EP2797082B1

EP2797082B1 - Method for processing solid radioactive waste

Info

Publication number: EP2797082B1
Application number: EP12860442.8A
Authority: EP
Inventors: Anatolij Anatoljevich Golubev; Jurij Alexandrovich Gudim
Original assignee: Obchestvo S Ogranichennoj Otvetstvennostju Promishlennaja Kompanija "Tehnologija Metallov"
Current assignee: Obchestvo S Ogranichennoj Otvetstvennostju Promishlennaja Kompanija "Tehnologija Metallov"
Priority date: 2011-12-23
Filing date: 2012-12-17
Publication date: 2016-10-26
Anticipated expiration: 2032-12-17
Also published as: WO2013095197A1; RU2486616C1; EP2797082A1; EP2797082A4

Description

The present invention relates to the field of environment control and to the field of retreatment of solid waste contaminated with radionuclides.
In the course of the service, repairs and removal from service of nuclear power and other plants, solid radioactive waste (SRW) is formed and accumulated. Such waste comprises: filters, sorbents, ion-exchange resins, products of hardening liquid radioactive waste, elements of technological equipment, of biological shielding, pipe-lines, tools, building structures, working clothes, heat insulation, etc.
Today's practice of handling radioactive waste at the Russian nuclear power stations requires storing of solid radioactive waste as well as of products of hardening liquid waste at the industrial yards of nuclear power stations for the whole time of the station service, the time of extended service life of the power-generating units and the time needed for the removal from service (60 to 100 years) at particular radioactive waste storage sites. Thereupon, the waste is buried definitively. Considering the above mentioned, the processing of the waste requires to reduce to minimum the volume of nonmetallic waste and to deactivate, wherever possible, metallic radioactive waste for recycling it to economical turnover.
As to the method of processing, solid radioactive waste is subdivided into:

materials to be burnt (woody waste, cloth waste, papers);
materials to be compacted (metallic waste, plastic compounds);
materials to be deactivated or remelted (metallic waste), previously deactivated;
materials to be packed without processing (high-radioactivity waste) [1,2].

There is observed a rather wide practical use of methods for deactivating and melting metallic radioactive waste [2]. Pressing and burning up nonmetallic solid radioactive waste are used more seldom due to low productivity and efficiency of units used as well as to a relatively low increase in density of the waste after such a treatment.
A much greater increase in waste density and, consequently a considerable decrease in their volume are obtained while melting nonmetallic solid radioactive waste [1, 2]. To carry out such a reprocessing, various melting units were proposed, at the beginning, these represented small-capacity melting units used in metallurgy, using electric power as a heat source: induction crucible furnaces, electric arc furnaces, electroslag remelting furnaces, induction furnaces with a "cold" crucible [2]. The use of such units for retreating solid radioactive waste is limited by the common drawbacks of the known processes as follows:

all the units mentioned operate in batch processes (as separated fusions), and, as a result, they have a low output;
considerable evaporation and escape of nuclides while remelting;
it is difficult to provide a sufficient degree of sealing for such units and to prevent the possibility of outbursts of gases containing radionuclides into the production floor area;
it is difficult to provide for a reliable radiation protection of the furnace attending personnel;
a thorough cropping into small lumps of the waste to be remelted is required, which increases the cost of the waste retreatment and results in some additional irradiation of the personnel;
the retreatment of solid radioactive waste produces an important amount of radioactive waste by-products due to a fast wear of the lining in melting units;
there is no possibility provided for a fast passage from a remelting process of solid radioactive waste to a process of deactivating the radioactive metallic waste due to the contamination of the refractory lining of a furnace with radioactive nuclides from the slag built up;
an important power consumption to retreat solid radioactive waste.

It is known a process and a device for the retreatment of solid radioactive waste, comprising the steps of: compressing said solid radioactive waste, successive conveying said solid radioactive waste by gravity through a drying area and then transferring the product of thermal treatment of the same through a pyrolysis area and a combustion area at a final temperature of 1400°C, while simultaneously supplying some oxygen-containing oxidant gas into the combustion area, consecutive conveying the ashes to melt from the combustion area to the fusion area at the initial temperature of 1400°C and at a final temperature of 1600°C, keeping the melt ashes for some time at the fusion area and discharging the melt ashes form the fusion area at simultaneous movement of the outgoing gases from each successive area via the previous ones in a direction opposite to that of conveying said solid radioactive waste, said products of the thermal processing of the same and of the melt ashes in a device comprising a smelting shaft with a loading assembly located in the upper part of the shaft, a gas conduit to remove outgoing gases located in a side wall of the upper part of the shaft, and devices to supply gas oxygen-containing oxidant, a horizontal homogenization chamber linked to said shaft, provided with a plasma reactor, and provided with a cover, walls and a bottom together with a device for withdrawing the melt, as well as a plasma generator, taken as the closest art (patent RU 2140109 ) [4].
The known process and device for retreating solid radioactive waste provide for adding, before the compressing step, aluminosilicates and some flux into said solid radioactive waste, said flux forming an eutectic mixture with the melt ashes, combining together the drying and pyrolysis areas to have in this combined area an initial temperature of 350°C and a final temperature of 600°C, dividing the combustion area into a precombustion area with an initial temperature of 600°C and a final temperature of 800°C and an afterburning area with an initial temperature of 1200°C, the products of the thermal processing of the solid radioactive waste with said aluminosilicates and said flux being conveyed, after the drying and pyrolysis areas, through the precombustion area, and then, by gravity, through a gasification area with an initial temperature of 800°C and a final temperature of 1200°C with simultaneous supply of water vapor into the same, through the afterburning area, the drying area and the pyrolysis area, the gasification area being submitted to a forced cooling, conveying of the ashes to melt from the afterburning area to the melting area being carried out forcedly, the current of melt ashes, while conveyed, being subdivided into jets, the melt ashes being submitted to forced homogenization during the hold period, the melt ashes being discharged forcedly, and a forced decrease of movement rate of the outgoing gases being provided in the precombustion area. Furthermore, the forced conveying of the ashes to melt from the afterburning area to the melting area and the discharge of the melt ashes from the melting area are carried out as a result of a dynamic action of the plasma jet on said ashes.
The known process for retreating solid radioactive waste presents drawbacks as follows:

the need to mix the waste with aluminosilicates and fluxes and to compress the mixture obtained, that represent complicated and low-output operations;
a complicated multi-phase process of retreating waste in different areas of a shaft plasmatic furnace;
the difficulty to control and to keep constant the temperature in different areas of the melting unit in the limits specified for said known process;
the use of high-temperature heating for the products obtained in the retreatment of solid radioactive waste leads to a higher wear of the shaft furnace lining resulting in some increase of the amount of radioactive waste by-products;
the forced cooling of the products obtained after the waste retreatment leads to some increase of heat losses and to some increase of energy consumption;
to carry out conveying and discharge of the melted slag and of the waste processing products by the dynamical action of a plasma jet onto the same is unlikely in practice; the experience in the service of electric arc furnaces, including for plasmatic furnaces in high-capacity metallurgy shows an extremely low dynamic effect of arcs and of plasma jets onto the melted slag and metal [7];
this known process provides for the retreatment of waste in a batch process, with separate fusions, which is the reason for a low output of the shaft unit;
some increase in energy consumption to carry out the retreatment of waste.

An object of the claimed process for the retreatment of solid radioactive waste is to improve the technical and economic performance of the retreatment process and the ecological security level.
The technical result of the present process for the retreatment of solid radioactive waste is to improve the drawbacks of the closest art, in particular:

increase in productivity of the process due to the provision of a continuous retreatment process in a fuel-oxygen slag-lining melting chamber;
decrease in the heat-transfer agent consumption;
considerable decrease in the staff training time;
decrease in the evaporation of volatile radionuclides as well as decrease in the amount of formed secondary radioactive waste due to the absence of refractory lining in the slag area and in the open space of the melting chamber.

Said technical result is obtained thanks to the fact that in a process for the retreatment of solid radioactive waste comprising the steps of loading, melting said waste, separate tapping of the products of the treatment as slag and metal from the melting chamber, according to the present invention, the waste to be processed is submitted to preliminary heating in a preheater by the heat of outgoing gases having a temperature of 1600-1750°C, the heated solid radioactive waste is loaded into the melting chamber with the help of an air-tight device via an opening in a side wall of the chamber at a rate of 0.8 to 1.1 tons per hour for 1 m² of the liquid melt, the waste fusion is carried out continuously in a fuel-oxygen slag-lining melting chamber, the outgoing gases from the last being channeled into the preheater, during the waste retreatment process, a constant level of liquid metal is maintained in the lined molten-metal pool of the chamber, the "dirty" radioactive slag from the melting chamber is discharged at the melting section after accumulating a slag layer 250-400 mm high on the surface of the metal melt, the casting of the metal produced in the melting chamber being carried out at a section separated from the melting section by a closed partition.
In addition, during the retreatment of solid radioactive waste, the melting chamber housing is cooled with a liquid-metal heat-transfer agent.
Besides, loading, preheating, melting and discharging of "dirty" radioactive slag are carried out at a "dirty" melting section contaminated with radiation and separated by a closed partition from the "clean" section of casting the metal obtained in the melting chamber.
Besides, loading, preheating, melting and discharging of "dirty" radioactive slag are carried out at a "dirty" melting section contaminated with radiation and separated by a wall from the "clean" section of casting the metal obtained in the melting chamber.
Besides, the pouring-off of the "dirty" radioactive slag is carried out at the radiation-contaminated melting section into containers for waste burial, mounted on a conveyor.
Besides, the temperature of outgoing gases issued from the preheater is maintained at the level 700-850°C, then these gases are quickly cooled down to 200°C to provide "quenching" of the same.
Besides, the gases outgoing from the melting chamber are treated to remove dust in a dust purifier, the dust trapped from the gases being packed and put onto the bottom of the containers before filling the same with radioactive slag, the slag being finally poured inside from above.
Besides, the gases outgoing from the melting chamber are purified in a gas-purifying unit, the dust trapped from the gases being blown into the containers by an injector while filling the same with slag.
Besides, burning and melting of loaded waste are carried out on the surface of the liquid melt while retreating the waste.
Besides, burning and melting of loaded waste are carried out inside the liquid melt while retreating the waste.
Besides, loading of preheated radioactive waste into the melting chamber is carried out while maintaining a preset height of the molten slag layer and at a constant level of melted metal in the molten metal pool.
Carrying out continuously the process for retreating solid radioactive waste in a fuel-oxygen slag-lining melting chamber enables to increase the output of the process, to reduce the consumption of heat-transfer agent, to significantly reduce as well the irradiation of the staff, to reduce the evaporation of volatile radionuclides and to reduce the amount of radioactive waste by-products formed due to the absence of refractory lining in the slag area and in the free space of the melting chamber.
Preheating of solid radioactive waste in a preheater by the gases outgoing from the melting chamber with a temperature of 1600-1750°C enables to reduce the heat-transfer agent consumption for the waste retreating process, to accelerate melting of the waste and to increase the output of the process of retreating the same.
At a temperature of outgoing gases below 1600°C and, respectively, at the same temperature of gases in the working space of the melting chamber, the output of the process is decreased and the slag heating is made difficult to perform.
At a temperature of outgoing gases above 1750°C, and respectively, at such a high temperature in the working space of the melting chamber, the heat losses of the process and the heat-transfer agent consumption are increased together with the increase in the evaporation of volatile radionuclides.
The preheater is located at the side of the melting chamber which enables to ease up loading of solid radioactive waste into the same. At the same time, the overall size of the production room is reduced which enables to decrease capital outlays to build the shop.
Loading of preheated solid radioactive waste with an air-tight device via an opening in a side wall of the melting chamber at a rate of 0.8-1.2 tons per hour per square meter of liquid melt area provides for optimal conditions to process solid radioactive waste in the melting chamber. The hermetically sealed device prevents radioactive bursts into the working space of the fusion section which reduces irradiation of the staff in the "dirty" section of the production room.
Loading of preheated solid radioactive waste at a rate of 0.8-1.1 tons per hour per square meter of liquid melt area provides for the maximum rate of waste burning and melting and for a high output of the retreatment process.
At a rate of waste loading of less than 0.8 ton per hour per square meter of liquid melt surface, the output of the retreatment process decreases, the temperature in the working space of the melting chamber increases and the consumption of heat-transfer agent increases as well.
The rate of loading the preheated solid radioactive waste of 1.1 tons per hour per square meter of liquid melt surface is hard to provide at a low density of the waste (for example, in the case of rock thermal insulation). Besides, at such a loading rate, the loaded waste has no time to be completely melted.
Keeping a constant level of liquid metal, during the process of retreating solid radioactive waste, in the lined metal pool of the melting chamber, this level being not lower than the upper limit of the last, enables a fast passage, without washing or deactivating the same, from the retreatment of solid nonmetallic radioactive waste to the process of deactivating metallic radioactive waste and back to the processing of nonmetallic waste.
Burning and melting of loaded waste on the surface of the liquid melt obtained during the waste reprocessing or inside the same accelerate the process of waste retreatment and decrease the evaporation of volatile radionuclides from the surface of loaded solid radioactive waste.
Performing loading, preheating, fusion and running-off of "dirty" radioactive slag at a "dirty", radiation-contaminated melting section isolated by a closed partition or a wall from a "clean" section of casting metal obtained in the melting chamber provides for a high-capacity operation of the melting chamber and isolates the hazardous site, which reduces irradiation of the production staff.
Casting the metal obtained in the melting chamber at a section isolated from the melting section by a closed partition of a wall additionally isolates the hazardous section, which reduces the irradiation of the production staff.
Dividing the production room where a melting chamber is located with a closed partition or a wall into a "clean" and a "dirty" sections enables to carry out the waste loading into a preheater without any additional irradiation of the staff and to keep the stocks of solid radioactive waste in the "dirty" section of the shop.
Pouring-off of the radioactive slag at the "dirty" section of the shop after accumulation of a slag layer as high as 250-400 mm on the surface of the metal melt provides for a normal highly productive operation of the melting chamber and for the reduced irradiation of the production staff.
Pouring-off of the "dirty" slag after accumulating a slag layer less than 250 mm reduces the capacity of the melting chamber and of the whole process, complicating the work of the staff, the pouring-off of the slag becoming necessary to carry out more often and with small portions.
Pouring-off of the "dirty" slag after accumulating a slag layer higher than 400 mm on the metal melt surface is unsuitable since it troubles the heating of lower slag layers due to increasing heat resistance of a high thickness of the slag layer, the conditions of slag pouring-off from the melting chamber getting worse as a result of the slag viscosity growth.
Pouring-off of the "clean" deactivated metal at the "clean" metal casting section enables practically to prevent any irradiation of the staff.
Loading waste through an opening in the side wall of the melting chamber reduces the entrainment of waste particles with the outgoing gases from the working space of the chamber.
Retreating solid radioactive waste in a slag lining fuel-oxygen melting chamber, the housing of the last being cooled with a liquid-metal heat-transfer agent provides for a longer service life of the same, reduces the formation of solid radioactive waste by-products (refractory materials of the outworn lining) and increases the output of the process.
Pouring-off of the "dirty" radioactive slag into containers or barrels to bury waste, that are placed on a conveyor accelerates and makes it easier to pour the slag, it reduces the labor intensity of the process and reduces the irradiation of the production staff.
Keeping the temperature of the gases outgoing from the charge preheater in the range of 700-850°C and successive chilling of the same to 200°C enable to exclude the formation of dioxins while heating and reprocessing the solid radioactive waste containing PVC-type plastics and to prevent resynthesis (a new synthesis) of dioxins while chilling outgoing gases in the temperature range of 700°C-200°C.
Purifying gases outgoing from the melting chamber to remove dust in a gas purifier, packing of the dust trapped from the gases and containing radionuclides, putting it onto the bottom of containers or barrels before filling the same with liquid radioactive slag and further pouring slag into the same enable to encase in safety the radioactive dust into a slag ingot and to facilitate the burial of such dust.
The essence of the present claimed process is explained by a flow sheet of the process for the retreatment of solid radioactive waste (Fig. 1).
The process for the retreatment of solid radioactive waste is carried out as follows.
A melting chamber 1 is charged, in small portions, with low-melting waste of ferrous metals: cast iron and steel chips, pig iron, small-sized steel waste ends, and fuel-oxygen burners 2 fuse metal 3 to a liquid state in an amount necessary to fill the maximum volume of a lined molten metal pool. Simultaneously, solid radioactive waste 4 situated at a "dirty" melting section of the shop, contaminated with radiation is charged into a preheater 5 situated at the side of the melting chamber 1, where it is preheated using the heat of gases outgoing from the melting chamber 1 and having a temperature of 1600-1750°C.
After filling the lined molten metal bath with liquid metal 3, the heated solid radioactive waste is loaded with an air-tight device from the preheater 5 to the melting chamber 1 through an opening in a side wall of the melting chamber at a rate of 0.8-1.1 tons per hour per 1 m² of the molten metal surface. Burning and fusing of the loaded waste 4 are performed on the surface of the liquid molten metal obtained in the waste retreating, or inside the same. During the solid radioactive waste retreating process, a constant level of liquid metal 3 is maintained in the lined molten metal pool of the chamber 1, not lower than the upper limit of the same.
After accumulating a layer of "dirty" radioactive slag 7, 250-400 mm high on the surface of the molten metal, the "dirty" slag is poured-off into a container 8 via a slag trough 9 from the melting chamber 1 at the "dirty", radiation-contaminated melting section separated by a closed partition 13 or a wall 13 from a "clean" section for casting the metal obtained in the melting chamber 1.
The "clean" metal is poured from the melting chamber 1 via a long trough 10 at the "clean" section of the shop into a pouring ladle 11 through a metal tap hole 12.
The solid radioactive waste is retreated in a slag lined fuel-oxygen melting chamber the housing of which is cooled by a liquid metal heat-transfer agent.
Pouring-off of the "dirty" radioactive slag is carried out into containers or barrels 8 to bury waste, that are placed on a conveyor to make easier the work of the staff and to reduce the irradiation of the staff.
The temperature of the gases outgoing from the preheater 5 is kept in the range of 700-850°C and after that, the gases are chilled rapidly to 200°C to exclude the formation of dioxins while reprocessing waste containing plastics and to prevent resynthesis of dioxins while the gases are cooled slowly.
The dust trapped in a gas purifier (not shown in the Figure) is placed in a particular package onto the bottom of the containers 8 or barrels 8 before filling the same with liquid radioactive slag, the last being poured to fill them and to embed it in the body of the slag ingot enclosed in the container or the barrel.
Examples follow confirming the possibility of industrial implementation of the process according to the invention.

1. In a 2 tons volume acid-lined electric arc steelmaking furnace, 3 experimental fusions were carried out with melting in each case 1.0 t of non metallic waste having a similar composition and composed of thermal rock fibrous insulation, broken glass and building rubbish. At the first fusion, the waste was melted without melt metal, the arcs being initiated on graphite rejects. The waste loading rate was 1.0 t/hour. At the second and third experimental fusions, the waste loading rate was 0.6 ton per hour per 1 m² of melt surface, and at the third fusion, the rate of waste loading was 0.9 ton per hour per 1 m² of melt surface. The slag obtained was poured into metal ingot molds. Into one of the ingot molds, before filling it with slag, a tube segment of 50 mm diameter was filled with 1 kg of well-packed mineral dust. The fusion was carried out at the same furnace input power.

The results of the experimental fusions are given in Table 1.

Table 1. Results of the experimental fusions

Fusion No	Waste smelting	Waste loading rate, t/hour per 1 m² of melt surface	Time of complete melting of waste, hours	State of the furnace lining
1	Without metal melt	1.0	2.6	Bad
2	On the metal melt surface	0.6	1.8	Good
3	On the metal melt surface	0.9	1.2	Good

The results of the experimental fusions showed that:

without a previously obtained metal melt in the melting chamber, solid non metallic waste is smelted very slowly, the refractory lining of the bath being in a bad condition after the fusion;
smelting of solid non metallic waste on the surface of a previously obtained metal melt runs much faster, the refractory lining of the bath being in a good condition after the fusion;
increasing the waste loading rate from 0.6 t/hour per 1 m² of melt surface to 0.9 t/hour per 1 m² of melt surface results in an important shortening of the time for a complete waste smelting;
the results of all the experimental fusions have given an increase of the waste density from 0.15 t/m³ (burden) to 3.5 t/m³ (slag in ingots) which is of 23 times;
a steel tube segment containing dust packed into the same, placed into an ingot mold before pouring slag into the last was safely embedded in the body of the slag ingot;
any process of dioxin formation under heating solid waste to high temperatures and any dioxin resynthesis process under a fast cooling of gases from a temperature o 700-800°C to 200°C are excluded.

Bibliography

1. Handling of radioactive waste in Russia and in the countries with developed nuclear power. Collection of papers (edited by Vasilenko V.A.). Saint-Petersburg: OOO "NITs" Morintekh, 2005 - 304 p.
2. Skachek M.A. Handling of ANS used up nuclear fuel and of radioactive waste, Moscow, MEI Editions House, 2007-448 p.
3. Patent RU 2123214 . Process of retreating solid radioactive waste. Authors: Sobolev I.A., Dmitriev S.A., Kniazev I.A., Lifanov F.A. Patent owner: Moscow state enterprise Joint Ecological and Technical Research Center for Neutralizing Radioactive Waste and Environment Protection.
4. Patent RU 2140109 . Process and device for retreating solid radioactive waste. Authors: Dmitriev S.A., Kniazev I.A., Lifanov F.A., Polkanov M.A. Patent owner: Moscow state enterprise Joint Ecological and Technical Research Center for Neutralizing Radioactive Waste and Environment Protection (Moscow NPO "Radon").
5. Patent RU 2157570 . Plasmatic shaft furnace for retreating solid radioactive and toxic waste. Authors: Lifanov F.A., Kniazev I.A., Polkanov M.A., Shvetsov S.Yu. Patent owner: Moscow state enterprise Joint Ecological and Technical Research Center for Neutralizing Radioactive Waste and Environment Protection.
6. Cherednichenko V.S., Anshakov A.S., Kuzmin M.G. Plasmatic electrical and technological installations. Novosibirsk, NGTU Editions, 2005-508p.
7. Povolotsky D.Ia. et al. Electrometallurgy of steel and ferroalloys. Moscow. "Metallurgia" 1995-592p.
8. Kudrin V.A. Theory and technology of steelmaking. Moscow. "Mir", 2003-528p.
9. Raile V.T. Improvement of thermal operation and of construction for a shaft preheater in an arc steelmaking furnace. Thesis for a candidate of technical sciences degree. Cheliabinsk. IuUrGU.2010.
10. Addink R., Olie K. Mechanisms of formation and destruction of polychlorinated dibenzo-dioxins and dibenzofurans in heterogeneous systems. Environ.Sci.Technol. 1995, v.29, No.6, p.1423-1435.

Claims

Process for the retreatment of solid radioactive waste comprising the steps of
waste loading,
smelting,
separate tapping of slag and metal, products of the retreatment, from a melting chamber,
wherein the waste to be retreated is submitted to a previous heating in a preheater by the heat of gases outgoing from the melting chamber at a temperature of 1600-1750°C,
the heated solid radioactive waste is loaded into the melting chamber with the help of an air-tight device through an opening in a side wall of the chamber at a rate of 0.8-1.1 tons per hour per 1 m² of liquid melt surface,
the waste smelting is carried out continuously in a fuel-oxygen slag lining melting chamber,
the outgoing gases issued from the same being channeled to the preheater,
a constant level of liquid metal in the lined metal pool of the chamber is maintained during the process of retreating the waste,
pouring-off of "dirty" radioactive slag from the melting chamber is carried out at the melting section after accumulation of a slag layer 250-400 mm high on the surface of the metal melt, the casting of the metal obtained in the melting chamber being performed at a site separated from the melting section by a closed partition.
Process for the retreatment of solid radioactive waste of claim 1, wherein during the retreating of solid radioactive waste, the housing of the melting chamber is cooled with a liquid-metal heat-transfer agent.
Process for the retreatment of solid radioactive waste of claim 1, wherein the steps of loading, preheating, smelting and pouring-off of "dirty" radioactive slag are carried out at a "dirty" melting section, contaminated by radiation and separated by a closed partition from a "clean" section for casting the metal obtained in the melting chamber.
Process for the retreatment of solid radioactive waste of claim 1, wherein the steps of loading, preheating, smelting and pouring-off of "dirty" radioactive slag are carried out at a "dirty" melting section, contaminated by radiation and separated by a wall from a "clean" section for casting the metal obtained in the melting chamber.
Process for the retreatment of solid radioactive waste of claim 1, wherein the discharging of the "dirty" radioactive slag is carried out at the radiation-contaminated melting section into containers for waste burial, mounted on a conveyor.
Process for the retreatment of solid radioactive waste of claim 1, wherein the temperature of outgoing gases issued from the preheater is maintained at the level 700-850°C, then these gases are quickly cooled down to 200°C to provide "quenching" of the same.
Process for the retreatment of solid radioactive waste of claim 1, wherein the gases outgoing from the melting chamber are treated to remove dust in a dust purifier, and the dust trapped from the gases is packed and put onto the bottom of the containers before filling the same with liquid radioactive slag, the slag being finally poured inside the same.
Process for the retreatment of solid radioactive waste of claim 1, wherein the gases outgoing from the melting chamber are purified in a gas-purifying unit, the dust trapped from the gases being blown into the containers by an injector while filling the same with slag.
Process for the retreatment of solid radioactive waste of claim 1, wherein burning and melting of loaded waste are carried out on the surface of the liquid melt while retreating the waste.
Process for the retreatment of solid radioactive waste of claim 1, wherein burning and melting of loaded waste are carried out inside the liquid melt while retreating the waste.
Process for the retreatment of solid radioactive waste of claim 1, wherein loading of preheated radioactive waste into the melting chamber is carried out while maintaining a preset height of the molten slag layer and at a constant level of melted metal in the molten metal pool.