RU2472862C1 - Processing method of metal radioactive waste - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: melting of metal radioactive waste (MRW) is performed in oxidising atmosphere with oxygen content of 8-10% in liquid oxidised metal bath at content of oxygen in metal of 0.020-0.035%. At that, in order to extract radionuclides from metals and to reliably fix them in slag, oxidised slag of low basicity is used, accumulated deactivated metal is drained from melting chamber, thus leaving 20-30% of all-weld deactivated metal in the chamber. Before the metal is drained, loading of MRW to the melting chamber is stopped for 5-12 minutes and the flow of supplied fuel and oxygen to fuel-oxygen burners is reduced by 2-3 times. Amount of drain metal and drain rate is controlled. After 70-80 % of metal is drained, MRW loading to the melting chamber is renewed and flow of supplied fuel and oxygen to fuel-and-oxygen burners is increased to initial level.

EFFECT: invention allows efficient MRW processing and provides the reduction of evaporation from MRW surface of volatile radionuclides during melting process; reduction of fouling of refractory lining with radioactive slag when metal is being drained from the chamber; excluding the possibility of formation of dioxins during MRW processing.

8 cl, 2 dwg, 1 ex

Description

The invention relates to metallurgy and to the field of waste processing of steels and alloys contaminated with radionuclides.

Decommissioning and dismantling of equipment of nuclear industry enterprises, nuclear reactors and other plants using fissile materials leads to the formation and accumulation of a large amount of metal waste contaminated with radionuclides, called: metal radioactive waste (MPO). As a result, a significant amount of high alloy metal is withdrawn from the economic turnover and significant areas have to be occupied for special storage facilities for MPO. Currently, only in Russia more than a million tons of MPO are stored. In this regard, the development and application of effective methods for decontamination of MPO are very relevant.

Known methods of processing and pyrometallurgical decontamination of MPO, providing for the melting of MPO and the conversion of most of the radionuclides into slag [1-10]. Such methods make it possible to reduce the level of metal contamination to the extent that it is possible to return to economic circulation.

Two types of radioactive contamination are possible in MPO: surface contamination due to contact with a radionuclide-containing, usually liquid, substance and sorption of radionuclides on a metal surface and contamination due to neutron irradiation, causing the formation of radioactive isotopes of metal components directly in the metal volume.

Known methods of processing and decontamination, providing for the melting of MPO in small electric furnaces under a layer of basic deoxidized slag with a low (less than 1% iron oxide content) [1-9]. Such slag, after being used as a medium for fixing radionuclides that passed into it from MPO during the melting process, is very inconvenient for subsequent disposal, since it has low strength and crumbles into small particles after some time. When exposed to moisture, radionuclides can be washed out of such particles.

To obtain a metal suitable for use without restrictions, it is necessary to ensure complete separation of the particles of radioactive slag from the deactivated metal during the discharge of metal from the smelter and subsequent casting to ingots. This can be achieved easier and more reliably by separate discharge of pure metal and “dirty” radioactive slag from the smelter.

However, most of the known methods of pyrometallurgical decontamination of MPO and the units used for their implementation do not provide this possibility [1-9]. It is necessary to carry out their preliminary surface decontamination by low-temperature methods (hydraulic, mechanical, chemical) before the MPO is melted, which complicates and increases the cost of obtaining a pure deactivated metal. Due to the impossibility of the separate release of pure metal and “dirty” radioactive slag, small electric furnaces (arc, induction, electroslag remelting) are used to decontaminate the MPO and cut the MPO into pieces of small size and mass. Such melting units have low productivity, which further complicates and increases the cost of decontamination of MPO [9].

A known method of processing metallurgical radioactive waste and a unit for its implementation, including loading the waste into the melting chamber, melting it, converting the radioactive nuclides to slag and fixing them in slag, separate release of pure deactivated metal and radioactive slag from the melting chamber, selected as the closest analogue (patent RU 2345141) [10].

A known method of processing metallurgical radioactive waste involves the continuous melting of the charged MPO in a liquid metal bath of the melting chamber, the casing of which is cooled by a liquid metal coolant, and heating the melting chamber with fuel-oxygen burners with a supersonic oxygen outflow rate. The specific thermal power of the burners is 1.5-2.0 MW per ton of fused waste with an excess of oxygen 5-7% of the calculated one. The burners are located in the side and end walls of the melting chamber at a height of 0.8-1.4 m from the melt level at an angle of 35-55 ° C to the surface of the melt. MPO before loading into the working space of the melting chamber is heated by the gases leaving the melting chamber to 700-800 ° C in an airtight shaft heater installed above the hole in the upper part of the casing of the melting chamber.

Heated waste is loaded into the melting chamber in batches, the mass of which is 7-8.5% of the mass of liquid metal in the chamber, with a maximum mass of one piece of 7% of the mass of liquid metal in the chamber. The waste is melted under a layer of acidic slag with a temperature of 1600-1650 ° C, the mass of which is 2-5% of the mass of the liquid metal in the unit, the flux additives support flux additives in the range,%: 28-45 SiO ₂ ; 20-35 ∑ (FeO + Fe ₂ O ₃ ); 2-8 CaO; 3-10 Al ₂ O ₃ ; 5-12 MgO.

Deactivated metal with a temperature of 1500-1580 ° C is discharged from the melting unit through a groove located at a height of 100-200 mm from the level of the refractory hearth and equipped with a heated siphon groove for better separation of the deactivated metal from radioactive slag.

Slag contaminated with radionuclides is periodically drained from the unit through a tap hole located on the opposite side of the unit, located at an altitude of 50-100 mm from the slag-metal interface, directly into the waste disposal containers. The dust trapped in the gas treatment of the smelter is blown into the molten slag in an oxygen stream by injectors.

In addition, the release of pure deactivated metal from the smelting unit is carried out periodically in accordance with the performance of a device that measures the level of liquid metal in the melting chamber.

A known method of processing metal radioactive waste has the disadvantages of:

- the complexity of monitoring and regulating the decontamination process, since, firstly, specific limits for the oxygen content in the oxidizing atmosphere of the melting chamber and the oxygen content in the metal during the melting and decontamination of MPO are not proposed, and secondly, there is no data on the thickness of the slag layer in the melting a chamber above the recyclable metal necessary for high-quality and effective decontamination;

- the difficulty of separating particles of "dirty" radioactive slag from pure deactivated metal, since the slag of the proposed composition has high adhesion to the metal due to the high content of iron oxides;

- insufficient efficiency of the MPO decontamination process due to the fact that, firstly, measures to remove entangled particles of “dirty” radioactive slag from the deactivated metal before draining the metal from the melting chamber are not provided, and secondly, measures to reduce contamination of the refractory lining of the metal bath of the melting chamber during the discharge of deactivated metal from the chamber;

- the complexity of the process of decontamination of MPO, since loading MPO into the melting chamber from above through an opening in the upper part of the casing of the melting chamber can cause increased spraying of metal and slag and lead to a significant increase in the number of particles of radioactive slag emulsified into metal;

- the formation of dioxins during processing of MPO contaminated with inclusions of plastics, varnishes and other substances containing chlorine and fluorine compounds is not excluded;

- there is an increased release of some radionuclides from the surface of the heated MPO due to the heating of the MPO in the shaft heater to a high temperature of 700-800 ° C.

The objective of the proposed method for processing metal radioactive waste is the implementation of a high-performance effective process for the decontamination of MPO at high technical and economic indicators.

The technical result of the proposed method for processing metal radioactive waste is to eliminate the shortcomings of the closest analogue, namely:

- conducting processes of melting and deactivation of MPO under oxidizing conditions with control of a given level of atmospheric oxidation of the working space of the melting chamber and the oxidation of liquid metal;

- the use for the extraction of radionuclides and their reliable fixation of oxidized slag of low basicity, having low adhesion to the metal, easily separated from it, but having in the solid state high strength and the ability to maintain strength when exposed to moisture and other adverse factors in the event of burial;

- ensuring the removal of entangled particles of "dirty" radioactive slag from deactivated metal before the release of metal from the melting chamber;

- reduction of evaporation from the surface of the LRA of volatile volatile radionuclides in the process of melting waste in a liquid metal bath;

- reduction of contamination of the refractory lining of the metal bath of the melting chamber with the falling "dirty" radioactive slag during the discharge of metal from the chamber;

- elimination of the possibility of the formation of dioxins during heating of MPO contaminated with inclusions of plastics and other substances containing chlorine and fluorine compounds in the heater and during melting of MPO in the melting chamber.

The technical result is ensured by the fact that in the method of processing metal radioactive waste, including loading into the melting chamber to start the process of low-melting metal waste, depositing liquid metal to fill half the maximum volume of the metal bath when operating at reduced power of fuel-oxygen burners, adding fluxes, loading of metal radioactive waste , their melting, transfer of radioactive nuclides to slag and their fixation in slag, separate release of deactivated metal and radioactive slag from the smelting chamber, according to the invention, the loading of waste is melted in an oxidizing atmosphere with an oxygen content of 8-10%, obtained by increasing the excess oxygen in fuel-oxygen burners, in a liquid oxidized metal bath with an oxygen content in the metal of 0.020-0.035%, for extraction of radionuclides from metal and their reliable fixation, oxidized slag of low basicity is used, which is obtained due to the partial oxidation of the components of the loaded metal radioactive waste c and an additional additive of fluxes in the amount of 1-1.5% of the mass of the processed metal radioactive waste, draining the accumulated clean deactivated metal from the smelting chamber, 20-30% of the deposited deactivated metal is left in the chamber, before loading the metal, loading is stopped for 5-12 minutes metal radioactive waste into the melting chamber and reduce by 2-3 times the thermal power introduced into the chamber by fuel-oxygen burners, regulate the amount of metal to be drained and the rate of discharge, after draining 70-80% of the metal ozobnovlyayut loading radioactive metal waste in the melting chamber and is increased to the original level of the fuel supply and oxygen-fuel burner thermal power inputted them.

Oxidized liquid slag of low basicity contains,%:

SiO ₂ 46-57 CaO 9-12 ∑ (FeO + Fe ₂ O ₃ ) 5-18 Al ₂ O ₃ 11-13 MgO 1-4 MnO 4-10

As fluxes, metallurgical slag, ash from thermal power plants, worn refractories of the lining of steel pouring ladles are used.

The amount of metal to be drained and the rate of metal discharge are controlled by a slide device.

The metal radioactive waste loaded into the melting chamber is preheated to a temperature of 600-650 ° C by the physical and chemical heat of the gases leaving the chamber in a special heater located to the side of the melting chamber, and loaded into the chamber through a side loading hole.

The temperature of the gases leaving the heater is maintained at a level of 800-900 ° C.

The thickness of the slag layer in the melting chamber during the decontamination of waste is maintained within 120-250 mm.

Before draining the pure deactivated metal from the melting chamber, 50-80% of the accumulated radioactive slag is poured through a slag notch located above the maximum level of liquid metal in the chamber.

The melting of the loaded waste in an oxidizing atmosphere with an oxygen content of 8-10%, obtained by increasing the excess oxygen to the calculated one in fuel-oxygen burners, in a liquid oxidized metal bath with an oxygen content in the metal of 0.020-0.035% provides the necessary oxidizing potential, which makes it possible to easily oxidize such radionuclides located in the metal, such as ⁵⁴ Mn, ⁵¹ Cr, ⁵⁵ Fe, ⁵⁹ Fe and others, and convert the oxides of these nuclides into slag. With less than 8% oxygen content in the atmosphere of the working space, and less than 0.020% oxygen content in the metal, metal radionuclides will be oxidized slowly and in small quantities. At a greater than 10% oxygen content in the atmosphere and less than 0.035% oxygen in the metal, the content of iron oxides in the slag above the metal melt increases noticeably, the adhesion of slag to the metal increases, and it becomes difficult to separate the particles of "dirty" slag from pure deactivated metal, and the amount of secondary solid radioactive waste in need of disposal is increasing.

The proposed oxidized slag of low basicity, containing,%: 46-57 SiO ₂ ; 9-12 CaO; 5-18 ∑ (FeO + Fe ₂ O ₃ ); 11-13 Al ₂ O ₃ ; 1-4 MgO, 4-10 MnO, has low adhesion to metal, extracts well from metal and assimilates radionuclide oxides, has high strength and the ability to resist the aggressive effects of moisture, acid and alkaline solutions. Such slag provides reliable fixation of radionuclides during long-term storage.

At a less than 5% iron oxide content, such slag does not have the necessary oxidizing ability with respect to liquid metal and does not make it possible to quickly and completely oxidize the radionuclides of the elements that make up the metal.

When the content of iron oxides in the slag is more than 18%, the adhesion of the slag to the metal increases and it becomes difficult to separate the particles of radioactive slag from a pure deactivated metal.

The content of SiO ₂ 46-57% provides slag in the solid state the necessary strength and ability to resist moisture, alkaline and acid solutions during long-term storage. The remaining components of the slag are necessary to reduce the melting temperature and increase the fluidity of the slag in the melting chamber and during discharge from the chamber.

Obtaining slag due to the partial oxidation of the components of the loaded metal radioactive waste (Fe, Mn, Si, Al) and the addition of a small amount of fluxes 1-1.5% of the mass of the processed metal radioactive waste, which are used as metallurgical slag, ash from thermal power plants, worn out refractories of the lining of steel pouring ladles, allows to accelerate the formation of slag in the melting chamber, due to this, to reduce the volatilization of volatile radionuclides from the surface of the melting waste and to reduce the amount of secondary solid radioactive waste (“dirty” slag) that need to be disposed of.

Leaving 20–30% of the metal in the chamber after draining the deactivated metal from the smelting chamber allows accelerating the melting of metal radioactive waste loaded after the end of the release, reducing the release of volatile radionuclides from the waste surface during the smelting process, and reducing the contamination of the refractory lining of the metal bath during the discharge by dropping radioactive slag. Leaving less than 20% of metal in the chamber will not significantly accelerate the melting of the waste and reduce the release of radionuclides from the surface of the melting waste. Leaving in the chamber more than 30% of the metal after the end of the release will lead to a decrease in the process productivity.

Stopping the loading of metal radioactive waste into the melting chamber for 5-12 minutes before draining and reducing the thermal power introduced into the chamber by fuel-oxygen burners at the same time allows particles of "dirty" radioactive slag to float from pure deactivated metal and obtain cleaner bars of deactivated metal. Stopping the loading of waste and supplying fuel and oxygen for a period of less than 5 minutes does not give the desired effect. Stopping the loading of waste and supplying fuel and oxygen for a period of more than 12 minutes does not significantly increase the amount of floating particles of radioactive slag, but leads to a decrease in the performance of the melting unit.

The regulation of the drain rate and the amount of metal to be drained by a vane device allows you to speed up and facilitate the casting of metal that is drained directly into the molds mounted on a cart conveyor.

The resumption after loading the necessary amount of metal, the loading of metal radioactive waste and the increase in the initial supply of fuel and oxygen to fuel and oxygen burners allows you to quickly switch to the standard mode of operation of the melting chamber.

Preheating the metal radioactive waste loaded into the melting chamber to a temperature of 600-650 ° C with the physical and chemical heat of the gases leaving the chamber in a heater located on the side of the melting chamber, and loading the heated waste into the chamber through the side loading device can increase the overall thermal efficiency the unit, to increase the unit’s productivity, to reduce the volatility of volatile radionuclides from the surface of the waste pieces, to facilitate the maintenance of the melting unit, radioactive minimal splashing of the slag in the melting chamber and to reduce the amount of slag particles into the metal emulsifiable boot waste.

When heating metal radioactive waste to temperatures below 600 ° C, the productivity of the melting unit decreases, when heating waste to temperatures above 650 ° C, the release of volatile radionuclides from the surface of the pieces of the charge increases.

Maintaining the temperature of the gases leaving the heater at the level of 800-900 ° C eliminates the possibility of the formation of dioxins during heating of metal radioactive waste contaminated with inclusions of plastics and other substances containing chlorine and fluorine compounds. When the temperature of the exhaust gases is less than 800 ° C, the possibility of the formation of dioxins is not completely ruled out [11], and when the temperature of the exhaust gases is more than 900 ° C, the heat losses of the smelting unit noticeably increase.

The thickness of the slag layer in the melting chamber during the decontamination of waste within 120-250 mm provides the necessary extraction of radionuclides from the metal and their reliable fixation in the slag, as well as reducing the amount of volatile radionuclides from the surface of the melting pieces of metal.

Less than 120 mm thickness of the slag layer does not provide the necessary extraction of radionuclides from metal and reduce the fly of volatile radionuclides.

With a slag layer thickness of more than 250 mm, the conditions of heat transfer from the torches of the burners to the melting metal deteriorate and the amount of secondary solid radioactive waste that needs to be disposed of increases.

Draining from the melting chamber before draining pure deactivated metal 50-80% of the accumulated “dirty” radioactive slag through a slag notch located above the maximum level of liquid metal in the chamber provides a lower level of contamination of the refractory lining of the metal bath with particles of the falling radioactive slag during metal discharge.

Draining less than 50% of the accumulated radioactive slag does not significantly reduce the contamination of the lining, draining more than 80% of the accumulated slag makes metal deactivation difficult and increases the release of volatile radionuclides after resuming the loading of waste into the melting chamber.

The essence of the claimed method is illustrated by drawings of the unit, designed to implement the proposed method for the decontamination of metal radioactive waste.

Figure 1 shows a section aa of the unit for implementing the inventive method of decontamination of metal radioactive waste.

Figure 2 shows a section bB of the unit for implementing the inventive method of decontamination of metal radioactive waste.

The method of decontamination of metal radioactive waste is as follows.

Relatively fusible metal waste is gradually loaded into the melting chamber 1 to start the process: steel and cast iron shavings, small steel trim and, working at a reduced power of fuel-oxygen burners 2, the amount of liquid metal 3 is deposited, which is necessary to fill half the maximum volume of the metal bath. Then a small amount of fluxes is added and the loading and penetration of metal radioactive waste 4, heated in the heater 5, begins through the side hole 6 (Fig. 2) in the wall of the housing of the melting chamber 1. At this time, the burners 2 operate at full power with an excess of oxygen, melting metal radioactive waste is conducted in an oxidizing atmosphere with an oxygen content of 8-10%, in a liquid oxidized metal bath with an oxygen content of 0.020-0.035% (oxygen content in the atmosphere of melting chamber 1 and in metal not monitored periodically). Above the metal bath is supported a layer of oxidized slag 7 of low basicity with a thickness of 120-250 mm, depending on the chemical composition of the metal waste (Fig.1-2). After filling the metal bath to a maximum level for 5-12 minutes, the loading of metal radioactive waste 4 into the chamber 1 stops and the supply of fuel and oxygen to burners 2 is reduced by 2–3 times. During this time, the particles of radioactive slag are separated from the pure metal and float into the layer slag 7 located above the metal 3. Before draining through the slag notch 9, metal 3 is poured from the melting chamber 1 into a container 8 of 50-80% of slag 7 located in the chamber 1. Then, metal 3 is drained through a metal notch 10 located on the other side of the pl villa chamber teeming ladle 11 or directly into the ingot mold mounted on a carriage (not shown). The drain rate and the amount of fused metal is regulated by a sliding device 12. The discharge of metal is stopped, leaving 20-30% of the deposited metal in the chamber. After draining the required amount of metal, the loading of metal radioactive waste 4 into the melting chamber 1 onto the remaining liquid metal 3 and slag 7 is resumed and the supply of fuel and oxygen to burners 2 and their power are increased to the initial level. Next, the metal decontamination cycle is repeated.

An example confirming the possibility of introducing the proposed method into production.

1. A liquid metal bath with a mass of 0.5 tons was melted in 1.5 tons of an arc furnace with an acid lining and 30 kg of flux (acidic slag from nickel production) was loaded onto the entire surface. Then 1.5 tons of metal radioactive waste of 10Kh18N9 steel of low pollution with a specific gamma radiation power of d = 4 · 10 ^-5 nGy · m ² / (s · kg) was melted in a liquid bath. Melting was carried out with the flap of the working window ajar to maintain the oxidizing atmosphere in the furnace. After the scrap was completely melted and the metal was heated, an exposure time of 10 minutes was made with the furnace turned off to allow the particles of radioactive slag to surface from the metal. After that, the slag was poured into the container, and then the metal was poured into the ladle and into the molds. The control of the degree of radioactive contamination of the metal confirmed the possibility of using the obtained metal without restrictions (d = 0.38 · 10 ^-5 nGy · m ² / (s · kg).

2. The metal extract in the ladle before casting steel for 10-12 minutes is widely used in metallurgy to float slag particles and gives the desired effect [12].

3. The melting of metal in a liquid bath under a slag layer of sufficient thickness significantly reduces metal loss due to fly in smelting units of ferrous metallurgy [12, 13].

Literature

1. Patent SU 1831879 "Method for the disposal of waste from ferrous alloys contaminated with radionuclides, and installation for its implementation." Authors: Nester A.T .; Paranin A.A. Patent holder Nester A.T.

2. Patent RU 2159473 "Method for the processing of metal waste containing radionuclides." Authors: Lositsky AF; Hansa N.A .; Rozhdestvensky V.V .; Kasimov R.N .; Zaykov Yu.P.; Goncharov A.I .; Plekhanov K.A .; Soloboev I.S. Patent holder of Clean Technologies in Industry Plus LLC.

3. Patent RU 2066496 "Method for the decontamination of radioactive metal waste and composite slag-forming alloy for the decontamination of radioactive metal waste by melting." Authors: Simanovsky V.M .; Bochkarev V.A .; Dmitriev E.N .; Chernichenko A.A .; Kinerov L.V .; Rzhevtsev N.P. Patentee of JSC Innovation company "Panorama".

4. Patent RU 2249270 "Method for the decontamination of radioactive metal waste by electroslag remelting." Authors: Bondin VV .; Bychkov S.I .; Kravchenko G.A. Patentee: Mining and Chemical Combine. GHK.

5. Patent RU 2231843 "Method for the decontamination of radioactive metal waste." Authors: Petrov G.A .; Suvorov I.S .; Sobolev I.A .; Dmitriev S.A .; Timofeev E.M .; Mayboroda M.A. Patent holder: State Unitary Enterprise MosNPO Radon.

6. Patent RU 2234154 "Method for the processing of metal waste and a furnace for its implementation." Authors: Podoynitsyn S.V .; Bychkov S.I .; Kravchenko G.A .; Bakhvalov S.G .; Vasiliev M.G .; Lapshin B.M. Patentee: Mining and Chemical Combine.

7. Patent RU 2239248 "Method for the disposal of surface-contaminated radioactive elements of stainless steel structures." Authors: Gunger Yu.R .; Filippov G.A .; Yuzhaninov E.G .; Ivanov R.V. Patent holder: Gunger Yu.R .; Shapov R.V.

8. Patent RU 2249056 “Method for processing radioactive contaminated equipment and method for the production of steels and alloys using scrap metal radioactive waste”. Authors: Filippov G.A .; Ivanova T.P .; Ivanov R.V .; Yuzhaninov E.G. Patent holder: Yuzhaninov E.G .; Ivanov R.V.

9. M.A. Skachek. Spent nuclear fuel and radioactive waste management. M.: Publishing House MPEI, 2007, 448 p.

10. Patent RU 2345141. “Method for processing metal radioactive waste and an aggregate for its implementation”. Authors: Golubev A.A., Gudim Yu.A. Patentee of LLC PK Metal Technology.

11. Rayle V.T. Improving the thermal performance and design of the shaft heater of an electric arc furnace. The dissertation for the degree of candidate of technical sciences. Chelyabinsk. SUSU. 2010.

12. V.A. Kudrin. Theory and technology of steel production. M.: Mir, 2003, 526 p.

13. Yu.A. Gudim, I.Yu. Zinurov, A.D. Kiselev. Steel production in arc furnaces. Constructions, technologies, materials. Novosibirsk Publishing house of NSTU. 2010.554 s.

Claims (8)

1. A method of processing metal radioactive waste, including loading fusible metal waste into the melting chamber, surfacing the amount of liquid metal to fill half the maximum volume of the metal bath when operating at reduced power of fuel and oxygen burners, adding fluxes, loading of metal radioactive waste and increasing fuel and oxygen consumption in fuel-oxygen burners, their melting, transfer of radioactive nuclides to slag and their fixation in slag, separate discharge are deactivated metal and radioactive slag from the melting chamber, characterized in that the melting of the loaded waste is carried out in an oxidizing atmosphere with an oxygen content of 8-10% in a liquid oxidized metal bath with an oxygen content of 0.020-0.035% in the metal, while extracting radionuclides from the metal and their reliable fixation in the slag, low basicity oxidized slag is used, which is obtained due to the partial oxidation of the components of the loaded metal radioactive waste and the addition of fluxes in an amount of 1-1.5% by weight of the collected metal radioactive waste, the accumulated deactivated metal is drained from the melting chamber, 20-30% of the deposited deactivated metal is left in the chamber, before the metal is drained for 5-12 minutes, the loading of metal radioactive waste into the melting chamber is stopped and fuel consumption is reduced by 2–3 times and oxygen in fuel and oxygen burners, regulate the amount of metal to be drained and the rate of discharge, after draining 70-80% of the metal, the loading of metal radioactive waste into the melting chamber is resumed and increased Chiva to its original level and fuel consumption of oxygen in the oxy-fuel burners. 2. The method according to claim 1, characterized in that the oxidized liquid slag of low basicity contains,%:
SiO ₂ 46-57 Cao 9-12 ∑ (FeO + Fe ₂ O ₃ ) 5-18 Al ₂ O ₃ 11-13 MgO 1-4 MnO 4-10 3. The method according to claim 1, characterized in that their own worn refractories are used as fluxes. 4. The method according to claim 1, characterized in that the amount of metal to be drained and the rate of metal discharge are controlled by a sliding device. 5. The method according to claim 1, characterized in that the metal radioactive waste loaded into the melting chamber is preheated to a temperature of 600-650 ° C by the physical and chemical heat of the gases leaving the melting chamber in a heater located on the side of the melting chamber, and loaded into the chamber through the side loading hole. 6. The method according to claim 5, characterized in that the temperature of the gases leaving the heater is maintained at a level of 800-900 ° C. 7. The method according to claim 1, characterized in that the thickness of the slag layer in the melting chamber during the decontamination of waste is maintained within 120-250 mm 8. The method according to claim 1, characterized in that before draining the deactivated metal from the melting chamber, 50-80% of the accumulated radioactive slag is poured through a slag notch located above the maximum level of liquid metal in the melting chamber.

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