Managing volatiles in nuclear waste vitrification
11508490 · 2022-11-22
Inventors
Cpc classification
B01J20/165
PERFORMING OPERATIONS; TRANSPORTING
B01J20/043
PERFORMING OPERATIONS; TRANSPORTING
B01J20/06
PERFORMING OPERATIONS; TRANSPORTING
B01J20/0288
PERFORMING OPERATIONS; TRANSPORTING
B01J20/12
PERFORMING OPERATIONS; TRANSPORTING
B01J20/186
PERFORMING OPERATIONS; TRANSPORTING
International classification
B01J20/04
PERFORMING OPERATIONS; TRANSPORTING
B01J20/06
PERFORMING OPERATIONS; TRANSPORTING
Abstract
Dangerous, toxic, and/or radioactive volatiles are produced from nuclear fission, nuclear decay, and/or as a byproduct from vitrification of radioactive wastes. Such volatiles are treated during and after vitrification of the radioactive waste, to be converted into fixed-chemicals, that are retained in, on, and/or proximate to a cold-cap located vertically above vitrified melt. The cold-cap may have one or more volatile fixing additives (VFAs) for retaining the fixed-chemicals. The VFAs are located in and/or the cold-cap. The vitrification may occur within at least one human-made cavern. The human-made cavern may be located within a deep geologic rock formation. The deep geologic rock formation may be located at least 2,000 feet below a terrestrial surface of the Earth. The human-made cavern may be formed by first drilling a wellbore from the terrestrial surface to the deep geologic rock formation and then underreaming the wellbore into the deep geologic rock formation.
Claims
1. A method for managing at least one volatile chemical produced from nuclear operations and/or produced from vitrification of waste within a vitrification chamber, the method comprising steps of: (a) filling the vitrification chamber with a predetermined quantity of radioactive waste; (b) installing at least a portion of a heater system to the vitrification chamber, wherein the heater system is configured to vitrify the predetermined quantity of the radioactive waste within the vitrification chamber; (c) energizing the heating system to heat the predetermined quantity of the radioactive waste within the vitrification chamber; (d) initiating a cold-cap vertically above the predetermined quantity of radioactive waste that is within the vitrification chamber; wherein vertical in this context is substantially parallel with a direction of pull of a gravitational field at the vitrification chamber; wherein the cold-cap thermally insulates a closest portion vertically above the cold-cap from portions of the vitrification chamber below the cold-cap; (e) adding at least one predetermined volatile-fixing-additive to the cold-cap, wherein the at least one predetermined volatile-fixing-additive is configured to convert most of the at least one volatile chemical into at least one fixed-chemical; wherein the at least one fixed-chemical is retained in the cold-cap; and (f) vitrifying the predetermined quantity of the radioactive waste within the vitrification chamber using the heater system resulting in a glass-waste-product and resulting in at least some of the at least one volatile chemical.
2. The method according to claim 1, wherein the at least one volatile chemical is a volatile chemical that comprises at least one element or isotope of the following chemical species: iodine.
3. The method according to claim 1, wherein the at least one volatile chemical is radioactive.
4. The method according to claim 1, wherein the vitrification chamber is at least one human-made cavern.
5. The method according to claim 4, wherein the at least one human-made cavern is located within a deep geologic rock formation; wherein the deep geologic rock formation is at least 2,000 feet below a terrestrial surface of the Earth.
6. The method according to claim 1, wherein the cold-cap is located within the vitrification chamber.
7. The method according to claim 1, wherein the method prior to the steps (a) through (f) first comprises a step of analyzing the radioactive waste to be filled in the step (a) to determine identification of the at least one volatile chemical.
8. The method according to claim 7, wherein the analyzing of the radioactive waste and the identification determination of the at least one volatile chemical utilizes one or more of the following techniques: chemical reaction simulation software running on a computer, empirical analysis, and/or chemical analysis of a sample of the radioactive waste and resulting products from a small-scale laboratory vitrification batch test run.
9. The method according to claim 7, wherein after the identification of the at least one volatile chemical, the method further comprises a step of determining and identifying the at least one predetermined volatile-fixing-additive.
10. The method according to claim 1, the at least one volatile-fixing-additive is selected from one or more of the following chemical species: silver; silver nitrate (AgNO.sub.3); an absorbent with silver; silver compounds; silver chloride (AgCl); silver iodide (AgI); silver hydroxide (AgOH); an absorbent with silver from a silver ion zeolite exchange system; a silver compound made from using silver ion exchange on a support matrix of faujasite and mordenite; a silica gel matrix impregnated with silver nitrate.
11. The method according to claim 1, wherein when the at least one volatile chemical comprises iodine, then the at least one predetermined volatile-fixing-additive is selected from one or more of the following chemical species: silver, silver nitrate, an absorbent with silver from a silver ion zeolite exchange system, a silver compound made from using silver ion exchange on a support matrix of faujasite and mordenite, or a silica gel matrix impregnated with silver nitrate.
12. The method according to claim 1, wherein when the at least one volatile chemical comprises cesium, then the at least one predetermined volatile-fixing-additive is selected from one or more of the following chemical species: metakaolin, bentonite, or pyrophyllite.
13. The method according to claim 1, wherein when the at least one volatile chemical comprises carbon-14, then the at least one predetermined volatile-fixing-additive is selected from one or more of the following chemical species: sodium hydroxide, calcium hydroxide, barium hydroxide, magnesium, an alkali metal hydroxide, an alkaline earth hydroxide, ascarite, LiOH.H.sub.2O, soda lime, baralyme, sodium zeolite, natural mordenite, hydrogenated mordenite, or modified hydrogenated mordenite.
14. The method according to claim 1, wherein when the at least one volatile chemical comprises tritium, then the at least one predetermined volatile-fixing-additive is selected from one or more of the following chemical species: hydrogen comprising manganese oxide having a spinel crystal structure, hydrogen-containing manganese oxide of formula, H.sub.xMn.sub.2O.sub.4, having a spinel crystal structure, lithium containing manganese oxide having a spinel crystal structure, or lithium-containing manganese oxide of formula, Li.sub.xMn.sub.2O.sub.4, having a spinel crystal structure.
15. The method according to claim 1, wherein when the at least one volatile chemical comprises technetium, then the at least one predetermined volatile-fixing-additive is selected from one or more of the following chemical species: an alkaline earth metal carbonate, calcium carbonate, barium carbonate, strontium carbonate, an alkaline earth metal oxide, calcium oxide, barium oxide, or strontium oxide.
16. The method according to claim 1, wherein when the at least one volatile chemical comprises cadmium, then the at least one predetermined volatile-fixing-additive is an aluminosilicate kaolinite with a chemical formula of Al.sub.2Si.sub.2O.sub.5(OH).sub.4.
17. The method according to claim 1, wherein when the at least one volatile chemical comprises molybdenum, then the at least one predetermined volatile-fixing-additive is selected from one or more of the following chemical species: sodium carbonate, calcium oxide, an aluminosilicate, or tin oxide.
18. The method according to claim 1, wherein when the at least one volatile chemical comprises antimony, then the at least one predetermined volatile-fixing-additive is selected from one or more of the following chemical species: silver, silver chloride, silver iodide, or calcium oxide.
19. The method according to claim 1, wherein when the at least one volatile chemical comprises selenium and/or tellurium, then the at least one predetermined volatile-fixing-additive is selected from one or more of the following chemical species: silver, silver hydroxide, or calcium oxide.
20. The method according to claim 1, wherein when the at least one volatile chemical comprises rhenium, then the at least one predetermined volatile-fixing-additive is selected from one or more of the following chemical species: calcium oxide, calcium carbonate, an aluminum silicate compound.
21. The method according to claim 1, wherein when the at least one volatile chemical comprises ruthenium, then the at least one predetermined volatile-fixing-additive is selected from one or more of the following chemical species: an alkaline earth metal carbonate, calcium carbonate, barium carbonate, strontium carbonate, an alkaline earth metal oxide, calcium oxide, barium oxide, strontium carbonate, ferric oxide, yttium oxide (Y.sub.2O.sub.3), lithium oxide (Li.sub.2O), or titanium dioxide.
22. The method according to claim 1, wherein when the at least one volatile chemical comprises rhodium, then the at least one predetermined volatile-fixing-additive is selected from one or more of the following chemical species: calcium carbonate or a borosilicate.
23. The method according to claim 1, wherein the step (e) occurs before or during the step (f).
Description
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
(1) Elements in the figures have not necessarily been drawn to scale in order to enhance their clarity and improve understanding of these various elements and embodiments of the invention. Furthermore, elements that are known to be common and well understood to those in the industry are not depicted in order to provide a clear view of the various embodiments of the invention.
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REFERENCE NUMERAL SCHEDULE
(27) 100 calciner/vitrifier 100 101 waste (contaminated soil) (melt) 101 103 inlet 103 105 melt chamber 105 107 (graphite) electrode 107 109 glass product (or crystalline product) 109 111 outlet 111 113 storage container 113 115 off-gas 115 117 outlet vent 117 119 cold cap 119 121 support 121 200 system for in-situ waste vitrification 200 201 human-made cavern 201 203 wellbore 203 207 deep geologic formation 207 209 Earth's surface (ground level) 209 211 waste 211 213 rig 213 215 power-source 215 217 site (wellhead) 217 219 cabling 219 221 heater 221 223 vane/mixer 223 225 weight 225 227 cold-cap 227 229 top 229 (of human-made cavern 201) 231 top 231 (of cold-cap 227) 233 bottom 233 (of cold-cap 227) 235 volatiles 235 235a off-gas-post-treatment 235a 235b off-gas in formation 235b 235c leading-edge of off-gas in formation 235c 237 gas-cap 237 239 casing 239 241 downhole sealing packer 241 243 boundary 243 (between different rock/formations) 245 side-wall 245 (of human-made cavern 201) 301 bottom 301 311 cooler upper zone 311 313 warmer lower zone 313 315 boundary layer 315 321 insulating (sealing) blanket 321 500 method of managing vitrification produced volatiles in deep underground cavern 500 501 step of determining volatiles from vitrification 501 502 step of constructing and/or installing necessary infrastructure and/or hardware 502 503 step of determining VFA(s) to react with the determined volatiles 503 505 step of loading waste, frit, and/or glass former materials into human-made cavern 505 507 step of energizing heaters initiating cold-cap above waste in human-made cavern 507 509 step of vitrifying the waste, frit, and/or glass former materials in cavern 509 511 step of produced volatiles penetrating and/or permeating into cold-cap 511 513 step of adding (introducing) VFA(s) to cold-cap for reaction with volatiles 513 515 step of the vitrification process continuing until completion 515 517 step of installing insulating blanket in human-made cavern above cold-cap 517 519 step of determining if a given cavern is full or can accept more waste 519 521 step of shutting down and/or sealing off wellbore(s) and/or cavern(s) 521 523 step of installing at least portions of vitrification means into cavern(s) 523 600 method of determining cold-cap components 600 601 step of quantitative chemical analysis 601 603 step of selecting sorbent(s) and/or reagent(s) for use in cold-cap 603 605 step of defining/determining cold-cap component(s) 605 607 step determining if other vitrification processes contemplated 607
DETAILED DESCRIPTION OF THE INVENTION
(28) In this patent application, the terms “radioactive material,” “radioactive waste,” “nuclear material,” “nuclear waste,” and/or “high-level nuclear waste” (HLW) may be used interchangeably. In addition, the term “waste” generally means nuclear and/or radioactive waste of any kind.
(29) “Chemical” as used herein may refer to a substance with a distinct and/or predetermined molecular structure; a substance with a molecular formula disclosed herein; and/or a substance with a commonly and readily understood common name (e.g., a carbonate as a common name is commonly and readily understood to include CO.sub.3).
(30) In this patent application, the terms “fixing,” “trapping,” “immobilizing,” and/or “stabilizing” may refer to a process wherein a volatile material/chemical is absorbed or adsorbed by another material or compound (reagent); and/or is converted from a volatile species to a non-volatile species (e.g., converted into a solid, liquid, and/or gel like species). Further, the converted former volatile species may be retained in/on (and/or near) a cold-cap as a solid (or solid like). These chemicals, chemical species, materials, compounds, and/or reagents that interact with the given volatile to result in retention of the former volatile in the cold-cap may be referred to as a “volatile fixing additive” (VFA) and/or as “at least one volatile-fixing-additive” within the claims. “Volatile fixing additive,” “volatile-fixing-additive,” VFA, and/or reagent may be used interchangeably herein.
(31) In this patent application, “formation,” “zone,” “host,” “host rock,” and/or “rock medium,” may be used interchangeably; and unless otherwise specified, may refer to a rock structure within a “deep geological formation” that may be hosting (housing) one or more human-made caverns.
(32) In this patent application, the terms “cavern,” and “cavity” may be used interchangeably with a same meaning. Further, “cavern” or “cavity” may mean a cavern/cavity that may be human-made (e.g., from underreaming operations within a given deep geologic formation).
(33) In this patent application, the terms “well” and “wellbore” may be used interchangeably and may refer to cylindrical drilled out elements implemented in design and/or installation processes of some embodiments of the present invention.
(34) In this patent application, “vertical wellbores” need not be geometrically perfectly vertical; but rather may be substantially vertical (e.g., more vertical than horizontal with respect to the Earth's surface). That is, a vertical wellbore may be substantially (mostly) parallel with a direction of a local gravitational field. Conversely, “horizontal” may be substantially (mostly) orthogonal with a direction of a local gravitational field.
(35) In this patent application, the terms “single well” or “common well” may refer to a wellbore that may be shared.
(36) In this patent application, the terms “wellbore packer,” “packer,” “wellbore seal,” “HYDRIL,” may be used interchangeably to mean a sealing device or a sealing system to seal an internal bore of a given wellbore.
(37) In this patent application, the term “ream,” “underream” and/or “under-ream” may be used interchangeably to mean the enlarging of a wellbore or hole in a rock medium.
(38) Note, as used herein: “° C.” may be an abbreviation for degrees Celsius; “mol” may be an abbreviation for “mole”; “g” may be an abbreviation for “grams”; “(g)” in a chemical reaction equation may be an abbreviation for gas phase; and “(s)” in a chemical reaction equation may be an abbreviation for solid phase. Unless otherwise stated, temperatures (temp) noted herein are in degrees Celsius (° C.).
(39) Various embodiments of the present invention show, describe, and teach management, treatment, fixing, trapping, stabilization, immobilization, conversion, and/or the like of various dangerous and/or undesirable volatiles into chemical species that may be generally be retained in, on, and/or near a cold-cap. These dangerous and/or undesirable volatiles may be radioactive and/or toxic to many ecosystems and/or environments. These dangerous and/or undesirable volatiles may be byproducts from nuclear operations (e.g., fission and/or decay) and/or may be byproducts from vitrification processes of nuclear waste products.
(40) Some embodiments of the invention may be described with non-limiting examples. In all examples, the volatile materials produced may be managed by sequestering the modified products (i.e., the former volatile) in, on, and/or near the cold cap region of the vitrification system.
(41) In the following description, and for the purposes of explanation, numerous specific details, apparatus, devices, systems, methods, process steps, process steps, process durations, and/or specific chemical formula are set forth in order to provide a thorough understanding of the various aspects of the various embodiments of the present invention. It will be understood, however, by those skilled in the relevant arts, that the apparatus, systems, and methods herein may be practiced without each and every of such these specific details, process durations, and/or specific chemical formula. It is to be understood that other embodiments may be utilized, and structural and functional changes may be made without departing from the scope of the apparatus, systems, and methods herein.
(42) In other instances, known structures and devices are shown or discussed more generally in order to avoid obscuring the embodiments. In many cases, a description of the operation is sufficient to enable one to implement the various forms, particularly when the operation analysis is to be implemented in analytical simulations. It should be noted that there are many different and alternative configurations, devices, and technologies to which the disclosed embodiments may be applied. The full scope of the embodiments is not limited to the examples that are described below.
(43) In the following examples of the illustrated embodiments, references are made to the accompanying chemical equations, that are molarly balanced, and in which is shown by way of illustration various embodiments in which the systems, methods, processes, and/or apparatuses disclosed herein may be practiced. It is to be understood that other embodiments may be utilized, and structural and functional changes may be made without departing from the scope.
(44) The present invention may be explained in greater detail in the following non-limiting examples for the treatment of various volatiles produced during the vitrification process for high level waste disposal.
(45) As noted above, embodiments of the present invention may describe various devices, apparatus, systems, mechanisms, means, methods, processes, and/or the like for the management of volatiles produced during the vitrification of radioactive materials and other waste products and/or volatiles resulting from nuclear operations. This vitrification may occur in surface systems or within human-made subterranean cavities within deep geological formations. In some embodiments, sequential operations of the vitrification process may be implemented.
(46) In some embodiments, a method may provide an operational method for nuclear waste disposal. Such operational methods described herein may provide more efficient methodology to allow safer, more economical and long-lasting disposal of the nuclear waste in the deep underground human-made caverns.
(47) The novel features which are considered characteristic for various embodiments of the invention are set forth in the appended claims. Embodiments of the invention itself, however, both as to its construction and its methods of operation, together with additional objects and advantages thereof, will be best understood from the following description of the specific embodiments when read and understood in connection with the accompanying drawings. Attention is called to the fact, however, that the drawings are illustrative only, and that changes may be made in the specific construction illustrated and described within the scope of the appended claims. In addition, certain elements may be omitted from certain drawings to enhance clarity without detracting from the meaning or the idea taught in the drawing.
(48) These and other advantages and features of the present invention are described herein with specificity so as to make the present invention understandable to one of ordinary skill in the art, both with respect to how to practice the present invention and how to make the present invention.
(49) In the following discussion that addresses a number of embodiments and applications of the present invention, reference is made to the accompanying drawings that form a part thereof, where depictions are made, by way of illustration, of specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and changes may be made without departing from the scope of the invention.
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(51) Continuing discussing
(52) In practice, the prior art technology taught in
(53) Embodiments of the current in-situ vitrification of waste materials inventions may provide significant advantages and improvements over the
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(57) The prior art vitrification processes “batch process” relatively small volumes of waste/melt 101. In one example, a Direct Liquid Fed Ceramic Melt system with melter dimensions of 1.22 meter×0.86 meter×0.71 meter produced about 25 kilograms (kg) of melt 101 per hour. The volumetric capacity of that prior art melter was estimated at 744 liters of melt 101. Whereas and in contrast, the embodiments contemplated in this invention, based on the projected deep underground human-made cavern 201 dimensions, may provide for melt 211 volumes significantly greater than prior art levels. Based on the projected dimensions of the underground human-made cavern 201, the embodiments taught herein may process between 20,000 liters to 500,000 liters of melt 211 per underground human-made cavern 201. And such melt 211 processing may occur over a matter of days depending on the heater 221 capacity and electric energy deliverability from the Earth's surface 209. By comparison, a Russian process discussed in the prior art, produced 160 tons melt 101 over an 18-month period. There is a great (and long felt) need for embodiments which can process the very large volumes of high-level waste (radioactive waste) that is present worldwide today (2020).
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(61) Note, even portions of deep geologic formation 207 near and/or proximate to human-made cavern 201 may be substantially unheated (i.e., not show a significant temperature increase), during vitrification, as the size and mass of deep geologic formation 207 far exceeds the size and mass of waste 211 within the given human-made cavern 201. That is, deep geologic formation 207 acts as a tremendous heat sink. Additionally, residual heating from the Earth's core greatly surpasses heating capacity from heater(s) 221, that is a temperature of deep geologic formation 207 is largely unchanged and largely dictated by the Earth's core.
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(65) In some embodiments, weight(s) 225 may provide continuous tension loading of cabling 219 and heater 221 at all times when these portions of the vitrification means are within wellbore 203 and human-made cavern 201. In some embodiments, weight(s) 225 may maintain cabling 219 (always) in tension for proper operational purposes in much the same way as “sinker rods” used below the sucker rods in pumping operations to maintain constant tension in sucker rods during oil well pumping field operations.
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(68) In one particular prior art dataset, a temperature range is reported from a high of 1,100 degrees Celsius (° C.) within the melt 101, to about 100 Celsius (° C.) at the top of the cold cap layer 119. Such a similar change in temperatures, or more, may be expected in the vitrification process occurring within the human-made cavern 201 of the present invention.
(69) Continuing discussing
(70) In some embodiments, cold-cap 227 may behave like a “fluidized bed reactor” (FBR), which is well known in the art, particularly when off-gas 235 may be generated during and shortly after vitrification and this off-gas 235 may be flowing up and into cold-cap 227, much like the fluid does in a FBR. In a FBR, multiple chemical reactions may be occurring back-to-back and/or simultaneously within that same FBR device (reactor) in which there is a vertical gradation from the bottom of the reactor system to the top. In some embodiments, the reacting materials in cold-cap 227 may exist in a mostly in a fluidized state.
(71) See also
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(73) Note, reference numeral “235” may refer to volatiles/off gases from vitrification of waste 211 and/or from nuclear operations of waste 211 before and during cold-cap 227 treatment; whereas, reference numerals “235a” may refer to off gases post cold-cap 227 treatment; reference numeral “235b” may refer to off gases (also post cold-cap 227 treatment) in formation 207; and reference numeral “235c” may refer to the leading edge of the off gases (also post cold-cap 227 treatment) in formation 207.
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(75) In some embodiments, vitrification of waste/melt 211 (and/or nuclear operations of waste 211, such as nuclear decay) may produce one or more of: at least one volatile chemical produced from nuclear operations and/or produced from vitrification of waste 211 within a vitrification chamber (e.g., human-made cavern 201); radioactive gases; radioactive volatiles; volatile cadmium (Cd); volatile cesium (Cs); volatile rhodium (Ru); volatile rhenium (Re); volatile molybdenum (Mo); volatile tellurium (Te); volatile antimony (Sb); volatile selenium (Se); volatile technetium (Tc); volatile carbon (.sup.14C); volatile iodine (.sup.129I); volatile tritium (.sup.3H); isotopes thereof; portions thereof; combinations thereof; and/or the like.
(76) In some embodiments, off-gas 235 may be one or more of the following gases: gas products and/or byproducts from nuclear operations (e.g., fission and/or nuclear decay) of waste 211; gas products and/or byproducts from vitrification of waste 211; at least one volatile chemical produced from nuclear operations and/or produced from vitrification of waste 211 within a vitrification chamber (e.g., human-made cavern 201); radioactive gases; radioactive volatiles; volatile cadmium (Cd); volatile cesium (Cs); volatile rhodium (Ru); volatile rhenium (Re); volatile molybdenum (Mo); volatile tellurium (Te); volatile antimony (Sb); volatile selenium (Se); volatile technetium (Tc); volatile carbon (.sup.14C); volatile iodine (.sup.129I); volatile tritium (.sup.3H); isotopes thereof; portions thereof; combinations thereof; and/or the like.
(77) In some embodiments, at least one volatile chemical produced from nuclear operations and/or produced from vitrification of waste 211 within a vitrification chamber (e.g., human-made cavern 201) may comprise one or more of: radioactive gases; radioactive volatiles; volatile cadmium (Cd); volatile cesium (Cs); volatile rhodium (Ru); volatile rhenium (Re); volatile molybdenum (Mo); volatile tellurium (Te); volatile antimony (Sb); volatile selenium (Se); volatile technetium (Tc); volatile carbon (.sup.14C); volatile iodine (.sup.129I); volatile tritium (.sup.3H); isotopes thereof; portions thereof; combinations thereof; and/or the like. In some embodiments, the at least one volatile chemical may be a volatile chemical at temperatures present during steps 509, 511, 513, and/or 515 of method 500, see e.g.,
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(80) Note in
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(82) Chemical absorption involves a chemical reaction between the substance being absorbed and the absorbing medium. In some cases, chemical absorption occurs in combination with physical absorption. Chemical absorption may depend upon the stoichiometry of the reaction and the concentration of the reactants.
(83) Chemical adsorption, also known as chemisorption, on solid materials is achieved by substantial sharing of electrons between the surface of adsorbent and adsorbate to create a covalent or ionic bond. Chemisorption capacity may quantify the ability of a given absorbent to absorb the adsorbate material.
(84) In some embodiments, the volatile 235 and/or gaseous compounds (constituents) to be managed by cold-cap 227 VFAs and/or other cold-cap 227 reagents may be one or more of the following: volatile cadmium (Cd); volatile cesium (Cs); volatile rhodium (Ru); volatile rhenium (Re); volatile molybdenum (Mo); volatile tellurium (Te); volatile antimony (Sb); volatile selenium (Se); volatile technetium (Tc); volatile carbon (.sup.14C); volatile iodine (.sup.129I); volatile tritium (.sup.3H); portions thereof; combinations thereof; and/or the like. In some embodiments, volatile cadmium (Cd); volatile cesium (Cs); volatile rhodium (Ru); volatile rhenium (Re); volatile molybdenum (Mo); volatile tellurium (Te); volatile antimony (Sb); volatile selenium (Se); volatile technetium (Tc); volatile carbon (.sup.14C); volatile iodine (.sup.129I); volatile tritium (.sup.3H); portions thereof; combinations thereof; and/or the like, may be produced from waste 211 and/or from vitrification of waste 211. In some embodiments, this list of volatiles 235 may be dangerous and/or radioactive. It may be desirable to treat such volatiles 235 to render them more safe and less dangerous (e.g., less radioactive).
(85) Continuing discussing
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(89) In some embodiments, the insulative blanket 321 may comprise of commercially available silica aerogel powder/granules and/or similar type products. In some embodiments, the insulative blanket 321 may be several inches thick. In some embodiments, silica aerogel powder/granules and/or similar type products may provide the physical and thermal qualities for insulative blanket 321 because of low density and mass for these materials. Silica aerogel powder/granules and/or similar type products has been shown to have good thermal insulation performance. On account of silica aerogel powder/granules and/or similar type products nanoporous structure (1˜100 nm), low density (3˜250 kg/m3), low dielectric constant (1.1˜2.5), low thermal conductivity (0.013˜0.025 W/(m-k)), high porosity (80˜99.8%), surface area (500˜1000 m2/g) and other unique physical characteristics silica aerogel powder/granules and/or similar type products may provide a means for thermally insulating the melt 211 while still allowing some evolved gas permeation from the melt 211.
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(101) In some embodiments, steps 509, 511, and 513 may overlap and/or occur at least partially concurrently. In some embodiments, once step 509 has ceased, step 513 may still continue to occur. In some embodiments, step 513 may occur before or during steps 509, 511, and/or step 515. In some embodiments, step 513 may occur before or during step 515. In some embodiments, step 513 may progress into step 515.
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(105) In some embodiments, from step 505, method 500 may iterate various steps, such as, but not limited to steps 505, 507, 509, 511, 513, 515, 517 to step 519 until the total disposal of all waste material 211 and the vitrification process is complete with respect to one or more human-made cavern(s) 201. Step 521 may be the last operational phase in which the wellbore 203 and the cavern 201 are sealed and shut down completely.
(106) Continuing discussing
(107) Continuing discussing
(108) In some embodiments, method 500 comprise: step 505 of filling the vitrification chamber (e.g., human-made cavern 201) with a predetermined quantity of radioactive waste 211; step 502 of installing at least a portion of a heater system (e.g., heater 221, vane/mixer 223, weight 225, and portions of cabling 219) to the vitrification chamber, wherein the heater system may be configured to vitrify the predetermined quantity of the radioactive waste 211 within the vitrification chamber; step 507 of energizing the heating system to heat the predetermined quantity of the radioactive waste 211 within the vitrification chamber; step 507 of initiating a cold-cap 227 vertically above the predetermined quantity of radioactive waste 211 that is within the vitrification chamber; wherein vertical in this context is substantially parallel with a direction of pull of a gravitational field at the vitrification chamber; wherein the cold-cap 227 thermally insulates a closest portion vertically above the cold-cap 227 from portions of the vitrification chamber below the cold-cap 227; step 513 of adding at least one predetermined volatile-fixing-additive (VFA) to the cold-cap 227, wherein the at least one predetermined volatile-fixing-additive (VFA) may be configured to convert most of the at least one volatile chemical 235 into at least one fixed-chemical; wherein the at least one fixed-chemical is retained in/on the cold-cap 227; and at least step 515 of vitrifying the predetermined quantity of the radioactive waste 211 within the vitrification chamber using the heater system resulting in a glass-waste-product 211 and resulting in at least some of the at least one volatile chemical 235, most of which reacts with the at least one VFA to produce the at least one fixed-chemical.
(109) In some embodiments, method 500 prior to steps 505, 502, 507, 513, and 515 may first comprise step 501 of examining the radioactive waste 211 to be filled in the step 505 to determine identification of the at least one volatile chemical 235 that may be associated with radioactive decay of the particular type of radioactive waste 211 and/or that may be produced from vitrifying that particular type of radioactive waste 211. In some embodiments, the examination of the radioactive waste 211 and the identification determination of the at least one volatile chemical 235 may utilize one or more of the following techniques: chemical reaction simulation software running on a computer, empirical analysis; chemical analysis of a sample of the radioactive waste 211 and resulting products from a small-scale laboratory vitrification batch test run; combinations thereof; and/or the like. In some embodiments, after the identification of the at least one volatile chemical 235, the method may further comprise step 503 of determining and identifying the at least one predetermined volatile-fixing-additive (VFA) that may be suitable for reacting with that VFA to produce the at least one fixed-chemical.
(110)
(111) Continuing discussing
(112) Continuing discussing
(113) Continuing discussing
(114) Continuing discussing
(115) Continuing discussing
(116) Continuing discussing
(117) Decontamination is regarded as the process of removing or neutralizing contaminants. In this application, the term “decontamination factor” (hereinafter, “DF”), is simply the radiation level prior to application of the cold-cap 227 treatment process divided by the radiation level after the process is employed.
(118) The present invention may be explained in greater detail in the following twelve (12) non-limiting examples for the treatment of various volatiles 235 produced during the vitrification processes and/or outgassed from nuclear reactions (e.g., fission and/or decay). These examples may detail chemical reactions, specific weights of reagents, stoichiometry, tabular data and/or operational conditions which may occur in the cold-cap 227 during (and after) the vitrification process of nuclear waste 211. In some embodiments, volatiles 235 (produced during the vitrification of radioactive waste 211 and/or from nuclear operations of waste 211) (i.e., the at least one volatile chemical 235) may comprise one or more of the following volatiles: iodine, cesium, carbon, tritium, technetium, cadmium, molybdenum, selenium, tellurium, rhenium, ruthenium, rhodium, portions thereof, isotopes thereof, radioactive isotopes thereof, compounds thereof, molecules thereof, derivatives thereof, combinations thereof, and/or the like. One or more VFAs may react with such volatiles 235 to produce at least one fixed-chemical, wherein the fixed-chemical may include the radioactive chemical species that are then retained within and/or on the cold-cap 227.
(119) In the figures with the chemical reaction equations (e.g.,
(120) In the chemical reaction equations VFAs and volatiles 235 may be on the left side of the given chemical reaction equation and produced fixed-chemical(s) may be on the right side of the given chemical reaction equation.
Example 1—Managing Volatile Iodine
(121) In some embodiments, cold-cap 227 may comprise one or more predetermined chemical species (reagent(s)/VFA(s)) configured to manage, treat, fix, and/or contain volatile iodine, such that managed, treated, fixed, and/or contained formerly volatile iodine is retained substantially (mostly) within and/or on cold-cap 227. Note, at least some volatile iodine may be radioactive.
(122) A variety of solid absorbents have been examined and developed over the past two decades. Of the solid absorbents for iodine removal, a promising approach is to use an inorganic absorbent in which a stable iodine compound is formed. Silver form absorbents were selected as the most promising materials tested at high temperature conditions. Most silver-form solid absorbents comprise silver in a range of fifteen (15) to twenty (20) percent by weight (wt %) of the silver containing solid absorbent. Such a solid containing solid absorbent may be used in commercial scale processes for controlling volatile iodine.
(123) The following Table 1, compares the operational efficiency of various absorbents for controlling iodine under varying conditions of temperature, indicating chemisorption capacity, NOx resistance, decontamination factors, and the commercial applicability of the absorbent.
(124) TABLE-US-00001 TABLE 1 Comparison of performance of solid sorbents/reagents for removing radio-iodine. Optimal Chemisorption Temperature capacity Decontamination NOx Commercial Absorbent (° C.) (mg-I.sub.2/g) factor resistance application AgX 150 500~250 10.sup.2~10.sup.5 Weak Commercial AgZ 150 170~500 10.sup.2~10.sup.5 Strong Lab-scale Ag.sup.oZ 150 170~500 10.sup.2~10.sup.5 Strong Commercial AC-6120 130 140 10.sup.2~10.sup.5 Strong Commercial AgA.sup.a 130 100~500 10.sup.2~10.sup.5 Strong Lab-scale CdX 150 5~10 — Weak Lab-scale PbX 150 5 — Weak Commercial 13X <50 5 10.sup.5 Weak Lab-scale
(125) See also
(126) The AgX, AgZ compounds noted in Table 1 are silver based absorbents fabricated using a silver ion exchange zeolite system. The range in weight of silver in AgX is from 15% to 20%. The AgZ compounds are established by silver ion-exchange using a support matrix of a faujasite and mordenite. AC-6120 is made by impregnating silver nitrate (AgNO.sub.3) on a silica gel matrix.
(127) For example, with respect to Table 1, AgX-10 with about ten (10) wt % of silver and that may use a radioactive methyl iodide tracer, showed that removal efficiency of radio-iodine at 150 degrees Celsius (° C.) was over 99.9%.
(128) Table 2 may show a limited comparison of unit process characteristics for trapping iodine species using AgX, AgoZ, and AC-6120.
(129) TABLE-US-00002 TABLE 2 Comparison of solid absorbent/reagents for removing radio-iodine. Absorbent Parameters AgX Ag.sup.oZ AC-6120 Relative Slight effect Slight effect up Slight effect humidity up to to 70% R. H. up to 70% (R. H) 70% R. H. R. H. NO gas Uncertain No influence Uncertain up to 2% NO conc. NO.sub.2 gas Negative effect No influence Protection on DF up to function of 2% NO conc. Ag oxidation CO.sub.2 gas Negligible Negligible Negligible Temperature Optimal Optimal Optimal temperature of temperature of temperature 150° C. 150° C.~500° C. of 150° C. Effecting Dodecane, H.sub.2S Dodecane, H2S Negligible impurity Column material Stainless steel Stainless steel Stainless steel Applicability to Applicable Suitable Applicable voloxidation Advantage: high Disadvantage: Advantage: Iodine loading high absorbent low absorbent capacity cost cost
(130) See also
(131) The following chemical equations may illustrate chemical reactions involved in iodine interactions with the silver reagents:
3I.sub.2 (g)+6AgNO.sub.3 (s).fwdarw.4AgI (s)+2AgIO.sub.3 (s)+6NO.sub.2 (Eq. 1)
CH.sub.3I (g)+AgNO.sub.3 (s).fwdarw.CH.sub.3NO.sub.3 (g)+AgI (s) (Eq. 2)
I.sub.2 (g)+2Ag (s).fwdarw.2AgI (s) (Eq. 3)
2CH.sub.3I (g)+2H.sub.2O (g)+2Ag (s).fwdarw.2AgI (s)+2CH.sub.3OH (g)+H.sub.2 (g) (Eq. 4)
(132) In some embodiments, the silver iodine complexed formed in chemical equations (1) through (4) may be solid and/or substantially non-volatile. In some embodiments, the silver iodine complexed formed in chemical equations (1) through (4) may be substantially retained within and/or on cold-cap 227.
(133) In some embodiments, chemical equation (1), (2), (3), (4), or the like, may be occurring in and/or on cold-cap 227.
(134) In some embodiments, the chemical species (e.g., reagent and/or VFA) of cold-cap 227 for managing, treating, fixing, and/or containing volatile iodine 235 may be one or more of: silver; silver nitrate (e.g., AgNO.sub.3); a silver compound from Table 1; a silver compound from Table 2; a silver containing absorbent; silver compounds; silver chloride (AgCl); silver iodide (AgI); silver hydroxide (AgOH); an absorbent with silver from a silver ion zeolite exchange system; a silver compound made from using silver ion exchange on a support matrix of faujasite and mordenite; a silica gel matrix impregnated with silver nitrate; a silver containing absorbent; portions thereof; combinations thereof; and/or the like.
(135) In some embodiments, the weight fraction of the specific chemical species (reagents/VFAs) applied in the cold-cap 227 relative to the expected weight of produced volatile iodine material may vary from 76% to 134% depending on the selected chemical species (reagents/VFAs) material.
Example 2—Managing Volatile Cesium
(136) In some embodiments, cold-cap 227 may comprise one or more predetermined chemical species (reagent(s)/VFA(s)) configured to manage, treat, fix, and/or contain volatile cesium, such that managed, treated, fixed, and/or contained formerly volatile cesium is retained substantially (mostly) within and/or on cold-cap 227. Note, at least some volatile cesium may be radioactive (e.g., .sup.137Cs).
(137) Cesium, as a semi-volatile fission gas, may be a major concern because of its half-life of 30.2 years (e.g., .sup.137Cs has a half-life of 30.2 years) and its intensive gamma radiation. Cesium may exist in the form of solid chemical compounds such as Cs, CsI, Cs.sub.2UO.sub.3. Cs.sub.2UO.sub.4, and Cs.sub.2MoO.sub.4 depending on Oxygen/Metal (O/M) ratio in spent nuclear fuel. Cesium may also exist in various volatile and/or gaseous forms such as, but not limited to, Cs, Cs.sub.2O, CsI, and/or CsOH (e.g., in air, steam, and/or hydrogen conditions). Cesium monoxide (Cs.sub.2O) is one of the chemical forms of cesium that could be present in waste operations, such as waste vitrification. Cesium monoxide vaporizes at 250 degrees Celsius (° C.) and tends to decompose into cesium metal and cesium peroxide (Cs.sub.2O.sub.2) at the temperature greater than 400 degrees Celsius (° C.). On exposing to dry air, Cs.sub.2O rapidly forms a mixture of Cs.sub.2O.sub.2 and CsO.sub.2. However, a major chemical form that may be released from spent nuclear fuel in steam conditions is cesium iodide (CsI).
(138) In some embodiments, a chemical fixation method using aluminosilicates materials such as, but not limited to, metakaolin (Al.sub.2O.sub.3.2SiO.sub.2), bentonite (Al.sub.2O.sub.3.4SiO.sub.2.6H.sub.2O), and/or pyrophyllite (Al.sub.2O.sub.3.4SiO.sub.2.H.sub.2O) may be used to manage the volatile cesium. Cesium oxide is readily incorporated into aluminosilicates compounds, and the resulting materials are stable. Very detailed chemical reactions that may immobilize cesium from the vapor phase may be represented by the following chemical reaction equations (5)-(7), (9), (11), and/or (13). Chemical reaction equations (8), (10), and (12) may show initial reactions that may lead into chemical reactions (9), (11), and (13), respectively.
Cs.sub.2O+Al.sub.2O.sub.3.2SiO.sub.2.fwdarw.2CsAlSiO.sub.4 (s) (Eq. 5)
Cs.sub.2O+Al.sub.2O.sub.3.4SiO.sub.2.fwdarw.2CsAlSi.sub.2O.sub.6 (s) (Eq. 6)
Cs.sub.2O+Al.sub.2O.sub.3.10SiO.sub.2.fwdarw.2CsAlSi.sub.5O.sub.12 (s) (Eq. 7)
(139) The reaction of Cs.sub.2O with aluminosilicate (Al.sub.2O.sub.3.4SiO.sub.2) under air conditions may be used for cesium fixation as given in equations (5) to (7).
Cs.sub.2SiO.sub.3(amorphous)+O.sub.2 (g).fwdarw.Cs.sub.2O (g)+SiO.sub.2(amorphous)+O.sub.2 (g) (Eq. 8)
Cs.sub.2O (g)+Al.sub.2O.sub.2.4SiO.sub.2 (s).fwdarw.2CsAlSi.sub.2O.sub.2 (s) (Eq. 9)
2CsI+½O.sub.2 (g).fwdarw.Cs.sub.2O (g)+I.sub.2 (g) (Eq. 10)
Cs.sub.2O (g)+Al.sub.2O.sub.3.4SiO.sub.2 (s).fwdarw.2CsAlSi.sub.2O.sub.6 (s) (Eq. 11)
2CsOH+O.sub.2 (g).fwdarw.Cs.sub.2O (g)+H.sub.2O (g)+O.sub.2 (g) (Eq. 12)
Cs.sub.2O (g)+Al.sub.2O.sub.2.4SiO.sub.2 (s).fwdarw.2CsAlSi.sub.2O.sub.2 (s) (Eq. 13)
(140) The following Table 3 compares the operational efficiency of methods using Clay material absorbents and Fly Ash absorbent for cesium trapping under various operating conditions.
(141) TABLE-US-00003 TABLE 3 Comparison of fixation (trapping) methods for cesium. Clay materials Fly Ash Description Metakaolin, bentonite, Fly Ash pyrophyllite Reaction Chemical adsorption Chemical adsorption Advantages Formation of CsAlSiO.sub.4, Formation of pollucite pollucite (CsAlSi.sub.2O.sub.6) Good thermal stability and/or CsAlSi.sub.5O.sub.12 Good manufacturability Very cheap material cost Disadvantages High operation High operation temperature (>450° C.) temperature (>450° C.) Difficult to form Dispersion of powder High pressure drop D. F 100 1,000 State of Lab-scale (Non-active Lab-scale (radioactive development test) test)
(142) See also
(143) In some embodiments, the chemical species (e.g., reagent and/or VFA) of cold-cap 227 for managing, treating, fixing, and/or containing volatile cesium may be one or more of: metakaolin (Al.sub.2O.sub.3.2SiO.sub.2), bentonite (Al.sub.2O.sub.3.4SiO.sub.2.6H.sub.2O), pyrophyllite (Al.sub.2O.sub.3.4SiO.sub.2.H.sub.2O), clay, Fly Ash, aluminosilicates and oxygen, absorbent, portions thereof, combinations thereof, and/or the like.
(144) In some embodiments, the weight fraction of the specific rea the chemical species (e.g., reagent and/or VFA) implemented in/on the cold-cap 227 relative to the expected weight of produced volatile cesium material may vary from 79% to 250% depending on the selected chemical species (e.g., reagent and/or VFA) material.
Example 3—Managing Volatile Carbon
(145) In some embodiments, cold-cap 227 may comprise one or more predetermined chemical species (reagent(s)/VFA(s)) configured to manage, treat, fix, and/or contain volatile carbon, such that managed, treated, fixed, and/or contained formerly volatile carbon is retained substantially (mostly) within and/or on cold-cap 227. Note, at least some volatile carbon may be radioactive (e.g., carbon-14 [.sup.14C]).
(146) In nuclear waste operations systems, .sup.14C is present as a mixture of carbon dioxide (CO.sub.2), carbon monoxide (CO), and/or hydrocarbons with relative fractions dependent on the chemistry prevalent in the specific system. A large portion of the .sup.14C in gas exists as hydrocarbons, mainly methane, whereas in other cases the .sup.14C in the gas may exist predominantly as CO.sub.2 and/or CO.
(147) The selection of a specific process for the capture and retention of CO.sub.2 from a gaseous stream depends on the volume of gas to be treated, the concentration of CO.sub.2 in the gas stream, the composition of the gas stream and the desired final waste form. The capture of CO.sub.2 by fixed bed adsorption using molecular sieves would require a pre-absorption step to dry the feed gas, removing essentially all the water. A widely used molecular sieve that effectively removes CO.sub.2 is a sodium zeolite absorber.
(148) Natural mordenite, hydrogenated mordenite, and/or modified hydrogenated mordenite NaX may perform well for the removal of .sup.14CO.sub.2 from dissolver off-gases. Modification of hydrogenated mordenite by sodium hydroxide (NaOH) may result in a larger adsorption capacity compared with the other absorbents. An absorbance capacity was found to decrease in the presence of 1% NOx.
(149) The following chemical reaction equations may illustrate at least some of the very detailed reactions involved in carbon management in volatiles from vitrification processes.
2NaOH+CO.sub.2.fwdarw.Na.sub.2CO.sub.3+H.sub.2O (Eq. 14)
(150) In some embodiments, reaction of CO.sub.2 with magnesium at 600° C. may be used for .sup.14C fixation.
.sup.14CO.sub.2+2Mg.fwdarw.2MgO+.sup.14C (Eq. 15)
(151) The solid carbon product in equation (15) is expected to be stable and suitable for direct immobilization and disposal.
(152) A number of absorbents, belonging to the group I (alkali metal) and group II (alkaline earth) hydroxides, may remove CO.sub.2 effectively from gas streams. These chemical species may comprise: ascarite (NaOH on asbestos), LiOH.H.sub.2O, Ca(OH).sub.2, Ba(OH).sub.2, soda lime (NaOH—Ca(OH).sub.2 mixtures), and/or baralyme (Ca(OH).sub.2.Ba(OH).sub.2 mixtures).
Ca(OH).sub.2+CO.sub.2.fwdarw.CaCO.sub.3+H.sub.2O (Eq. 16)
(153) Absorption of carbon dioxide (CO.sub.2) by scrubbing with a caustic aqueous solution is a familiar industrial process that may be used herein.
2NaOH+CO.sub.2.fwdarw.Na.sub.2CO.sub.3+H.sub.2O (Eq. 17)
Na.sub.2CO.sub.3+Ca(OH).sub.2.fwdarw.2NaOH+CaCO.sub.3 (Eq. 18)
(154) In some embodiments, the chemical species (e.g., reagent and/or VFA) of cold-cap 227 for managing, treating, fixing, and/or containing volatile carbon may be one or more of: sodium hydroxides, calcium hydroxides, magnesium, alkali metal hydroxides, alkaline earth hydroxides, caustic powders, caustic pellets, caustic aqueous solution, ascarite (NaOH on asbestos), LiOH.H.sub.2O, Ca(OH).sub.2, Ba(OH).sub.2, soda lime (NaOH—Ca(OH).sub.2 mixtures), baralyme (Ca(OH).sub.2.Ba(OH).sub.2 mixtures), sodium zeolite absorber, natural mordenite, hydrogenated mordenite, modified hydrogenated mordenite, absorbent, portions thereof, combinations thereof, and/or the like.
(155) In some embodiments, the weight fraction of the specific chemical species (e.g., reagent and/or VFA) implemented in the cold-cap 227 relative to the expected weight of produced volatile carbon material may vary from 109% to 182% depending on the selected chemical species (e.g., reagent and/or VFA) material.
Example 4—Managing Volatile Tritium
(156) In some embodiments, cold-cap 227 may comprise one or more predetermined chemical species (reagent(s)/VFA(s)) configured to manage, treat, fix, and/or contain volatile tritium, such that managed, treated, fixed, and/or contained formerly volatile tritium is retained substantially (mostly) within and/or on cold-cap 227. Note, at least some volatile hydrogen may be radioactive (e.g., tritium [T]).
(157) Spontaneous fission of uranium and thorium may contribute small quantities of tritium (T). Tritium may be formed within nuclear reactor fuels, both light water reactors and liquid metal breeder reactors by ternary fission. Tritium decays with a half-life of 12.33 years.
(158) Tritium oxidation may proceed through the reactions show below in chemical reaction equations (19) and (20), both of which may result in tritium species that may be volatile and/or gaseous.
T.sub.2+½O.sub.2.fwdarw.T.sub.2O (Eq. 19)
T.sub.2+H.sub.2O.fwdarw.HTO+HT (Eq. 20)
(159) In some embodiments, the tritium adsorbent chemical species (reagent(s)/VFA(s)) of the present invention may be a tritium adsorbent which traps tritium from tritium-containing water and may comprise hydrogen and/or lithium containing manganese oxide(s) having a spinel crystal structure. In some embodiments, this tritium adsorbent to which tritium is adsorbed may be subjected to an acid treatment to elute and recover the tritium from the tritium adsorbent.
(160) The adsorption mechanism of tritium by the tritium adsorbent of the present embodiment may be considered to be based on the adsorption reaction of the tritium ion (.sup.3T.sup.+) to the present adsorbent and the adsorption of tritium ion (.sup.3T.sup.+) generated from the oxidation reaction (OT.sup.−.fwdarw..sup.3T.sup.++2e−+(½)O.sub.2) of a hydroxide ion (OT.sup.−) containing tritium which takes place on the surface of the present adsorbent which contains manganese oxide exhibiting high oxidizing power as a main component. In general, the degree of dissociation of the water molecule is significantly low, and thus tritium in water is mostly present as water molecules (T.sub.2O, THO) but not as ions. The present adsorbent promotes the dissociation reaction.
(161) It is considered that the present tritium adsorbent adsorb the tritium ion in water based on the ion exchange reactions represented by the following chemical reaction equations (21), (22), and (23). Chemical reaction equations (21) and (22) represent a reaction using hydrogen-containing manganese oxide (H.sub.xMn.sub.2O.sub.4) having a spinel crystal structure as the tritium adsorbent, and chemical reaction equation (23) represents a reaction using lithium-containing manganese oxide (Li.sub.xMn.sub.2O.sub.4) having a spinel crystal structure as the tritium adsorbent.
H.sub.xMn.sub.2O.sub.4+yT.sup.+.fwdarw.H.sub.x-yT.sub.vMn.sub.2O.sub.4+yH.sup.+ (Eq. 21)
H.sub.xMn.sub.2O.sub.4+yOT.sup.−.fwdarw.H.sub.x-yT.sub.vMn.sub.2O.sub.4+yH.sup.++y(2e.sup.−)+y(½O.sub.2) (Eq. 22)
Li.sub.xMn.sub.2O.sub.4+yT.sup.+.fwdarw.H.sub.x-yT.sub.vMn.sub.2O.sub.4+yLi.sup.+ (Eq. 23)
(162) In some embodiments, the chemical species (e.g., reagent and/or VFA) of cold-cap 227 for managing, treating, fixing, and/or containing volatile tritium may be one or more of: hydrogen containing manganese oxide(s) having a spinel crystal structure, hydrogen-containing manganese oxide (H.sub.xMn.sub.2O.sub.4) having a spinel crystal structure, lithium containing manganese oxide(s) having a spinel crystal structure, lithium-containing manganese oxide (Li.sub.xMn.sub.2O.sub.4) having a spinel crystal structure, absorbent, portions thereof, combinations thereof, and/or the like.
(163) In some embodiments, the weight fraction of the specific chemical species (e.g., reagent and/or VFA) implemented in the cold-cap 227 relative to the expected weight of produced volatile tritium material may vary from 926% to 6259% depending on the selected chemical species (e.g., reagent and/or VFA) material.
Example 5—Managing Volatile Technetium
(164) In some embodiments, cold-cap 227 may comprise one or more predetermined chemical species (reagent(s)/VFA(s)) configured to manage, treat, fix, and/or contain volatile technetium, such that managed, treated, fixed, and/or contained formerly volatile technetium is retained substantially (mostly) within and/or on cold-cap 227.
(165) The radioactive technetium product from nuclear operations may be Tc.sub.2O.sub.7. Radioactive technetium is a long-term radiation hazard because of its long half-life (2.13×10.sup.5yr). In high temperature processes, it is possible to volatilize technetium Tc oxides. The most stable oxide, Tc.sub.2O.sub.7, has a melting point of 119.5 degrees Celsius (° C.) and a boiling point of 311 degrees Celsius (° C.). Technetium dioxide sublimates at temperature above 900 degrees Celsius (° C.) and decomposes into Tc and Tc.sub.2O.sub.7 at temperatures above 1,100 degrees Celsius (° C.).
(166) The technetium oxide(s) may be fixed by a chemical fixation method using alkaline earth metal carbonates (e.g., calcium carbonate (CaCO.sub.3), barium carbonate (BaCO.sub.3), and/or strontium carbonate (SrCO.sub.3)) and/or using alkaline earth metal oxides (e.g., calcium oxide (CaO), barium oxide (BaO), and strontium oxide (SrO)). See for example the below chemical reaction equations (24) to (27):
CaO+Tc.sub.2O.sub.7.fwdarw.Ca(TcO.sub.4).sub.2 (Eq. 24)
BaO+Tc.sub.2O.sub.7.fwdarw.Ba(TcO.sub.4).sub.2 (Eq. 25)
3BaO+Tc.sub.2O.sub.7.fwdarw.Ba.sub.3(TcO.sub.5).sub.2 (Eq. 26)
SrO+Tc.sub.2O.sub.7.fwdarw.Sr(TcO.sub.4).sub.2 (Eq. 27)
(167) The following Table 4 compares the trapping methods for the volatile technetium.
(168) TABLE-US-00004 TABLE 4 Comparison of trapping methods for technetium. Adsorption on Solids Description By chemical reaction between gas and solid absorbent (Y, Ca, Ba, and Sr) at over 600° C. Advantages Formation of stable chemical compounds and good thermal stability Disadvantages Discontinuous operation Development Status Lab Scale Remarks ERERC, US - Most promising: under development at KAERI
(169) See also
(170) In some embodiments, the chemical species (e.g., reagent and/or VFA) of cold-cap 227 for managing, treating, fixing, and/or containing volatile technetium may be one or more of: alkaline earth metal carbonates, calcium carbonate (CaCO.sub.3), barium carbonate (BaCO.sub.3), and/or strontium carbonate (SrCO.sub.3), alkaline earth metal oxides, calcium oxide (CaO), barium oxide (BaO), strontium oxide (SrO), absorbent, portions thereof, combinations thereof, and/or the like.
(171) In some embodiments, the weight fraction of the specific chemical species (e.g., reagent and/or VFA) implemented in the cold-cap 227 relative to the expected weight of produced volatile technetium material may vary from 18% to 149% depending on the selected chemical species (e.g., reagent and/or VFA) material.
Example 6—Managing Volatile Cadmium
(172) In some embodiments, cold-cap 227 may comprise one or more predetermined chemical species (reagent(s)/VFA(s)) configured to manage, treat, fix, and/or contain volatile cadmium, such that managed, treated, fixed, and/or contained formerly volatile cadmium is retained substantially (mostly) within and/or on cold-cap 227. Note, at least some volatile cadmium may be radioactive.
(173) In general, hazardous metals like cadmium cannot be destroyed in most waste thermal processes but may be transformed chemically and/or physically to more stable and/or less dangerous forms. There may potential for hazardous metals, such as cadmium, to vaporize and become volatile at high temperatures. The emissions of volatile metals may be managed by the in-situ capture using inorganic reagents and/or absorbents. In some embodiments, volatile hazardous metals, such as, but not limited to, cadmium, may be reactively scavenged by inorganic absorbents or reagents. Cadmium-113 is produced by neutron activation of the stable isotope cadmium-112 and as a fission product. In some embodiments, an absorbent for cadmium volatile compounds may be kaolinite with chemical formula Al.sub.2Si.sub.2O.sub.5(OH).sub.4.
(174) The following chemical reaction equations (28) and (29) may illustrate the reactions involved in cadmium management interactions with the VFA reagents.
CdO+Al.sub.2Si.sub.2O.sub.5(OH).sub.4.fwdarw.CdOAl.sub.2O.sub.3.2SiO.sub.2+2H.sub.2O (Eq. 28)
2CdO+2Al.sub.2Si.sub.2O.sub.5(OH).sub.4.fwdarw.2CdOAl.sub.2O.sub.3.2SiO.sub.2+4H.sub.2O (Eq. 29)
(175) In some embodiments, the chemical species (e.g., reagent and/or VFA) of cold-cap 227 for managing, treating, fixing, and/or containing volatile cadmium may be one or more of: aluminosilicates, kaolinite with chemical formula Al.sub.2Si.sub.2O.sub.5(OH).sub.4, absorbent, portions thereof, combinations thereof, and/or the like.
(176) In some embodiments, the weight fraction of the specific chemical species (e.g., reagent and/or VFA) implemented in the cold-cap 227 relative to the expected weight of produced volatile cadmium material may vary from 200% to 202% depending on the selected chemical species (e.g., reagent and/or VFA) material.
Example 7—Managing Volatile Molybdenum
(177) In some embodiments, cold-cap 227 may comprise one or more predetermined chemical species (reagent(s)/VFA(s)) configured to manage, treat, fix, and/or contain volatile molybdenum, such that managed, treated, fixed, and/or contained formerly volatile molybdenum is retained substantially (mostly) within and/or on cold-cap 227. Note, at least some volatile molybdenum may be radioactive.
(178) Most of the dangerous .sup.99Mo produced from the nuclear waste operations may be treated with the appropriate reagents/absorbers. Among different reagents and/or absorbers, sodium carbonate may be effective in this capacity; and the reaction may occur at temperatures of from 600 to 800 degrees Celsius (° C.). The following chemical equations may illustrate the chemical reactions involved in molybdenum management interactions with the VFA reagents.
MoO.sub.3+Na.sub.2CO.sub.3.fwdarw.Na.sub.2MoO.sub.4+CO.sub.2 (Eq. 30)
MoO.sub.3+SnO.sub.2.fwdarw.MoO.sub.3:SnO.sub.2(thin film) (Eq. 31)
(179) In some embodiments, the trapping of molybdenum may be done by a calcium based material absorber (e.g., an absorber with calcium oxide [CaO]) that results in a trapped CaMoO.sub.4 phase.
MoO.sub.3+CaO.fwdarw.CaMoO.sub.4(calcium absorber) (Eq. 32)
(180) In some embodiments, the trapping of molybdenum may be done by an aluminosilicate absorbent (e.g., Al.sub.2O.sub.3.4SiO.sub.2) that results in trapped molybdenum.
2MoO.sub.3+2Al.sub.2O.sub.3.4SiO.sub.2.fwdarw.2MoAlSi.sub.2O.sub.6 (Eq. 33)
(181) In some embodiments, the chemical species (e.g., reagent and/or VFA) of cold-cap 227 for managing, treating, fixing, and/or containing volatile molybdenum may be one or more of: sodium carbonate (e.g., Na.sub.2CO.sub.3), calcium based material absorber (e.g., an absorber with calcium oxide [CaO]), aluminosilicates (e.g., alumino-silicate absorbent such as Al.sub.2O.sub.3.4SiO.sub.2), tin oxide, absorbent, portions thereof, combinations thereof, and/or the like.
(182) In some embodiments, the weight fraction of the specific chemical species (e.g., reagent and/or VFA) implemented in the cold-cap 227 relative to the expected weight of produced volatile molybdenum material may vary from 39% to 158% depending on the selected chemical species (e.g., reagent and/or VFA) material.
Example 8—Managing Volatile Antimony
(183) In some embodiments, cold-cap 227 may comprise one or more predetermined chemical species (reagent(s)/VFA(s)) configured to manage, treat, fix, and/or contain volatile antimony, such that managed, treated, fixed, and/or contained formerly volatile antimony is retained substantially (mostly) within and/or on cold-cap 227. Note, at least some volatile antimony may be radioactive.
(184) Antimony volatiles like stibine (e.g., SbH.sub.3) have been shown to be transported though several gas absorbers and HEPA filters in the PUREX operations and it may suggest that stibine (e.g., SbH.sub.3) is a volatile 235 of concern, and the methylated and ethylated antimony volatiles might behave similarly and thus also be volatiles 235 of concern. The following chemical reaction equations may illustrate various chemical species (reagents and/or VFAs) for immobilizing, trapping, and/or managing volatile antimony compounds produced by the vitrification processes.
2SbH.sub.3+6Ag.fwdarw.2Ag.sub.3Sb+3H.sub.2 (Eq. 34)
SbH.sub.3+3AgCl.fwdarw.Sb+3Ag+3HCl (Eq. 35)
SbH.sub.3+3AgI.fwdarw.Sb+3Ag+3HI (Eq. 36)
2(CH.sub.3).sub.3Sb+O.sub.2.fwdarw.2(CH.sub.3).sub.3SbO (Eq. 37)
2SbH.sub.3+3O.sub.2.fwdarw.Sb.sub.2O.sub.3+3H.sub.2O (Eq. 38)
(185) Sb.sub.2O.sub.3 and Sb.sub.2O.sub.5 are both volatile compounds at higher temperatures and may be formed from the oxidation of stibine (SbH.sub.3). The volatilizing species Sb.sub.2O.sub.5 readily condenses to a particulate at lower temperatures and may be easily trapped.
(186) In some embodiments, volatile antimony compounds (e.g., oxides) may be trapped by using calcium based absorbents (such as, calcium oxide [CaO]) which form the products CaSb.sub.2O.sub.6 and CaSb.sub.2O.sub.7.
Sb.sub.2O.sub.5+CaO.fwdarw.CaSb.sub.2O.sub.6 (calcium material absorber) (Eq. 39)
Sb.sub.2O.sub.5+CaO.fwdarw.CaSb.sub.2O.sub.7 (Eq. 40)
(187) In some embodiments, the chemical species (e.g., reagent and/or VFA) of cold-cap 227 for managing, treating, fixing, and/or containing volatile antimony may be one or more of: silver, silver compounds (e.g., silver chloride [AgCl] and silver iodide [AgI]), oxygen, calcium based absorbents (such as, calcium oxide [CaO]), absorbent, portions thereof, combinations thereof, and/or the like.
(188) In some embodiments, the weight fraction of the specific chemical species (e.g., reagent and/or VFA) implemented in the cold-cap 227 relative to the expected weight of produced volatile antimony material may vary from 10% to 568% depending on the selected chemical species (e.g., reagent and/or VFA) material.
Example 9—Managing Volatile Selenium and/or Tellurium
(189) In some embodiments, cold-cap 227 may comprise one or more predetermined chemical species (reagent(s)/VFA(s)) configured to manage, treat, fix, and/or contain volatile selenium and/or tellurium, such that managed, treated, fixed, and/or contained formerly volatile selenium and/or tellurium is retained substantially (mostly) within and/or on cold-cap 227. Note, at least some volatile selenium and/or tellurium may be radioactive.
(190) In the nuclear waste operations, selenium (Se) and tellurium (Te) may form volatiles hydrides (e.g., H.sub.2Se and H.sub.2Te) and/or volatile dimethyl (e.g., Se(CH.sub.3).sub.2) compounds. Additionally, volatile diethyl compounds (e.g., Se(C.sub.2H.sub.5).sub.2 and/or Te(C.sub.2H.sub.5).sub.2) may be formed (and appear to be thermodynamically stable). The following chemical reaction equations may illustrate various chemical species (reagents and/or VFAs) for immobilizing, trapping, and/or managing volatile selenium and/or tellurium compounds produced by the vitrification processes and/or produced from outgassing (e.g., from nuclear waste operations).
H.sub.2Se+2Ag.fwdarw.Ag.sub.2Se+H.sub.2 (Eq. 41)
H.sub.2Se+2Ag(OH).fwdarw.2H.sub.2O+Ag.sub.2Se (Eq. 42)
H.sub.2Te+2Ag.fwdarw.Ag.sub.2Te+H.sub.2 (Eq. 43)
H.sub.2Te+2AgOH.fwdarw.Ag.sub.2Te+2H.sub.2O (Eq. 44)
(191) Calcium based materials (e.g., calcium oxide [CaO]) may successfully trap volatile selenium and/or tellurium compounds from nuclear waste gas streams. The trapping efficiency of tellurium compounds by using calcium based materials is very high. Published experimental research by the (KAERI) Korean Atomic Energy Research Institute (TR-3884/2009) in 2009 indicates that trapping efficiency of tellurium compounds by calcium based materials may be as high as 99%. Chemical analysis may show that volatile selenium and/or tellurium compounds trapped by calcium-based media may be Ca.sub.2Te.sub.3O.sub.8, CaTeO.sub.3, Ca.sub.2Se.sub.3O.sub.8, and/or CaTeO.sub.3.
2CaO+3TeO.sub.2.fwdarw.Ca.sub.2Te.sub.3O.sub.8 (Eq. 45)
CaO+TeO.sub.2.fwdarw.CaTeO.sub.3 (Eq. 46)
2CaO+3SeO.sub.2.fwdarw.Ca.sub.2Se.sub.3O.sub.8 (Eq. 47)
CaO+SeO.sub.2.fwdarw.CaSeO.sub.3 (Eq. 48)
(192) In some embodiments, the chemical species (e.g., reagent and/or VFA) of cold-cap 227 for managing, treating, fixing, and/or containing volatile selenium and/or volatile tellurium may be one or more of: silver, silver hydroxide (AgOH), silver compounds, calcium based materials (e.g., calcium oxide [CaO]), absorbent, portions thereof, combinations thereof, and/or the like.
(193) In some embodiments, the weight fraction of the specific chemical species (e.g., reagent and/or VFA) implemented in the cold-cap 227 relative to the expected weight of produced volatile selenium material may vary from 34% to 311% depending on the selected chemical species (e.g., reagent and/or VFA) material. In some embodiments, the weight fraction of the specific chemical species (e.g., reagent and/or VFA) implemented in the cold-cap 227 relative to the expected weight of produced volatile tellurium material may vary from 23% to 193% depending on the selected chemical species (e.g., reagent and/or VFA) material.
Example 10—Managing Volatile Rhenium
(194) In some embodiments, cold-cap 227 may comprise one or more predetermined chemical species (reagent(s)/VFA(s)) configured to manage, treat, fix, and/or contain volatile rhenium, such that managed, treated, fixed, and/or contained formerly volatile rhenium is retained substantially (mostly) within and/or on cold-cap 227. Note, at least some volatile rhenium may be radioactive.
(195) The following chemical reaction equations may illustrate various chemical species (reagents and/or VFAs) for immobilizing, trapping, and/or managing volatile rhenium compounds produced by the vitrification processes and/or produced from outgassing (e.g., from nuclear waste operations).
CaO+Re.sub.2O.sub.7.fwdarw.Ca(ReO.sub.4).sub.2 (Eq. 49)
CaCO.sub.3+ReO.sub.3.fwdarw.CaReO.sub.3+CO.sub.2 (a perovskite like structure) (Eq. 50)
(196) Per either or both of the above two chemical reactions, the fixation or trapping of volatile rhenium compounds may be implemented by calcium based absorber materials (e.g., calcium oxide [CaO] and/or calcium carbonate [CaCO.sub.3]). The trapping mechanism is very efficient at more than 90% efficiency. The resultant product may be Ca(ReO.sub.4).sub.4 when calcium oxide is used as the VFA.
(197) Volatile rhenium may be captured by aluminum silicate compounds.
Re.sub.2O.sub.7+Al.sub.2O.sub.3.fwdarw.SiO.sub.2.fwdarw.Re.sub.2O.sub.7/SiO.sub.2—Al.sub.2O.sub.3 (Eq. 51)
(198) In some embodiments, the chemical species (e.g., reagent and/or VFA) of cold-cap 227 for managing, treating, fixing, and/or containing volatile rhenium may be one or more of: calcium oxide (e.g., CaO), calcium carbonate (e.g., CaCO.sub.3), calcium compounds, aluminum silicate compounds (e.g., Al.sub.2O.sub.3.SiO.sub.2), absorbent, portions thereof, combinations thereof, and/or the like.
(199) In some embodiments, the weight fraction of the specific chemical species (e.g., reagent and/or VFA) implemented in the cold-cap 227 relative to the expected weight of produced volatile rhenium material may vary from 12% to 33% depending on the selected chemical species (e.g., reagent and/or VFA) material.
Example 11—Managing Volatile Ruthenium
(200) In some embodiments, cold-cap 227 may comprise one or more predetermined chemical species (reagent(s)/VFA(s)) configured to manage, treat, fix, and/or contain volatile ruthenium, such that managed, treated, fixed, and/or contained formerly volatile ruthenium is retained substantially (mostly) within and/or on cold-cap 227. Note, at least some volatile ruthenium may be radioactive (e.g., .sup.106Ru).
(201) Ruthenium-106 (.sup.106Ru) is a source of radioactivity among the gaseous effluents from nuclear operations. Additional problems may be associated with the volatility of ruthenium-106 are generation of substantial heat and radiation produced by ruthenium-106 decay, which rapidly decays to palladium-106 (.sup.106Pd). A certain amount of ruthenium-106 may be included in spent nuclear fuel as a fission product and may generally exist in the form of metallic precipitates and is easily oxidized to RuO.sub.2 when heated under certain conditions. However, when RuO.sub.2 is exposed to high temperature and an oxidative condition during separation trapping processes, it is oxidized and volatilized to gaseous RuO.sub.4, whose boiling point is 25.4 degrees Celsius (° C.).
(202) Several VFA fixation materials to treat and fix/immobilize gaseous ruthenium oxides arising from the related nuclear operations may be shown in Table 5, along with their respective chemical reactions.
(203) The chemical fixation method of volatile ruthenium compounds may use alkaline earth metal carbonates (e.g., CaCO.sub.3, BaCO.sub.3, and/or SrCO.sub.3) and/or alkaline earth metal oxides (e.g., CaO, BaO, and/or SrO) as the VFA. For each alkaline earth metal carbonates such as CaCO.sub.3, BaCO.sub.3 and/or Sr, the minimum reaction temperatures may be 495, 425, and 515 degrees Celsius (° C.), respectively.
(204) Other volatile ruthenium fixation VFAs may include ferric oxide (Fe.sub.2O.sub.3, iron(III) oxide), yttrium oxide (Y.sub.2O.sub.3), Li.sub.2O, and/or titanium dioxide (TiO.sub.2). Yttrium oxide (Y.sub.2O.sub.3) may be formed into a pyrochlore structure of Y.sub.2Ru.sub.2O.sub.7 by its reaction with ruthenium oxide, which is thermally stable up to 1,400 degrees Celsius (° C.) and has a large theoretical capacity of trapping per unit mass (0.89 g/g). The comparison of stoichiometric capacities of trapping materials is shown in Table 6.
(205) The following Table 5 shows the expected reactions of metal ruthenates with various VFAs.
(206) TABLE-US-00005 TABLE 5 Expected chemical reactions of metal ruthenate. Structure VFA Expected Chemical Reaction Perovskites BaCO.sub.3 BaCO.sub.3 + RuO.sub.2 .fwdarw. BaRuO.sub.3 + CO.sub.2(g) (MRuO.sub.3) CaCO.sub.3 CaCO.sub.3 + RuO.sub.2 .fwdarw. CaRuO.sub.3 + CO.sub.2(g) SrCO.sub.3 SrCO.sub.3 + RuO.sub.2 .fwdarw. SrRuO.sub.3 + CO.sub.2(g) Pyrochleres Y.sub.2O.sub.3 Y.sub.2O.sub.3 + 2RuO.sub.2 .fwdarw. Y.sub.2Ru.sub.2O.sub.7 (M.sub.2Ru.sub.2O.sub.7) Nd.sub.2O.sub.3 Nd.sub.2O.sub.3 + 2RuO.sub.2 .fwdarw. Nd.sub.2Ru.sub.2O.sub.7 Hollandite K.sub.2O K.sub.2O + 8RuO.sub.2 .fwdarw. 2KRu.sub.4O.sub.8 + 1/2O.sub.2(g) (MRu.sub.4O.sub.8) Rb.sub.2O Rb.sub.2O + 8RuO.sub.2 .fwdarw. 2RbRu.sub.4O.sub.8 + 1/2O.sub.2(g) Na.sub.2O.sub.2 Na.sub.2O.sub.2 + 4RuO.sub.2 .fwdarw. 2NaRu.sub.2O.sub.4 + O.sub.2(g) Li.sub.2O Li.sub.2O + RuO.sub.2 .fwdarw. Li.sub.2RuO.sub.3
(207) See also
(208) The following Table 6 compares the stoichiometric capacities of a plurality of trapping VFA materials utilized for ruthenium trapping or fixation and the chemical products.
(209) TABLE-US-00006 TABLE 6 Comparison of stoichiometric capacities of trapping materials. Trapping capacity VFA Reaction Product (g-Ru/g-material) CaO CaRuO.sub.3 1.82 CaCO.sub.3 CaRuO.sub.3 1.01 SrCO.sub.3 SrRuO.sub.3 0.68 BaCO.sub.3 BaRuO.sub.3 0.51 Li.sub.2O Li.sub.2RuO.sub.3 4.41 Y.sub.2O.sub.3 Y.sub.2Ru.sub.2O.sub.7 0.89 Nd.sub.2O.sub.3 Nd.sub.2Ru.sub.2O.sub.7 0.20
(210) See also
(211) The following Table 7 compares a plurality of trapping methods and their advantages or disadvantages for volatile ruthenium trapping or fixation.
(212) TABLE-US-00007 TABLE 7 Comparison of trapping methods for ruthenium. Adsorbent Advantages Disadvantages Remarks Silica gel effective sorbent at temperature limit: generally silica low temperature (about under 100° C. gel includes 80° C.): removal over 100° C.: impurities (Fe, efficiency of about decrease of DF Co, Ni, Cr, etc.) 99.8% values (loss of regeneration available thermal stability) Metal oxide 500~550° C.: 99.5% over 600° C.: (Fe.sub.2O.sub.3, TiO.sub.2, good trapping capacity ruthenium desorption MnO.sub.2 etc.) and good resistance Fe.sub.2O.sub.3 powder against impurities difficulty in good trapping stability fabrication process Yttria (Y.sub.2O.sub.3) below 1400° C.: good higher operation Y.sub.2Ru.sub.2O.sub.7 formation thermal stability temperature (900° C.) (pyrochlore) Complex metal high efficiency: not available need to develop [oxide alkaline BaCO.sub.3—Fe.sub.2O.sub.3 at solidification over adsorbent including earth metal 450~750° C., 95~96% 1500° C. (loss of higher thermal (Ba—CO.sub.3) + BaCO.sub.3—TiO.sub.2 at 650° C., thermal stability and stability, stability metal oxide] 95% generation of CO.sub.2) of filter trapped BaCO.sub.3—MnO.sub.2 at and high efficiency 550~750° C., 94% for a long time high efficiency for a over 1500° C. long time: for 60 hours in [BaCO.sub.3—Fe.sub.2O.sub.3]
(213) See also
(214) In some embodiments, the chemical species (e.g., reagent and/or VFA) of cold-cap 227 for managing, treating, fixing, and/or containing volatile ruthenium may be one or more of: alkaline earth metal carbonates (e.g., calcium carbonate [CaCO.sub.3], barium carbonate [BaCO.sub.3], and/or strontium carbonate [SrCO.sub.3]), alkaline earth metal oxides (e.g., calcium oxide [CaO], barium oxide [BaO], and/or strontium carbonate [SrO]), ferric oxide (Fe.sub.2O.sub.3, iron(III) oxide), yttrium oxide (Y.sub.2O.sub.3), Li.sub.2O, titanium dioxide (TiO.sub.2), absorbent, portions thereof, combinations thereof, and/or the like.
(215) In some embodiments, the weight fraction of the specific chemical species (e.g., reagent and/or VFA) implemented in the cold-cap 227 relative to the expected weight of produced volatile ruthenium material may be calculated based on the trapping capacity (see e.g., Table 6) of the chemical species (e.g., reagent and/or VFA) absorbent which may vary from 0.20 to 1.82 g/g depending on the selected reagent material.
Example 12—Managing Volatile Rhodium
(216) In some embodiments, cold-cap 227 may comprise one or more predetermined chemical species (reagent(s)/VFA(s)) configured to manage, treat, fix, and/or contain volatile rhodium, such that managed, treated, fixed, and/or contained formerly volatile rhodium is retained substantially (mostly) within and/or on cold-cap 227. Note, at least some volatile rhodium may be radioactive.
(217) Rhodium produced in nuclear operations has one unusual property which permits the separation thereof from at least mostly all other constituents; i.e., the volatility-of rhodium tetroxide (RhO.sub.4). Nuclear product waste streams may be treated in such a manner as to separate out the rhodium tetroxide. The rhodium tetroxide may then be reduced to rhodium hydrated oxide or metallic rhodium. The following chemical reaction equations may illustrate various chemical species (reagents and/or VFAs) for immobilizing, trapping, and/or managing volatile rhodium compounds produced by the vitrification processes and/or produced from outgassing (e.g., from nuclear waste operations).
RhO.sub.4+4H.sub.2.fwdarw.Rh (s)+4H.sub.2O (Eq. 52)
8CaCO.sub.3+2Rh.sub.2O.sub.3+O.sub.2.fwdarw.4Ca.sub.2RhO.sub.4+8CO.sub.2 (Eq. 53)
(218) In some embodiments, porous borosilicate may be used to capture rhodium tetroxide (RhO.sub.4) through the reaction below (equation (54).
RhO.sub.4+B.sub.2O.sub.3*SiO.sub.2.fwdarw.RhB.sub.2O.sub.7*SiO.sub.2 (Eq. 54)
(219) In some embodiments, the chemical species (e.g., reagent and/or VFA) of cold-cap 227 for managing, treating, fixing, and/or containing volatile rhodium may be one or more of: calcium carbonate (e.g., CaCO.sub.3), borosilicates (e.g., porous and/or B.sub.2O.sub.3*SiO.sub.2), hydrogen, absorbent, portions thereof, combinations thereof, and/or the like.
(220) In some embodiments, the weight fraction of the specific chemical species (e.g., reagent and/or VFA) implemented in the cold-cap 227 relative to the expected weight of produced volatile rhodium material may vary from 5% to 134% depending on the selected chemical species (e.g., reagent and/or VFA) material.
(221) In some embodiments, volatile(s) 235 may be a volatile form of: iodine, cesium, carbon, tritium, technetium, cadmium, molybdenum, selenium, tellurium, rhenium, ruthenium, rhodium, portions thereof, isotopes thereof, radioactive isotopes thereof, compounds thereof, molecules thereof, derivatives thereof, combinations thereof, and/or the like.
(222) In some embodiments, the chemical species (e.g., reagent and/or VFA) of cold-cap 227 for managing, treating, fixing, and/or containing at least one of the volatile(s) 235 may be one or more of: silver; silver nitrate (e.g., AgNO.sub.3); a silver compound from Table 1; a silver compound from Table 2; a silver containing absorbent; silver compounds; silver chloride (AgCl); silver iodide (AgI); silver hydroxide (AgOH); an absorbent with silver from a silver ion zeolite exchange system; a silver compound made from using silver ion exchange on a support matrix of faujasite and mordenite; a silica gel matrix impregnated with silver nitrate; metakaolin (Al.sub.2O.sub.3.2SiO.sub.2); bentonite (Al.sub.2O.sub.3.4SiO.sub.2.6H.sub.2O); pyrophyllite (Al.sub.2O.sub.3.4SiO.sub.2.H.sub.2O); clay; Fly Ash; caustic powders; caustic pellets; caustic aqueous solution; alkali metal hydroxides; sodium hydroxide; ascarite (NaOH on asbestos); LiOH.H.sub.2O; alkali metal carbonates; sodium carbonate (e.g., Na.sub.2CO.sub.3); alkali metal oxides; lithium oxide (Li.sub.2O); alkaline earth metal hydroxides; calcium hydroxide (Ca(OH).sub.2); barium hydroxide (Ba(OH).sub.2); alkaline earth metal oxides; calcium oxide (CaO); barium oxide (BaO); strontium oxide (SrO); alkaline earth metal carbonates; calcium carbonate (CaCO.sub.3); barium carbonate (BaCO.sub.3); strontium carbonate (SrCO.sub.3); calcium-based absorbents (e.g., an absorber with calcium oxide [CaO]); magnesium; magnesium-based absorbents; soda lime (NaOH—Ca(OH).sub.2 mixtures); baralyme (Ca(OH).sub.2—Ba(OH).sub.2 mixtures); sodium zeolite absorber; natural mordenite; hydrogenated mordenite; modified hydrogenated mordenite; hydrogen containing manganese oxide(s) having a spinel crystal structure; hydrogen-containing manganese oxide (H.sub.xMn.sub.2O.sub.4) having a spinel crystal structure; lithium containing manganese oxide(s) having a spinel crystal structure; lithium-containing manganese oxide (Li.sub.xMn.sub.2O.sub.4) having a spinel crystal structure; aluminosilicates; kaolinite with chemical formula Al.sub.2Si.sub.2O.sub.5(OH).sub.4; alumino-silicate absorbent such as Al.sub.2O.sub.3.4SiO.sub.2; aluminum silicate compounds (e.g., Al.sub.2O.sub.3.SiO.sub.2); tin oxide; ferric oxide (Fe.sub.2O.sub.3, iron(III) oxide); yttrium oxide (Y.sub.2O.sub.3); titanium dioxide (TiO.sub.2); borosilicates (e.g., porous and/or B.sub.2O.sub.3*SiO.sub.2); oxygen; hydrogen; absorbents thereof, portions thereof, combinations thereof, and/or the like.
(223) In some embodiments, such chemical species (e.g., reagent and/or VFA) of cold-cap 227 in and/or on the cold-cap 227 may be in the form of and/or part of one or more of: gas, liquid, solids, gels, aerogels, slurries, foams, pellets, powders, granules, beads, spheres, glasses, ceramics, clays, hollow cylinders, structures made from resin(s), layers, laminates, media commonly used to house catalysts, portions thereof, combinations thereof, and/or the like.
(224) In some embodiments, at least some of the chemical species (e.g., reagent and/or VFA) of cold-cap 227 may reside within container(s) within and/or placed in the cold-cap 227 region. In some embodiments, such container(s) may be perforated with the perforations being configured for gas movement. In some embodiments, such container(s) may be perforated mesh bag(s) with the perforations being configured for gas movement.
(225) Various products, devices, apparatus, systems, mechanisms, means, methods, and/or processes have been described that relate to the management of volatiles produced from vitrification of nuclear wastes and/or of volatiles from nuclear operations. The foregoing description of the various embodiments of the invention has been presented for the purposes of illustration and disclosure. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teaching without departing from the spirit of the invention.
(226) While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.