JP2597571B2 - Isotope separation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to an isotope separation apparatus by a laser method, and in particular, by improving a laser light multiple reflection mechanism for multiple reflection of laser light, The present invention relates to an isotope separation device that improves the recovery efficiency of isotopes as products.

(Prior Art) In general, an isotope separation apparatus using an atomic method of a laser method heats and melts and evaporates a metal material containing a plurality of types of isotopes, for example, a uranium metal material, and irradiates the metal vapor stream with laser light. , A specific isotope, eg, U-235, in the vapor stream is selectively cationized, and an electric field is applied to the cationized isotope to separate and recover the isotope.

2. Description of the Related Art Conventionally, this type of isotope separation apparatus is configured as shown in FIG. 2, and an evaporating crucible 2 is installed on the bottom of an evacuated vacuum vessel 1.

The evaporating crucible 2 has excellent thermochemical resistance, and contains therein a metal material 3 such as a uranium metal material containing a plurality of types of isotopes.

The metal material 3 is irradiated with an electron beam 5 emitted from an electron gun 4 and bent by a deflecting magnetic field, heated and melted to evaporate, thereby generating a vapor flow 6.

The vapor flow 6 is sealed in a fan-shaped vapor enclosure 7 whose diameter increases upward, and a product recovery electrode 8 is disposed in the flow path of the vapor flow 6 in the upper part of the vapor enclosure 7. I have.

The product collection electrode 8 has a plurality of positive electrodes 8a to which a positive potential is applied.
And a plurality of negative electrodes 8b to which a negative potential is applied are alternately arranged at a required pitch so as to oppose each other in the vertical direction of the vapor flow 6.

An electric field is formed between each positive electrode 8a and each negative electrode 8b, and each electric field space is irradiated with a laser beam 9 in a direction perpendicular to the vapor flow 6 (in FIG. 2, perpendicular to the plane of the drawing).
Only specific isotopes in the vapor stream 6, eg, U-235, are excited and ionized, and the specific cationized isotope is converted to a negative electrode.
Suctioned by 8b and attached to its outer surface.

The metal vapor attached to the outer surface of the negative electrode 8b drops along the outer surface, and is received and stored by a gutter-shaped product collection tray 10 opened below each negative electrode 8b.

On the other hand, a vapor stream 11 containing isotopes, for example, U-238 and neutral metal atoms, which are not ionized by the irradiation of the laser light 9.
, Passes straight through without being affected by the electric field of the product collection electrode 8, and collides with the lower surface of the upwardly convex arc-shaped waste collection plate 12.

Generally, when the vapor stream 6 is selectively excited and ionized by a photoreaction or the like, the collision between the metal vapors may be ignored because the vapor stream 6 is in the region of the molecular flow, and the waste collection plate 12 The metal vapor of the steam flow 11 colliding with the waste product adheres to the lower surface (inner surface) of the waste product recovery plate 12 or is reflected.

Then, the metal vapor attached to the inner surface of the waste collection plate 12 is liquefied into liquid metal 13 and guided by the inner surface of the arc-shaped curve to flow down to the curved end (the left and right ends in FIG. 2). Received by 14 and collected as waste.

FIG. 3 shows a conventional laser beam multiple reflection mechanism 15, which is an incident laser beam 9i from a laser light source (not shown).
n is reflected multiple times, and a laser beam is positively and negatively applied to the flow path of the vapor flow 6 which is a gap between the positive electrode 8a and the negative electrode 8b.
The laser beam 9 is repeatedly irradiated onto the vapor flow 6 by repeatedly irradiating along the axial direction of b.

That is, the laser beam multiple reflection mechanism 15 is connected to each of the positive and negative electrodes 8.
Vertical front and rear of each steam flow path between a and 8b (left and right in Fig. 3)
, The front reflector 15a and the rear reflector 15b are arranged to face each other. Each of the front and rear reflectors 15a and 15b has a plurality of prism-type reflecting elements 15c for reflecting and bending the laser beam 9 by approximately 90 ° on its opposing surfaces. Approximately 90 by sequentially reflecting 9
It can be bent by ゜, and can be reciprocated zigzag between the front and rear reflectors 15a and 15b.

Therefore, when the incident laser light 9in from a laser light source (not shown) is irradiated on the reflecting element 15c ₁ at the lower end of the rear reflecting plate 15b, the reflected laser beam 9 is bent approximately 90 degrees element 15c ₂
Is reflected to the further drawing is 90 ° bends leftwards is reflected to the reflective elements 15c ₃ of the lowermost end of the front reflector 15a by the reflecting element 15c _2.

Thereafter, the laser light 9 gradually moves downstream (upward in FIG. 3) of the steam flow 6 while repeating the reflection between the front and rear reflectors 15a and 15b in a zigzag manner, and the rear reflector 15
The emitted laser light 9out is emitted from the upper end of b.

(Problems to be Solved by the Invention) However, in such a conventional laser light multiple reflection mechanism 15, the beam diameter 9a of the laser light 9 gradually increases as it goes downstream of the steam flow 6, as shown in FIG. Therefore, there is a problem that the intensity of laser light per unit cross-sectional area decreases as it goes downstream of the vapor flow 6, and the ability to excite and excite the laser light 9 with respect to the vapor flow 6 decreases, thereby lowering the product recovery efficiency.

When the irradiation path (reflection path) of the laser beam 9 irradiated to the vapor flow 6 is increased in order to increase the excitation ionization ability of the laser beam 9, the front and rear reflection plates 15a and 15b need to be enlarged. There is a problem of inviting.

Further, the front and rear reflectors 15a and 15b and the expanding reflector 15c
Are fixed to the respective mounting members, so that the adjustment of the optical axis of the laser beam 9 is almost impossible, and there is a problem that the assembly of the laser beam multiple reflection mechanism 15 is extremely difficult.

SUMMARY OF THE INVENTION An object of the present invention is to provide an isotope separation apparatus that can simplify a laser beam multiple reflection mechanism and improve product recovery efficiency.

[Configuration of the invention]

(Means for Solving the Problems) The present invention increases the irradiation path of the laser beam 9 to the vapor stream 6 by circulating the laser beam 9 applied to the vapor stream 6 through a circulation optical path. Beam diameter of laser light 9
The diameter of the beam 9a is reduced by a collimating lens to prevent the beam diameter 9a from being increased, and is configured as follows.

That is, the present invention heats and evaporates a metal material containing a plurality of types of isotopes to generate a vapor stream, and irradiates the vapor stream with a laser beam through a laser beam multiple reflection mechanism to thereby specify a specific isotope in the vapor stream. In addition to selectively cationizing the isotope, an electric field is applied between the positive electrode and the negative electrode of the product collection electrode, and the cationized isotope is collected as a product by the negative electrode, while the vapor stream passing through the electric field is collected as a waste product. In the isotope separation apparatus which receives the liquid metal liquefied by collision with the plate by a waste collection tray and collects the waste as waste, the laser beam multiple reflection mechanism uses a plurality of total reflection mirrors for the laser light incident from the back of the half mirror. A circulating optical path that is reflected by and returned to the reflecting surface of the half mirror again to circulate;
A collimating lens interposed in the middle of the circulating optical path to reduce the beam diameter of the circulating laser light to the beam diameter of the incident laser light incident on the half mirror; It is characterized in that it is configured to irradiate the vapor stream.

(Operation) Laser light emitted from a laser light source (not shown) enters the circulation optical path through the back surface of the half mirror of the laser light multiple reflection mechanism, and this incident laser light is reflected and circulated by the half mirror and a plurality of total reflection mirrors. Circulates in the light path.

The laser light passing through the circulating light path is applied to a vapor flow of a metal raw material containing a plurality of types of isotopes.

Since the laser light circulates in the circulation optical path, the vapor flow is repeatedly irradiated with the laser light, and the irradiation path is increased.

In addition, since the laser light circulating in the circulating optical path is reduced in diameter by the collimating lens to the beam diameter of the incident laser light at the time of the circulation, it is possible to prevent the laser beam from increasing in diameter. It is possible to prevent a decrease in the intensity of the laser beam per unit cross-sectional area, that is, a decrease in the excitation ionization ability of the laser beam due to the diameter enlargement.

As a result, the laser beam with reduced excitation ionization force can be repeatedly applied to the vapor stream, so that specific isotopes, which are products in the vapor stream, are promoted by excitation ionization, and the product recovery efficiency is improved. Can be planned.

(Embodiment) An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, portions common to FIG. 2 are denoted by the same reference numerals.

FIG. 1 is an enlarged schematic view showing a main part of an embodiment of the present invention. This embodiment is characterized by an improvement of the laser beam multiple reflection mechanism 20.

That is, the laser beam multiple reflection mechanism 20 has first and second circulating optical paths 21 and 22. The first circulating optical path 21 is located at the chamfered position of each corner of the virtual rectangle so to speak.
a, and first, second, and third total reflection mirrors 21b, 21c, and 21d are arranged so that their reflection surfaces can be directed inward to adjust the reflection angle. For this reason, the optical axis adjustment of all the mirrors 21a to 21d becomes easy.

Further, the first half mirror 21a and the first total reflection mirror 2
1b, the second total reflection mirror 21c, and the third total reflection mirror 21d are disposed so as to face the vapor flow path in the product recovery electrode 8 vertically forward and rearward. Therefore, the first half mirror 21a and the first total reflection mirror 2
An optical path a connecting the two reflection surfaces 1b and a second total reflection mirror 21c
An optical path b connecting the two reflection surfaces of the third total reflection mirror 21d is formed along the vertical direction in the flow path of the vapor flow 6 in the product recovery electrode 8, and the laser light 9 passing through the respective optical paths a and b is formed. Is repeatedly irradiated on the steam flow 6 in the vertical direction.

The first half mirror 21a transmits almost half of the incident light amount of the laser beam 9 incident on the reflecting surface thereof almost linearly, and reflects almost half of the laser light 9 by bending it to the right by approximately 90 °. Moreover, when the laser beam 9 is incident from the back surface, almost the entire amount of the laser beam 9 is transmitted almost linearly.

Therefore, incident laser light 9i from a laser light source (not shown)
n is incident on the first circulating optical path 21 through the back surface of the first half mirror 21a, and almost the total light amount W is reduced by the first total reflection mirror.
The laser beam 9 is applied to the first, second, and third total reflection mirrors 21b, 21c, and 21d in this order.
The first half mirror 2 is bent and reflected by 0 °, and is reflected again.
1a, and the laser light 9 returns to the first surface.
In the circulating light path 21 of FIG.

Therefore, the laser light 9 circulating in the first circulating optical path 21
Is applied to the vapor flow 6, so that the irradiation light amount W of the laser light 9 is
Is attenuated exponentially, but the irradiation path of the laser beam 9 applied to the vapor stream 6 increases almost infinitely.

Then, a first collimating lens 23 is interposed in an optical path connecting both reflecting surfaces of the first half mirror 21a and the third total reflection mirror 21d, and the laser light 9 has transmitted through the first collimating lens 23. Sometimes, the beam diameter 9a is reduced to the beam diameter 9a of the incident laser light 9in from the laser light source.

Therefore, the laser light 9 circulating in the first circulating optical path 21
The beam diameter 9a of the laser beam 9 is always maintained at the beam diameter 9a of the incident laser light 9in, and the expansion of the diameter is prevented. Therefore, it is possible to prevent the excitation ionization ability per unit sectional area of the laser light 9 from decreasing.

On the other hand, the second circulating light path 22 is configured to be vertically symmetrical with respect to the first circulating light path 21 in the drawing, and the second half mirror 22a and the fourth
Fifth and sixth total reflection mirrors 22b, 22c and 22d are arranged at vertically symmetric positions of the first circulating optical path 21 so that the reflection surfaces can be adjusted inward with their reflection surfaces facing inward. For this, all mirrors 22a
The optical axis adjustment of ~ 22d becomes easy.

The second half mirror 22a and the sixth total reflection mirror 2
2d, and the fourth total reflection mirror 22b and the fifth total reflection mirror 22c are disposed so as to face the front and rear of the vapor flow path in the product recovery electrode 8, respectively.

Therefore, an optical path c connecting the two reflecting surfaces of the second half mirror 22a and the sixth total reflection mirror 22d,
An optical path d connecting both reflection surfaces of the total reflection mirrors 22b and 22c is formed in the flow path of the vapor flow 6 in the product recovery electrode 8, and the laser beam 9 passing through each optical path c and d is converted into the vapor flow 6. Irradiated repeatedly.

Similarly to the first half mirror 21a, the second half mirror 22a almost linearly transmits approximately half of the amount of incident light incident on the reflecting surface, while reflecting approximately half of the incident light by bending it by approximately 90 [deg.]. When the laser beam 9 is incident from the back surface, almost the entire light amount is transmitted substantially linearly.

Therefore, on the back surface of the second half mirror 22a, the incident laser beam 9 that has transmitted linearly through the first half mirror 21a is placed.
A substantially half light amount (1 / 2W) of the total light amount W of “in” is incident, and a substantially total light amount of the laser light 9 having the half light amount (1 / 2W) is applied to the fourth total reflection mirror 22b.

Further, a second collimating lens 24 is interposed in the optical path connecting the reflection surface of the second half mirror 22a and the reflection surface of the fourth total reflection mirror 22b. When 9 is transmitted, its beam diameter 9a
Is reduced to the beam diameter 9a of the incident laser light 9in from the laser light source.

Therefore, the laser light 9 circulating in the second circulating light path 22
The beam diameter 9a of the incident laser light 9in is always maintained at the beam diameter 9a of the incident laser light 9in, and the expansion of the beam cage 9a is prevented. Therefore, it is possible to prevent the excitation ionization ability per unit cross-sectional area of the laser light 9 from decreasing.

Then, the laser light 9 returning to the second half mirror 22a again has approximately half of the total light amount transmitted linearly through the second half mirror 22a and emitted to the outside, and another half of the laser light 9 has returned to the second half mirror 22a again. The light is reflected by the second half mirror 22a and circulates through the second circulation optical path 22.

Accordingly, the amount of the emitted laser light 9out emitted from the second half mirror 22a to the outside is incident on the first half mirror 21a in the first round of the first and second circulating optical paths 21 and 22. This is approximately 1/4 of the total light amount W of the incident laser light 9in.

As described above, since the laser beam multiple reflection mechanism 20 irradiates the vapor stream 6 with the laser beam 9 circulating through the first and second circulation optical paths 21 and 22, the irradiation light amount W of the laser beam 9 is a geometric series. However, the irradiation path of the laser beam 9 to the vapor stream 6 is almost infinitely increased, and the ability to excite and ionize a specific isotope as a product in the vapor stream 6 is increased, thereby improving the product recovery efficiency. Can be planned.

 Next, the operation of the present embodiment will be described.

As shown in FIG. 2, the uranium metal raw material 3 containing a plurality of types of isotopes accommodated in the evaporation crucible 2 having excellent thermochemical resistance is irradiated with an electron beam 5 by an electron gun 4, The raw material 3 is heated and melted and evaporated to generate a vapor flow 6, and the vapor flow 6 is guided by the vapor enclosure 7 and flows upward.

On the other hand, as shown in FIG. 1, the laser beam multiple reflection mechanism 20 transmits incident laser light 9in from a laser light source (not shown) to the first
Received from the back of the half mirror 21a of the first circulating optical path 2
The laser light 9 is circulated through the first circulating light path 21 by being incident on the inside of the laser light 9.

When the laser light 9 circulating in the first circulating optical path 21 passes through the first collimating lens 23, its beam diameter 9a is always reduced to substantially the same diameter as the beam diameter 9a of the incident laser light 9in.

Therefore, the beam diameter 9a of the circulating laser light 9 is always maintained at the beam diameter 9a of the incident laser light 9in, and the excitation ionization ability of the laser light 9 per unit cross-sectional area is kept substantially constant.

When the laser beam 9 whose beam diameter 9a is reduced by the first collimating lens 23 is returned to the reflection surface of the first half mirror 21a, almost half of the incident light amount is reflected at an angle of about 90 °. While returning to the first circulating light path 21 and circulating again, the other half of the light passes through the reflecting surface in a substantially vertical direction and passes through the rear surface of the second half mirror 22a to substantially the entire light amount (1/2 W). ) Enters the second circulating light path 22, and the laser light 9 circulates in the second circulating light path 22.

When the laser light 9 circulating through the second circulating optical path 22 passes through the second collimating lens 24, the beam diameter 9a is reduced to substantially the same diameter as the beam diameter 9a of the incident laser light 9in. The beam diameter 9a is always the beam diameter 9a of the incident laser light 9in
, And the ionization ability of the laser beam 9 per unit sectional area is kept substantially constant.

When the laser light 9 circulating in the second circulating optical path 22 is returned to the reflection surface of the second half mirror 22a, the incident light amount (1/2
One half of W), that is, 1/4 of the incident light amount W is emitted to the outside, and half (1 / 4W) circulates through the second circulation optical path 22 again.

The laser beam 9 circulating in the first and second circulating optical paths 21 and 22 is repeatedly applied to the vapor flow 6 when passing through the optical paths a to d.

Since the laser light 9 circulates through the first and second circulating optical paths 21 and 22, the light amount W is gradually attenuated in a geometric progression as the number of circulations increases, but is circulated almost infinitely repeatedly. Therefore, the irradiation of the vapor flow 6 with the laser light 9 is repeated almost infinitely, and the irradiation path of the laser light 9 to the vapor flow 6 is significantly increased.

Moreover, the beam diameter 9a of the laser light 9 circulating in the first and second circulating optical paths 21 and 22 is equal to the first and second collimating lenses 2
Since the beam diameter 9a of the incident laser light 9 is always narrowed down by 3 and 24, it is possible to prevent the excitation ionization ability of the laser light 9 per unit sectional area from decreasing.

Then, only a specific isotope, for example, U-235 in the vapor stream 6 repeatedly irradiated with the laser light 9 is excited and ionized,
Cationized.

The specific cationized isotope is sucked by the negative electrode 8b of the product collection electrode 8, and is received and collected as a product by the product collection tray 10.

Therefore, according to the present embodiment, the laser beam 9 circulating in the first and second circulating optical paths 21 and 22 is applied to the steam flow 6, so that the laser beam 9 can be repeatedly applied to the steam flow 6, The irradiation path can be increased.

As a result, cationization of a specific isotope, which is a product in the vapor stream 6, can be promoted, and the product recovery efficiency can be improved.

Further, the beam diameter 9a of the laser beam 9 applied to the vapor flow 6
Is narrowed by the first and second collimating lenses 23 and 24 to substantially the same beam diameter 9a as the incident laser light 9in.
It is possible to prevent the excitation ionization ability per unit sectional area of the laser beam 9 from being lowered.

Further, in this embodiment, the number of mirrors is eight, the configuration is simple, and the mirrors 21a to 21d and 22a to 22d are configured so that the reflection angles can be freely adjusted, so that the optical axis adjustment is easy.

In the above embodiment, the first and second circulating optical paths 21 and 22 are used.
Has been described, but the present invention is not limited to this. For example, one or three or more circulating optical paths may be provided.

Further, the first collimating lens 23 may be interposed in the optical path connecting the two reflecting surfaces of the first total reflection mirror 21b and the second total reflection mirror 21c. It may be interposed in the middle of an optical path connecting both reflecting surfaces of the total reflection mirror 22c and the sixth total reflection mirror 22d.

〔The invention's effect〕

As described above, the present invention irradiates a laser beam passing through a circulating optical path to a vapor stream containing a plurality of types of isotopes,
The irradiation path of the laser beam irradiated to the vapor flow can be increased.

Therefore, it is possible to promote the excitation ionization of the specific isotope, which is the product in the vapor stream, by the irradiation of the laser beam, and to improve the product recovery efficiency.

[Brief description of the drawings]

1 is an enlarged schematic view showing an embodiment of an isotope separation device according to the present invention, FIG. 2 is an overall configuration diagram of a conventional isotope separation device, and FIG. 3 is a conventional structure shown in FIG. FIG. 4 is a schematic diagram showing a laser beam multiple reflection mechanism incorporated in the isotope separation device.
The figure is a view for explaining one of the problems of the laser beam multiple reflection mechanism shown in FIG. DESCRIPTION OF SYMBOLS 1 ... Vacuum container, 2 ... Crucible for evaporation, 3 ... Metal raw material, 4 ... Electron gun, 5 ... Electron beam, 6, 11 ... Vapor flow, 8 ... Product recovery electrode, 8a ... Positive Electrode, 8b Negative electrode, 9 Laser light, 20 Laser light multiple reflection mechanism, 21
... First circulation optical path, 21a First half mirror, 21
b, 21c, 21d ... first, second, third total reflection mirrors, 22 ...
... Second circulating optical path, 22a ... Second half mirror, 22b, 2
2c, 22d... Fourth, fifth, and sixth total reflection mirrors.

Claims (4)

(57) [Claims] 1. A method for heating and evaporating a metal material containing a plurality of types of isotopes to generate a vapor stream, and irradiating the vapor stream with a laser beam through a laser beam multiple reflection mechanism, to thereby specify a specific isotope in the vapor stream. In addition to selectively cationizing the isotope, an electric field is applied between the positive electrode and the negative electrode of the product collection electrode, and the cationized isotope is collected as a product by the negative electrode, while the vapor stream passing through the electric field is collected as a waste product. In the isotope separation apparatus which receives the liquid metal liquefied by colliding with the plate by the waste collection tray and collects it as waste, the laser beam multiple reflection mechanism device performs total internal reflection of laser light incident from the back of the half mirror. A circulating optical path that is reflected by the mirror and circulated again to the reflecting surface of the half mirror, and a beam diameter of the circulating laser light that is interposed in the middle of the circulating optical path and is adjusted by the half mirror. Isotope separation apparatus characterized by comprising a collimating lens reduced in diameter to the beam diameter of the incident laser beam incident on the over, the laser beam passing through the circulation path and configured to illuminate the said flow of steam. 2. A patent in which a circulating optical path is formed in a plurality of stages, and a part of the laser light emitted from the half mirror in the previous circulating optical path is made to enter the next circulating optical path through the next half mirror. The isotope separation device according to claim 1. 3. The isotope separating apparatus according to claim 1, wherein the collimating lens is interposed in the middle of the circulating optical path in front of the half mirror. 4. The isotope separation apparatus according to claim 1, wherein the half mirror and the total reflection mirror are configured so that the reflection angle can be adjusted.