JP3403360B2 - High density dispersed nuclear fuel using uranium alloy spherical powder rapidly solidified by spraying as a dispersant and its production method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-density dispersed nuclear fuel in which spherical powder of uranium alloy rapidly solidified by a spraying method is dispersed, and a method for producing the same. U- (A) Q, U- (A)
Q- (B) X (Q: Mo, Nb, Zr element, X: Mo,
Nb, Zr, Ru, Pt, Si, Ir, Pd, W, T
a, Os, etc., a trace additive element, Q ≠ X, (A) = 4 to 9w
t. %, (B) = 0.1 to 4 wt. %) Homogenizing heat treatment and the like uranium alloy spherical powder alloy, crushing and without going through the grinding process, aluminum uranium alloy spherical powder dispersed spherical powder to produce directly from molten alloy by centrifugal atomization rapid solidification method
TECHNICAL FIELD The present invention relates to a high-density dispersed nuclear fuel dispersed in fabrics such as mums and a manufacturing method thereof.

[0002]

2. Description of the Related Art A conventional method for producing a nuclear fuel powder by crushing a mold after producing a uranium alloy is to maintain a uranium alloy mold at about 900 ° C. for about 100 hours and then quench it to obtain a metastable γ. -Manufacturing an alloy having a U phase, crushing the mold with a lathe etc. into a chip form, hardening coarse chips at extremely low temperature and crushing using a steel mill etc., cutting after crushing A wash / dry step was performed to remove the oil. Since such a conventional uranium alloy powder manufacturing method uses an iron-based tool, a magnetic separation step is required during powder manufacturing.

However, U-8w which has been homogenized and heat treated after alloying
t. % Mo alloys and other uranium alloys have strong properties,
It is very difficult to crush and pulverize, and the manufacturing process is complicated in many steps because the nuclear fuel powder is manufactured by a mechanical method. During the cryogenic milling, the powder yield of 212 μm or less per cycle is 20 wt. % Or less, the productivity was very low.

In addition, in order to remove a substance having a high Fe content from the produced powder by the magnetic separation method, 30% of the recovered powder is used.
The degree had been lost again.

The nuclear fuel powder produced by the mechanical method as described above is composed of the cutting oil component used for cooling the high temperature oxidizing uranium alloy, which is the object to be cut, and the tool generated during crushing or crushing. Impurities due to abrasion were mixed in the powder and the purity was limited.

That is, since the uranium alloy is oxidative, the chips can be ignited and burned violently during coarse crushing work on a lathe or the like, so the cutting oil must be supplied while working.
After crushing, the chips are washed with an organic solvent such as acetone to remove the cutting oil components adhering to the chips and then dried in a high temperature vacuum atmosphere, but some of the cutting oil components remain in the nuclear fuel powder.

[0007] The chips washed with the organic solvent are subjected to magnetic separation of powder pulverized at extremely low temperature using a steel mill or the like, and about 35% of the powder is removed together with iron, and the surface of the nuclear fuel powder is enlarged and examined. It can be seen that there are innumerable spots and the like containing the Fe component. In this way, since the main substance of the impurities mixed during the crushing work is the iron component,
At the time of magnetic separation, a considerable amount of Fe component containing uranium alloy powder is also removed. At this time, low enriched uranium, which is a raw material for nuclear fuel, is very expensive, and such a manufacturing method causes a large economical loss.

Further, the elongated crushed particles impede the heat flow because the arrangement direction is perpendicular to the heat flow direction, and the uranium alloy is mainly produced from the dispersed nuclear fuel by the infiltration reaction of the aluminum dough into the nuclear fuel powder. Porosity is formed in the low density uranium aluminite (UAIx) and the nuclear fuel material at the powder interface to swell the nuclear fuel core material.

When powder is directly produced using a high-speed lathe provided with a rotary file, the high-speed lathe produces about 1 to 2 g of powder per hour, and the powder production yield is 212 μm or less. On the other hand, it is about 50%. At this time, the nuclear fuel alloy rod is manufactured by using a tungsten carbide or tantalum carbide tool coated with titanium nitride, which rotates at about 2500 rpm. The manufactured powder is 0.1 to 8% due to wear of the rotating file. There were various problems such as the inclusion of some carbides and nitrides.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object thereof is to produce a fine spherical nuclear fuel powder directly from a molten alloy by spray metal solidification, whereby metastable γ- U-phase formation, process simplification, production space minimization, powder recovery and productivity improvement, purity improvement, moldability improvement, porosity reduction, heat conduction in the heat flow direction, and high temperature reaction due to interface area reduction It is an object of the present invention to provide a nuclear fuel and a nuclear fuel manufacturing method in which a material such as aluminum having a reduced volume expansion is dispersed at high density .

According to the present invention, uranium and a metal raw material are weighed and placed in a heat-resistant crucible provided with a nozzle, the heat-resistant crucible is installed in a spraying device, and then a heat-resistant crucible is installed in a spraying device using a vacuum pump. While maintaining the inside of the chamber at a vacuum degree of 10 ^-3 _torr or more, the uranium and the metal raw material charged in the heat-resistant crucible are melted by using a high frequency current generator,
While supplying the melted alloy volume, a droplet (drop) is formed by using a centrifugal disk or high pressure gas such as an electrode.
It is an object of the present invention to provide a uranium alloy spherical powder-dispersed nuclear fuel in which fine nuclear fuel particles are rapidly solidified in an inert atmosphere such as a cooling gas of argon or helium at the same time as producing a let) and a production method thereof.

[0012]

FIG. 1 is a schematic view showing the structure of a manufacturing apparatus according to the present invention, and FIG. 2 is a block diagram of the apparatus according to the present invention. The present invention is directed to a heat-resistant crucible 1 provided with a nozzle 11, a high-frequency current generator 2 for increasing the temperature in the crucible 1, a vacuum pump 4 for forming an appropriate degree of vacuum in the chamber 3, a gas 10 in the chamber 3. A gas supply valve 5 for supplying the gas, a check valve 6 for discharging the gas supplied into the chamber 3 by the gas supply valve 5 to the outside of the chamber 3, a disc 7 installed in the chamber 3, and a manufactured powder stored The collecting container 8 and the cyclone 9 in which fine powder is collected.

The heat-resistant crucible 1 is U-8 wt. A metal raw material of% Mo can be put in, the nozzle 11 is provided in the lower part, it is installed in the upper part of the centrifugal spraying device 100, and the sprue plug 13 is provided inside.

The high-frequency current generator 2 is a heat-resistant crucible 1.
And heats the molten metal at a temperature of about 200 ° C or higher than the melting temperature with a high frequency current.

The inside of the chamber 3 of the vacuum pump 4 is 10
^It forms an appropriate degree of vacuum of ^-3 _torr or more and is connected to one side of the chamber 3 and installed.

The disk 7 has a nozzle 1 below the nozzle 11.
The alloy melt having the same center line as that of No. 1 and installed in the chamber 3 and operated by the electric motor 71 and discharged into the chamber 3 through the nozzle 11 is formed into a fine spherical nuclear fuel powder . That is, the molten alloy discharged through the nozzle 11 is formed into fine nuclear fuel powder by the centrifugal force of the disk 7 by the operation of the electric motor 71, and flies to the wall of the chamber 3.

The gas supply valve 5 is connected to and installed in the upper part of the chamber 3 and supplies inert argon or helium cooling gas 10 into the chamber to rapidly solidify the fine nuclear fuel powder formed by the rotating force of the disk 7. At this time, the inert argon or helium cooling gas 10 introduced into the chamber by the gas supply valve 5 is injected into the chamber 3 by the gas nozzle 31 installed in the upper portion of the chamber 3.

The recovery container 8 is installed at the lower end of the chamber to collect the spherical nuclear fuel powder formed in the chamber 3 and collect the spherical nuclear fuel powder flowing down along the inclined wall surface 32 of the chamber 3.

The cyclone 9 collects ultrafine powder which is not collected in the recovery container 8 in the nuclear fuel powder rapidly solidified by the cooling gas 10, and is connected and installed between the chamber 3 and the recovery container 8.

The check valve 6 is the gas supply valve 5
When the pressure of the gas 10 introduced into the chamber 3 is equal to or higher than a certain pressure, the introduced gas 10 is discharged to the outside of the chamber 3 and is installed between the chamber 3 and the cyclone 9.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention configured as described above will be described in detail with reference to Examples. (Example 1) U-8 wt. % Mo alloy powder, when uranium and the alloying element Mo raw material are weighed so as to match the alloy composition and put in the heat-resistant crucible 1 provided with the nozzle 11, the crucible 1 and the heat insulating material ( (Not shown) are assembled in order. At this time, using the vacuum pump 4, the crucible 1
The inside of the atomizing device chamber of the centrifugal atomizing device 100 thus assembled is maintained at an appropriate vacuum degree of 10 ⁻³ torr or more.

When the crucible 1 and the heat insulating material are assembled into the centrifugal spraying device 100 in order, the high frequency current generator 2 is operated to heat the capacity to 200 ° C. or more above the melting temperature with the high frequency current, and then the electric motor 71 is used. Disk 7 is about 300
Rotate to 00 rpm.

When the rotation speed of the disk 7 operated by the electric motor 71 is stabilized at 30,000 rpm, the crucible 1
The sprue plug 13 installed inside is lifted upward, and the molten alloy melted in the crucible 1 is discharged.

The discharged molten alloy passes through a small nozzle 11 having a diameter of about 2 mm and is supplied onto a disk 7 which rotates at a high speed of about 30,000 rpm, and is formed into fine nuclear fuel powder by centrifugal force and flies to a chamber wall 32. .

At this time, when the gas supply valve 5 is operated to inject the inert argon or helium cooling gas 10 into the chamber 3, the fine nuclear fuel particles flying to the chamber wall surface 32 by the disk 7 are inert argon or helium during the flight. It is rapidly solidified (10 ⁴ ° C / sec or more) by the cooling gas 10 and is manufactured into a γ-U phase nuclear fuel powder that is metastable at room temperature.

In this way, the γ-U phase that is metastable at room temperature is immediately obtained by the rapid solidification effect during spraying. Therefore, after maintaining the temperature at about 900 ° C. during powder production by uranium alloy crushing, it is quenched to form the γ-U phase. The heat treatment step for obtaining is unnecessary.

The powder thus produced flows down along the inclined chamber wall surface 32 and is collected in the collection container 8 installed in the lower part of the chamber 3, and the very fine powder is collected in the cyclone 9. The size of the average powder collected in the recovery container 8 is about 65 μm, and 95% or more of powder having an appropriate size of the nuclear fuel of 125 μm or less can be obtained.

The U-8 wt. % M
o Alloy spherical powder is mixed with aluminum powder at a volume fraction of 30 to 50%, and then compacted to a diameter of about 40 mm at room temperature to produce a billet, and the container and mold of the extruder are preheated to about 420 ° C. After charging billet
After maintaining for 5 minutes, it is squeezed out in an inert atmosphere to produce a dispersed nuclear fuel core material. (Example 2) Further, the present invention includes U- (A) Q alloys including U- (A) Q alloys.
-(B) X (Q: Mo, Nb, Zr element, X: Mo, N
b, Zr, Ru, Pt, Si, Ir, Pd, W, Ta,
Trace additive elements such as Os, Q ≠ X, (A) = 4 to 9 wt,
%, (B) = 0.1 to 4 wt. %) Applicable to uranium alloy dispersed nuclear fuel such as alloy. That is, U-8 wt.
% Mo alloy Centrifugal spray powder, uranium and alloying element Mo during manufacturing
The metal raw material was weighed so as to match the alloy composition and put in a ceramic crucible, and then U-8 wt. After the vacuum degree inside the sprayer chamber 3 is set to 10 ^-3 _torr or more by using the vacuum pump 4 as in the manufacturing process of centrifugal spray powder of% Mo alloy, the melt temperature in the crucible is about 200 ° C. higher than the melting temperature. The molten alloy is raised and melted, and the molten alloy is supplied through a nozzle 11 onto a disk 7 rotating at about 30,000 rpm. The supplied molten metal is formed into fine particles by the centrifugal force of the disk 7, and is rapidly solidified (10 ^-4 ° C / sec or more) by the inert gas injected into the chamber 3 through the gas supply valve 5 and the gas nozzle 31 to form a spherical shape. Manufactured into nuclear fuel powder.

The U- (A) Q- produced in this way
(B) X (Q: Mo, Nb, Zr element, X: Mo, N
b, Zr, Ru, Pt, Si, Ir, Pd, W, Ta,
Trace addition elements such as Os, Q ≠ X, (A) = 4 to 9 wt.
%, (B) = 0.1 to 4 wt. %) The spherical alloy powder was mixed with aluminum powder at a volume fraction of 30 to 50%, and was pressed at room temperature to a diameter of about 20 mm to produce a billet, and the container and mold of the extruder were preheated to about 370 ° C. After that, a billet is put in, and the mixture is squeezed out in an inert atmosphere to produce a dispersed nuclear fuel.

[0030]

As described above, according to the present invention, a uranium alloy such as a U-Mo alloy is melted, and the molten metal is immediately quenched to directly produce a powder, which has a tough property and is extremely crushed and crushed. The nuclear fuel powder production yield and productivity are superior to the difficult uranium alloy, and the heat treatment process to obtain a stable γ-U phase at 550 ° C or higher and the cutting oil component mixed during crushing and crushing are removed. Since the cleaning / drying process and the magnetic separation process required when using iron-based tools can be eliminated,
The nuclear fuel manufacturing process is shortened compared to the conventional nuclear fuel manufacturing method,
It is possible to produce high-purity spherical uranium alloy powder and improve the quality of nuclear fuel powder.

Further, a high purity spherical uranium alloy powder can be produced by directly producing the powder from the molten alloy and applying the surface tension during spraying. Since the spherical uranium alloy powder has a smaller surface area than the crushed powder which is the atypical powder, it reduces the diffusion reaction with the aluminum material by about 30% at high temperature.
Swelling of nuclear fuel can be reduced.

Since the atomized powder-dispersed nuclear fuel according to the present invention has a smooth particle surface and a spherical shape, unlike the crushed powder-dispersed nuclear fuel which is arranged in the extruding direction, it is randomly and evenly arranged, so that the heat conduction in the extruding vertical direction is conducted. Spherical powders with improved particle flowability and excellent particle fluidity reduce the extrusion pressure during molding to improve moldability, and the higher the powder blending ratio, the greater the effect.

Furthermore, since the sprayed powder reduces the formation of pores during extrusion and increases the continuity with the aluminum material, it has many effects such as improving the ductility of the nuclear fuel core.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of a powder manufacturing apparatus of the present invention.

FIG. 2 is a block diagram of the device of the present invention.

[Explanation of symbols]

1 heat-resistant crucible 2 High frequency current generator 3 chambers 4 vacuum pump 5 gas supply valve 6 check valves 7 discs 8 collection containers 9 cyclones 10 gas 11 nozzles 13 Faucet 31 gas nozzle 32 chamber wall 71 electric motor 100 Centrifugal spraying device

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kim Ki-fan               Republic of Korea               Songdong Haneul Apartment 110-1406 (72) Inventor Chang Se-jun               Republic of Korea               Ndon Hanbit Apartment 126-1102 (72) Inventor Kim Unsu               Republic of Korea               Nmin Dong Chong-Nare Apartment               102-1102 (72) Inventor Guill-Hyun               Republic of Korea               Hyundai Apartment 103-602 (72) Inventor Son Dong-Son               Republic of Korea               Hyundai Hyundai Apartment 102-701                (56) References JP-A-60-233589 (JP, A)                 Japanese Patent Laid-Open No. 10-26683 (JP, A)                 JP-A-60-125303 (JP, A)                 JP 64-65205 (JP, A)                 Japanese Patent Sho 38-22110 (JP, B1)

Claims (2)

(57) [Claims] 1. U- (A) Q, U- (A) Q- (B) X
(However, Q: Mo, Nb, Zr element, X: Mo, Nb,
Zr, Ru, Pt, Si, Ir, Pd, W, Ta, Os
Trace additive elements selected from among: Q ≠ X; (A) = 4 to 9
wt. %, (B) = 0.1 to 4 wt. % ) Molten alloy
On a high-speed rotating plate that rotates at about 30,000 rpm.
And feeding to give a fine droplet, quenched with 10 ⁴ ° C. / sec or more fine droplets formed by the centrifugal force at the cooling inert gas
Was prepared by a quasi comprises a stable gamma phase (body-centered cubic lattice), A spherical nuclear fuel powder powder particle size less 125μm in average about 65μm is having a particle size distribution of 95% or more
A high-density dispersed nuclear fuel characterized by being dispersed in a luminium dough at a volume fraction of 30% or more. 2. A step of supplying 1) uranium and the alloying element Q, and optionally the alloying element X to a spraying apparatus chamber that maintains a vacuum degree of 10 ⁻³ torr or more, 2) the supplied uranium and the alloying element, etc. Melting to form a molten alloy, 3) supplying the molten alloy onto a high-speed rotating plate rotating at about 30,000 rpm to obtain fine droplets, and at the same time, cooling to a centrifugal atomization chamber. U- (A) Q, U- (A) Q- (B) X having a metastable gamma phase by injecting an inert gas for cooling and rapidly cooling the fine droplets at 10 ⁴ ° C / sec or more (however,
Q: Mo, Nb, Zr element; X: Mo, Nb, Zr, R
u, Pt, Si, Ir, Pd, W, Ta, Os, a trace additive element; Q ≠ X; (A) = 4 to 9 wt.
%, (B) = 0.1 to 4 wt. %) Alloy with flat powder particle size
A step of producing a spherical nuclear fuel powder having a particle size distribution of 95% or more with an average diameter of 65 μm and 125 μm or less , 4) a volume fraction of the spherical nuclear fuel powder in aluminum dough
It is characterized by comprising the step of dispersing to 30% or more.
High-density dispersed nuclear fuel manufacturing method.