RU2453620C1 - Procedure for processing uranium hexafluoride and device of implementing same - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: procedure for processing uranium hexafluoride involves supply of the main stream of gaseous uranium hexafluoride into uranium-fluorine plasma generator, supply of an additional flow of gaseous uranium hexafluoride into an additional circuit to the uranium-fluorine plasma generator, forming of a cluster of uranium-fluorine plasma out of the primary and secondary streams of uranium hexafluoride at the entrance to the uranium-fluorine plasma generator. Then uranium-fluorine plasma flow is formed in the separation chamber of the magnetic separator, removal of the neutral atomic fluorine from the uranium-fluorine plasma flow, condensation of uranium, collecting of molten metallic uranium, formation of a bar of metallic uranium and output of the formed uranium bar. The precession of a cluster of uranium-fluorine plasma is performed along a conical surface in the skin layer by means of magnetic and/or gas-dynamic scanning of additional flow of uranium hexafluoride. A device for implementation of the said procedure is also suggested.

EFFECT: increased stability of the radio frequency discharge by improving the communication of radio frequency generator with the load - the flow of uranium-fluorine plasma of uranium hexafluoride.

7 cl, 3 dwg

Description

The invention relates to the processing technology of uranium hexafluoride - one of the key products of the nuclear fuel cycle. The use of the invention is most preferred for the recovery of uranium and fluorine from uranium hexafluoride dump in the isotope U-235.

A known method of processing uranium hexafluoride, (RF patent No. 2090510, publ. 09/20/97), including its interaction with water vapor at high temperature and the subsequent separation of solid and gas phases, while the interaction of uranium hexafluoride with water vapor is carried out in a water vapor plasma for the discharge zone, water vapor is taken in excess not exceeding 5% with respect to the stoichiometric amount, the specific energy consumption is at least 0.5 kWh / kg of uranium hexafluoride at a treatment time of at least 4.1 · 10 ^-3 s and after separation phases gas the base is condensed and anhydrous hydrogen fluoride and an azeotrope hydrogen fluoride water are isolated by rectification, and an azeotrope hydrogen fluoride water is used to create a 5% excess water vapor.

The technology is based on the conversion of dump UF ₆ in water vapor plasma (H-OH plasma) at a stoichiometric or close ratio of UF ₆ and (H-OH) plasma.

Technical results achieved:

- productivity - 0.14-0.15 t UF ₆ / h;

- the power of the plasma reactor is 0.26 MW;

- molar ratio (H-OH) / UF ₆ = 3-4;

- the concentration of HF in the gas stream before entering the condenser is up to 88.5%;

- the concentration of HF in the gas stream after the condenser is up to 95.4%;

- fluorine yield in the target products (anhydrous HF and hydrofluoric acid) - 96-98%;

- fluorine content in uranium oxides up to 2%;

- average energy consumption - 1.7-1.9 kWh / kg UF ₆ .

To date, some disadvantages of this technology have been identified:

- incomplete extraction of fluorine in anhydrous hydrogen fluoride (~ 90%);

- uranium oxides - an acceptable but inconvenient form of storage and especially disposal of actual dump uranium; in addition, the optimization of the process from the point of view of maximum fluorine extraction leads to a deterioration in the physicochemical properties of uranium oxides, which impede any use in the nuclear fuel cycle.

Known plasma-hydrogen concept of processing dump uranium hexafluoride, in accordance with which the processing products are anhydrous hydrogen fluoride and molten metal uranium; the latter is much more consistent with the needs of disposal and storage - RF patent N 2120489 from 06.24.97. BI No. 29 dated 10/20/98. The process is based on hydrogen reduction of uranium hexafluoride at high temperatures, is carried out in one technological apparatus and consists of four series-parallel stages. The first stage is the reduction of uranium from uranium hexafluoride to elemental uranium or to lower uranium fluorides. This intermediate goal is achieved by exciting an electric discharge in a stream of a mixture of gaseous uranium hexafluoride with hydrogen; the UF ₆ + H ₂ mixture is converted into a uranium-hydrogen fluoride plasma containing a mixture of uranium, hydrogen and fluorine atoms, fluoride molecules of uranium, fluorine, hydrogen, positively and negatively charged ions and electrons. If during this operation the plasma temperature is 6000 K at atmospheric or close to it, the bulk of the uranium is contained in the form of U atoms, i.e. in the gas phase there is a complete reduction of uranium.

At the second stage, the products of reduction of uranium hexafluoride are transferred to the condensed phase, in which the recombination processes are slowed down, and the process of reduction of uranium continues until liquid uranium is obtained. For this, the uranium-hydrogen fluoride plasma obtained in the first stage is sent to a molten bath of uranium tetrafluoride, which is obtained as follows. The uranium tetrafluoride charge is placed in a cooled cylindrical shell, transparent to the frequency electromagnetic field, resistant to the corrosive action of the uranium fluoride melt. The specified shell is inserted into the inductor of the frequency generator coaxially with the discharge chamber, in which receive (UFH) -plasma. The plasma stream interacts with the loading surface of uranium tetrafluoride and melts the upper layer of the latter. A frequency voltage is applied to the inductor; The melt zone of uranium tetrafluoride interacts with the frequency field, which is why the entire load is quickly heated by direct induction heating and melts. On the surface of the UF ₄ melt, when interacting with (UHF) - plasma, condensation of uranium and lower uranium fluorides occurs; at the same time, the disproportionation of the latter occurs in accordance with the equations:

As reactions (1-3) proceed in the condensed phase, intense mass transfer occurs due to the ratios of the melting temperatures and densities of the resulting products. The melting point of uranium is 1133 ° C, density is 19.04 g / cm ³ ; the melting point of uranium tetrafluoride is 1036 ° C, the density is 6.43-6.95 g / cm ³ ; the melting point of uranium trifluoride is 1427 ° C, the density is 8.95 g / cm ³ . Uranium tetrafluoride melts first, then uranium, and uranium trifluoride last. Due to the large difference in the density of uranium and uranium fluorides, uranium precipitates and uranium fluorides float to the surface layer exposed to hydrogen plasma, and uranium tetrafluoride will float in the melt of uranium trifluoride.

Thus, within a few minutes, under the influence of plasma flow and direct frequency heating, complete recovery of uranium from uranium hexafluoride and initial loading of uranium tetrafluoride takes place. The loss of the latter is continuously filled with uranium fluorides from (U-F-H) -plasma. In this case, fluorine binds to gaseous hydrogen fluoride, which evaporates from the uranium reduction zone. To increase the stability of the radio-frequency discharge, the connection of the radio-frequency generator with the load — the plasma stream — is improved by introducing an additional power source and adapter, which can be used as a waveguide, inductor, external electrodes, internal electrodes, etc.

The third stage, carried out simultaneously with the first two, is the removal of liquid uranium from the lower part of the shell reactor and pouring it into cooled molds.

The fourth stage, carried out simultaneously with the first three, is the removal and collection of the second marketable product, anhydrous hydrogen fluoride. The withdrawal of gaseous hydrogen fluoride is carried out through a filtration module, consisting of multilayer regenerated cermet elements that do not pass micron and submicron powders and aerosols and thereby ensure process safety from uncontrolled penetration of the pyrophoric product outside the technological zone.

Next, the stream of anhydrous hydrogen fluoride, purified from the dispersed phase, is condensed, collected in the form of a liquid in transport tanks and sent to the implementation or to recharge electrolysis baths to obtain elemental fluorine. A significant drawback of this process is the low reaction rates (1-3).

An alternative to this process is the method and device for processing uranium hexafluoride, as claimed in RF patent No. 2216390, publ. November 20, 2003, analogue application WO No. 97/34684. The flow of gaseous uranium hexafluoride UF ₆ is introduced into a microwave or radio frequency plasmatron equipped with an adapter to increase the stability of the discharge with increasing pressure, which requires increasing the coupling of the radio frequency generator with the load (inductor for the radio frequency induction plasmatron; waveguide for the microwave plasmatron), in which the feedstock converted to a uranium-fluorine plasma stream with a temperature of about 4000 K. When using a radio frequency induction discharge, the plasmatron is made water-cooled from longitudinal copper sections, separated by dielectric inserts, transparent to electromagnetic radiation from the inductor of the radio frequency generator. For simplicity, this plasmatron is called a metal-dielectric plasmatron. This name reveals the principle of its operation: the frame is made of non-magnetic metal, sealed dielectric inserts provide free penetration of the magnetic field inside the plasmatron.

When using a microwave discharge, the plasmatron is made in the form of a metal pipe made of non-magnetic metal, into which one or more waveguides coming from magnetrons of microwave generators are inserted at an angle of 90 °.

A stream of uranium-fluorine plasma enters the separation chamber, in which it is crimped by a magnetic field of approximately 0.1 Tesla generated by a magnet. To achieve a given degree of uranium ionization in an uranium-fluorine plasma stream, an electron cyclotron resonance antenna is installed outside the stream. This antenna gives the plasma electrons the extra energy they spend on ionizing uranium atoms, while the fluorine atoms remain neutral. This atomic fluorine is pumped out of the uranium-fluorine plasma stream by dry pumps, thus creating a fluorine stream. The flux of uranium ions is crimped with a magnetic field from another magnet, and a uranium beam appears downward.

The flow of uranium is directed to a bath of uranium melt in a graphite crucible, which, as it is filled, is removed and at the same time replaced by a rotary device with another crucible without breaking the vacuum.

The separation chamber was divided into three zones by partitions equipped with holes, and in the first zone pressure was maintained in the range of 10-50 Pa, in the second 5-20 Pa, in the third 2-10 Pa. Each of these zones is equipped with individual pumps for pumping fluorine.

The apparatus for converting a stream of uranium hexafluoride into streams of condensed uranium and fluorine gas included:

- a radio frequency or microwave generator of uranium-fluorine plasma and a stream of uranium ions;

- funds for the selective ionization of the uranium plasma component;

- Means for accelerating the flow of uranium-fluorine plasma to supersonic speeds;

- means for generating a magnetic field that compresses the charged component of the plasma (uranium ions);

- means for removing the uncharged component (fluorine) from the stream of uranium-fluorine plasma, compressed by a magnetic field;

- Means for removing molten uranium.

A stream of uranium-fluorine plasma was introduced from the plasma torch into the separation chamber through a nozzle, holes in the partitions corresponded to the diameters of the primary stream of uranium-fluorine plasma and the secondary stream of uranium ions. The diameter of the primary and secondary flows gradually increased along the axial coordinate of the process, so the diameters of the holes in the partitions were also increased so as not to create resistance to the downward flow of uranium material and to provide a pressure drop when moving along the axial coordinate of the apparatus.

In order to keep the flow of uranium ions in the center of the chamber, in each of the three compartments of the apparatus placed inductors powered by a separate power source, creating a magnetic field. The diameter of the nozzle at the exit of the plasma torch reaches 0.03 m; this is enough to maintain a pressure of about 2 kPa in the chamber and provide the necessary flow rate of uranium-fluorine plasma. This flow at the exit from the nozzle to the chamber expands and, in accordance with the Joule-Thomson effect, tends to self-cool. Therefore, the second purpose of the above-mentioned inductors is induction heating of the plasma stream, which compensates for the initial cooling and allows maintaining the temperature in the plasma stream at a level sufficient for uranium to be in the form of U ⁺ ions.

The flow of uranium ions is held in the center of the chamber by a magnetic field of approximately 0.1 Tesla. Thus, in the chamber, the components of the uranium-fluorine plasma are separated and two material streams are created: the atomic fluorine stream, which is sent for disposal, and the uranium ion stream, which is advanced in a magnetic field into a collector filled with uranium melt. The uranium stream is discharged from the chamber in the form of a melt, which is poured into molds. With a plant capacity of 17.75 kg UF ₆ / h, 12 kg U / h are obtained; this causes a fluorine flux of 5.7 kg / h.

The disadvantages of this solution are that the radio frequency discharge (frequency range 0.5-14 MHz) unstably burns in an electronegative gas such as uranium hexafluoride, UF ₆ or uranium-fluorine plasma at pressures of about 4 kPa and above. The lower the frequency of the radio-frequency generator, the lower the permitted pressure range in which the discharge burns steadily. At the same time, the power of high-frequency power sources increases with decreasing frequency. In addition, an electric discharge in gases such as UF ₆ is accompanied by strong self-cooling of the plasma due to the endothermic effects of the decomposition of UF ₆ and its fragments.

Due to these limitations, any technological and metallurgical devices equipped with high-frequency induction plasmatrons have restrictions on pressure, frequency, and service life.

To remove these restrictions, it is necessary to equip the plasma torch with an additional device that introduces additional power into the discharge from an autonomous power supply, with which you can lay a more reliable power channel for the plasma reactor.

A microwave discharge in uranium hexafluoride, UF ₆ (frequencies 900 and 2450 MHz) burns relatively stably even at a pressure close to atmospheric. However, the disadvantage of a microwave discharge is the relatively low temperature of the gas-discharge plasma (~ 5000 K at atmospheric pressure), which limits the ability to maintain a stationary regime in which uranium is completely ionized and fluorine is predominantly neutral.

The practical use of electron cyclotron resonance for ionization of uranium in a uranium-fluorine plasma is difficult, since the initial temperature of a uranium-fluorine plasma of 4000 K is low not only for ionization of uranium atoms, but also for complete dissociation of uranium fluorides. In addition, the use of antennas inside the device is too complicated design.

In connection with the foregoing, it is proposed to use a radio frequency discharge for processing uranium hexafluoride, and to increase the stability of the radio frequency discharge with increasing pressure, an additional circuit is installed with an auxiliary power source and an adapter, for example, as in patent No. RF N2120489. But this solution also does not fully ensure the stability of the radio-frequency discharge.

The technical result, which the invention is directed to, is to further increase the stability of the radio-frequency discharge by improving the coupling of the radio-frequency generator with the load - a stream of uranium-fluorine plasma, which leads to the expansion of the functional and technological capabilities of the claimed technical solution.

To achieve this result, a method for processing uranium hexafluoride is proposed, including supplying the main stream of gaseous uranium hexafluoride to a uranium-fluorine plasma generator, made in the form of an induction frequency plasmatron, supplying an additional stream of gaseous uranium hexafluoride to an additional circuit to the uranium-fluorine plasma generator, forming a uranium cluster -fluorine plasma from an additional stream of uranium hexafluoride at the inlet to the generator of uranium-fluorine plasma, the formation of a stream of uranium-fluorine plasma in the separation chamber of the magnetic separator, removal of neutral atomic fluorine from the uranium-fluorine plasma stream, condensation and collection of uranium melt in a cold crucible type device, the formation of an uranium metal ingot, while the uranium-fluorine plasma cluster is precessed over the conical surface into the skin layer by magnetic and / or gas-dynamic scanning of an additional stream of uranium hexafluoride.

In addition, magnetic scanning is carried out by applying a magnetic field. Gas-dynamic scanning is carried out by tangentially directed additional flow of uranium hexafluoride.

The skin layer is formed at the level of the high-voltage coil of the plasmatron inductor.

Also proposed is a device for processing uranium hexafluoride, consisting of a means for introducing the main stream of uranium hexafluoride connected to a generator of uranium-fluorine plasma, made in the form of an induction frequency plasmatron connected to a separation chamber of uranium-fluorine plasma, made in the form of a magnetic separator connected to fluorine pumping means, and in the lower part - with a means for collecting and conclusions of the uranium melt, while an additional circuit consisting of additional a relative power source, adapter, nozzle for introducing an additional stream of uranium hexafluoride and means for gas-dynamic and / or magnetic scanning of an additional stream of uranium hexafluoride.

Moreover, the means for magnetic scanning of the additional stream of uranium hexafluoride is made in the form of an annular solenoid.

Moreover, the means for gas-dynamic scanning of the additional stream of uranium hexafluoride is made in the form of nozzles for introducing uranium hexafluoride introduced tangentially to the side surface of the nozzle.

Figure 1 and 2 schematically shows an embodiment of a device for processing uranium hexafluoride.

The device consists of a separation chamber 1, made in the form of a magnetic separator and divided by partitions 2 into three zones I, II, III. In the partitions 2, holes 3 are made, forming flows of uranium-fluorine plasma. The inductors 4 of the magnetic separator are connected to a power source 5. Each zone of the separation chamber is connected by nozzles for pumping fluorine 6 to pumps (not shown in the figure). The generator of uranium-fluorine plasma 7 is made in the form of a frequency induction plasmatron, which is a pipe made of metal-dielectric material. The inductor 8 is connected to the main power source 9 - a radio frequency generator. The plasma torch 7 is connected to the separation chamber 1 by a nozzle 10. In the upper part of the plasma torch there is a nozzle 11 connected to an adapter 12 connected to an auxiliary power supply 13. The main flow UF _{6 is} fed through a pipe 14 to the plasma torch 7 through an opening in the nozzle 11. Additional flow UF _{6 is} fed through a pipe 15 to the adapter 12 through a nozzle 27 mounted on it made of non-magnetic material. For magnetic scanning of the indicated stream, an annular solenoid 28 is mounted on the adapter. At the bottom of the separation chamber 1 there is an outlet 16 for collecting the uranium metal melt in a cold crucible device 17. Cold crucible inductors 18 are connected to a power supply 19. A formed ingot uranium 20 is pulled using the device 21.

The magnetic field generated in the separation chamber 1 is conventionally shown by lines 22, the magnetic field keeps the plasma flow of uranium 23 in the center of the chamber 1.

Figure 2 shows in more detail the implementation of the upper part of the device.

In the upper part of the plasma torch 7, a cluster of uranium-fluorine plasma 24 is formed, while at the level of the first high-voltage turn of the inductor 8 a skin layer is formed with an external boundary 25, which extends at a distance of about half of the inner radius of the plasma generator 7. Next, a flow forms in the plasma torch uranium-fluoride plasma 26.

The figure 3 shows the location of the skin layer in cross section at the level of the high-voltage first turn of the inductor of the plasma torch 8.

In the description of the invention, when using the terms, the following is understood.

Cluster of uranium-fluorine plasma - a plasma stream formed from additional and main flows of uranium hexafluoride in the upper part of the plasma torch to the first coil of inductor 8.

A skin layer is a layer in which ~ 95% of the power absorbed by the conductive medium from the inductor is released due to the so-called skin effect.

The skin effect or surface effect is the attenuation of electromagnetic waves as they penetrate deep into the conductive medium (attenuation coefficient - α), as a result of which the alternating current is not distributed evenly over the conductor cross section, but mainly in the surface layer (skin layer). The higher the frequency of the electromagnetic field ω and the greater the magnetic permeability μ of the conductor, the stronger the vortex electric field in this layer created by the alternating magnetic field. The higher the conductivity of the conductor (σ), the greater the current density and power dissipated in this layer.

At a depth x = δ = 1 / α, the amplitude of the electromagnetic waves decreases e times. This depth is conventionally taken as the thickness of the skin layer (Physical Encyclopedic Dictionary, Moscow: Big Russian Encyclopedia, 1995).

Magnetic scanning - swirling the flow of uranium-fluorine plasma by applying a magnetic field using an annular solenoid 28.

Gas-dynamic scanning - swirling the flow of uranium-fluorine plasma due to the tangential introduction of an additional stream of uranium-fluorine plasma into the nozzle 27 of the additional circuit.

Precession - the movement of a cluster of uranium-fluorine plasma over the surface of a cone, the base of which is the skin layer.

This invention is based on the fact that the power of the RF generator 9 is allocated not over the entire cross section of the plasma torch tube 7, but in the skin layer, see Fig. 3. Therefore, the flow of uranium-fluorine plasma, formed in the form of a cluster 24 at the entrance to the plasmatron, should not be directed in the center, but in the skin layer, the outer radius of which is approximately half the radius of the plasma torch. Taking into account the presence of the skin layer means that the additional flow of uranium hexafluoride must be initially twisted so that the formed cluster performs motion, describing the conical surface at the base of which the skin layer lies, the so-called precession. This can be achieved by magnetic scanning of the flow by installing an annular solenoid 28 on an additional circuit. Also, an additional stream of uranium-fluorine plasma can be initially swirled by gas-dynamic scanning due to tangential entry into the nozzle 27. Magnetic and gas-dynamic scanning can be used together. When two streams of uranium hexafluoride are mixed, a cluster of uranium-fluorine plasma is formed 24. For each particular device, the necessary parameters must be calculated: flow rates, magnetic characteristics, etc. As a result of the address direction of the flow of uranium hexafluoride, the load – induction discharge stability increases.

The device operates as follows.

Both power supplies (radio-frequency generator 9 and auxiliary generator 13) turn on simultaneously, supply cooling to all the cooling elements of the installation: a metal-dielectric plasma torch 7, nozzles 11 and 27, etc. The feed pipelines UF _{6 are} heated to avoid condensation of the raw materials. Then, the supply of an additional UF ₆ stream to the nozzle 27 is turned on and an auxiliary (UF) plasma stream is generated through the adapter 12; this plasma stream is transported to a metal-dielectric plasma torch 7, where the main stream UF _{6 is} supplied, and the radio frequency voltage is supplied to the inductor 8 of the radio-frequency generator 9. The radio-frequency electromagnetic field freely penetrates the metal-dielectric plasma torch through the cuts. A radiofrequency induction discharge occurs in a metal-dielectric plasmatron, supported by an auxiliary (UF) plasma stream, which precesses around the center of the plasma torch along the skin layer ring and enhances the generator’s interaction with the load.

The implementation of the additional circuit may be different, for example:

- if the generator of radio frequency induction (U-F) -plasma 9 is used as the main power source, then an additional circuit can be performed with the redistribution of vibrational energy through two channels: a communication channel through a flare electrode and an induction channel;

- if a radio-frequency induction (U-F) -plasma generator 9 is used as the main power source, then an additional circuit can be performed using an electric arc plasma torch as an additional power source 13;

- if a radio frequency induction (UF) -plasma generator 9 is used as the main power source, then an additional circuit can be performed using a microwave plasma torch operating on UF ₆ as an additional power source 13.

Next, the flow of (U-F) -plasma is fed into the magnetic separator 1 for subsequent processing:

sequential passage of sections I, II, III, in which fluorine is removed through the holes, and at the end of the separation chamber, a stream of practically pure uranium plasma leaves through hole 16 and is collected in the form of a uranium metal melt in a device 17, known as a “cold crucible” / cm. I.N. Toumanov Plasma and High Frequency Processes for Obtaining and Processing Materials in the Nuclear Fuel Cycle. The 2nd Edition, reprocessed, supplemented. N.Y., Nova Science Publishers, 2008, 660 p.p./. The “cold crucible” is located inside the inductor of the frequency generator 18. The uranium melt in the “cold crucible” is created simultaneously with the start of the process of uranium reduction from uranium hexafluoride: for this, a certain amount of uranium is preliminarily placed in the “cold crucible” and melted, applying a frequency voltage of turns of an inductor 18 from a frequency power supply 19.

The uranium melt is squeezed out in the magnetic field of the “cold crucible” and practically does not come into contact with the water-cooled copper shaped tubes of the “cold crucible”. A device for drawing the uranium ingot 21 is mounted in the bottom of the “cold crucible”.

A relatively low frequency of 2400-2500 kHz is used to form a uranium melt. At this frequency, electromagnetic forces almost completely squeeze the uranium melt from the walls of the "cold crucible". As a result of this squeezing, a meniscus 29 is formed in the upper part of the melt, the feature of which is its damping of changes in the power introduced into the melt. Due to these phenomena, the walls of the “cold crucible” experience less stress and the quality of the uranium ingot drawn from the “cold crucible” increases. The purity of the elongated uranium ingot by chemical impurities is thus determined by the purity of uranium hexafluoride. The residual fluorine content in uranium is ~ 10 ^-4 % by weight.

As an example of the invention, consider a circuit where the additional circuit consisted of an auxiliary power source 13 — a microwave generator connected by waveguides to a plasma torch 7.

A quadrangular waveguide was used to transfer electromagnetic energy from a microwave generator, which is joined at right angles to a circular waveguide, into which an additional stream of gaseous UF ₆ is supplied. In the place of docking is a mode converter - a transformer of an electromagnetic wave H ₀₁ into a wave H ₁₁ . A circular waveguide is at the same time a microwave plasmatron operating on an additional gaseous stream UF ₆ supplied through pipeline 15. A dielectric insert (seal-decoupling) made of alumina separates the microwave generator and the microwave plasmatron.

The installed power of the radio-frequency generator is 9-100 kW, the oscillatory power is 25-60 kW, the frequency is 5.25 MHz. The temperature of the water cooling the metal-dielectric discharge chamber, the flange, and the supply pipelines was 73 ° C. The input of the main flow of UF ₆ was 9.2-17.6 kg / h.

The power of the microwave generator (UF) -plasma is ~ 5 kW, the frequency is 2.45 GHz. The standard quadrangular waveguide had a cross section of 90 × 45 mm; Such a waveguide is convenient for switching to a circular waveguide, which, in turn, is a transport pipeline (UF) -plasma for connecting with a metal-dielectric tube of a plasma torch. The flow rate of UF ₆ in a circular waveguide is maintained in the range 1.2-2.3 kg / h. Forced precession of the auxiliary plasma flow along the ring of the skin layer was carried out using magnetic scanning. For this, an annular solenoid was mounted on a round waveguide.

The pressure in the metal-dielectric tube of the plasma torch was 41-83.8 kPa. Lowering the frequency from 5.25 MHz to 1.76 MHz is not accompanied by a decrease in discharge stability in UF ₆ .

Calculations showed that with a productivity of 76 kg UF ₆ / h, 51.4 kg U / h are obtained; this causes a fluorine flux of 24.6 kg / h: at this capacity ~ 17.1 kg of fluorine / h is pumped out of zone (I), ~ 5.97 kg of fluorine / h is pumped out of zone (II), ~ 1.53 kg of fluorine / h is pumped out of zone (III) )

Thus, the following occurs.

1. The stability of the radio-frequency induction discharge in uranium hexafluoride (and in other strongly electronegative gases) increases to pressures of at least ~ 10 ² kPa.

2. It is possible to use more powerful frequency generators of a lower frequency (0.3-0.44 MHz, etc.) to obtain flows of (U-F) plasma.

3. When an additional address power flow is introduced into the metal-dielectric plasmatron of an additional frequency power flow, it is possible to change the quantitative ratio of the primary and secondary (U-F) plasma flows over a wide range: from the power level required for simple ignition of the discharge and stabilization to flows comparable in magnitude.

Claims (7)

1. A method of processing uranium hexafluoride, comprising supplying a main stream of gaseous uranium hexafluoride gas to a uranium-fluorine plasma generator in the form of an induction frequency plasmatron, supplying an additional stream of gaseous uranium hexafluoride to an additional circuit to a uranium-fluoride plasma generator, forming a cluster of uranium-fluorine plasma from the main and additional flows of uranium hexafluoride at the inlet to the generator of uranium-fluorine plasma, the formation of a stream of uranium-fluorine plasma in the separation chamber of a magnetic separator a, removal of neutral atomic fluorine from the uranium-fluorine plasma stream, condensation of uranium, collection of a metal uranium melt, formation of a metal uranium ingot and withdrawal of a formed uranium ingot, while the uranium-fluorine plasma cluster is precessed over the conical surface in the skin layer by magnetic and / or gas-dynamic scanning of an additional stream of uranium hexafluoride. 2. The method according to claim 1, characterized in that the magnetic scan is carried out by applying a magnetic field. 3. The method according to claim 1, characterized in that the gas-dynamic scanning is carried out by means of a tanzentically directed additional flow of uranium hexafluoride. 4. The method according to claim 1, characterized in that the skin layer is formed at the level of the high-voltage coil of the plasma torch inductor. 5. A device for processing uranium hexafluoride, consisting of a means for supplying a main stream of uranium hexafluoride connected to a generator of uranium-fluorine plasma, made in the form of an induction frequency plasmatron connected to a separation chamber of uranium-fluorine plasma, made in the form of a magnetic separator connected to fluorine evacuation means, and in the lower part - with a “cold crucible” means for condensation, collecting molten metal uranium, forming an ingot of metallic uranium and withdrawing the formed a uranium ingot, with an additional circuit connected to the upper part of the plasma generator, consisting of an additional power source, an adapter, a nozzle, means for introducing an additional stream of uranium hexafluoride to form from it together with the main stream of uranium hexafluoride at the input to the generator of the uranium-fluoride plasma cluster and means for gasdynamic and / or magnetic scanning of the additional stream of uranium hexafluoride. 6. The device according to claim 5, characterized in that the means for magnetic scanning of the additional stream of uranium hexafluoride is made in the form of an annular solenoid. 7. The device according to claim 5, characterized in that the means for gas-dynamic scanning of the additional stream of uranium hexafluoride is made in the form of uranium hexafluoride inlet nozzles introduced tangentially to the side surface of the nozzle.

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