface diffusion, MoO ₃ grains by grain boundary diffusion are (surface) fusion. On the other hand, in the compacting and sintering methods, MoO ₃ particles do not fuse together because the sintering temperature is low. The reason why the sintering temperature cannot be increased to 720 ° C. or higher in the compacting and sintering method is that MoO ₃ is sublimated at a temperature higher than that.

For the above reasons, according to this embodiment, it is possible as compared with the compacting sintering even sintered low temperature (600 ° C.) to obtain a high-density MoO ₃ pellets, MoO ₃ grains This (surface) fusion makes it difficult for pulverization to occur, and the pulverized product generated from the MoO ₃ pellets can be made minute.

  Thus, according to the present embodiment, the limitation of the irradiation pellet volume can be solved, and the problem of activated powder peeling can be solved for the first time in the field of RI manufacturing of nuclear reactors.

Sectional drawing which shows the structure of the sintering apparatus used for the Example of this invention. The external view of the produced | generated molybdenum oxide pellet. The figure which shows an experimental result. Irradiation diagram of molybdenum oxide pellets in the reactor. The flowchart figure of the Example of this invention. Micrograph. The figure which shows melt | fusion of particle | grains.

  DESCRIPTION OF SYMBOLS 1 ... Sintering apparatus, 2 ... Molding die, 3 ... Punch, 4 ... Outer cylinder, 5 ... Pressing base, 6 ... Inner wall surface, 7, 8 ... Depression, 9 ... Space part, 10 ... Convex-shaped part, 11 ... Press punch part, 12 ... Molybdenum oxide carry-in part, 13 ... Molybdenum oxide powder, 16 ... Electric wiring, 20 ... Pelted molybdenum oxide sintered body.

Claims (5)

A powdered material is placed in a forming die, and a pulsed current is applied in a state compressed by a punch to generate a discharge plasma, which is then manufactured using a discharge plasma sintering method in which sintering is performed. In a method for producing high purity (n, γ) ⁹⁹ Mo from a ligation,
As a powdered material, a molybdenum oxide material having a high purity of 99.9% or more and 90% or more in a range of 2 to 4 μm is charged into a forming die, and is in a low temperature state of 550 to 630 ° C. In a compressed state with a low load of 30 kN, a pulsed current is applied to generate discharge plasma, and molybdenum oxide powder is sintered by a discharge plasma sintering method to sinter molybdenum oxide with high density and high purity of 80 to 98% TD. A high-density, high-purity characterized in that a compact is formed, and the high-density, high-purity molybdenum sintered body is irradiated with neutrons in a nuclear reactor to produce high-density, high-purity (n, γ) ⁹⁹ Mo. A method for producing purity (n, γ) ⁹⁹ Mo. The method for producing high-density, high-purity (n, γ) ⁹⁹ Mo according to claim 1, wherein molybdenum trioxide or molybdenum dioxide is used as the molybdenum oxide material. The high density, high purity (n) characterized in that the sintering process is continued at 550 to 630 ° C and 10 to 30 kN for 4 to 18 minutes for sintering molybdenum oxide. , Γ) A method for producing ⁹⁹ Mo. 4. The high-density, high-purity (n, γ) ⁹⁹ Mo is produced according to claim 1, wherein molybdenum metal is mixed with molybdenum oxide material to form a composite molybdenum sintered body. Method. In any of claims 1 to 3, a flat plate-shaped high density, by forming a high-purity molybdenum sintered body, to produce a plurality of molybdenum sintered pellets from a flat plate-shaped molybdenum sintered body the molded A method for producing high-density, high-purity (n, γ) ⁹⁹ Mo characterized by comprising steps.

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