JPH0487628A - Isotope separation system - Google Patents

Abstract

PURPOSE:To obtain an efficient and cheap system by providing a free-electron laser, several separation cells to separate isotopes with the laser light, and a lens system to distribute the laser light to specified cells. CONSTITUTION:First, laser light is generated with an electron accelerator 21 and wiggler magnet series 22. To obtain the isotope of material (I), the laser light is introduced to a separation cell 27 with a reflecting mirror 29. In this process, the wavelength of the laser light is measured with a wavelength meter 31 by partly deviding the light with a split mirror 33. The wavelength of the laser light is then adjusted to the resonance absorption wavelength at which the isotope of material (I) is selectively ionized by controlling the electron beam energy with a voltage controller 32. Next, to separate the isotope of material (II), the reflecting mirror 29 is removed out of the optical path of the beam so that the laser light is introduced to a separation cell 28 with a reflecting mirror 30. The wavelength of the laser light is adjusted to the resonance absorption wavelength of the isotope of material (II) by the same method as above described. Thereby, isotopes or specified materials can efficiently be separated.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Application Field) The present invention is directed to the production of specific substances or isotopes in nuclear fuel materials, nuclear fuel coating materials, neutron absorbing materials, and nuclear fuel reprocessing products using laser light. This invention relates to an isotope separation system for separating .

(Prior Art) A system related to uranium enrichment is known as a system for isotopically separating nuclear fuel materials using a laser. Uranium enrichment is a process that increases the concentration of ``U'' contained in natural uranium from 0.7% to 3-5% for use as fuel for light water reactors.

A conventionally used uranium enrichment system will be explained with reference to FIG. The main components of the system are a laser family [[101] and a separation cell device 104. The laser device 101 consists of copper vapor lasers 101a, 101b, 101c and dye lasers 102a, 102b, 102c.

The wavelength of the dye laser is tunable, and its wavelength band is 55
0 nm to 650 rv+. Since the dye laser cannot oscillate by itself, a copper vapor laser is used as the excitation laser. The dye laser 102a is tuned to the absorption spectrum of 235U and is used to excite only this isotope. In addition, dye lasers 102b, 10
2c is used for intermediate excitation of 235U and also for reaching ionization luchel. In this way, the combination of a copper vapor laser and a dye laser requires three laser beams to ionize uranium. The three laser beams are combined into one beam by a beam combiner 103 and sent to a separation cell device 104.

Schematic diagrams of the interior of the separation cell device 104 are shown in FIGS. 7 and 8.
As shown in the figure. The separation cell device 104 is mainly composed of a sealed container 2, and the inside of this sealed container 2 is constructed as follows and is maintained in a vacuum state. That is, uranium metal 3 is loaded into a crucible 4 installed in a sealed container 2, and an electron gun 5 is loaded into the crucible 4.
The electron beam 6 extracted from the coil is deflected by a coil and irradiated.

By this irradiation, the metallic uranium 3 is heated and liquefied, and uranium vapor 7 is generated from the irradiated surface of the electron beam 6 and rises as shown by the arrow. This uranium vapor 7 is condensed by a collimator 8 and then introduced into the photoreaction section.

When this uranium vapor is irradiated with laser light 9, 235U
Only the uranium absorbs the laser beam, and the three beams eventually turn it into ionized uranium. Ionized 235U is used as product recovery electrode 1
It is collected by the electrode 10 by the voltage applied to 0. On the other hand, 238U, which does not react with the laser beam, flies as a neutral uranium atom and attaches to the waste collection plate 11 installed at the top. FIG. 8 is a knee I arrow view in FIG. 7.

The above system allows separation of 23SU and 23' tJ isotopes.

(Problem to be Solved by the Invention) Systems similar to the uranium enrichment device described above can be used for elemental separation and isotope separation in other nuclear fuel materials, cladding materials, neutron absorbing materials, and nuclear fuel reprocessing products. can do. However, if the uranium concentrator is applied as is, the wavelength band in which the dye laser oscillates will be limited depending on the dye used, so the dye will need to be replaced. Furthermore, for other substances such as uranium that do not require isotopic separation in large quantities, it is economically unfeasible to prepare laser equipment for uranium enrichment.

The present invention has been made to solve the above problems, and provides an isotope separation system that uses a common laser device for separating uranium and other substances related to the nuclear fuel cycle, and that can be easily switched. It is in.

[Structure of the invention]

(Means for Solving the Problems) The present invention uses a free electron laser to separate specific substances or specific isotopes of nuclear fuel materials, nuclear fuel coating materials, neutron absorbing materials, and nuclear fuel reprocessing products using laser light from the free laser. The present invention is characterized in that it comprises a plurality of separation cells for separating the cells, and a lens system for distributing the laser beam to predetermined cells among the separation cells.

In addition, it has the function of branching a part of the laser from the free electron laser beam and measuring the wavelength to control the wavelength to the resonance wavelength of the material of interest in the separation cell into which the laser beam is introduced. It is characterized in that the maintenance time is used for isotope separation of other substances.

(Function) The present invention uses a free electron laser, which is a type of wavelength tunable laser, and utilizes its wide range of wavelength controllability to separate nuclear fuel materials, cladding tube materials, neutron absorbing materials, and nuclear fuel products. Allocate your time appropriately.

The free electron laser is operated by an electron accelerator 21 as shown in Figure 1.
and a wiggler magnet array 22.

A high-speed electron beam 23 generated by an electron accelerator 21 is made to meander synchronously by a fluctuating magnetic field of a wiggler magnet array 22 to emit synchrotron radiation. This can be used to oscillate laser light 24 using the optical resonator of the total reflection mirror 25 and the output mirror 26. Laser light wavelength λ
8 is the energy γ of the incident electron beam, the strength of the wiggler magnetic field, and λ the pitch. , ao, and by changing the above parameters, the required laser light wavelength λ5 can be obtained.

Among these, the energy of the incident electron beam can be changed by controlling the voltage of the accelerator, and the strength of the wiggler's magnetic field can also be changed without changing the structure.

As described above, by using a free electron laser, different wavelengths that are required alternately to be sent to multiple or more separation cells can be transmitted without the need for long-term operations such as dye exchange, which is required when using a combination of a copper vapor laser and a dye laser. Can be sent.

Free electron lasers are shorter than dye lasers by 100 to 20
It is also possible to oscillate at a wavelength of 0 nm. Therefore, since there is enough energy to ionize many elements in a single wavelength, there is no need to overlap three or more laser beams as in the combination of a copper vapor laser and a dye laser, making it possible to configure a more efficient system. It is. On the other hand, in a free electron laser system, only one free electron laser set is required for the separation of many elements, so by consolidating separation cell devices, the system can be made relatively inexpensive.

(Example) Each example of the isotope separation system according to the present invention will be described with reference to the drawings.

FIG. 2 shows a first embodiment of the invention. In FIG. 2(a), a laser beam is oscillated by an electron accelerator 21 and a wiggler magnet array 22. In FIG. In a plant in which a cell (1) 27 for separating isotopes of nuclear fuel material uranium and a cell (II) 28 for separating isotopes of plutonium are installed, a reflecting mirror 29 is shown in FIG. 2(a). Laser light is introduced into the separation cell (1). In this case, the wavelength is measured by the wavelength meter 31 using a laser beam that is partially split by the split mirror 33. The energy of the electron beam is controlled by the voltage control panel 32 so that the wavelength of this laser light is matched to the resonant absorption wavelength for selectively ionizing 23&U of uranium. Next, as shown in FIG. 2(b), when plutonium isotopes are to be separated, the reflection mirror 29 is removed from the optical path of the laser beam so that the laser beam can be introduced into the separation cell (II). Also,
At this time, the wavelength of the laser light is plutonium isotope 239p
must match the resonant absorption wavelength of u.

FIG. 3 shows, as a second embodiment of the present invention, a system that integrates devices for separating specific substances and specific isotopes in nuclear fuel materials, nuclear fuel cladding materials, neutron absorbing materials, and nuclear fuel reprocessed products.

Uranium contains 0.7% isotope 23 to be used as light water reactor fuel.
The aim is to concentrate 5U by 3-5%.

Plutonium is used as fuel for fast reactors, but 2:39
Since PU has a large fission cross section and a long lifespan, the aim is to improve the performance of fuel by enriching it. The purpose of zirconium is to reduce the 912r isotope, which has a large neutron absorption cross section, from about 11% to several percent. In the case of gadolinium, the purpose is to enrich 157 cd to make it into a fuel that is unlikely to absorb neutrons even if combustion progresses. Sm is 1
This enrichment is beneficial because 498 m has a large capture cross section for thermal neutrons.

The undissolved residue produced in nuclear fuel reprocessing plants consists of ruthenium, rhodium, and palladium.

By extracting specific substances from this, it becomes possible to utilize them beneficially. The laser wavelengths with the energy required to ionize the above elements are 200nL of uranium, 214nm of plutonium, and 187nm of zirconium.

Gadolinium 202 nm, Ruthenium 168 rv+. The required wavelength band is approximately 170 to 220 nm.
This is within the range that can be sufficiently controlled with one free electron laser. In the case of FIG. 3, six separation cell devices are prepared, and a laser beam is guided to the cell where the Gd isotope is separated by a reflecting mirror 29d.

FIG. 4 shows the state of wavelength switching when the isotope separation system shown in FIG. 3 is operated. That is,
Figure 4 shows wavelength on the vertical axis and time on the horizontal axis, showing the process of separating isotopes such as plutonium, gadolinium, and zirconium by changing the wavelength during uranium isotope separation. The operation will focus on isotope separation of uranium, which is in high demand, and separation of other elements will be carried out by switching wavelengths according to a predetermined plan. Maintenance time for uranium separation cells can be effectively utilized.

FIG. 5 shows a conceptual diagram of the arrangement of the isotope separation system of the present invention. Each separation cell also handles highly radioactive materials such as plutonium and nuclear fuel products.
They are separated by barriers.

That is, in FIG. 5, an electron accelerator, a wiggler magnet array 22, a beam deflector 34, a total reflection mirror 25, an output mirror 26, and a voltage control panel 32 are arranged inside the first partition 35, and inside the second partition 36. Reflection mirror 29a.

29b, 29c, and 29d, and the third partition wall 37
Separation cells 27a, 27b, 27c, and 27d are arranged within.

Here, separation cell 27a is for uranium isotope, 27b is for plutonium isotope, 27c is for zirconium isotope,
27d is for nuclear fuel reprocessing products.

Free electron lasers are used in these separation cells 27a to 27d, and the respective substances are separated by switching the optical system.

〔Effect of the invention〕

According to the present invention, specific substances or isotopes are collected in each separation cell of nuclear fuel cladding, neutron absorbing material, and nuclear fuel reprocessing products by using a free electron laser and appropriately controlling its wavelength. can be efficiently separated.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram of a free electron laser for explaining the present invention in detail, and FIGS. 2(a) and 2(b) each show an apparatus for separating two elements according to the present invention. 3 is a block diagram showing an example of a multi-purpose plant, FIG. 4 is a graph showing the operation pattern of FIG. 3, and FIG. 5 is a diagram showing the equipment arrangement of the system according to the present invention. 6 is a configuration diagram showing a conventional separation system using a combination of a copper vapor laser and a dye laser. FIG. 7 is a schematic cross-sectional view showing the inside of the separation cell in FIG. 6. FIG. 7 is a sectional view taken along the line II in FIG. 7; 21...Electron accelerator 22...Wiggler magnet array 23...Electron beam 24...Laser beam 27...Separation cell 29...Reflection mirror 31...Wavemeter 32...Voltage control board ( 8733) Representative Patent Attorney Yoshiaki Inomata (1 idiot) 30 shaku-C Goji

Claims (1)

[Claims] a free electron laser, a plurality of separation cells that separate specific substances or specific isotopes of nuclear fuel materials, nuclear fuel coating materials, neutron absorption materials, and nuclear fuel reprocessing products using laser light from the free electron laser, and the laser light an isotope separation system comprising a lens system for distributing the isotope to predetermined ones of the separation cells.