JPH07169B2 - Isotope separation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of use) The present invention is directed to ionization by selectively exciting only a specific isotope in a metal raw material containing plural kinds of isotopes by laser light. The present invention relates to improvement of an isotope separation device that electrically separates and collects isolated isotopes.

(Prior Art) A metal atom isotope separation device using a laser beam is used in a uranium enrichment process for producing a fuel for a nuclear reactor.

FIG. 4 is a block diagram conceptually showing a conventional isotope separation device by a laser method. The isotope separation device 1 is composed of a vacuum container 2 that hermetically houses a main body in a substantially vacuum state and each device that constitutes the main body, and a metal raw material 3 containing a plurality of types of isotopes.
Are housed in a thermochemically resistant evaporation crucible 4.

On the other hand, the electron beam 6 emitted from the linear electron gun 5
The metal raw material 3 which is deflected by the deflection magnetic field and accommodated in the evaporation crucible 4 is irradiated. Upon being irradiated with the electron beam 6, the metal raw material 3 is heated up to about 2700 ° K, evaporates through a molten state, and forms a vapor stream 7 of isotope metal. The vapor stream 7 is guided by a collimator 8 so as to flow in a predetermined direction.

In the vapor stream 7, a specific isotope for separation and recovery and other isotopes and metal atoms not for recovery are mixed. Next, the vapor stream 7 is irradiated with a laser beam 9 that selectively excites only a specific isotope. Here, the laser light 9 is a laser light having a wavelength equal to the resonance excitation energy of a specific isotope. The excited specific isotope further receives laser light stepwise, and the outermost shell electron of the atom is expelled to become an ionized isotope having a positive charge.

A product recovery electrode 10 formed by alternately arranging positive electrodes and negative electrodes is provided in the passage of the vapor flow 7, and the vapor flow 7 containing an ionized isotope is formed between the product recovery electrodes 10. When passing through the generated electric field space, only specific ionized isotopes having a positive charge are attracted to the negative electrode surface and collected as a product.

On the other hand, the vapor flow containing non-ionized isotopes and neutral metal atoms passes between the product recovery electrodes 10 without being affected by the electric field, and is attached and recovered to the waste product recovery electrode 11 arranged on the secondary side. Is configured to.

(Problems to be Solved by the Invention) In order to improve the separation coefficient in the isotope separation device having the above configuration, it is important to selectively excite only a specific isotope for recovery. Therefore, it is necessary to accurately match the wavelength of the laser light to be irradiated with the resonance wavelength of a specific isotope.

For example, as a laser light source used in the uranium enrichment process, a dye laser having a wavelength range of 4000 to 6000Å is adopted. Since the uranium atom has a large number of resonance absorption lines in the above wavelength range, it is possible to obtain a laser beam that selectively excites the target U-235 by tuning the wavelength of the dye laser.

However, in order to confirm whether or not the actual device is operating under the optimum operating conditions, it is difficult to always accurately calibrate the wavelength of the laser beam applied to the vapor flow.
That is, the shift of the resonance wavelength of the isotope is generally about 0.1 Å, but considering the splitting of the resonance line due to the hyperfine structure of the isotope nucleus, a finer 0.01% is needed to set the wavelength of the laser light to an appropriate value. Å Fine adjustment accuracy is required.

However, it is difficult to equip the isotope separation device with a wavelength meter having a measurement accuracy of up to 0.01 Å by the conventional technology.
Therefore, the suitability of the wavelength of the laser light is judged by the amount of the target isotope recovered per unit time or the content ratio of the specific isotope in the recovered product. That is, it takes a long time to understand the effect of adjusting the wavelength of the laser light, and there is a problem that the operation management of the isotope separation device becomes complicated.

The present invention was devised to solve the above problems, and provided with a mechanism for quantifying the proportion of a specific isotope ionized and ionized by laser light irradiation in a vapor flow, and the proportion of the proportion was large or small. It is configured so that the appropriateness of the wavelength of the laser light during irradiation can be grasped by
It is an object of the present invention to provide an isotope separation device in which the wavelength of laser light can be adjusted as appropriate, operation management is easy, and separation efficiency is high.

[Structure of Invention]

(Means for Solving Problems) An isotope separation device according to the present invention heats and vaporizes a metal raw material containing a plurality of types of isotopes to generate a vapor stream, and irradiates the vapor stream with laser light. An isotope separation device that selectively ionizes a specific isotope in a vapor stream and separates the ionized isotope by an electric field is provided with a monitor device that quantitatively detects the ionized isotope. .

(Operation) According to the above configuration, the ionized isotope is quantified by the monitor device within a short time. Then, it is possible to judge whether the wavelength of the laser light being radiated is appropriate or not based on the magnitude of the deviation of the measured value from the planned value. Further, if the wavelength is appropriately adjusted so that the ratio of the ionized isotope in the entire vapor flow is directed to the maximum value, the separation efficiency in the separation device can always be kept high.

In addition, when the ratio of the ionized isotope is small, it is determined that the wavelength of the laser light deviates from the wavelength of the absorption line of the isotope for the purpose of recovery. In this case, the optimum operating state can be restored by adjusting the wavelength of the laser light in the direction of increasing the ratio of ionized isotopes.

That is, using the amount of ionized isotope generated detected by the monitor as a criterion, the wavelength of the laser light is appropriately set.
Since it can be adjusted and maintained at an appropriate value, the isotope separation efficiency is high and the operation management is extremely easy.

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

The isotope separation device according to the present invention is characterized in that a monitor device for separating and quantifying ionized isotopes is provided, and is configured as shown in FIGS. 1 and 2.

That is, a vaporizing crucible 4 containing a metal raw material 3 containing a plurality of isotopes, and a linear electron gun that irradiates the metal raw material 3 with an electron beam 6 to heat and vaporize the metal raw material 3 to generate a vapor stream 7. And 5 are arranged at the bottom of the vacuum container 2. Above the evaporation crucible 4, a collimator 8 for guiding the flow of the vapor stream 7 in a predetermined direction is provided. The passage of the vapor flow 7 on the secondary side of the collimator 8 is irradiated with the laser beam 9 and only specific isotopes become ionized isotopes selectively excited.

A product recovery electrode 10 and a waste product recovery electrode 11 are provided along the flow of the vapor stream 7 above the irradiation region of the laser light 9. The product recovery electrode 10 is formed by alternately arranging a plurality of positive electrodes and negative electrodes in parallel.

A steam hole 13 for introducing a part of the steam flow 7 into the monitor device 12 is formed in the center of the waste product recovery electrode 11 arranged on the secondary side of the product recovery electrode 10. Monitor device 12 has a steam hole
Ion lens 14 directly above 13 and this ion lens
14 and a mass filter 15 installed so as to face each other.

Here, the detailed structure of the ion lens 14 will be described with reference to FIG.

The ion lens 14 is formed in a hollow cylindrical shape, two vapor flow passage holes 16 are provided in the side surface radial direction so that the vapor flow 7 penetrates, and the branch laser is irradiated from a direction perpendicular to the vapor flow 7. Two branched laser light passage holes 18 through which the light 17 penetrates are provided. Further, an ionized isotope passage hole 20 that serves as an exit of the ionized isotope 19 generated by irradiating the vapor stream 7 introduced into the ion lens 14 with the branched laser light 17 is provided at one position on the axial end surface of the ion lens 14. To be The mass filter 15 is the first facing the ionized isotope passage hole 20.
Arranged as shown.

In the isotope separation device having the above-mentioned configuration, the metal raw material 3 containing a plurality of isotopes is heated and evaporated to form the vapor stream 7, and then the vapor stream 7 is irradiated with the laser beam 9 so that only specific isotopes are produced. It is selectively excited to become an ionized isotope. The ionized isotope is separated and recovered in a predetermined direction by the electric field formed on the product recovery electrode 10.

On the other hand, the vapor stream 7 containing non-ionized neutral atoms passes through the product recovery electrode 10 and is mostly collected by the waste product recovery electrode 11. On the other hand, a part of the vapor flow 7 reaching the waste product collecting electrode 11 is introduced into the ion lens 14 of the monitor device 12 via the vapor hole 13 and the vapor flow passage hole 16. Furthermore, ion lens 14
The branched laser light 17 is irradiated from a direction perpendicular to the vapor flow 7 introduced therein. This branched laser light 17 is branched from the laser light 9 by a partial reflection mirror 21 and a total reflection mirror 22 which are provided on the way of the laser light 9 as shown in FIG.

The specific isotope in the vapor stream 7 introduced into the ion lens 14 is changed to the ionized isotope selectively excited by the irradiation of the branched laser beam 17. The ionized isotope vapor flow generated in the ion lens 14 is focused in the direction of the ionized isotope passage hole 20 by the applied electric field, and further focused on the entrance of the mass filter 15 facing the ionized isotope passage hole 20. Tie

The mass filter 15 executes mass spectrometry of the components contained in the vapor of the ionized isotope and quantifies the abundance ratio of the specific isotope for the purpose of recovery. That is, the mass filter 15 applies an electromagnetic field to the ionized isotope to automatically measure the amount of the specific isotope separated and collected at a predetermined position. The suitability of the wavelength of the laser beam 9 radiated is judged by the magnitude of the deviation of the measured value from the planned design value. That is, when the deviation is large, the wavelength is insufficiently adjusted, the selective excitation of a specific isotope is small, and the separation efficiency is reduced. Therefore, in order to increase the separation efficiency, it is necessary to adjust the wavelength of the laser light 9 so as to increase the specific amount of ionized isotope.

That is, according to the isotope separation device of the present embodiment, it is possible to directly confirm the ionization state of the specific isotope for the purpose of recovery by the monitor device. Therefore, the wavelength adjustment of the laser light can be appropriately performed during the operation, and the laser light can always be operated under the optimum operating conditions. for that reason,
Isotope separation efficiency is high and operation management is extremely simplified.

〔The invention's effect〕

The isotope separation device according to the present invention is equipped with a monitor device for detecting and quantifying the amount of ionized isotopes produced for the purpose of recovery, and the laser light is based on the measured amount of ionized isotopes produced. Since it is possible to judge the suitability of the wavelength in a short time and adjust the wavelength to an appropriate value as appropriate, the isotope separation efficiency is high and the operation management is easy.

[Brief description of drawings]

FIG. 1 is a cross-sectional view schematically showing one embodiment of the isotope separation device according to the present invention, FIG. 2 is a cross-sectional view taken along the line II-II in FIG. 1, and FIG. 3 shows the structure of an ion lens. FIG. 4 is a transverse sectional view schematically showing the structure of a conventional isotope separation device. 1 ... Isotope separation device, 2 ... Vacuum vessel, 3 ... Metal raw material, 4 ... Evaporating crucible, 5 ... Linear electron gun, 6 ...
Electron beam, 7 ... Vapor flow, 8 ... Collimator, 9 ...
Laser light, 10 …… Product recovery electrode, 11 …… Waste product recovery electrode,
12 ... Monitor device, 13 ... Vapor hole, 14 ... Ion lens, 15 ... Mass filter, 16 ... Vapor flow passage hole, 17 ...
Branched laser light, 18 ... Branched laser light passage hole, 19 ... Ionized isotope, 20 ... Ionized isotope passage hole, 21 ... Partial reflection mirror, 22 ... Total reflection mirror.

Claims (2)

[Claims] 1. A metal raw material containing a plurality of isotopes is heated and evaporated to generate a vapor stream, and the vapor stream is irradiated with laser light to selectively ionize a specific isotope in the vapor stream.
An isotope separation device for separating ionized isotopes by an electric field, comprising a monitor device for quantitatively detecting the ionized isotopes. 2. A monitor device branches part of each of the laser beam and the vapor flow and brings them into contact with each other, and collects and focuses the resulting ionized isotopes, and the focused ionized isotopes. 2. An isotope separation device according to claim 1, further comprising a mass filter for executing the mass spectrometry of 1. to quantify the abundance ratio of ionized isotopes.