Selective electromagnetic heating

Abstract

An example system includes at least one processing chamber defining an interior region. The system also includes one or more heating elements configured to heat one or more hot materials disposed in the interior region and at least one EM radiation source. The system includes a controller configured to control at least the heating elements and the EM radiation source. The controller is configured to cause the EM radiation source to, in a first stage, generate calcining EM radiation exhibiting first parameters and direct the calcining EM radiation towards the hot materials. The controller is configured to cause the EM radiation source to, in a second stage, generate primary EM radiation exhibiting second parameters and direct the primary EM radiation towards the one or more hot materials.

Description

SELECTIVE ELECTROMAGNETIC HEATINGCROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This application claims priority to U.S. Provisional Application No. 63 / 562,055 filed on March 6, 2024. The aforementioned application is incorporated herein by reference, in its entirety, for any purpose.BACKGROUND

[0002] The challenge of isolating radioactive waste from the environment is very formidable. Radioactive waste can be melted into a glass mixture to isolate the radioactive material in the glass mixture. Such isolation can prevent the radioactive material within the glass mixture from entering the environment.

[0003] Melters, such as j oule heated melters, melt material to form a molten bath. The material in the molten bath may be drained out of the melter and disposed of. The melters may utilize joule heating to melt the material. The molten bath may have a cold cap on an upper surface thereof.SUMMARY

[0004] In an embodiment, an electromagnetic (“EM"’) wave heating system is disclosed. The EM wave heating system is configured to heat nuclear waste that is deposited on the top of molten glass in electrically heated glass melter. The EM wave heating system includes at least one EM radiation source configured to generate EM radiation and a controller configured to control at least the at least one EM radiation source. The controller is configured to cause the at least one EM radiation source to, in a first stage, to generate calcining EM radiation exhibiting first parameters and direct the calcining EM radiation towards the nuclear waste. The calcining EM radiation is selected to at least partially calcine the nuclear waste. The controller is configured to cause the at least one EM radiation source to, in a second stage after the first stage, generate primary EM radiation exhibiting second parameters and direct the primary EM radiation towards the nuclear waste. The primary EM radiation is selected to pass through the calcined nuclear waste and heat a desired layer of the molten glass on which the calcined nuclear waste sits. The first parameters are different than the second parameters. The first parameters and the second parameters include at least one of EM wave power, EM wave intensity (power per cm2), EM wave frequency, or EM wave heating duration.

[0005] In an embodiment, a method of using an EM wave heating system is disclosed. The method includes heating the nuclear waste that is deposited on the top of molten glass in electrically heated glass melter with the EM wave heating system. Heating the nuclear waste includes, in the first stage, with the at least one EM radiation source, generating the calcining EM radiation and direcring the calcining EM radiation towards the nuclear waste to at least partially calcine the nuclear waste. Heating the nuclear waste also includes, in the second stage after the first stage, with the at least one EM radiation source, generating the primary EM radiation and directing the primary7EM radiation towards the nuclear waste to pass through the calcined nuclear waste and heat the desired layer of the molten glass on which the calcined nuclear waste sits.

[0006] In an embodiment, a system is disclosed. The system includes at least one processing chamber defining an interior region, a waste inlet, and a waste outlet. The system also includes one or more heating elements configured to heat one or more hot materials disposed in the interior region. The system further includes at least one EM radiation source configured to generate EM radiation and direct the EM radiation towards the one or more hot materials disposed in the interior region. Additionally, the system includes controller configured to control at least the one or more heating elements and the at least one EM radiation source. The controller is configured to cause the at least one EM radiation source to, in a first stage, generate calcining EM radiation exhibiting first parameters and direct the calcining EM radiation towards the one or more hot materials. The calcining EM radiation is selected to at least partially calcine the one or more hot materials. The controller is configured to cause the at least one EM radiation source to, in a second stage, generate primary7EM radiation exhibiting second parameters and direct the primary7EM radiation towards the one or more hot materials. The primary EM radiation is selected to at least partially pass through the one or more hot materials and heat at least one of a portion of a cold cap of the one or more hot materials under atop surface of the cold cap or a desired layer of molten glass on which the cold cap of the one or more hot materials sits. The first parameters are different than the second parameters.

[0007] In an embodiment, a method of using a system is disclosed. The method includes, responsive to receiving instructions from the controller, with the at least one EM radiation source, generating the calcining EM radiation and directing the calcining EM radiation towards the one or more hot materials to at least partially calcine the one or more hot materials. The method also includes, responsive to receiving instructions from the controller, with the at least one EM radiation source, generating the primary EM radiation and directing the primary EM radiation towards the one or more hot materials to heat at least one of the portion of the coldcap of the one or more hot materials under the top surface of the cold cap or the desired layer of molten glass on which the cold cap of the one or more hot materials sit.

[0008] Features from any of the disclosed embodiments may be used in combination with one another, without limitation. In addition, other features and advantages of the present disclosure will become apparent to those of ordinary skill in the art through consideration of the following detailed description and the accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The drawings illustrate several embodiments of the present disclosure, wherein identical reference numerals refer to identical or similar elements or features in different views or embodiments shown in the drawings.

[0010] FIG. 1 is a schematic of a system 100 for melting hot material, according to an embodiment.

[0011] FIG. 2 is a schematic of a system 100 for melting hot material, according to an embodiment.

[0012] FIG. 3 is a schematic of a system 100 for melting hot material, according to an embodiment.

[0013] FIG. 4 is a schematic of a system 100 for melting hot material, according to an embodiment.

[0014] FIG. 5 is a flow chart of a method 500 for melting material, according to an embodiment.DETAILED DESCRIPTION

[0015] Embodiments disclosed herein related to systems (e. , melters) configured for selective electromagnetic ("EM") heating and methods of using such systems. Examples of systems and methods include EM heating of waste to calcine the waste and selective EM heating of waste to incorporate the waste into a molten glass bath. An example system includes at least one processing chamber defining an interior region, a waste inlet, and a waste outlet. The system also includes one or more heating elements configured to heat one or more hot materials disposed in the interior region and at least one EM radiation source configured to generate EM radiation and direct the EM radiation towards the one or more hot materials disposed in the interior region. The system includes a controller configured to control at least the one or more heating elements and the at least one EM radiation source. The controller is configured to cause the at least one EM radiation source to, in a first stage, generate calciningEM radiation exhibiting first parameters and direct the calcining EM radiation towards the one or more hot materials. The calcining EM radiation is selected to at least partially calcine the one or more hot materials prior to, contemporaneous with, or after introduction of the one or more hot materials into the processing chamber. The controller is configured to cause the at least one EM radiation source to, in a second stage, generate primary EM radiation exhibiting second parameters and direct the primary EM radiation towards the one or more hot materials. The primary EM radiation is selected to at least partially pass through the one or more hot materials and heat at least one of a portion of a cold cap of the one or more hot materials under a top surface of the cold cap or a desired layer of molten glass on which the cold cap of the one or more hot materials sits. The first parameters are different than the second parameters.

[0016] The systems disclosed herein are configured to at least partially resolve the challenge of isolating radioactive waste from the environment, which is very formidable. New technology is needed to reduce the time and cost for addressing this need. For example, in the United States there is an urgent need to accelerate the vitrification of radioactive defense waste, such as at the Department of Energy Hanford site.

[0017] Examples of the systems and methods disclosed herein may address an urgent need to accelerate the processing rate in melters (e.g., joule-heated melters) that are employed for waste vitrification (e.g., melting radioactive waste and vitrifying the same in a highly stable glass). It is estimated that using systems and methods disclosed herein, vitrification of present stocks of radioactive waste will take many decades under even the most optimistic assumptions. For example, the processing rate in joule heated melters is limited by the amount of heating at the interface of the newly added hot material that has not melted (the "cold cap") and the molten material in the melter. This is because the primary mode of thermal energy transfer into the cold cap is conduction from the molten glass pool below the cold cap. Additional heating may be needed at this interface in order to remove this processing rate limitation. However, it may also be necessary to prevent overheating of the cold cap and not increase the desired bulk average temperature of the glass bath to prevent and / or reduce emission of radioactive material from the surface of the cold cap that faces the plenum of the processing chamber of the melter.

[0018] Examples of methods and systems herein utilize EM energy (e.g., microwave radiation) to aid in melting the material (e.g., waste material and glass particles) in the cold cap. For example, examples of methods and systems described herein direct EM radiation into the cold cap to the interface between the cold cap and the molten material to accelerate heating subsurface portions of the cold cap. In some examples, the EM radiation is controlled topenetrate to a selected depth within the cold cap to aid melting / vitrifi cation of waste material in the hot material. For example, the EM radiation may supplement the heat in a joule heated melter so as to accelerate heating of the cold cap and increase the processing rate of new material without causing emissions of radioactive material from the surface of the cold cap to exceed a selected level.

[0019] Example methods and systems described herein may substantially accelerate melting of the cold cap (e.g., incorporation of the cold cap into the molten material) without raising the temperature of the material on the top surface (e.g., surface opposite the molten material) of the cold cap above a volatilization temperature of the hot material or without raising the bulk average temperature of the molten glass bath. Thus, the examples of methods and systems disclosed herein may allow for faster vitrification of material into a molten bath than conventional melters while preventing volatilization (e.g., vaporization) of the material. Accordingly, radioactive materials may be quickly and safely processed (e.g., vitrified) to isolate the radioactive materials from the environment.

[0020] One issue with using EM radiation to supplement heating in the systems disclosed herein is the presence of water (e.g., moisture in the cold cap and / or gaseous water) in the melter. For example, the EM radiation that is selected to melt the material in the cold cap is at least partially absorbed by the water. The EM radiation absorbed by the water (e.g., water present in the hot material or steam emitted from the hot material), instead of passing at least partially through the cold cap and heating the melted material, interferes with the eventual melting of the material. Such absorptions of the EM radiation decreases the energy from the EM radiation that may be used to melt the material in the cold cap. In other w ords, the presence of water decreases the efficiency of the EM radiation. Conventionally, the systems and methods may increase the power of the EM radiation to deal with the issue of water absorption. However, increasing the power of the EM radiation may cause uncontrolled heating of the hot material in the cold cap (e.g. , due to a localized decrease in the water or completely removal of water from the cold cap) which can cause emissions of radioactive material from the surface of the cold cap to exceed a selected level.

[0021] The systems and methods disclosed herein solve this issue by using the EM radiation to at least partially calcine (e.g. , dry or otherwise remove) water from the hot material before using the EM radiation to facilitate incorporation of the hot material in the cold cap into the molten material. For example, the systems and methods disclosed herein may emit the EM radiation in a first stage and a second stage. The EM radiation of the first stage may be configured to at least partially calcine the hot material of the cold cap and the EM radiation ofthe second stage may be configured to heat the material of the cold cap or the molten material on which the cold cap sits to melt selected portions of the cold cap. The EM radiation of the first stage may be configured to reduce the water in the system that may interfere with the EM radiation of the second stage. After the hot material (e.g., above or in the cold cap) has been sufficiently calcined, a high fraction of the EM radiation may pass through at least a portion the cold cap without absorption by the now absent water and, instead, the EM radiation may then be absorbed in a desired location within (e.g., layer) of the cold cap. in a desired location or layer (e.g., top surface layer) of the molten material, or the molten material / cold cap interface. As such, the systems and the methods disclosed herein increase the efficiency of the system compared to systems and methods that do not perform the first and second stages of EM radiation heating.

[0022] FIG. 1 is a schematic of a system 100 for melting hot material, according to an embodiment. The system 100 includes a processing chamber 110, at least one EM radiation source 120, one or more waveguides 122, a waste inlet 130, and a controller 140 operably coupled to the EM radiation source 120 and the waste inlet 130. The processing chamber 110 may include a container with a wall thickness and material composition sufficient to contain a molten material therein. For example, the processing chamber 110 may include a waste processing chamber (e.g., melter), such as a radioactive waste processing chamber. The processing chamber 110 may include an interior region 112 to contain a hot material 132 therein. For example, the processing chamber 110 may include a refractory metal lining disposed within a housing (e.g., ceramic body). In some examples, the processing chamber may have a relatively long shallow design to aid volumetric heating from the EM radiation source 120.

[0023] The hot material 132 may include a waste material such as radioactive waste (i.e., nuclear waste) or any other material to be incorporated into the molten material 139 (e.g., molten glass). The hot material 132 may initially include the waste material, one or more solvents (such as an acid), water, and one or more dissolved portions of the waste material. The hot material 132 may include a slurry of the waste material and the one or more solvents. The hot material 132 may include glass particles for forming a molten glass bath (e.g., molten material 139), such as borosilicate glass beads or any other glass suitable for vitrifying (radioactive) materials. For example, the slurry may include the glass particles. The molten glass may incorporate or encapsulate (e.g. vitrify) the waste materials therein upon melting. Accordingly, the waste material in the hot material 132 may be vitrified using the system 100.

[0024] The hot material 132 may be processed in the processing chamber 110 to include a molten material 139 and a cold cap 134 disposed on the molten material 139. The cold cap 134 may have an interface with the molten material 139 where the cold cap 134 is melted into the molten material 139. The primary’ mode of thermal energy transfer into the cold cap 134 is conduction from the molten material 139 (e.g., molten glass bath) below the cold cap 134. This conduction is the rate limiting step of the incorporation (e.g., melting) of the unmelted material (cold cap) into the molten material 139. There may also be accumulation of a gas layer or bubbles at the interface of the cold cap 134 and the molten material 139 further limiting thermal energy transfer into the cold cap 134. If bubbles are present, localized heating of the cold cap 134 directly above the bubble layer would also increase thermal energy transfer into the cold cap 134. It is noted that the bubble layer may be at least partially formed from water present in the hot material 132. As such, at least partially removing the water from the hot material 132 in the first stage may decrease the number of bubbles in the bubble layer.

[0025] Additional heating may be needed at the interface of the cold cap 134 and the molten material 139 in order to remove this processing rate limitation. However, it may be desirable to only enhance melting and dissolution as this may be the rate limiting step in melting, such as in a joule-heated or induction-heated melter process. Applying excess heat to the cold cap 134 could result in higher volatilization of hot material 132 (e.g., waste feed components) into gas phase within the processing chamber 110 which may be unintentionally removed or vented with other gas phase constituents within the processing chamber 110 to prevent overpressure.Increasing the bulk temperature of the molten material 139 may increase the wear of melter components such as the refractory lining and electrodes (e.g., joule heating electrodes 160) that supply the electric current into the molten material 139. It may be desirable to prevent overheating of the cold cap 134 and thereby prevent and / or reduce emission of waste material (e.g., radioactive material) from the surface of the cold cap 134 that faces the plenum (e.g., unfilled space of the interior region 112) of the processing chamber 110.

[0026] Using a directed beam of EM radiation 125 from the EM radiation source 120, in the second stage, can provide the localized heating in the interface region between the bottom of the cold cap 134 and the surface of the molten material 139 (e.g., glass bath). The localized beam may have high enough frequency to concentrate most of the heating in the cold cap 134 but be a low enough frequency to prevent volatilization of the cold cap 134 due to overheating of the upper surface of the cold cap 134. The molten glass in the molten material 139 may be conductive and may readily absorb the EM radiation to rapidly heat. Accordingly, the frequency of the EM radiation 125 may be limited to prevent penetration of the EM radiation125 into molten glass bath to prevent emissions of volatilized waste material caused by overheating of the molten glass bath.

[0027] The EM heating systems can be used with melters where one or both of joule heating or induction heating is used to heat the molten material and the EM radiation (e.g., microwave) heating power is less than the joule heating or induction heating power because the volume of material in the cold cap is much less than the volume of molten material. For example, the volume of the hot material in the cold cap may be less than one tenth, one eighth, one fifth, one quarter, or one third of the volume of the material in the molten material 139.

[0028] The EM radiation source 120 generates and emits the EM radiation 125 at various frequencies, such as 750 MEIz to 30 GHz, 0.8 GHz to 0.9 GHz, 0.9 GHz to 10 GHz, 0.9 GHz to 3 GHz, 3 GHz to 6 GHz, 6 GHz to 10 GHz, 0.9 GHz to 5 GHz, 5 GHz to 10 GHz, 10 GHz to 30 GHz, 0.8 GHz to 2.5 GHz, 1 GHz to 5 GHz, 2.5 GHz to 7.5 GHz, 5 GHz to 10 GHz, 7.5 GHz to 12.5 GHz, 10 GHz to 15 GHz, 12.5 GHz to 17.5 GHz, 15 GHz to 20 GHz, 17.5 GHz to 22.5 GHz, 20 GHz to 25 GHz, 22.5 GHz to 27.5 GHz, 25 GHz to 30 GHz. The frequency- may be preset or may be varied during processing. Under certain circumstances, the EM radiation heating range may extend to the 300 MHz to 750 MHz microwave range and / or the 30 GHz to 300 GHz microwave range. Generally, increasing the frequency of the EM radiation source 120 may reduce the depth of absorption in the cold cap 134 and / or the molten material 139 and obtain smaller spot sizes. In some examples, the EM radiation source 120 may include a microwave generator or emitter, such as an array of microwave generators or emitters. An advantage of the systems disclosed herein is that there are EM radiation generators (e.g., microwave generators) in the 0.75 GHz to 40 GHz frequency range which provide a relatively low cost radiation source and for which there is a large amount of commercial experience.

[0029] The duration that the EM radiation source 120 may emit the EM radiation 125 at various power levels may be employed to affect whether the EM radiation 125 is absorbed by water or penetrates at least partially through a thickness of the cold cap 134. This duration may be varied so as to achieve the most effective heating by EM radiation. The dependence of EM heating effectiveness on duration may be most usefully determined by measurements of representative material processing conditions for various EM power levels. The EM radiation may be delivered in discrete pulses or in a continuous manner where the power level that may vary with time. The EM radiation power level as a function of time and its duration may be determined by closed loop control using measurements of temperature at different spatial positions and by other measurements including measurements of emissions. The EM radiationpower level can also be determined by open loop control using information from experimental studies.

[0030] In some examples, the EM radiation source 120 may emit the EM radiation 125 at a selected EM power level during a discrete duration or cyclically (e.g., on-off or in combination with a higher or lower power level), such as in one or more of any of the ranges disclosed above. The selected duration(s) may be about 1 microsecond (“ps”)toabout 10 minutes, such as about 1 ps to about 50 ps, about 25 ps to about 100 ps, about 100 ps to about 300 ps, about 250 ps to about 1 millisecond (‘’ms”), about 1 ms to about 10 ms, about 5 ms to about 50 ms, about 50 ms to about 200 ms, about 200 ms to about 500 ms, about 500 ms to about 1 minute ("min"), about 1 min to about 3 min, about 3 min to about 5 min, about 5 min to about 7 min, about 7 min to about 9 min, less than about 10 minutes, or less than about 1 hour. In some examples, the EM radiation source 120 may emit the EM radiation 125 substantially continuously (e.g., for a duration greater than 10 min). It is believed that the duration that the EM radiation source 120 emits the EM radiation 125 may effect whether the EM radiation 125 is absorbed by water or penetrates at least partially through a thickness of the cold cap 134.

[0031] The EM radiation source 120 may be positioned outside of the processing chamber 110. For example, in examples where the processing chamber is a radioactive waste processing chamber, the life of the EM radiation source 120 can be prolonged by shielding the EM radiation source 120 from harmful radiation (e.g. from the radioactive materials) inside of the processing chamber 1 10. In some examples, the EM radiation source 120 may be isolated from the radiation in the processing chamber 110 by shielding (of the processing chamber) and by one or more bends in the one or more waveguides.

[0032] The EM radiation source 120 generates and emits the EM radiation 125 at various powers, such as 1 kW to 700 kW, 2 kW to 600 kW, 2 kW to 40 kW, 3 kW to 30 kW, 10 kW to 100 kW, or 20 kW to 600 kW. The power may be preset or may be varied during processing. It is believed that the power of the EM radiation 125 may effect whether the EM radiation 125 is absorbed by water or penetrates at least partially through a thickness of the cold cap 134.

[0033] By controlling the power or frequency of the EM radiation, the penetration depth of the EM radiation during the first stage and / or, more preferably, during the second stage may be selectively customized to at least one of heat the water, reach into and through the steam generated by heating the water, and / or reach into and through the cold cap 134 to the interface between the molten material 139 and the cold cap 134. For example, in the frequency range of 0.9 GHz to 10 GHz, the penetration lengths of the EM radiation can be more than ten timesgreater than those in the millimeter wave frequency range and can be well matched to penetrate a selected depth into a cold cap 134. For example, the penetration depth can be 1 cm or more, such as 1 cm to 20 cm, 1 cm to 3 cm, 3 cm to 6 cm, 6 cm to 10 cm, 10 cm to 15 cm, 15 cm to 20 cm, 1 cm to 15 cm, 1 cm to 5 cm, or 5 cm to 10 cm, 5 cm to 15 cm, more than 2 cm, more than 5 cm, less than 20 cm, less than 10 cm, or less than 5 cm. Moreover, since the penetration depth can be increased by around a factor of ten as the frequency is decreased from 10 GHz to 0.9 GHz, the systems and methods herein provide capability for selective adjustment of penetration depth for different processing conditions or hot materials.

[0034] Radiation in the 0.9 GHz to 10 GHz frequency range is well suited to obtaining desired penetration lengths in the 1 cm to 10 cm range in calcined cold caps (e.g., the cold cap 134 after the first stage). Such radiation may also be well suited to penetrating to the selected penetration depths in the cold cap 134 with little to no water content. The selected penetration depth may be adjusted by choice of the EM radiation power or frequency. For example, as the frequency is decreased, the penetration depth will increase. When there is a relatively lower water content in the hot material 132 it may be advantageous to use EM radiation in the 10 GHz to 30 GHz range, such as 10 GHz to 20 GHz, 20 GHz to 30 GHz, 10 GHz to 20 GHz, 10 GHz to 25 GHz, less than 30 GHz, less than 25 GHz, or less than 20 GHz.

[0035] Examples of systems and methods described herein may selectively control the frequency, power, and other parameters of EM radiation heating, including the water content of the radioactive material that is introduced to the processing chamber (e.g., melter), so as to selectively control and increase the processing rate while keeping cold cap surface emissions at a sufficiently low level (e.g., below7a threshold level). For example, EM (e.g., micro wave) heating may be used to increase the processing rate of melting in a processing chamber, such as a joule-heated melter or an induction-heated melter, while limiting surface heating of the cold cap 134 to limit or prevent surface emissions of material therefrom. The EM radiation heating can be employed on existing melters (e.g., systems) as well as on new melters.

[0036] Examples of systems and methods disclosed herein may overcome limitations of utilizing directed beams of higher frequency (e.g., millimeter) wave EM radiation 125 to aid in melting the hot material 132. For example, because of the relatively short wavelength of the EM radiation 125 in the 30 GHz to 300 GHz range, it may have a penetration depth in the cold cap 134 that is much shorter than the thickness of the cold cap 134, especially if there is a substantial water content in the hot material 132 (e.g., the first stage did not remove all or a substantially percentage of the water). Accordingly, the EM radiation 125 in the 30 GHz to 300 GHz range can cause excess heating at the surface of the cold cap 134. This can result in poorheating of the cold cap 134 at the interface with the molten material 139 and elevated emissions of one or more components of the hot material 132 from the surface of the cold cap 134 (that faces the plenum of the processing chamber 110). The relatively short penetration depth of the EM radiation 125 with the frequency of 30 GHz to 300 GHz can be due to the chemistry of the cold cap 134 and / or the presence of water therein.

[0037] Examples of systems and methods disclosed herein may overcome the limitations of bubbling gas through the molten material 139 to heat the interface between the cold cap 134 and the molten material 139. For example, utilizing EM radiation in a frequency range of 750 MHz to 30 GHz as disclosed herein does not cause emission of material from the surface of the cold cap 134, whereas bubbling gas through the molten material 139 causes volatilization and carries one or more components of the hot material 132 (e.g., radioactive waste material) to be carried in the bubbling gas. The example EM (e.g., microwave) heating systems and methods described here can achieve cold cap-modification enabled processing rate enhancement without the issues that have prevented rate enhancement attainment by bubbling and could thereby increase the processing rate of hot material therein by a factor of three or more for a joule heated melter.

[0038] The EM radiation 125 may be directed into the interior region 112 of the processing chamber 110 via one or more waveguides 122. For example, the one or more waveguides may be operably coupled to the EM radiation source 120. The one or more waveguides may guide the EM radiation into the cold cap 134 of the hot material in the processing chamber 110. For example, each of the one or more waveguides 122 may include a conduit with one or more bends therein. The conduit may have a circular, square, or rectangular cross-sectional profile. The conduit may have one or more bends or curves therein. An advantage of using micro waves (e.g., EM radiation in the 750MHz to 30 GHz range) may be that the requirement on window material in the waveguides 122 would be less demanding than in the millimeter radiation frequency range (e.g., 30 GHz to 300 GHz radiation). For example, the window could be made of ceramic rather than a diamond. In some examples, the one or more waveguides 122 may be translatable, such as being movable in one or more of lateral, vertical, or angular direction.

[0039] In examples, the system 100 may include one or more collimating devices 124 operably coupled to the one or more waveguides 122. The one or more collimating devices 124 may collimate and direct (e.g., guide) the EM radiation 125 into one or more beams. For example, the one or more collimating devices 124 may direct the EM radiation 125 at one or more selected portions of the hot material 132 (e.g., interface below the cold cap 134). The one or more collimating devices 124 may collimate the EM radiation 125 to a selected beam width.In an embodiment, the one or more collimating devices 124 may include a hom, such as a radiative hom. In an embodiment, the one or more collimating devices 124 may include a phased array. The hom or phased array may direct the EM radiation 125 at one or more discrete portions of the hot material 132 (e.g., the interface of the cold cap 134 and the molten material 139 or portions). In some examples, the EM radiation generator could use a frequency source in combination with a klystron amplifier system which could send the EM radiation (e.g., microwave radiation) into a phased array of waveguides that would protmde into the processing chamber. Examples of the hom and the phased array are disclosed in U.S. Patent No. 11,232,879 issued on January 25, 2022, the disclosure of which is incorporated herein, in its entirety , by this reference.

[0040] With use of example systems and methods disclosed herein, the EM radiation 125 (e.g., microwave radiation having a frequency of 750 MHz to 30 GHz) can be introduced into the processing chamber 110 with a significant amount of collimation and spatial localization. For example, the one or more waveguides 122 and one or more collimating devices 124 may provide localized and directed heating of a selected discrete portion (e.g., the interface between the cold cap 134 and the molten material 139 or a portion of the cold cap ) of the hot material 132.

[0041] The system 100 includes the controller 140. The controller 140 may be operably coupled to one or more components of the system 100 via one or more connections 144 (e.g., wireless or hardwired connections) to control the system 100. The controller 140 may be operably coupled to at least the EM radiation source 120 and the waste inlet 130 via the connections 144. The controller 140 may be used to selectively adjust one or more of the power of the EM radiation, intensity of the EM radiation, frequency (e.g., wavelength) of the EM radiation, duration that the EM radiation source 120 emits the EM radiation, or angle at the EM radiation irradiates the cold cap 134 to selectively control at least one of a water content of the cold cap 134, a temperature profile in the cold cap 134, or a temperature of the molten material 139 all while inhibiting emissions of volatile components from the cold cap 134 from exceeding a selected level (e.g., below a threshold level).

[0042] For example, the controller 140 may direct the EM radiation source 120 to initiate generation or alter the parameters (e.g, power or frequency) of the EM radiation 125. For example, the controller 140 may cause the EM radiation source 120 to vary' the power or frequency of EM radiation 125 emitted into (e.g.. to calcine the cold cap 134) and / or at least partially through the cold cap 134 during a selected duration. For example, the controller 140 may direct the EM radiation source 120 to vary the parameters of the EM radiation 125 everysecond or more (e.g., 1 second, 10 seconds, 30 seconds, 1 minute, 10 minutes, 3 minutes, etc.). The controller 140 be operably coupled to the waveguide 122 or the one or more collimating devices 124. In such examples, the controller 140 may control the waveguide 122 or the one or more collimating devices 124 to direct the EM radiation 125 to a selected depth or lateral location within the processing chamber 110. The controller 140 may actively control the target location of the EM radiation 125 to coincide with a dry section of the cold cap 134. or a newly added portion of the hot material 132. For example, the controller 140 may cause the waveguide 122 and the one or more collimating devices 124 to direct the EM radiation 125 to move locations in the cold cap 134, such as to an untreated area of the cold cap 134.

[0043] The controller 140 can use preset or vary parameters of the EM radiation 125 such as EM radiation power or frequency, amount of drying of the hot material in the cold cap; processing rate; or spatial positioning of the EM radiation using sensed information that such as cold cap 134 temperature, molten material 139 temperature, and emissions of material from the cold cap 134. Sensed information on material emissions from the cold cap 134 can be used to keep radioactive material emissions from the melting / vitrification process below selected levels. The controller 140 can use closed loop or real time monitoring of these and other parameters and / or open loop control using a look-up table. The look-up table can make use of experimental measurements of the impact of microwave power, frequency, and other parameters on processing rate enhancement, emissions from the cold cap 134 and other characteristics of system's 100 operation.

[0044] Responsive to direction from the controller 140, the EM radiation source 120 may switch between a first stage and a second stage. For example, in the first stage, the controller 140 may direct the EM radiation source 120 to emit calcining EM radiation. As used herein, “calcining EM radiation” is the EM radiation 125 that is configured to calcine (e.g., dry) the hot material 132 (e.g., the cold cap 134). In some examples, the calcining EM radiation is selected to at least partially calcine the material (e.g., waste, hot material, nuclear waste) without melting the material. In the second stage, the controller 140 may direct the EM radiation source 120 to emit primary’ EM radiation. As used herein, the primary EM radiation is the EM radiation 125 configured to heat the cold cap 134 and / or the molten material 139 to facilitate incorporation of the cold cap 134 into the molten material 139. It has been found that the water in the hot material 132 may interfere with the primary’ EM radiation. For example, the water in the hot material 132 may absorb the primary EM radiation which causes the primary EM radiation to heat undesired portions of the hot material 132 or excessively heat the hot material 132. Further, steam emitted from the hot material 132 may absorb at least some ofthe primary' EM radiation thereby at least partially preventing the primary EM radiation reaching the cold cap 134 or the molten material 139. However, calcining the hot material 132 in the first stage using the calcining EM radiation at least partially removes the water from the hot material 132 and the interior region 112 thereby decreasing the effect water has on heating the cold cap 134 and / or the molten material 139 with the primary EM radiation.

[0045] In an embodiment, the controller 140 may direct the EM radiation source 120 to emit the calcining EM radiation before directing the EM radiation source 120 to emit the primary EM radiation. In other words, the controller 140 may direct the EM radiation source 120 to sequentially conduct the first stage followed by the second stage. In such an embodiment, the controller 140 may direct the EM radiation source 120 to emit the calcining EM radiation until the hot material 132 exhibits a water content that is at or below a threshold value. The threshold value may be selected to be a value at which any interference with the primary EM radiation caused by the water is satisfactory small and the energy and time required to further decrease the water content is unsatisfactorily high. In an example, the threshold water content may be about 50% or less, about 40% or less, about 30% or less, about 20% or less, about 10% or less, about 5% or less, about 1% or less, substantially 0%, or in ranges of about 0% to about 2%, about 1% to about 3%, about 2% to about 4%, about 3% to about 5%, about 4% to about 6%, about 5% to about 8%, about 7% to about 10%, about 8% to about 12%, about 11% to about 18%, about 15% to about 25%, about 20% to about 30%. about 25% to about 35%. about 30% to about 40%, or about 35% to about 50%. As used herein, the water content may refer to the weight percent of water in the hot material 132 or the percent of the remaining water in the hot material 132 compared to the initial percentage of water in the hot material 132 (z'.e., the final percentage of water in the hot material 132 divided by the initial percentage of water in the hot material 132 multiplied by 100). The methods of detecting the water content in the hot material 132 will be discussed below. After detecting that the water content is at or below the threshold value, the controller 140 may direct the EM radiation source 120 to emit the primary EM radiation.

[0046] In some embodiments, the controller 140 may direct the EM radiation source 120 to emit the calcining EM radiation and the primary EM radiation simultaneously. For example. the EM radiation source 120 may include an array of a plurality of EM radiation emitters. The controller 140 may direct at least one of the plurality of EM radiation emitters to emit the calcining EM radiation and at least one of the plurality of EM radiation emitters to emit the primary EM radiation. In a particular example, the controller 140 may direct the EM radiation source 120, the waveguides 122, and the collimating device 124 to direct the calcining EMradiation and the primary EM radiation to different portions of the hot material 132. The controller 140 may direct the EM radiation source 120. the waveguides 122, and the collimating device 124 to direct the calcining EM radiation to portions of the hot material 132 exhibiting a water content that is above the threshold value. Such portions of the hot material 132 that the calcining EM radiation may be directed towards includes the hot material 132 entering the interior region 112 that has not yet formed the cold cap 134 or the most recently formed portions of the cold cap 134. The controller 140 may direct the EM radiation source 120. the waveguides 122, and the collimating device 124 to direct the primary EM radiation to portions of the hot material 132 that has been at least partially calcined, such as hot material 132 exhibiting a water content that is below the threshold value. The portions of the hot material 132 that the primary EM radiation is directed towards may be downstream from the portions of the hot material 132 that receive the calcining EM radiation. In a particular example, the controller 140 may direct the EM radiation source 120, the waveguides 122, and the collimating device 124 to direct the calcining EM radiation and the primary7EM radiation to the same portion of the hot material 132. In such an example, the calcining EM radiation may help the efficiency of the primary EM radiation to increase over time as the calcining EM radiation removes water from the portion of the hot material 132 irradiated by the calcining and primary EM radiations.

[0047] In an embodiment, the controller 140 may direct the EM radiation source 120 to emit the primary EM radiation before directing the EM radiation source 120 to emit the calcining EM radiation. In other words, the controller 140 may direct the EM radiation source 120 to sequentially conduct the second stage followed by the first stage. For example, while operating in the second stage, the controller 140 may determine that the water in the hot material 132 is unsatisfactorily interfering with the primary EM radiation and inhibiting effective heating of the cold cap 134 and / or the molten material 139. Such a determination by the controller 140 may be caused, for instance, by incorrectly7determining that the water content was below a threshold value, the introduction of new hot material 132 into the interior region 112. or the heating of portions of the hot material 132 having higher than average water content. The controller 140 may determine that the water is unsatisfactorily interfering with the primary EM radiation when it is determined at least one of the primary7EM radiation is not effectively heating the cold cap 134 or the molten material 139, the quantity7of steam in the interior region 112 is too high, or otherwise determines that the water in the hot material 132 is unsatisfactorily interfering with the primary EM radiation. Once it is determined that the water is unsatisfactorily interfering with the primary7EM radiation, the controller 140 maydirect the EM radiation source 120 to emit the calcining EM radiation. In an example, the controller 140 may direct the EM radiation source 120 to emit the primary EM radiation after emitting the calcining EM radiation, for instance, after determining that the water content in the hot material 132 is below the threshold value.

[0048] Whether the controller 140 directs the EM radiation source 120 to emit the calciningEM radiation before the primary EM radiation, the calcining and primary EM radiation simultaneously, or the primary EM radiation before the calcining radiation may depend on how the hot material 132 is introduced into the interior region 112. In an example, the hot material 132 may be introduced into the interior region 112 in batches (e.g., the controller 140 directs the waste inlet 130 to introduce the hot material 132 in batches). In such an example, the controller 140 may direct the EM radiation source 120 to emit the calcining EM radiation as the hot material 132 is introduced into the interior region 112 and, optionally, for a duration thereafter. After at least partially calcining the hot material 132, the controller 140 may direct the EM radiation source 120 to emit the primary EM radiation. A new batch of hot material 132 may be introduced into the interior region 112 once at least a portion (e.g., all) of the hot material 132 in the initial batch is incorporated into the molten material 139. The controller 140 may direct the EM radiation source 120 switch from the primary EM radiation to the calcining EM radiation responsive to the introduction of the new7batch of hot material 132. In an example, the hot material 132 may be continuously introduced into the interior region 112. In such an example, the EM radiation source 120 may simultaneously emit the calcining and primary EM radiations, such as emitting the calcining EM radiation towards the newly introduced hot material 132 and the primary EM radiation towards the hot material 132 that has been at least partially calcined.

[0049] As previously discussed, the calcining EM radiation and the primary EM radiation are configured to perform different tasks, namely calcine the hot material 132 and facilitate heating of the cold cap 134 and / or the molten material 139 to facilitate incorporation (e.g., melting) of the cold cap 134 into the molten material 139, respectively. To facilitate these functions, the calcining EM radiation is selected to be different than the primary7EM radiation. For example, the calcining EM radiation may be selected to be more efficient or otherwise more effective at calcining the hot material 132 than the primary EM radiation and / or the primary' EM radiation may be selected to be more efficient or otherwise more effective at heating the cold cap 134 or the molten material 139 to facilitate incorporation of the cold cap 134 into the molten material 139 than the calcining EM radiation. The effectiveness of the EM radiation 125 to calcine the hot material 132 and heat the cold cap 134 and / or the moltenmaterial 139 depends on the parameters of the EM radiation 125. As such, the calcining EM radiation may exhibit one or more parameters that are different than the primary EM radiation. It is currently believed that the parameters of the EM radiation 125 that may have the largest effect on the effectiveness of the EM radiation 125 to calcine the hot material 132 and heat the cold cap 134 and / or the molten material 139 include the frequency (e.g., wavelength) of the EM radiation 125, power of the EM radiation 125. intensity of the EM radiation 125, the angle at which the EM radiation 125 irradiates the hot material 132, the duration that the EM radiation source 120 emits the EM radiation 125, and the spatial extent of the incoming EM radiation 125. As such, the calcining EM radiation may exhibit at least one of the above parameters that is different (e.g. , higher or lower) than the primary' EM radiation.

[0050] The parameters of the EM radiation 125 that affect the effectiveness of the EM radiation 125 to calcine the hot material 132 depends on a number of factors. Examples of such parameters include the composition of the hot material 132, the temperature of the cold cap 134, the temperature of the molten material 139, and the weight percent of liquid and solid material in the cold cap 134 since the absorption of the EM radiation 125 in the hot material 132 depends on these factors. These factors may affect which parameters of the EM radiation 125 are most effective at calcining the hot material 132 and heating the cold cap 134 and / or the molten material 139. For example, the calcining EM radiation may exhibit a higher or lower frequency than the primary EM radiation when the hot material 132 exhibits a first composition (e.g.. the EM radiation 125 that penetrates at least partially through the cold cap 134 for a selected distance exhibits a frequency that is higher than the EM radiation 125 that is most effectively absorbed by water) and the calcining EM radiation may exhibit a higher or lower frequency than the primary' EM radiation when the hot material 132 exhibits a second composition (e.g., the EM radiation 125 that penetrates at least partially through the cold cap 134 for a selected distance exhibits a frequency that is higher or lower than the EM radiation125 that is most effectively absorbed by water). The absorption of microw ave radiation by water ty pically increases with frequency and this increase with frequency may be stronger than the increase of microwave radiation with frequency for material that has less water content. It may therefore be advantageous to use a higher microwave frequency for calcining.

[0051] In examples, the system 100 may include one or more sensors 150 positioned to sense a temperature of one or more portions of the hot material 132 (e.g., the cold cap 134). The one or more sensors 150 may include a millimeter wave pyrometer, infrared wave pyrometer, a scanning (e.g.. infrared) thermometer, a laser thermometer, a thermocouple, or any other suitable temperature sensor. The one or more sensors 150 may include radiationdetectors (e.g., Geiger counter) or spectrometers (e.g., atomic absorption spectrometer, inductively coupled plasma atomic emission spectrometer), a moisture sensor, or any other suitable sensor for detecting the presence or amount of a specific material. The one or more sensors may be positioned to measure a volatile material (e.g., cesium or technetium) in gases emitted from the processing chamber (e.g., from the cold cap). The one or more sensors 150 may be positioned to measure the temperature of the surface of the cold cap 134, chemical emissions of one or more components from the cold cap 134. or the temperature of emissions from the cold cap 134. The one or more sensors 150 may be operably coupled to the controller 140. For example, the sensors 150 located at various levels to have a side view of the hot material 132 (e.g., the cold cap 134) and / or the molten material 139. The controller 140 may receive the sensed temperature from the one or more sensors 150 (e.g., of the cold cap) and responsive thereto, selectively adjust one or more of the power or the frequency of the EM radiation, such as to maintain a selected penetration depth of the EM radiation or a selected material processing (e.g., melting) rate. Such selective control can be according to one or more operational programs stored in the controller 140.

[0052] In an embodiment, the controller 140 may direct the EM radiation source 120 to emit the calcining EM radiation, the primary EM radiation, or both responsive to one or more characteristics sensed by the sensors 150. In an example, the sensors 150 may include one or more temperature sensors. The controller 140 may direct the EM radiation source 120 to emit the calcining EM radiation when the temperature sensors detect that a temperature one or more portions of the hot material 132 (e.g., the cold cap 134) or the molten material 139 exhibit a temperature that is too high or too low which may indicate a high water content. For instance, the reduced absorption of the primary EM radiation as the hot material 132 is dried may be determined by a decrease in the rate of the increase of the surface temperature of a layer of the top material 132 as a function of time. In such an instance, when the sensors 150 indicate that the hot material 132 is sufficiently transparent through sufficient calcination, the controller 140 may direct the EM radiation source 120 to emit the primary' EM radiation. In an instance, the sensors 150 may detect the depth of penetration of the EM radiation 125 in the cold cap 134 and / or determine which portions of the cold cap 134 are being melted by the EM radiation 125. In an example, the sensors 150 may include a moisture sensor. The controller 140 may direct the EM radiation source 120 to emit the calcining EM radiation when the moisture sensor detect higher than desired gaseous water in the interior region 112.

[0053] In an embodiment, the controller 140 does not direct the EM radiation source 120 to emit the calcining EM radiation or primary EM radiation responsive to characteristics sensedby the sensors. Instead, the controller 140 may direct the EM radiation source 120 to emit the calcining EM radiation for a selected period of time. In an example, the period of time may be preselected to be long enough that the hot material 132 is most likely to be sufficiently calcined after irradiating the hot material 132 with the calcined EM radiation for the preselected period of time. In an example, the period of time may be adjusted based on the quantity of hot material132 introduced into the interior region 112 (e.g, the hot material 132 is provided in batches) or the rate at which the hot material 132 is introduced into the interior region 112 (e.g.. the hot material 132 is continuously provided). In such an example, the period of time may be increased as the quantity or rate is increased and the period of time may be decreased as the quantity or rate is decreased. In an example, the water content of the hot material 132 may be determined before the hot material 132 is introduced into the interior region 112 and the period of time may be selected based on the measured water content.

[0054] In examples, the system 100 may include one or more joule heating electrodes 160 positioned to heat the molten material 139. For example, one or more joule electrodes 160 may be positioned in the lower region of the processing chamber 110 to heat the molten material 139 to a selected temperature (e.g., maintain the molten material in a molten state). The processing chamber 110 may be a joule heated melter. The one or more joule heating electrodes 160 may melt the hot material and vitnfy the waste in the hot material or maintain the hot material in a molten state where the heating is provided by the passage of current between the joule heating electrodes 160. The one or more joule heating electrodes 160 may be operably coupled to the controller 140. The controller 140 may direct the joule heating electrodes 160 to heat the molten material 139 in the processing chamber 110 to a selected temperature.

[0055] In examples, the sy stem 100 may include one or more induction heating elements 180, such as an induction coil or electromagnet disposed about one or more portions of the processing chamber 110 (e.g., the lower region). The induction coil or electromagnet may be operably coupled to an electronic oscillator. The one or more induction heating elements may be operably coupled to the controller 140. The controller 140 may direct the induction heating elements to heat the molten material 139 in the processing chamber 110 to a selected temperature.

[0056] In examples, the controller 140 may be operably coupled to the waste inlet 130. The controller 140 may control the flow rate of the hot material 132 into the processing chamber 110. In an example, the controller 140 may direct the w aste inlet 130 to provide the hot material 132 is batches. In such an example, the controller 140 may direct the inlet 130 to input a selected quantity of the hot material 132 to the processing chamber 1 10. In an example, thecontroller 140 may direct the waste inlet 130 to continuously provide the hot material 132. In such an example, the controller 140 may increase or decrease the flow rate of hot material 132 into the processing chamber 110 to achieve a selected processing rate, a cold cap thickness, or a penetration depth of the EM radiation into the cold cap. The controller 140 may be operably coupled to a pre-dryer (e.g., evaporator or heater) to control pre-drying of the hot material that is introduced into the processing chamber (e.g.. melter) based on one or more of temperature or emissions detected by the one or more sensors 150.

[0057] The system 100 may include an outlet 170 for removing the molten material (e.g., vitrified waste) from the processing chamber 110. For example, the outlet 170 may be located in the bottom of the processing chamber 110. The outlet 170 may be operably coupled to the controller 140. The outlet 170 may be selectively opened, closed, or partially restricted to control the rate of removal of the molten material therefrom.

[0058] The system 100 may include a gas vent 175 for removing gasses from the processing chamber 110. For example, the gas vent 175 may be located in upper portion of the processing chamber 110. The gas vent 175 may be used to remove steam, volatilized components of the waste material, or any other process gases. The gas vent 175 may be operably coupled to the controller 140. The gas vent 175 may be selectively opened, closed, or partially restricted to control the rate of removal of one or more gasses from the processing chamber 110. The gas vent 175 may be operably coupled to a downstream gas cleaning apparatus, such as an apparatus for cleaning one or more chemicals or radioactive materials from the one or more gases. Generally, the gas vent 175 is open when the EM radiation source 120 emits the calcining EM radiation to allow7removal of steam from the processing chamber 110.

[0059] In examples, the system 100 may include a containment structure 190, such as cladding or shielding to contain one or more emissions from the processing chamber 110. For example, the containment structure 190 may include a sealed enclosure disposed about one or more portions of the system 100. The containment structure 190 may prevent leaks of fluids (e.g., off gasses) and / or radioactivity from the system 100. In some examples, the containment structure 190 may include lead, depleted uranium, depleted thorium, barium sulfate, tungsten. iron, alloys of any of the foregoing, or high density concrete typically used in radioactive processing facilities.

[0060] The system 100 may include a power source (not shown). The power source may be operably coupled to any of the components of the system 100 to supply electrical energythereto. The power source may include at least one of a motor, generator, batteries, solar cells, or any other source of electrical energy.

[0061] The EM generation devices, waveguides, collimating devices, controllers, and other components of the example systems disclosed herein can be used on existing melters or on new melters. For example, the EM radiation source 120, waveguides 122, collimating devices 124, controller 140, and other components of the example systems disclosed herein can be retrofit onto existing waste melters, such as the melter disclosed in U.S. Patent No. 11.232,879 issued on January 25, 2022, the disclosure of which is incorporated herein, in its entirety, by this reference.

[0062] In examples, the EM radiation source 120 can serve as the sole source of heating.Such examples can be of particular interest for small melters with molten bath depths in a range of 1 cm to 15 cm. For example, low volume melters for processing radioactive material may be used where the volume of fissile material (e.g., barium, cesium, iodine, strontium, technetium, xenon, etc.) being melted is limited in order to avoid a critical mass that would result in a nuclear criticality event.

[0063] The system described here could increase the waste processing rate of a joule heated melter by a factor of at least two, at least three, at least four, and possibly greater than six.

[0064] The system 100 illustrated in FIG. 1 is merely one example of a system that is configured to use calcining EM radiation to calcine a hot material and primary EM radiation to facilitate incorporation of a cold cap into the molten material. FIGS. 2-4 illustrate other examples of systems that are configured to use both calcining EM radiation and primary EM radiation. Except as otherwise disclosed herein, the systems illustrated in FIGS. 2-4 may be the same as or substantially similar to any of the systems disclosed herein.

[0065] FIG. 2 is a schematic of a system 200 for melting material, according to an embodiment. The system 200 includes a processing chamber 210 defining an interior region 212. The processing chamber 210 defines a waste inlet 230 configured to provide hot material 232 to the interior region 212. The processing chamber 210 may include a molten material 239 disposed therein. The hot material 232 provided to the processing chamber 210 may form a cold cap 234 on the molten material 239. The system 200 is configured to incorporate the cold cap 234 into the molten material 239. The system 200 may also include a controller 240 that is configured to control one or more components of the system 200, as previously discussed.

[0066] The system 200 includes a plurality of EM radiation sources, such as (as illustrated) at least one first EM radiation source 220a and at least one second EM radiation source 220b.The first and second EM radiation sources 220a, 220b may be the same as or substantiallysimilar to any of the EM radiation sources disclosed herein. For example, the first and second EM radiation sources 220a, 220b may be positioned external to the interior region 212 and configured to provide EM radiation into the interior region 212, for instance, using one or more waveguides 222 and / or collimating devices 224.

[0067] In an embodiment, the first EM radiation source 220a is configured to emit at least the calcining EM radiation and the second EM radiation source 220b is configured to emit at least the primary EM radiation. In such an embodiment, the first and second EM radiation sources 220a, 220b may allow the system 200 to provide the calcining and primary EM radiations to the hot material 232 substantially simultaneously. The first EM radiation source 220a (e.g, via the waveguide 222 or the collimating device 224 connected to the first EM radiation source 220a) is configured to emit the calcining EM radiation towards a first location of the hot material 232 and the second EM radiation source 220b (e.g., via the waveguide 222 or the collimating device 224 connected to the second EM radiation source 220b) is configured to emit primary EM radiation towards a second location of the hot material 232. The first and second locations of the hot material 232 may be different from each other. In an example, the first location may be positioned upstream from the second location relative to the flow of the hot material 232. In such an example, the calcining EM radiation from the first EM radiation source 220a may at least partially calcine the hot material 232 before the hot material 232 reaches the second location and is exposed to the primary EM radiation from the second EM radiation source 220b. In an example, the first location may be closer to the gas vent 275 than the second location. In such an example, at least some of the steam generated by the calcining EM radiation does not flow into the path of primary' EM radiation thereby minimizing any absorption of the primary' EM radiation by the steam before the primary' EM radiation reaches the cold cap 234. It is noted that the first EM radiation source 220a configured to emit the calcining EM radiation and the second EM radiation source 220b configured to emit the primary EM radiation may be used when the waste inlet 230 continuous provides the hot material 232 or provides the hot material 232 in batches in this embodiment.

[0068] In an embodiment, the first EM radiation source 220a and the second EM radiation source 220b are each configured to emit both the calcining EM radiation and the primary EM radiation. In an example, the first EM radiation source 220a and the second EM radiation source 220b may be configured to emit the calcining EM radiation simultaneously and, after at least partially calcining the hot material 232, the first the first EM radiation source 220a and the second EM radiation source 220b may be configured to emit the primary EM radiation simultaneously. In such an example, using the first and second EM radiation sources 220a,220b to simultaneously emit the same type of EM radiation may facilitate the first and second stages by at least one of accelerating calcining of the hot material 232, simultaneously calcining a larger percentage of the hot material 232, or actively facilitating incorporation of a larger percentage of the cold cap 234 into the molten material 239. It is noted that using the first and second EM radiation sources 220a, 220b to simultaneously emit the same type of EM radiation may be beneficial when relatively large quantities of the hot material 232 are provided to the processing chamber 210 and / or the processing chamber 210 is relatively large. In an example, the first EM radiation source 220a may be configured to perform the first and second stages on a first location of the hot material 232 and the second EM radiation sources 220b may be configured to perform the first and second stages on a second location of the hot material 232.In such an example, the first and second EM radiation sources 220a, 220b may be independently operated such that the first EM radiation source 220a performs the first stage on the first location when the first location includes water and the second stage after the first location is sufficiently calcined, regardless of the water content in the hot material 232 at the second location.

[0069] It is noted that the system 200 may include one or more EM radiation sources in addition to the first EM radiation source 220a and the second EM radiation source 220b, without limitation.

[0070] FIG. 3 is a schematic of a system 300 for melting material, according to an embodiment. The system 300 is an example of a plasma enhanced melter. That said, except as otherwise disclosed herein, the system 300 may be the same as or substantially similar to any of the systems disclosed herein. For example, the system 300 includes a processing chamber 310 defining an interior region 312. The processing chamber 310 defines a waste inlet 330 configured to provide hot material 332 to the interior region 312. The processing chamber 310 may include a molten material 339 disposed therein. The hot material 332 provided to the processing chamber 310 may form a cold cap 334 on the molten material 339. The system 300 is configured to incorporate the cold cap 334 into the molten material 339. The system 300 may also include a controller 340 that is configured to control one or more components of the system 300, as previously discussed.

[0071] The system 300 includes one or more electrodes 362, such as a first electrode and a second electrode. The electrodes 362 of the system 300 are configured to introduce energy into the processing chamber 310. For example, the system 300 is configured to provide electrical energy to the electrodes 362 (e. . responsive to direction from the controller 340). The electrical energy provided to the electrodes 362 may provide plasma heating to the processingchamber 310. The plasma heating may facilitate calcining of the hot material 332 and facilitate heating of the hot material 332 and the molten material 339 which, in turn, facilitates incorporation of the cold cap 334 into the molten material 339. The plasma heating may also induce reactions between any organic material in the hot material 332 and oxygen in the processing chamber 310 to form synthesis gas. Further examples of the structures of the plasma enhanced melters and methods of using plasma enhanced melters are disclosed in U.S. Patent No. 9,771,532 issued on September 26. 2017. the disclosure of which is incorporated herein, in its entirety, by this reference.

[0072] The system 300 includes at least one EM radiation source 320. Similar to the other EM radiation sources disclosed herein, the EM radiation source 320 may be used to calcine the hot material 332. The EM radiation source 320 may also be used to heat at least one of the cold cap 334 or the molten material 339 to facilitate incorporation of the cold cap 334 into the molten material 339. It is currently believed that use of the EM radiation source 320 in a plasma enhanced melter facilitates maintaining a sufficiently high and uniform temperature in the melter. Such temperature control can be achieved using less joule heating than is possible without the EM radiation. Less joule heating in-glass, avoids the potential for over current and avoiding overheating of the glass which otherwise results in damaged refractory within the processing chamber, as can be the case if only joule heating is applied as the only means of 'defrosting' a melter (e.g., a plasma enhanced melter).

[0073] In an embodiment the EM radiation source 320 may be used to facilitate start-up of the system 300 (e g., the melter) from an idle, such as a cold or hot idle. For example, while idling the system 300, the molten material 339 may cool and, optionally, may at least partially solidify at or near a surface thereof due to radiative cooling. Just using the non-EM radiation heat sources of the system 300 (e.g.. one or more of the joule heating electrodes 360, the (plasma) electrodes 362, or the induction heating elements 380) to restart the system 300 from the idle may take significant time and energy. However, the EM radiation provided by the EM radiation source 320 may more quickly increase the temperature of the molten material 339 thereby quickening restart of the system 300 in an efficient manner. The EM radiation provided by the EM radiation source 320 may be especially effective at melting any solidified portions of the molten material 339 since the solidified portions may absorb the EM radiation e.g., the solidified portions that are spaced from a top surface to avoid emission of the molten material 339) and / or the EM radiation may reach and heat the liquid portions of the molten material 339 that are adjacent to the solidified portions.

[0074] FIG. 4 is a schematic of a system 400 for melting material, according to an embodiment. The system 400 includes a primary processing chamber 410 and calcining processing chamber 411 that is distinct and separate from the primary processing chamber 410. The calcining processing chamber 411 is configured to calcine the hot material 432 received thereby and output the calcined hot material 433 to the primary processing chamber 410 where the calcined hot material 433 is incorporated into the molten material 439. Except as otherwise disclosed herein, the primary processing chamber 410 and the calcining processing chamber 411 may be the same as or substantially similar to any of the processing chambers disclosed herein.

[0075] The calcining processing chamber 411 may be disposed in a containment structure490, such as the same containment structure 490 that holds the primary processing chamber 410. The calcining processing chamber defines a calcining interior region 413, a calcining waste inlet 431, a calcining outlet 471, and a calcining gas outlet 476. The system 400 includes at least one first EM radiation source 421 that is configured to provide the calcining EM radiation 426 to the calcining processing chamber 411 and direct the calcining EM radiation 426 towards the hot material 432 (e.g., via the waveguides 422 and the collimating device 424). As such, the hot material 432 received by the calcining processing chamber 411 may be at least partially calcined to form the calcined hot material 433 (e.g., hot material with some or all of the water content removed therefrom). The calcining waste inlet 431 and / or the calcining outlet 471 may control the rate and / or quantity of hot material 432 and calcined hot material 433 flowing therethrough, respectively, to ensure that the calcined hot material 433 is sufficiently calcined in the calcining processing chamber 411. The system 400 may include one or more sensors 450 configured to detect one or more characteristics of the calcining processing chamber 411.

[0076] The calcining processing chamber defines a primary interior region 412, a primary waste inlet 430, a primary outlet 470, and a primary gas outlet 475. The system 400 includes at least one second EM radiation source 420 that is configured to provide the primary EM radiation 425 to the primary processing chamber 410 and direct the primary EM radiation 425 towards the calcined hot material 433 (e.g., via the waveguides 422 and the collimating device 424). As such, the primary EM radiation 425 may heat at least one of the cold cap 434 or the molten material 439 to facilitate incorporation of the cold cap 434 into the molten material 439. The primary waste inlet 430 may control the rate and / or quantity of the calcined hot material 433 provided into the primary processing chamber 410. The system 400 may include one ormore sensors 450 configured to detect one or more characteristics of the primary processing chamber 410.

[0077] The calcining processing chamber 411 is in fluid communication with the primary processing chamber 410. For example, the calcining outlet 471 may be connected to the waste inlet 430 such that the calcined hot material 433 outputted from the calcining processing chamber 411 is provided to the waste inlet 430 and into the primary processing chamber 410. It is noted that the system 400 may be able to provide a continuous flow of calcined hot material 433 to the primary processing chamber 410.

[0078] The systems disclosed herein can be used in methods of efficiently melting material (e.g., waste, hot material, nuclear waste, or the like) for sequestration, isolation, or destruction in a melter. For example, FIGS. 1-4 also depict flow charts for methods of using the systems 100-400, according to embodiments.

[0079] FIG. 5 is a flow chart of a method 500 for melting material, according to an embodiment. The example method 500 includes an act 510 of, in a first stage, with the EM radiation source, generating the calcining EM radiation and directing the calcining EM radiation towards the hot material, the calcining EM radiation configured to calcine the hot material and an act 520 of, in a second stage, with the EM radiation source, generating the primary EM radiation and directing the primary7EM radiation towards the hot material. It is noted that acts 510 and 520 may be performed using any of the systems disclosed herein.

[0080] The acts 510 and 520 may include producing EM radiation (e.g., the calcining and primary EM radiations) outside of a processing chamber configured to hold hot material therein, wherein the hot material includes a molten material and a cold cap that is disposed on the molten material and is at least semi-solid, and wherein a frequency of the electromagnetic radiation may be between 750 MHz and 30 GHz. Acts 510 and 520 may include producing the EM radiation with any suitable EM radiation source, such as a microwave radiation generator.The EM radiation source may be located outside of the processing chamber. The acts 510 and 520 may include producing EM radiation exhibiting any of the parameters disclosed herein.

[0081] In examples, act 510 includes directing the calcining EM radiation in the cold cap that is effective to heat at least a portion of the cold cap, such as at least a portion of the cold cap forming an exterior surface (z. e. , a surface of the cold cap exposed to air) thereby calcining such portions of the cold cap. In examples, act 520 includes directing the primary EM radiation into the cold cap of the hot material that is effective to cause the primary EM radiation to heat a portion of the cold cap that is under an exterior surface (without heating the portion of the cold cap forming the exterior surface to a temperature in excess of a vaporization temperatureof the hot material. For instance, act 520 may include heating one or more of the interface between the cold cap and the molten material, the portion of the cold cap adjacent to the interface, or the molten material adjacent to the interface.

[0082] In act 10, the calcining EM radiation may exhibit one or more parameters such that the exterior surface temperature of the hot material is maintained at or is about 100 °C. In act 520, the primary EM radiation may exhibit one or more parameters such that the surface temperature of the hot material is maintained at or adjusted to 150 °C to 500 °C. or greater. The parameters of the primary EM radiation should be such as to keep surface emissions of the hot material (e.g., cold cap) below a selected level (e.g., below a threshold level), such as where volatilization of radioactive species (e.g., barium, cesium, iodine, strontium, technetium, xenon, etc.) or material the radioactive species is disposed in are limited to below the selected level or even prevented.

[0083] Acts 510 and 520 may include producing the EM radiation at a power level (or power supplied to the EM radiation generator) effective to cause heating of one or more portions of the cold cap without overheating the cold cap to cause emissions of one or more components of the hot material to exceed a selected level. The power level may be controlled by the controller 140. The power level may be controlled responsive to sensed information, such as temperature of the cold cap emissions from the cold cap feed rate of the hot material, etc. A suitable level power of the EM radiation to heat the cold cap without causing emissions above the selected level may be preset or vary depending upon on one or more of the geometry of the processing chamber, the chemical composition of the hot material, the thickness of the cold cap an acceptable level of emissions of the one or more components, the dry ness of the hot material before and after act 510, the other parameters of the EM radiation, the temperature of the cold cap the temperature of the molten material, etc. The suitable level of power may include any of the levels of power disclosed herein, such as 2 kW to 600 kW.

[0084] Act 520 may include producing the primary EM radiation at a power level effective produce a selected penetration depth of the primary' EM radiation into the calcined cold cap, such as in the range of 1 cm to 15 cm.

[0085] In examples, the selected level of emissions of the one or more components of the hot material (e.g., cesium, technetium, etc.) may depend on one or more of the chemical composition of the hot material, the species of the one or more components of the hot material that is emitted, the rate of processing of the hot material, the amount of hot material in the processing chamber, the duration of time that the hot material resides in the processing chamber, the parameters of the EM radiation applied to the hot material, environmentalregulations, safety standards, etc. The selected level may be based on a rate of emission, such as parts per million per minute or hour.

[0086] The acts 510 and 520 may include directing the EM radiation into the cold cap with one or more waveguides 122. For example, one or more waveguides 122 may be operably coupled to the EM radiation source and protrude to (e.g., into) the interior region 112 of the processing chamber.

[0087] In examples, acts 510 and 22 may include directing the EM radiation into the cold cap effective to cause the cold cap to have a selected temperature profile. The selected temperature profile may include a temperature at the exterior surface of the cold cap that is below the volatilization temperature of the hot material (e.g., waste material therein). The selected temperature profile may include a temperature in an interior of the cold cap that is higher than the temperature where the EM radiation is not emitted therein.

[0088] The acts of the example method 500 may be effective to heat the hot material in the cold cap to a selected temperature profile within the cold cap without causing emissions of one or more components of the hot material in the cold cap to exceed a selected level. For example, producing the EM radiation outside of a processing chamber and directing the EM radiation into the cold cap of the hot material may be effective to cause the EM radiation to heat the interior of cold cap without heating the exterior surface of the cold cap to a temperature in excess of a vaporization temperature of the one or more components (e.g., barium, cesium, iodine, strontium, technetium, xenon, etc.) of the hot material.

[0089] In examples, the method 500 may include adding hot material into the processing chamber. Adding hot material into the processing chamber may include adding any of the hot materials disclosed herein into the processing chamber via a waste inlet operably coupled thereto. The hot material may include one or more of waste particles (e.g., radioactive waste particles), dissolving agents (e.g., acids), glass particles, or dissolved particles of any of the foregoing. For example, adding the hot material into the processing chamber may include adding radioactive waste particles and glass particles into the processing chamber via a waste inlet 130 operably coupled thereto, such as in a slurry. The hot material provided to the processing chamber may include calcined hot material or uncalcined hot material.

[0090] In examples, the hot material (e g., slurry waste feed stream) may be fed in batches or continuously into the processing chamber.

[0091] In examples, adding the hot material into the processing chamber may include adding the hot material into the processing chamber so as to vary the thickness of the cold cap and thus vary the ratio of the radiation penetration depth to the cold cap thickness. The coldcap thickness could be controlled so as to achieve a selected ratio of radiation penetration depth to thickness for a given power and / or frequency. For a selected ratio this could enable selecting the power and / or frequency of the EM radiation so as to meet objectives that could include availability and cost of the EM radiation source and ease of transmitting and collimating the EM radiation. The ratio of the EM radiation penetration depth to cold cap thickness could be chosen so as to achieve a selected hot material processing (e.g., vitrification) rate or meet some other objective while limiting or eliminating emissions from the surface of the cold cap that faces the plenum.

[0092] In examples, the method 500 may include determining a temperature of the cold cap with one or more sensors. In some examples, determining the temperature of the cold cap with one or more sensors may include determining the temperature of the cold cap materials emitted from the cold cap or the temperature of the molten material. In some examples, the method 500 may include adjusting one or more parameters of the EM radiation responsive to determining the temperature. For example, adjusting one or more parameters of the EM radiation responsive to determining the temperature may include switching the EM radiation from the calcining EM radiation to the primary EM radiation, switching the primary EM radiation to the calcining EM radiation, causing the cold cap to exhibit a selected temperature profile, causing a vitrification rate of the hot material (e.g., the waste material therein), or causing a selected penetration depth of the EM radiation.

[0093] In examples, the method 500 may include collimating the EM radiation with one or more of a phased array or a radiative horn. Collimating the EM radiation with one or more of the phased array or the radiative horn may include collimating the EM radiation into one or more beams of a selected width. Collimating the EM radiation with one or more of the phased array or the radiative hom may include directing the collimated beam in one or more directions in the processing chamber. Collimating the EM radiation with one or more of the phased array or the radiative hom may include collimating the EM radiation effective to cause the EM radiation to penetrate into the cold cap to a selected depth, calcine selected portion of the hot material, etc.

[0094] The collimation of the EM radiation may allow use of the example systems and methods disclosed herein in cold crucible batch processing. In some examples, the sole source of heating of the hot material may be the EM radiation from the EM radiation source. For example, the longer penetration length of microwaves relative to millimeter wave radiation may allow examples, where EM radiation is the only form of heating in the system.

[0095] In examples, the method 500 may include joule heating the hot material in the processing chamber, such as joule heating at least the molten glass bath. In some examples, the method 500 may include induction heating the hot material in the processing chamber. In embodiments, heating the hot material in the processing chamber may include controlling one or more joule heaters or induction heaters to control the temperature of the hot material, such as to exhibit a selected temperature profile in the cold cap or process the hot material at a selected rate. In some examples, the method 500 may include heating the molten material via one or more of joule heating or induction heating, wherein the power (e.g., heating energy) supplied by the EM radiation is less than the power (e.g., heating energy) supplied by the joule heating or induction heating. For example, the power applied to joule heating electrodes of a joule heated melter may be in a range of 100 kW to 3,000 kW and the power applied to the EM radiation source may be 20 kW to 600 kW (or about kW to 150 kW). In some examples, the power applied to induction heating elements of in induction heating melter may be in a range of 10 kW to 500 kW and the power applied to the EM radiation source may be 2 kW toO kW (or about 0.5 kW to 10 kW).

[0096] In examples, the method 500 may include controlling one or more parameters of the EM radiation (e.g., microwave radiation), such as with one or more of the controller, the EM radiation source, the one or more waveguides, or the one or more collimating devices. These parameters may include one or more of power, frequency, intensity, duration, or spatial location (e.g., depth or lateral location) of the EM radiation. In some examples, controlling one or more parameters of the EM radiation may be responsive to sensor information detected by one or more sensors. The sensor information may include measurement of the temperature of the cold cap, moisture level, or emissions from heating of the surface of the molten material. In some examples, controlling one or more parameters of the EM radiation may include directing the EM radiation to one or more locations (e.g., laterally or to a depth) that have not been treated with EM radiation (e.g., for a selected amount of time). Accordingly, controlling the one or more parameters of the EM radiation may include varying one or more of the location, the frequency, or the power of the EM radiation over a selected duration of time, such as continuously or intermittently.

[0097] In an embodiment, the method 500 may include changing one or more parameters of the EM radiation, for instance, to change the EM radiation from the calcining EM radiation to the primary EM radiation, or vice versa. In some examples, the method 500 may include varying the frequency of the EM radiation, such as with the controller. In some examples, the method 500 may include adjusting one or more of the power or the frequency of the EMradiation to achieve a selected temperature profile in the cold cap. In some examples, the method 500 may include adjusting one or more of the power or the frequency of the EM radiation to a power or frequency that is effective to provide a selected EM radiation penetration depth into the cold cap, selectively heat the water, or selectively heat the cold cap and / or the molten material.

[0098] Using adjustable frequency radiation, it is possible to tune the adsorption of energy in the cold cap so that it is absorbed throughout the cold cap. thus enhancing the overall kinetics of the calcining and melting process. Such control of EM radiation may provide significant melt rate enhancement without heating the surface of the cold cap to a temperature where unwanted volatilization of constituents of the hot material (e.g., waste) would occur. The frequency of the EM radiation could be chosen so as to achieve different objectives or a combination of these objectives. One objective may be to produce a certain temperature profile (e.g., temperature as a function of distance from the interface between molten material and the cold cap) and average temperature in the cold cap. Another objective may be to achieve a selected processing rate. An additional objective may be to reduce reflection.

[0099] The control system can also be used to control the material feed rate based on information from sensors, such as temperature or emissions.

[0100] It is noted that other acts that may be included in the method 500 are apparent from the discussion of the systems 100-400.

[0101] While the method 500 is discussed with respect to “hot material” the methods disclosed herein may be used with any material, such as waste (e.g., municipal waste, nuclear waste, household waste), biomass, soil(s), or the like.

[0102] While various aspects and embodiments have been disclosed herein, other aspects and embodiments are contemplated. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting.

[0103] Terms of degree (e.g., “about,” “substantially,” “generally,” etc.) indicate structurally or functionally insignificant variations. In an example, when the term of degree is included with a term indicating quantity, the term of degree is interpreted to mean ± 10%, ±5%, or ±2% of the term indicating quantity. In an example, when the term of degree is used to modify a shape, the term of degree indicates that the shape being modified by the term of degree has the appearance of the disclosed shape. For instance, the term of degree may be used to indicate that the shape may have rounded comers instead of sharp comers, curved edges instead of straight edges, one or more protrusions extending therefrom, is oblong, is the same as the disclosed shape, etc.

Claims

CLAIMSWhat is claimed is:

1. An electromagnetic (“EM”) wave heating system configured to heat nuclear waste that is deposited in an electrically heated glass melter, the system comprising: at least one EM radiation source configured to generate EM radiation; and a controller configured to control at least the at least one EM radiation source, wherein, the controller is configured to cause the at least one EM radiation source to: in a first stage, to generate a calcining EM radiation exhibiting first parameters and direct the calcining EM radiation towards the nuclear waste, the calcining EM radiation selected to at least partially calcine the nuclear waste; and in a second stage after the first stage, generate primary EM radiation exhibiting second parameters and direct the primary EM radiation towards the nuclear waste, the primary EM radiation selected to pass through the calcined nuclear waste and heat a desired portion of a molten glass or a cold cap thereon containing the calcined nuclear waste; wherein the first parameters are different than the second parameters; and wherein the first parameters and the second parameters include at least one of EM wave power, EM wave intensity (power per cm2), EM wave frequency, or EM wave heating duration.

2. The EM wave heating system of claim 1, further comprising one or more sensors configured to measure a temperature of the nuclear waste that sits on top of the molten glass; and wherein the controller is configured to select at least one of the first parameters or the second parameters responsive to measuring the temperature of the nuclear waste that sits on top of the molten glass.

3. The EM wave heating system of claim 1. further comprising one or more sensors configured to measure a temperature of the molten glass under the nuclear waste; and wherein the controller is configured to select at least one of the first parameters or the second parameters responsive to measuring the temperature of the molten glass under nuclear waste.

4. The EM wave heating system of claim 1, further comprising at least one processing chamber defining an interior region, a waste inlet, and a waste outlet; and wherein the controller is communicably coupled to the waste inlet, the controller configured to direct the inlet to introduce the nuclear waste into the interior region in batches.

5. The EM wave heating system of claim 4, wherein the controller is configured to direct the waste inlet to introduce a new batch of the nuclear waste after a previous batch of the nuclear waste is incorporated into the molten glass; and wherein the controller directs the at least one EM radiation source to generate the EM radiation and direct the EM radiation towards the molten glass between incorporating the previous batch of the nuclear waste into the molten glass and before introducing the new batch of the nuclear waste.

6. The EM wave heating system of claim 1 , wherein the at least one EM radiation source includes at least one first EM radiation source configured to generate and emit at least the calcining EM radiation and at least one second EM radiation source configured to generate and emit at least the primary EM radiation.

7. The EM wave heating system of claim 6, further comprising a processing chamber defining an interior region, the at least one first EM radiation source configured to generate and emit at least the calcining EM radiation into the interior region and the at least one second EM radiation source configured to generate and emit at least the primary EM radiation into the interior region.

8. The EM wave heating system of claim 6, further comprising a calcining processing chamber defining a calcining interior region and a primary processing chamber defining a primary interior region, the calcining interior region being distinct and separate from the primary interior region, the at least one first EM radiation source is configured to generate and emit at least the calcining EM radiation into the calcining interior region, and the at least one second EM radiation source is configured to generate and emit at least the primary EM radiation into the primary interior region.

9. A method of using the EM wave heating system of claim 1, wherein the method comprises: heating nuclear waste that is deposited on a molten glass in an electrically heated glass melter with the EM wave heating system, wherein heating the nuclear waste includes: in a first stage, with the at least one EM radiation source, generating a calcining EM radiation and directing the calcining EM radiation towards the nuclear waste to at least partially calcine the nuclear waste; and in a second stage, with the at least one EM radiation source, generating primary EM radiation and directing the primary EM radiation towards the nuclear waste, the primary EM radiation selected to pass through the calcined nuclear waste and heat a desired portion of a cold cap of calcined nuclear waste or molten glass on which thecold cap sits.

10. A system, comprising: at least one processing chamber defining an interior region, a waste inlet, and a waste outlet; one or more heating elements configured to heat one or more hot materials disposed in the interior region; at least one electromagnetic (“EM ’) radiation source configured to generate EM radiation and direct the EM radiation towards the one or more hot materials disposed in the interior region; and a controller configured to control at least the one or more heating elements and the at least one EM radiation source; wherein, the controller is configured to cause the at least one EM radiation source to: in a first stage, generate calcining EM radiation exhibiting first parameters and direct the calcining EM radiation towards the one or more hot materials, the calcining EM radiation selected to at least partially calcine the one or more hot materials; and in a second stage, generate primary EM radiation exhibiting second parameters and direct the primary EM radiation towards the one or more hot materials, the primary EM radiation selected to at least partially pass through the one or more hot materials to heat at least one of a portion of a cold cap of the one or more hot materials under a top surface of the cold cap or a desired location of a molten glass on which the cold cap containing the one or more hot materials sits; and wherein the first parameters are different than the second parameters.

11. The system of claim 10, wherein the at least one EM radiation source includes at least one first EM radiation source configured to generate at least the calcining EM radiation and at least one second EM radiation source configured to generate at least the primary EM radiation.

12. The system of claim 11, wherein the at least one first EM radiation source is configured to emit at least the calcining EM radiation into the interior region and the at least one second EM radiation source is configured to emit at least the primary EM radiation into the interior region.

13. The system of claim 11, wherein the at least one processing chamber includes a calcining processing chamber and a primary processing chamber, the interior region of the calcining processing chamber is distinct and separate from the interior region of the primary processing chamber, the waste outlet of the calcining processing chamber in fluidcommunication with the waste inlet of the primary processing chamber, the at least one first EM radiation source is configured to generate and emit at least the calcining EM radiation into the interior region of the calcining processing chamber and the at least one second EM radiation source is configured to generate and emit at least the primary EM radiation into the interior region of the primary' processing chamber.

14. The system of claim 10, further comprising one or more sensors configured to measure a temperature of the one or more hot materials that sits on top of the molten glass; and wherein the controller configured to select at least one of the first parameters or the second parameters responsive to measuring the temperature of the nuclear waste that sits on top of the molten glass.

15. The system of claim 10, further comprising one or more sensors configured to measure a temperature of the molten glass under the cold cap of the one or more hot materials; and wherein the controller is configured to select at least one of the first parameters or the second parameters responsive to measuring the temperature of the molten glass under the cold cap of the one or more hot materials.

16. The system of claim 10, wherein: the one or more heating elements includes at least one electrode extending into the interior region of the at least one processing chamber; and the controller is configured to cause the at least one EM radiation source to generate the EM radiation and direct the EM radiation towards at least one of the cold cap, a liquid molten glass, or an at least partially solidified molten glass while in idle mode or while transitioning from idle mode to full operation.

17. A method of using the system of claim 10. the method comprising: responsive to receiving instructions from the controller, with the at least one EM radiation source, generating the calcining EM radiation and directing the calcining EM radiation towards the one or more hot materials to at least partially calcine the one or more hot materials; and responsive to receiving instructions from the controller, with the at least one EM radiation source, generating the primary EM radiation and directing the primary EM radiation towards the one or more hot materials to heat at least one of the portion of the cold cap of the one or more hot materials under the top surface of the cold cap or the desired portion of the molten glass on which the cold cap of the one or more hot materials sit.

18. The method of claim 17, wherein generating the primary EM radiation anddirecting the primary' EM radiation towards the one or more hot materials is performed after generating the calcining EM radiation and directing the calcining EM radiation towards the one or more hot materials.

19. The method of claim 17, wherein generating the calcining EM radiation and directing the calcining EM radiation towards the one or more hot materials and generating the primary’ EM radiation and directing the primary EM radiation towards the one or more hot materials includes emitting the calcining EM radiation and the primary EM radiation into the same interior region.

20. The method of claim 17, wherein: the at least one EM radiation source includes at least one first EM radiation source configured to generate at least the calcining EM radiation and at least one second EM radiation source configured to generate at least the primary EM radiation; the at least one processing chamber includes a calcining processing chamber and a primary' processing chamber, the interior region of the calcining processing chamber is distinct and separate from the interior region of the primary processing chamber, the waste outlet of the calcining processing chamber in fluid communication with the waste inlet of the primary processing chamber; generating the calcining EM radiation and directing the calcining EM radiation towards the one or more hot materials includes generating the calcining EM radiation with the at least one first EM radiation source and directing the calcining EM radiation towards the one or more hot material in the interior region of the calcining processing chamber; and generating the primary' EM radiation and directing the primary' EM radiation towards the one or more hot materials includes generating the primary EM radiation with the at least one second EM radiation source and directing the primary EM radiation towards the one or more hot material in the interior region of the primary processing chamber.

21. The method of claim 17, wherein at least a portion of generating the primary EM radiation and directing the primary’ EM radiation towards the one or more hot materials is performed simultaneously with at least a portion of generating the calcining EM radiation and directing the calcining EM radiation towards the one or more hot materials.

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