Electromagnetic heating for vitrification
Methods and systems for melting or augmenting a melt rate of material in a melter using electromagnetic radiation with a frequency between 0.9 GHz and 10 GHz. In some examples, a power and/or frequency of radiation used may be selected so as to control a temperature of a cold cap in the melter while maintaining emissions from the melter below a threshold level. In this manner, examples described herein may provide for efficient and safe melting and vitrification of radioactive wastes.
1. A system, comprising:
a processing chamber configured to hold hot material therein, wherein the hot material includes a molten portion and a cold cap that is disposed on the molten portion and is at least semi-solid;
an electromagnetic radiation source located outside of the processing chamber and configured to selectively generate electromagnetic radiation with a frequency between 0.9 GHz and 10 GHz;
one or more waveguides operably coupled to the electromagnetic radiation source and configured to guide the electromagnetic radiation into the cold cap of the hot material in the processing chamber; and
a controller operably coupled to the electromagnetic radiation source, wherein the controller is configured to selectively adjust one or more of a power or the frequency of the electromagnetic radiation to selectively control a temperature profile in the cold cap while preventing emissions of volatile components from the cold cap from exceeding a selected level,
wherein the cold cap includes a calcined portion and a solid portion, the calcined portion is disposed between the solid portion and the molten portion, and
wherein the controller is further configured to cause the electromagnetic radiation to heat the calcined portion of the cold cap without heating the solid portion.
2. The system of claim 1 , further comprising one or more collimating devices operably coupled to the one or more waveguides, wherein the one or more collimating devices are configured to collimate the electromagnetic radiation.
3. The system of claim 2 , wherein the one or more collimating devices includes one or more radiative horns operably configured to collimate the electromagnetic radiation.
4. The system of claim 2 , wherein the one or more collimating devices includes one or more phased arrays configured to collimate the electromagnetic radiation.
5. The system of claim 1 , further comprising at least one of one or more sensors positioned and configured to sense a temperature of the cold cap or positioned and configured to measure emissions from a surface of the cold cap.
6. The system of claim 5 , wherein the controller is configured to receive a sensed temperature of the cold cap and in response thereto, selectively adjust the power of the electromagnetic radiation.
7. The system of claim 5 , wherein the controller is configured to receive the sensed temperature of the cold cap and in response thereto, selectively adjust the frequency of the electromagnetic radiation emitted from the electromagnetic radiation source.
8. The system of claim 5 , wherein the controller is configured to control a pre-drying of the hot material that is introduced into the processing chamber based on one or more of a sensed temperature or emissions detected by the one or more sensors.
9. The system of claim 1 , further comprising one or more sensors positioned to measure a volatile material in gases emitted from the processing chamber, wherein the volatile material includes cesium or technetium.
10. The system of claim 1 , wherein the system includes one or more joule heating electrodes positioned and configured to heat the molten portion.
11. The system of claim 1 , wherein the system includes one or more induction heating elements positioned and configured to heat the molten portion.
12. The system of claim 1 , wherein the electromagnetic radiation source is the only means of heating the hot material.
13. The system of claim 1 , wherein a maximum depth of the molten portion is less than 15 cm.
14. The system of claim 1 , wherein the electromagnetic radiation source is configured to emit the electromagnetic radiation at a frequency and power effective produce a penetration depth of the electromagnetic radiation into the cold cap of 1 cm to 15 cm.
15. The system of claim 1 , wherein the controller is configured to alter the frequency of the electromagnetic radiation to provide a selected temperature profile in the cold cap.
16. The system of claim 1 , wherein:
the processing chamber is configured to contain radioactive material; and
the hot material includes radioactive material.