JP2603983B2 - 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 that separates and collects only a specific isotope from a metal containing a plurality of types of isotopes by using a laser beam. About.

(Prior Art) A metal isotope separation apparatus using a laser beam is used, for example, in a uranium enrichment step when producing uranium as a fuel for a nuclear reactor.

A conventional isotope separation apparatus using a laser beam is shown in FIGS. FIG. 3 is a longitudinal sectional view schematically showing a conventional isotope separation apparatus, and FIG. 4 is a sectional view taken along line II-II of FIG. The inside of the separation chamber indicated by reference numeral 1 is substantially kept in a vacuum, and the bottom thereof has a thermochemically resistant evaporation crucible 2 for accommodating the metal 3 and linear electrons for emitting an electron beam 5 for irradiating the metal 3. A gun 4 is provided. Above the evaporating crucible 2, there is a vapor flow 6 generated from the metal 3.
A collimator 29 for guiding the ascending direction is provided, and above the collimator 29, a product recovery electrode 7 is provided in which positive and negative electrodes erected along the ascending direction of the vapor flow 6 are alternately juxtaposed. A voltage is applied between these two electrodes,
A laser beam 10 having a wavelength for selectively exciting and ionizing a specific isotope in the metal 3 as a recovery target is applied along the longitudinal direction of the electrode. Here, a laser beam having a wavelength equal to the resonance excitation energy of the specific isotope is employed. Further, a waste product recovery plate 8 is provided generally above the product recovery electrode 7.

The metal 3 contained in the evaporation crucible 2 is
And evaporates into a vapor stream 6, passes through the inside of the collimator 29, and rises between the electrodes of the product recovery electrode 7. Here, when the laser beam 10 is applied to the vapor stream 6, only specific isotopes in the vapor stream 6 are excited and ionized. Since this ionized isotope has a positive charge, it is attracted to the negative electrode by an electric field formed between the electrodes, and is adsorbed and collected as a product on the surface thereof. On the other hand, the vapor flow containing other non-ionized isotopes and the like passes through the product recovery electrode 7 without being affected by the electric field, and is adhered and recovered to the waste product recovery plate 8 provided secondarily.

(Problems to be Solved by the Invention) In the isotope separation apparatus as described above, in order to improve the separation coefficient of the recovery target, an operation of selectively exciting and ionizing only the characteristic isotope which is the recovery target. is important. Therefore, it is necessary to match the wavelength of the laser light to be irradiated with the resonance wavelength of the specific isotope with high accuracy.

For example, as a laser light source used in the uranium enrichment step, a dye laser having a wavelength range of 4000 to 7000 ° is employed. Since uranium atoms have a large number of resonance absorption lines in the preceding wavelength range, it is possible to obtain a laser beam that selectively excites uranium 235 as a recovery target by accurately tuning the wavelength of the dye laser. Generally, the shift of the resonance absorption wavelength of an isotope is about 0.1 ° or less,
Taking into account the splitting of the absorption line due to the hyperfine structure of the isotope nucleus, a fine adjustment precision of about 0.01 ° is required in order to set the wavelength of the laser beam to an appropriate value.

Actually, in order to confirm whether or not the actual device is operating under the optimum operating conditions, it is necessary to always accurately verify the wavelength of the laser beam applied to the steam flow.
It is difficult to install a wavelength meter having a measurement accuracy of up to に in an actual device. Therefore, adjustment of the wavelength of laser light
It has been proposed to measure fluorescence equal to the wavelength of the absorbed laser light emitted in proportion to the number of excited atoms when the isotope excited by the laser light returns to the ground state again. However, the structure of the device that detects and measures the fluorescence is complicated, and installing the device in the reaction section between the laser beam and the vapor flow affects the arrangement and dimensions of the structure in the separation chamber, and the recovery There has been a problem that the separation performance of the target object is reduced.

The present invention has been made in order to solve such a problem, and an object of the present invention is to provide an isotope separation apparatus that can adjust the wavelength of laser light with high accuracy and that does not decrease the separation performance. .

[Configuration of the invention]

(Means for Solving the Problems) The isotope separation apparatus according to the present invention heats and evaporates a metal containing a plurality of types of isotopes into a vapor flow in a separation chamber, and excites only a specific isotope in this vapor flow. A configuration in which the specific isotope alone is ionized by irradiating a laser beam having a wavelength to be dissociated, and the specific isotope ion is adsorbed and collected on the electrode by the voltage by passing between electrodes to which a voltage is applied. In the isotope separation apparatus, an optical path deflecting device that branches and reduces the diameter of a part of the laser light applied to the inside of the separation chamber and collimates the laser light, and an auxiliary chamber that introduces the reduced diameter collimated laser light is provided. A part of the laser beam is irradiated to a vapor stream of the metal containing the plurality of types of isotopes generated in the auxiliary chamber, and the amount of ionized ions is applied to an ion collection collector electrode. A mass filter for collecting and measuring is installed, and a fluorescence detection device for detecting fluorescence generated when the excited isotope atoms transition to the ground state is provided, and the amount of fluorescence from the fluorescence detection device is used in the separation chamber. And a wavelength controller for controlling the wavelength of the laser light incident on the laser beam.

(Operation) In the auxiliary chamber provided separately from the separation chamber, the same metal as the metal stored in the separation chamber stored in the steam crucible is heated by a heat source to form a steam flow, and the inside of the auxiliary chamber is To rise. In this vapor flow, a part of the laser beam irradiated into the separation chamber is deflected by an optical path deflecting device, collimated and irradiated, and creates the same environment as the separation chamber in a configuration different from the separation chamber. be able to. The specific isotope is excited by the laser beam irradiation. The amount of excited and ionized ions is measured with a mass filter via a collector electrode for ion collection. Further, the fluorescence generated when a part of the excited isotope returns to the ground state again is detected by the fluorescence measuring device, and the wavelength of the laser light is controlled with high precision by the wavelength controller based on the amount of the generated fluorescence.

(Embodiment) An embodiment of the isotope separation apparatus according to the present invention will be described with reference to FIG. 1 and FIG. FIG. 1 is a configuration diagram partially showing an embodiment of the present invention in a schematic cross-section, and FIG. 2 is a cross-sectional view taken along line II in FIG. The same parts as those of the conventional example described above are denoted by the same reference numerals, and duplicate description will be omitted.

In a separation chamber indicated by reference numeral 1 in FIG. 1, a metal housed in an evaporating crucible 2 is heated by an electron beam from a linear electron gun 4 to form a vapor flow 6, and a laser beam 10
Is irradiated to excite and ionize a specific isotope, and the specific isotope is collected by the product collection electrode 7. On the other hand, a small auxiliary chamber 15 provided separately from the separation chamber 1 also has the same configuration as this separation chamber, and as shown in FIGS. An evaporation crucible 16 containing the same metal 17 as the metal 3 contained therein, and an electron beam 19 for heating the metal 17
A linear electron gun 18 is provided above the collimator 27.A collimator 27 guides the ascending direction of the vapor flow 20 generated from the metal 17 above the metal electron gun 18, and an ion collector for standing ions is provided along the ascending direction of the vapor flow 20. A mass filter 28 having a collector electrode 21 is provided. Above the collector electrode 21 for ion recovery, a fluorescent light concentrator 22 is provided, and the fluorescent light collector 22 is connected to a photomultiplier tube 24, an integrator via an optical fiber 23.
The fluorescence measurement device 30 is configured to be connected to the reference numeral 25. Further, the fluorescence measuring device 30 is connected to the wavelength controller 26 and the laser light oscillating device 9. Further, in order to irradiate the laser light generated from the laser light oscillator 9 between the electrodes of the collector electrode 21 for collecting ions in the auxiliary chamber 15, a semi-reflection mirror 12, a total reflection mirror 13, and collimator lenses 14a and 14b. An optical path deflecting device 11 is provided.

The metal 17 accommodated in the steam crucible 16 in the auxiliary chamber 15 is heated by the electron beam 19 from the linear electron gun 18 and evaporates into a steam flow 20. The vapor flow 20 rises inside the collimator 27 and is introduced into a space between the ion collection collector electrodes 21. On the other hand, a part of the laser light 10 generated from the laser oscillation device 9 to be irradiated into the separation chamber 1 is deflected by the semi-reflection mirror 12 and the total reflection mirror 13 and passes through the collimator lenses 14a and 14b into the space. Then, only the specific isotope in the vapor stream 18 is excited and ionized in the same environment as the inside of the separation chamber 1 by irradiation with the vapor stream 20.
A part of the specific isotope excited in this manner returns to the ground state again, and emits fluorescence having the same wavelength as the absorbed laser light. This fluorescent light is collected by a fluorescent light collector 22 and converted into a fluorescent light generation signal which is an electric signal by a photomultiplier tube 24.
The waveform is analyzed by the integrator 25, and the deviation between the analysis result and the standard value of the fluorescence generation amount at the wavelength of the irradiating laser light is calculated by the wavelength controller 26, and the laser light oscillating device 9 is operated.
A wavelength control signal is output to control the wavelength of the laser light with high accuracy. In addition, the ionized isotope can be monitored by measuring the ionized isotope collected by the collector electrode 21 for ion collection with the mass filter 28.

In the present embodiment, an example in which one separation chamber is provided is described. However, the present invention is not limited to this, and a plurality of separation chambers may be provided.

〔The invention's effect〕

According to the present invention, by providing an auxiliary chamber having a mass filter and a fluorescence measurement device, the same environment as the separation chamber can be obtained in a configuration different from that of the separation chamber for the purpose of separating specific isotopes. By controlling the wavelength of the laser beam using this auxiliary chamber, it is possible to control with higher precision, and thus the separation efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram partially showing an embodiment of the present invention in a schematic cross-section, FIG. 2 is a cross-sectional view taken along a line II in FIG. 1, and FIG. FIG. 4 is a sectional view of FIG.
It is II-II arrow sectional drawing. 1 ... Separation chamber, 2,16 ... Crucible for evaporation, 3,17 ... Metal, 4,18 ... Linear electron gun, 5,19 ... Electron beam, 6,20 ... Vapor flow, 7 ... Product recovery electrode, 8: waste collection plate, 9: laser beam oscillator, 10: laser beam, 11: optical path deflector, 12: semi-reflective mirror, 13: total reflection mirror, 14a, 14b ... Collimator lens, 15 ... Auxiliary chamber, 21 ... Collector electrode for ion collection, 22 ... Fluorescent concentrator, 23 ... Optical fiber, 24 ... Photomultiplier tube, 25 ... Integrator, 26 ... Wavelength Controllers, 27, 29: Collimator, 28: Mass filter, 30: Fluorescence measuring device.

Claims (1)

(57) [Claims] 1. A method for heating and evaporating a metal containing a plurality of types of isotopes in a separation chamber to form a vapor stream, and irradiating the vapor stream with a laser beam having a wavelength for exciting and dissociating only the specific isotope. In the isotope separation apparatus configured to ionize only the body and pass between the electrodes to which a voltage is applied, and adsorb and recover the specific isotope ion on the electrode by the voltage, the separation chamber is irradiated with the isotope. An optical path deflecting device for branching and reducing the diameter of a part of the laser light and collimating the laser light; and an auxiliary chamber for introducing the laser light having the reduced diameter and collimation, the plurality of types of isotopes generated in the auxiliary chamber. Irradiating a part of the laser light to the vapor stream of the metal containing, and installing a mass filter for collecting and measuring the amount of ionized ions to the collector electrode for ion collection. A fluorescence detector for detecting fluorescence generated when the generated isotope atoms transition to the ground state is provided, and a wavelength for controlling the wavelength of laser light incident into the separation chamber with the amount of fluorescence from the fluorescence detector. An isotope separation device provided with a controller.