JPH0415010B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an isotope separation device, and particularly to an isotope separation device equipped with an evaporation crucible that is less affected by impurities in raw materials.

(Prior Art) An isotope separation device for metal atoms using a laser beam has a much higher separation efficiency than a conventional isotope separation device using a gas diffusion method or a centrifugation method. Therefore, there is little need to repeat the same separation process in multiple stages in a cascade system until a specific isotope reaches a predetermined concentration level, and the entire apparatus is small and economical.

FIG. 4 is a conceptual diagram of a conventional laser method-based metal atom isotope separation apparatus.

In FIG. 4, the isotope separation apparatus 1 consists of a separation cell 2 that airtightly accommodates the main body and various devices constituting the main body.

A metal raw material 3 containing multiple types of isotopes is loaded into an evaporation crucible 4 having thermochemical resistance. A cooling water passage hole 7 is buried in the evaporation crucible 4.

An electron beam 6 emitted from a filament 5a of a linear electron gun 5 is deflected by a deflecting magnetic field 8, and is irradiated onto a metal raw material 3 loaded in an evaporation crucible 4. The metal raw material 3 irradiated with the electron beam 6 is heated to about 2700°C, evaporates through a molten state, and forms a vapor flow 9.

In this vapor stream 9, a specific isotope 10 to be recovered and other isotopes 11 are mixed. This vapor flow 9 is irradiated with an excitation laser beam 12 that selectively excites only a specific isotope 10 .
As the excitation laser beam 12, a laser beam having a wavelength corresponding to the absorption line of the specific isotope 10 is employed. The excited specific isotope is further irradiated with an ionizing laser beam 13, at which time electrons are ejected and the specific isotope 10 becomes an ionized isotope 14 having a positive charge.

When the vapor flow 9 containing this ionized isotope 14 passes through an electric field space formed by applying a voltage between the ground electrode 15 and the negative electrode 16, only the ionized isotope 14 is transferred to the negative electrode. 16 and are attracted to the surface and collected by adsorption.

On the other hand, neutral atoms such as non-ionized isotopes 17
travels straight between the electrodes without being affected by the electric field,
The neutral atom collecting plate 18 arranged on the secondary side of the electrode is configured to attract and collect the atom.

Next, a portion of the configuration of the conventional isotope separation apparatus shown in FIG. 4 that is related to the present invention will be explained with reference to FIG.

That is, the metal raw material 3 heated by the electron beam 6 and turned into a molten liquid is housed in the evaporation crucible 4 . A ground electrode 15 and a negative electrode 16 are alternately arranged above the evaporation crucible 4.
It constitutes a recovery electrode 19 for a specific ionized isotope. A neutral atom collection plate 18 is provided above the collection electrode 19 and is arranged in a roof-like manner, and the neutral atoms 17 that have traveled straight between the electrodes collide with the inner wall of the neutral atom collection plate 18. Next, it descends along the slope and is accommodated in the neutral atom recovery container 20.

In addition, enclosing partition walls 21 are provided on both upper edges of the evaporation crucible 4. This enclosing partition wall 21 is provided to effectively guide the vapor flow of the metal raw material 3 toward the recovery electrode 19 without diffusing it. A portion of the metal atoms 22 adsorbed on the enclosing partition 21 forms droplets, descends, and is configured to flow back into the evaporation crucible 4.

The metal raw material 3 contained in the evaporation crucible 4 is evaporated, and a part is collected and separated by the collection electrode 19, and a part is collected by the neutral atom collection plate 18 and discharged to the outside of the system.

Further, a part of the vaporized metal raw material 3 collides with the sealing partition wall 21 to condense, descends, and flows back into the evaporation crucible 4 again.

When the isotope separator device is operated continuously, the metal raw material 3 is continuously supplied from the outside into the evaporation crucible 4 so as to compensate for the decrease in the metal raw material 3 that is evaporated and discharged outside the system. be done.

(Problems to be solved by the invention) However, the metal raw materials supplied from the outside contain impurities such as oxides, and the metal atoms flowing back into the evaporation crucible along the sealing partition are exposed to high temperature conditions. It may react with the members of the encapsulation barrier and generate impurities such as metal oxides. When these impurities are heated and melted in the evaporation crucible, they float on the surface of the molten liquid and form a film layer that hides the evaporation surface.
This film layer prevents the evaporation of the metal isotope that is to be recovered, and at the same time, because it floats on the liquid surface, it is intensively exposed to the electron beam. As a result, the amount of evaporation of metal oxides, which are impurities, increases, which poses an obstacle to the operation of separating only the desired isotope, resulting in a reduction in separation efficiency.

Also, if impurities get mixed into the evaporation crucible,
The temperature of the evaporation section decreases, and the amount of evaporation of the metal raw material also decreases. Therefore, in continuous operation in which the amount of evaporation is kept constant, the output of the linear electron gun, which is a heating source, is inevitably increased in order to increase the amount of evaporation. At this time, there was a risk that the evaporation crucible would be damaged due to a rapid temperature rise.

Furthermore, when impurities are irradiated with an electron beam in a concentrated manner, the component metal becomes sparks and scatters into the upper space, contaminating the inside of the device.

The present invention was devised to solve the above-mentioned problems, and is configured so that impurities mixed in the evaporation crucible are confined only in a part of the molten liquid surface for the purpose of recovery. By always ensuring a constant amount of evaporation area for metals containing metal isotopes, reducing the amount of impurities that occupy the vapor flow targeted for separation operation,
The purpose of the present invention is to provide an isotope separation device with excellent separation efficiency.

[Structure of the invention]

(Means for Solving the Problems) The isotope separation device according to the present invention introduces a metal raw material containing multiple types of isotopes into an evaporation crucible, heats and evaporates the introduced metal raw material, and generates a vapor flow. In an isotope separation device that generates vapor, selectively ionizes a specific isotope in the vapor flow by irradiating the vapor flow with a laser beam, and separates the ionized isotope using an electric field, the evaporation crucible A partition is provided inside to divide the inside of the evaporation crucible into a metal raw material supply chamber and a molten metal evaporation chamber, and a communication hole is provided below the molten metal liquid surface to communicate the metal raw material supply chamber and the molten metal evaporation chamber. It is characterized by having been established.

(Function) The isotope separation apparatus having the above configuration includes an evaporation crucible having a metal raw material supply chamber and a molten metal vapor chamber separated by a partition, and the evaporation crucible communicates both chambers. Since the communicating holes are provided below the molten metal liquid level, there is little influence from impurities that enter the steam crucible.

That is, the metal raw material containing many impurities supplied from the outside and the metal atoms that react with the enclosed partition wall to generate impurities are supplied or refluxed into the metal raw material supply chamber. The supplied metal raw material and the refluxed metal atoms are heated and melted within the metal raw material supply chamber. At this time, impurities float to the surface of the liquid in the metal raw material supply chamber and are separated.

On the other hand, the molten metal raw material passes through the communication hole and is introduced into the molten metal evaporation chamber, where it evaporates from the evaporation liquid surface and becomes a vapor flow.

Since impurities are confined in a certain area above the liquid level of the metal raw material supply chamber defined by the partition, they rarely float on the evaporated liquid level of the molten metal evaporation chamber.

Therefore, the amount of impurity vapor that occupies the vapor flow is extremely small, and the isotope separation operation for the purpose of recovery can be carried out efficiently. In addition, since the amount of metal raw material evaporated from the evaporation liquid level can be maintained almost constant, there is little temperature change in the molten metal evaporation chamber, enabling stable separation operations and providing an isotope separation device that is easy to manage. can do.

(Example) Next, an example of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a sectional view showing an embodiment of an isotope separation apparatus according to the present invention. The present invention is characterized by the structure of the evaporation crucible, and other components are similar to the conventional example shown in FIG.

In FIG. 1, a partition 23 is provided inside the evaporation crucible 4, and the interior of the evaporation crucible 4 is divided into a metal raw material supply chamber 24 and a molten metal evaporation chamber 25.
Further, a communication hole 27 is provided below the molten metal liquid surface 26 to communicate the chambers 24 and 25. The partition 23 is formed, for example, by arranging two partition plates 23a in parallel in the longitudinal direction of the evaporation crucible 4, as shown in FIG. A metal raw material supply port 30 is provided on the side surface of the enclosure partition 21 .

The molten metal raw material 3 is accommodated in the evaporation crucible 4 and forms a molten metal liquid level 36. metal liquid level 2
The metal raw material 3 is
is further heated to form a vapor stream. The process for separating specific isotopes contained in the vapor stream is similar to the conventional example shown in FIG. That is, a specific isotope in the vapor flow is selectively ionized by irradiating the vapor flow with a laser beam, and the ionized isotope is separated and recovered by electrolysis applied to a recovery electrode.

In order to compensate for the decrease in the metal raw material 3 that was evaporated into a vapor flow, separated and recovered and discharged outside the system,
The metal raw material 3a is supplied to the metal raw material supply chamber 24 through the metal raw material supply port 30. The supplied metal raw material 3a is heated and melted by irradiation with the electron beam 6. At this time, impurities contained in the metal raw material 3a float to the liquid surface of the metal raw material supply chamber 24 and are separated.

On the other hand, the molten metal raw material is supplied to the metal raw material supply chamber 24.
descends, passes through the communication hole 27, and enters the molten metal evaporation chamber 2.
5 and evaporates from the molten metal liquid level 26 to form a vapor flow.

Furthermore, metal atoms 22 that collide with the enclosure partition 21 and react with the partition member to generate impurities are also introduced into the metal raw material supply chamber 24 formed on both sides of the evaporation crucible 4.

All impurities float to the surface of the liquid in the metal raw material supply chamber 24 and form a film layer 28 that hides the liquid surface. However, since the impurities are sealed in the region above the liquid level of the metal raw material supply chamber 24 defined by the partition plate 23a, the impurity film layer 28 invades the evaporated liquid surface of the molten metal evaporation chamber 25. There aren't many.

Therefore, the amount of impurity vapor that occupies the total vapor flow is extremely small, and the isotope separation operation for the purpose of recovery can be carried out efficiently. In addition, since the film layer of impurities can be removed from the evaporated liquid surface, the amount of evaporation of the metal raw material from the evaporated liquid surface can be maintained almost constant, so there is less need to adjust the output of the electron beam, and the molten metal evaporates. There is also little temperature change in the room. Therefore, it is possible to provide an isotope separation apparatus that enables stable separation operations and that is easy to manage.

Next, another embodiment of the evaporation crucible used in the isotope separation apparatus according to the present invention will be described with reference to FIG.

In the embodiment shown in FIG. 3, the partition 23 disposed inside the evaporation crucible 4 is formed by arranging a heat-resistant container 29 smaller than the evaporation crucible 4 at a distance from the bottom of the evaporation crucible 4. do. Therefore, the inside of the heat-resistant container 29 becomes the molten metal evaporation chamber 25, and the space formed between the heat-resistant container 29 and the evaporation crucible 4 becomes the metal raw material supply chamber 24. A predetermined number of communication holes 27 a are provided in the bottom of the heat-resistant container 29 to communicate the metal raw material supply chamber 24 and the molten metal evaporation chamber 25 .

The metal raw material containing impurities and the metal atoms flowing back from the enclosure partition are introduced into the metal raw material supply chamber 24, where they are heated and melted. The impurities are trapped on the liquid surface of the metal raw material supply chamber 24, while the molten metal raw material passes through the communication hole 27a and enters the molten metal evaporation chamber 2.
5 and is further heated to form a vapor stream.

According to this embodiment, since the heat-resistant container 29 is simply fixed in the evaporation crucible 4, the existing evaporation crucible can be easily modified. In addition, impurities are confined only in the liquid surface region of the metal raw material supply chamber 24 and rarely float on the evaporated liquid surface of the molten metal evaporation chamber 25.

Therefore, as in the case of the embodiment shown in FIG. 2, the amount of evaporation from the evaporated liquid level can be kept constant, and a vapor flow with less impurities can be formed.

In the embodiment shown in FIGS. 2 and 3, a partition plate 23a or a heat-resistant container 29 is provided in the longitudinal direction of the evaporation crucible to form a metal raw material supply chamber 24 and a molten metal evaporation chamber 25. However, the same effect can be obtained by forming a metal raw material supply chamber at one or both longitudinal ends of the evaporation crucible by arranging a partition in the cross-sectional direction of the evaporation crucible.

〔Effect of the invention〕

The isotope separation apparatus according to the present invention includes an evaporation crucible having a metal raw material supply chamber and a molten metal evaporation chamber that are partitioned by partitions, and a communication tube that communicates the two chambers below the molten metal liquid surface. Since the holes are provided, the metal raw material introduced into the metal raw material supply chamber is heated and melted, and is further introduced into the molten metal evaporation chamber through the communication hole, where it evaporates from the evaporation liquid surface and becomes a vapor flow.

On the other hand, since impurities float above the liquid surface in the metal raw material supply chamber and are confined in that region, impurities rarely enter the evaporated liquid surface in the molten metal evaporation chamber.

Therefore, the amount of impurity vapor that occupies the total vapor flow is extremely small, and the isotope separation operation for the purpose of recovery can be carried out efficiently. In addition, since the amount of metal raw material evaporated from the evaporation liquid level can be maintained almost constant, stable separation operation is possible with little temperature change in the molten metal evaporation chamber, and an isotope separation device that is easy to manage is provided. be able to.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the isotope separation device according to the present invention, FIG. 2 is a perspective view showing the structure of the evaporation crucible in FIG. 1, and FIG. 3 is another embodiment of the evaporation crucible. A perspective view showing an example, FIG. 4 is a configuration diagram conceptually showing an isotope separation device using a conventional laser method, and FIG. 5 is a sectional view showing the specific structure of the isotope separation device shown in FIG. 4. be. 1...Isotope separation device, 2...Separation cell, 3,
3a...metal raw material, 4...evaporation crucible, 5...
Linear electron gun, 5a... filament, 6... electron beam, 7... water hole, 8... deflection magnetic field, 9...
...Vapour flow, 10...Specific isotope, 11...Other isotopes, 12...Laser beam for excitation, 13...
... Laser beam for ionization, 14 ... Ionized isotope, 15 ... Ground electrode, 16 ... Cathode electrode, 17 ...
...neutral atom, 18...neutral atom collection plate, 19...
Recovery electrode, 20... Neutral atom recovery container, 21...
Encapsulation partition, 22...metal atom, 23...partition, 2
3a... Partition plate, 24... Metal raw material supply room, 25
... Molten metal evaporation chamber, 26 ... Molten metal liquid level, 2
7, 27a... Communication hole, 28... Film layer, 29...
...Heat-resistant container, 30...Metal raw material supply port.

Claims (1)

[Claims] 1. A metal raw material containing multiple types of isotopes is introduced into an evaporation crucible, the introduced metal raw material is heated and evaporated to generate a vapor flow, and the vapor flow is irradiated with a laser beam. In an isotope separation device that selectively ionizes a specific isotope in a vapor flow and separates the ionized isotope using an electric field, a partition is provided inside the evaporation crucible to separate the inside of the evaporation crucible. It is divided into a metal raw material supply chamber and a molten metal evaporation chamber,
An isotope separation device characterized in that a communication hole is provided below the molten metal liquid level to communicate a metal raw material supply chamber and a molten metal evaporation chamber. 2. The isotope separation device according to claim 1, wherein the partition comprises a plurality of partition plates arranged in parallel within the evaporation crucible. 3. The partition is formed of a heat-resistant container smaller than the evaporation crucible, and the heat-resistant container is accommodated in the evaporation crucible at a distance from the bottom of the evaporation crucible, and a communication hole is bored in the bottom of the heat-resistant container. The isotope separation device according to scope 1.