Oxidation of cesium as a method for removing cesium vapor from cover gas inside a nuclear reactor.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- TERRAPOWER LLC
- Filing Date
- 2023-04-18
- Publication Date
- 2026-07-30
Smart Images
Figure 0007898011000012 
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Abstract
Description
Detailed description of the invention
[0001] [Cross-reference of related applications] This application claims the benefits of U.S. Provisional Patent Application No. 63 / 388,981, filed on 13 July 2022, entitled “OXIDATION OF CESIUM AS METHOD FOR REMOVING CESIUM VAPOR FROM COVER GAS IN NUCLEAR REACTORS.” The entire contents of that application are incorporated herein by reference.
[0002] [Government licensing rights] This invention was developed with government support under DOE Cooperation Agreement No. DE-NE0009054, granted by the U.S. Department of Energy. The government has certain rights to this invention.
[0003] [Areas of Disclosure] This disclosure relates to an improved process for removing radioactive cesium from an inert cover gas in a nuclear reactor. The process includes oxidizing cesium vapor in the cover gas to produce cesium oxide particles, and removing the cesium oxide particles by mechanical filtration.
[0004] 〔background〕 Radioactive cesium-134 and cesium-137 may be present in the coolant of a sodium-cooled fast reactor. Due to the high vapor pressure of elemental cesium, radioactive cesium-134 and cesium-137 can move into the cover gas (usually argon). Cesium has a relatively high vapor pressure at the expected cover gas temperatures of 20°C to 550°C, and cesium vapor can be carried by the cover gas through the vapor condenser and aerosol filter, accumulating on or within equipment in downstream piping, valves, and radioactive gas handling systems. Enough cesium may be transported to raise concerns about radiation levels for maintenance personnel.
[0005] Many nuclear reactors are equipped with sodium coolant processing systems that include filters. These filters are placed in the flow of the cooling fluid to remove cesium and other radioactive fission byproducts. However, sufficient amounts of cesium can still evaporate into the cover gas system to raise concerns about radiation doses for workers. For example, near downstream processing equipment (e.g., piping, service valves, and compressor cells), dose rates of up to 320 millirem / hour for cesium-134 and up to 13 rem / hour for cesium-137 can be detected. Such downstream processing equipment requires periodic maintenance, partly due to the accumulation of cesium. Performing such maintenance requires a high level of caution to ensure that maintenance workers are not exposed to unacceptable radiation levels.
[0006] U.S. Publication No. 2017 / 0263339 by Eichel et al., published on September 14, 2017, describes an example of a known reactor filter. Publication No. 2017 / 0263339 discloses embodiments of a getter element for removing one or more fission products from a gaseous and / or liquid cooling fluid flow in a reactor. The getter element comprises one or more internal passages that facilitate continuous throughput of the cooling fluid, and a getter material that chemically reacts with a target fission product to remove the fission product from the flow. The disclosed fission products include cesium and cesium-based compounds, rubidium and rubidium-based compounds, strontium and strontium-based compounds, and iodine and iodine-based compounds. The disclosed getter materials include zirconium oxide, titanium oxide, niobium oxide, and tantalum oxide. However, as explained above, known filters placed in the cooling fluid flow are not sufficient to prevent cesium vapor from moving into the cover gas flow, and a considerable amount of uncaptured cesium vapor may move into the cover gas flow and subsequently accumulate on or within downstream equipment, potentially raising concerns about radiation exposure for maintenance workers.
[0007] 〔overview〕 Embodiments of the present disclosure relate to a method for removing cesium vapor from a cover gas flow in a nuclear reactor using an oxidation and filtration device positioned within the cover gas flow. According to some embodiments, the method may not be intended to replace any filtration device or method conventionally used in cooling fluid flows, but rather to remove cesium that would otherwise leak out of the cooling fluid into the cover gas flow before it could reach downstream processing facilities.
[0008] The boiling point of cesium is 670°C. However, due to its high vapor pressure, cesium evaporates at much lower temperatures and enters the cover gas flow. This much lower temperature range includes temperatures in the range of approximately 20°C to 550°C. Temperatures in this range can be found at various locations within the cover gas flow of any reactor among many reactors. As a result, a cover gas flow containing an inert gas (usually argon) is created that carries small but radioactively significant amounts of cesium-134 (half-life 2.1 years) and cesium-137 (half-life 30 years). In a typical example, at a high cover gas temperature of approximately 550°C, the mole fraction of cesium vapor in the cover gas is at most approximately 2.2 x 10⁻¹⁶. -10 This is possible. As a result, the partial pressure in the cover gas flow of a reactor operating at atmospheric pressure can be approximately 2.2 x 10⁻¹⁰ in some cases. -10 Atmospheric pressure is created. Over time, even if the concentration of cesium vapor is small, it can condense (solidify) and accumulate significantly in downstream processing facilities, making removal necessary.
[0009] According to the disclosed method, a cover gas flow containing an inert cover gas and cesium vapor is provided (prepared) within the reactor. The cover gas flow contains a first mole fraction of cesium vapor. This first mole fraction of cesium vapor is approximately 2.2 x 10⁻¹⁶, as in a typical example. -10This may be any mole fraction typically encountered in reactors of various embodiments. The method further includes the steps of: oxidizing cesium vapor in a cover gas flow to obtain cesium oxide (Cs2O) particles having a very low vapor pressure; and removing the cesium oxide particles from the cover gas flow using a particle filter placed in the cover gas flow to obtain a filtered cover gas. The filtered cover gas flow may have cesium vapor at a second mole fraction of 0% to about 2%, or 0% to about 0.2%, or 0% to about 0.02%, or 0% to about 0.002%, or 0% to about 0.0002% of the first mole fraction of cesium vapor.
[0010] In some embodiments, the step of oxidizing cesium vapor in a cover gas flow includes a step of reacting the cesium vapor with a metal oxide to form cesium oxide particles. The metal oxide may have a first Gibbs free energy, and the cesium oxide particles may have a second Gibbs free energy. The difference in Gibbs free energies between the two solid metal oxides is the Gibbs free energy of formation (ΔG). f This corresponds to the difference in ). This is known and published for various metal oxides using reference conditions of 298K (25°C) and 1 atmosphere. Metal oxides can be selected such that the first Gibbs free energy is higher than the second Gibbs free energy. In other words, metal oxides can be selected such that the first Gibbs free energy of formation is higher than the second Gibbs free energy of formation. Selecting metal oxides in this way helps enable the spontaneous progress of chemical reactions in a temperature environment of approximately 20°C to approximately 400°C. This temperature environment of approximately 20°C to approximately 400°C is a temperature environment that is typically present in the cover gas processing flow of a nuclear reactor.
[0011] Suitable metal oxides having a Gibbs free energy of formation higher than that of cesium oxide (Cs2O) include, but are not limited to, selected oxides of copper, bismuth, antimony, lead, nickel, selenium, tellurium, cobalt, and combinations thereof. It should be understood that "selected oxides" may refer to a selection of, rather than all, of these metal oxides, so as to have a Gibbs free energy of formation higher than that of cesium oxide. The selected metal oxides would preferably be stable in low-oxygen or oxygen-free environments at the operating temperature. Suitable copper oxides that are "selected oxides" include cuprous oxide (Cu2O), cupric oxide (CuO), and combinations thereof.
[0012] Oxides of bismuth include bismuth oxide (Bi2O3) and bismuth oxide (Bi3O4). These may be “selected oxides”. Oxides of antimony include diantimony tetroxide (Sb2O4) and antimony pentoxide (Sb2O5). These may be eligible as selected oxides. Also, oxides of antimony include antimony trioxide (Sb2O3) and antimony hexatridecoxide (Sb6O3). 13) are included. These are not eligible as selected oxides. Lead oxides include lead monoxide (PbO) and lead dioxide (PbO2). Both are selected oxides. Lead oxides also include lead(III,IV) oxide (Pb3O4). This is not a selected oxide. Nickel oxides may include nickel(II) oxide (NiO) (which is a selected oxide) and nickel(III) oxide (Ni2O3). Selenium oxides may include selenium dioxide (SeO2), selenium trioxide (SeO3), diselenium pentoxide (Se2O5), and combinations thereof. Tellurium oxides may include tellurium dioxide (TeO2). This is barely a selected oxide. Cobalt oxides include cobalt(I) oxide (CoO). This is a selected oxide. Cobalt oxides also include cobalt(II) oxide (Co2O3) and cobalt(III) oxide (Co3O4). These are not the selected oxides. The metal oxide reacts with a stoichiometric amount of cesium vapor to a degree that is thermodynamically accelerated, determined by the relative Gibbs free energy of formation of the metal oxide with respect to cesium oxide, and as a result, cesium oxide (Cs2O) and the metal element (Cu, Ag, Bi, Sb, Pb, Ni, Se, Te, and / or Co) or a partially reduced version of the metal oxide may be obtained. For example, CuO can be partially reduced to Cu2O.
[0013] In some embodiments, the metal oxide may be a copper oxide selected from cuprous oxide (Cu2O), cupric oxide (CuO), and combinations thereof. According to the following exemplary reaction equation, cuprous oxide and cupric oxide react with cesium vapor, resulting in cesium oxide particles and copper metal and / or partially reduced oxides:
[0014] [ka]
[0015] [ka]
[0016] [Chemical]
[0017] According to known data, cerium oxide has a Gibbs free energy of formation (ΔG f ) of -308.36 kJ / mole. For comparison, cuprous oxide and cupric oxide have ΔG f values of -146.03 kJ / mole and -129.56 kJ / mole, respectively, at 25 °C and 1 atmosphere. See "Thermodynamic Properties of Minerals and Related Substances at 298.15 K and 1 Bar (10 5 Pascals) Pressure and at Higher Temperatures" by Robie et al., U.S. Geological Survey Bulletin 1452, U.S. Department of the Interior (1984). Cerium oxide has a much lower Gibbs free energy of formation than copper oxides. Therefore, forming cerium oxide from copper oxides is very thermodynamically favorable.
[0018] Some of the oxides of the listed metallic elements do not have a higher Gibbs free energy of formation than cerium oxide and they are not included in the selected group. The following table shows the Gibbs free energies of formation for some of the selected oxides of these metallic elements, based on the aforementioned U.S. Geological Survey Bulletin 1452. Those not within the selected group are also shown. A higher Gibbs free energy of formation, or a "less negative" Gibbs free energy of formation, corresponds to a higher Gibbs free energy in the compound.
[0019] [Table 1]
[0020] In some embodiments, the metal oxide may be provided in the form of a porous material disposed within the cover gas flow, and cesium vapor may react with the metal oxide as the cover gas flow passes through the porous material. For example, the porous material containing the metal oxide can be a packing material, wool, mesh, or screen material. Cesium vapor can react with the metal oxide in the porous material to form cesium oxide particles.
[0021] When cesium oxide particles are formed by reacting the metal oxide with cesium vapor, the cesium oxide particles are removed from the cover gas flow using a particle filter, and as a result, a filtered cover gas flow can be obtained. In some embodiments, the porous material containing the metal oxide can serve as a particle filter or the first stage of a two-stage particle filter. This not only reacts with cesium vapor to form cesium oxide particles but also retains at least some or all of the cesium oxide particles and removes them from the cover gas flow. For example, packing materials, wool, mesh, screens, powders, and / or granules, which can be formed from copper oxide or other suitable metal oxides, can act as particle filters that retain at least some of the cesium oxide particles while forming the cesium oxide particles.
[0022] In some embodiments, the particle filter can include a particle filter or the second stage of a two-stage particle filter. This is separate from the porous material used to react cesium vapor with the metal oxide to form cesium oxide particles. When a separate particle filter is used, the separate particle filter can include physical constraints designed to capture small particles of cesium oxide. For example, the separate particle filter can include a mesh screen or a series of screens having pores less than about 20 microns, or less than about 15 microns, or less than about anic acid and the method of producing the same.
[0023] In some embodiments, the separate particle filter may also include a suitable metal oxide. The suitable metal oxide may react with residual cesium vapor that remains entrained in the cover gas stream even after passing through the reactive porous material. For example, the separate particle filter may include copper oxide or other suitable metal oxides as a constituent material for a mesh sieve or series of sieves, or in addition to (one or more) sieves.
[0024] In some embodiments, the cover gas stream includes an inert gas (e.g., argon) and cesium vapor at a first molar concentration. The filtered cover gas stream includes an inert gas and cesium vapor at a second molar concentration. Depending on the temperature of the cover gas stream and other conditions under which the reaction occurs, the second molar concentration of cesium vapor can be from 0% to about 2% of the first molar concentration of cesium vapor, or from 0% to about 0.2% of the first molar concentration of cesium vapor, or from 0% to about 0.02% of the first molar concentration of cesium vapor, or from 0% to about 0.002% of the first molar concentration of cesium vapor, or from 0% to about 0.002% of the first molar concentration of cesium vapor.
[0025] The above target concentration of cesium vapor is R verified using FactSage 6 thermochemical software with an initial molar concentration of cesium vapor of 1.0X10 -6 in an argon cover gas at a pressure of 1 atmosphere. At a pressure of 1 atmosphere, the molar concentration of cesium vapor would correspond to its partial pressure in the atmosphere. In this example, the molar concentration can be approximated as 1X10 R Using FactSage
[0026] [Table 2]
[0027] Using the same conditions and assumptions, the aforementioned modeling was repeated for the reaction between cesium vapor and cuprous oxide (Cu2O). R Using thermochemical software, the following partial pressures can be expected to occur at the equilibrium state for the reaction between cesium vapor and cuprous oxide (Cu2O):
[0028] [Table 3]
[0029] From Tables 2 and 3 above, it can be understood that the amount of cesium vapor in the cover gas flow can be reduced to a negligible level using the oxidation process, and in some cases, to an undetectable level. Experimental work can be used to determine the optimal temperature of the cover vapor flow used to achieve the equilibrium reaction state, or a reaction state as close to equilibrium as possible. As shown in the table, the partial pressure of residual Cs at equilibrium is expected to be very low at relatively low temperatures. However, at relatively low temperatures, the reaction rate will also be slower, and the time required to reach the equilibrium reaction state will be longer. The optimal placement of the reaction and filtration apparatus within the cover gas flow requires consideration of both the temperature and time required to complete the reaction at that location.
[0030] In some embodiments, oxidation can be carried out by directly injecting oxygen gas into the cover gas flow. In this case, the oxygen gas readily reacts with cesium vapor to form cesium oxide particles. Only a small amount of oxygen gas may be required to complete the following reaction. This reaction is highly exothermic and can proceed spontaneously:
[0031] [ka]
[0032] Direct injection of oxygen gas necessitates the use of a particle filter placed within the vapor flow to remove cesium oxide particles from the cover vapor flow. This particle filter may include any of the filter assemblies described above. The particle filter may include a mesh sieve, a series of sieves, or other porous material having pores of less than approximately 20 microns, less than approximately 15 microns, less than approximately 10 microns, or approximately 5 to 10 microns. In some embodiments, the particle filter may be formed using a suitable reactive metal oxide to facilitate the capture of cesium oxide particles and residual cesium vapor accompanying the cover gas flow.
[0033] The aforementioned and other features of this disclosure will become even clearer when the following detailed description is read in conjunction with the drawings.
[0034] [Brief explanation of the drawing] Figure 1 schematically shows one embodiment of a reaction and filtration apparatus that may be placed in a cover gas flow to carry out an exemplary embodiment of the disclosed method.
[0035] [Detailed explanation] Refer to Figure 1. An exemplary reaction and filtration apparatus 10 can be placed within the cover gas flow 12 of a reactor and can be used to carry out exemplary embodiments of the disclosed method. The cover gas flow 12 contains an inert cover gas (which may in some cases be argon). The cover gas flow 12 may contain small but radioactively significant amounts of cesium-134 and cesium-137 (collectively referred to as cesium) in the form of vapor. Depending on the type and state of the reactor, the cover gas flow 12 may contain up to approximately 2.2 × 10⁻¹⁶ per mole of cover gas. -10 This may include, but is not limited to, moles of cesium vapor at a first concentration. Assuming ideal gas behavior and a pressure of 1 atmosphere, the amount of cesium present at these concentrations is approximately 2.2 x 10⁻⁶. -10This will show the corresponding partial pressures of atmospheric pressure. The methods of this disclosure are not limited to these partial pressures, nor are they limited to a total pressure of 1 atmosphere, but can be carried out under a variety of pressures.
[0036] The reaction and filtration device 10 can be placed anywhere within the cover gas flow. The reaction and filtration device 10 can be placed in a location selected, for example, based on the cover gas temperature at that location. The range of cover gas temperatures is typically about 20°C to about 550°C in various locations and in cover gas processing systems of various reactors. The disclosed method is not limited to implementation within this temperature range. The reaction rate of one or more chemical reactions from cesium vapor to cesium solid particles typically increases with increasing temperature. Therefore, according to this factor, it may be advantageous to place the device 10 in a location with a relatively high temperature in the cover gas flow. As used herein, the term “relatively high temperature location” refers to a location where the cover gas flow is above 250°C. On the other hand, the chemical reaction can proceed to a higher degree of equilibrium of completion at relatively lower temperatures. According to this, it may be advantageous to place the device 10 in a location with a relatively low temperature within the cover gas flow. The optimal placement of the device 10 within the cover gas flow will depend on several factors. For example, these factors include the amount or concentration of cesium vapor that needs to be removed, the flow rate and residence time of the cover gas flow within the apparatus 10, and the specific type of reaction used to convert the cesium vapor to cesium oxide particles (whether by contact with a metal oxide or by direct injection of oxygen, and if a metal oxide is used, the specific type thereof). In some exemplary embodiments, two or more apparatuses 10 may be positioned at selected locations within the cover gas flow. In some embodiments, the first apparatus may be positioned at a first location within the cover gas flow, and the second apparatus may be positioned at a second location within the cover gas flow. In some cases, the first location may have a higher cover gas flow temperature than the second location.
[0037] In some embodiments, the reaction and filtration apparatus 10 may be heated or cooled so as to achieve a desired reaction temperature and / or filtration temperature. In some embodiments, a selected portion of the reaction and filtration apparatus 10 may be heated or cooled so as to achieve a desired reaction temperature and / or filtration temperature in the selected portion of the apparatus. Similarly, the first and second apparatuses may be heated or cooled to various temperatures so as to achieve a desired reaction temperature and / or filtration temperature in the first and second apparatuses 10.
[0038] A cover gas stream 12 containing a first concentration of cesium vapor can enter the apparatus 10 at the inlet position 14 and pass through a narrower constriction 16 into the reaction chamber 18. In some embodiments, the reaction chamber 18 may be filled with a metal oxide material having a first Gibbs free energy of formation higher than the second Gibbs free energy of formation of solid cesium oxide. The metal oxide may be in the form of any porous material. The metal oxide may include, for example, at least one of packing material, wool, mesh, sieve, powder, and / or granules, among various designs. The porous material may be formed of a metal oxide or of another material (e.g., stainless steel). The porous material may have particles of metal oxide dispersed therein.
[0039] In some embodiments, the metal oxide material may be copper oxide, bismuth oxide, antimony oxide, lead oxide, nickel oxide, selenium oxide, tellurium oxide, and / or cobalt oxide, or a combination of one or more oxides. In some embodiments, the metal oxide material may include copper oxides selected from cupric oxide, cuprous oxide, and combinations thereof. In some embodiments, the metal oxide material may be cupric oxide. In some embodiments, the metal oxide material may be cuprous oxide. In some embodiments, the metal oxide material may be a mixture of cupric oxide and cuprous oxide or other combinations. In some embodiments, two or more metal oxides can be provided in the apparatus 10. In some cases, a first metal oxide, or a first combination of multiple metal oxides, can be provided in the first apparatus 10, and a second metal oxide, or a second combination of multiple metal oxides, can be provided in the second apparatus 10.
[0040] As the cover gas vapor passes through the reaction chamber 18, the cesium vapor reacts with the metal oxide to obtain cesium oxide particles and the elemental metal and / or the reduced metal oxide. For example, if the metal oxide is cuprous oxide, the reaction proceeds as follows:
[0041] [ka]
[0042] In another example, when the metal oxide is cupric oxide, the reaction proceeds as follows:
[0043] [ka]
[0044] [ka]
[0045] The resulting cesium oxide particles are then filtered out of the cover gas flow using a particle filter positioned within the cover gas flow. This yields a filtered cover gas flow 20. In some embodiments, a porous metal oxide material positioned within the reaction chamber 18 may act as a particle filter or as a component of the particle filter. Thus, the metal oxide particles may remain embedded within the porous material. In some embodiments, the apparatus 10 may further include a separate particle filter 22 designed to remove smaller particles. The particle filter 22 may be positioned downstream of the reaction chamber 18, between the reaction chamber 18 and the outlet opening 24 of the apparatus 10. The particle filter 22 may act as a primary filter (if the reaction chamber 18 performs little or no filtration) or as a secondary filter (if the porous material within the reaction chamber 18 performs substantial filtration of the metal oxide particles). The reaction chamber 18 may include an end cap 19 or other mechanism for directing the cover gas flow toward the particle filter 22.
[0046] In some embodiments, the particle filter 22 may include a sieve, a series of sieves, or other porous material having pores of less than about 20 microns, less than about 15 microns, less than about 10 microns, or about 5 to about 10 microns. The particle filter may be formed using a durable sieving material (e.g., stainless steel).
[0047] Alternatively, in some embodiments, a suitable reactive metal oxide may be used to form the particle filter so as to facilitate the capture of cesium oxide particles and residual cesium vapor accompanying the cover gas flow.
[0048] In some embodiments, the reaction and filtration apparatus 10 may include an oxygen supply system 28 and a flow meter located in an auxiliary inlet conduit 26. The oxygen supply system 28 may be isolated and controlled using a check valve 30. If the reaction chamber 18 is filled with a porous material containing a reactive metal oxide, a separate oxygen source may not be required, and the apparatus 10 can operate with the check valve 30 and the inlet conduit 26 closed. In alternative embodiments, the reaction chamber 18 may not contain a metal oxide material, and the oxygen supply system 28 may be used to convert cesium vapor to cesium oxide particles according to the following exothermic reaction:
[0049] [ka]
[0050] To regulate the supply of highly reactive oxygen, the check valve 30 can be used as a three-way check valve to selectively open and close and regulate the inflow 32 of air mixed with an inert gas (e.g., argon) and the inflow 34 of pure inert gas (e.g., argon). The reaction between cesium and oxygen can occur spontaneously. If too much oxygen or heat is added to the reaction chamber 18, the reaction can proceed violently. By carefully controlling the oxygen supply using additional argon as a diluent, the reaction can be controlled to a manageable level while successfully converting cesium vapor to cesium oxide particles.
[0051] In embodiments in which cesium is reacted with oxygen gas in the reaction chamber 18, the reaction chamber 18 does not need to perform a filtration function. In these embodiments, the particle filter 22 may act as a primary and / or sole filter for removing cesium oxide particles from the cover gas flow, thereby obtaining a filtered cover gas flow 20, which exits through the outlet 24.
[0052] The disclosed method provides a highly effective method for removing cesium vapor from a reactor cover gas flow. The incoming cover gas flow comprises an inert cover gas and cesium vapor at a first molar concentration. The filtered cover gas flow comprises an inert cover gas and cesium vapor at a second molar concentration. The range of the second molar concentration of cesium vapor may be 0% to about 2% of the first molar concentration of cesium vapor. In some embodiments, the range of the second molar concentration of cesium vapor may be 0% to about 0.2%, or 0% to about 0.02%, or 0% to about 0.002%, or 0% to about 0.0002% of the first molar concentration of cesium vapor.
[0053] The general nature of the embodiments of this disclosure will be sufficiently evident from the preceding description of such particular embodiments to the extent that others can readily modify and / or adapt specific embodiments for various applications without excessive experimentation by applying the knowledge of those skilled in the art without departing from the overarching concept of the embodiments of this disclosure. Therefore, such adaptations and modifications are intended to fall within the meaning and scope of the equivalents of the disclosed embodiments based on the teachings and guidance presented herein. The terminology or language used herein is intended to be explained, and not to be limiting, so that such terminology or language may be interpreted by those skilled in the art in light of the teachings and guidance presented herein.
[0054] The breadth and scope of the embodiments of this disclosure should not be limited by any of the exemplary embodiments described above, but should be defined solely by the following claims and their equivalents.
[0055] Unless otherwise specified or understood in the context in which they are used, conditional terms, particularly "can," "could," "might," or "may," are generally intended to indicate that a particular implementation may include certain features, elements, and / or behaviors, while other implementations may not. Thus, such conditional terms are generally not intended to imply that features, elements, and / or behaviors are required in any one or more implementations, nor are they intended to imply that logic for determining whether these features, elements, and / or behaviors are included in any particular implementation, or whether these features, elements, and / or behaviors should be performed in any particular implementation, is necessarily included in one or more implementations, regardless of user input or prompts.
[0056] Those skilled in the art will recognize that any process or method disclosed herein can be modified in many ways. The process parameters and sequence of steps described and / or illustrated herein are given for illustrative purposes only and can be changed as desired. For example, while steps illustrated and / or described herein may be illustrated or discussed in a particular order, these steps do not necessarily have to be performed in the illustrated or discussed order.
[0057] Furthermore, in the various exemplary methods described and / or illustrated herein, one or more steps of the processes described or illustrated herein may be omitted, or additional steps may be included in addition to the disclosed steps. Moreover, any step of any method disclosed herein may be combined with any one or more steps of any other method disclosed herein.
[0058] Furthermore, in the various exemplary methods described and / or illustrated herein, one or more steps of the processes described or illustrated herein may be omitted, or additional steps may be included in addition to the disclosed steps. Moreover, any step of any method disclosed herein may be combined with any one or more steps of any other method disclosed herein.
[0059] Of course, it is impossible to describe all possible combinations of elements and / or methods for the purpose of illustrating the various features of this disclosure. However, those skilled in the art will recognize that many further combinations and substitutions of the disclosed features are possible. Thus, various modifications can be made to this disclosure without departing from the scope or spirit of this disclosure. Furthermore, other embodiments of this disclosure may become apparent by considering the specification and the accompanying drawings and by carrying out the disclosed embodiments presented herein. The examples presented herein and in the accompanying drawings should be considered in all respects as illustrative and not restrictive. Certain terms are used herein, but these terms are used in a general and descriptive sense only and not for restrictive purposes.
[0060] Unless otherwise specified, the terms "a" or "an" as used herein shall be interpreted as meaning "at least one of." Finally, for ease of use, the terms "including" and "having" (and their derivatives) as used herein are interchangeable with and have the same meaning as the term "comprising."
[0061] From the above description and accompanying drawings, it will be understood that while specific implementations are described herein for illustrative purposes, various modifications can be made without departing from the intent and scope of the attached claims and the elements described in the claims. In addition, while specific embodiments are presented below in specific claims, the inventors envision various embodiments in any available claims. For example, while only some embodiments may be described as being embodied in a particular configuration, other embodiments may be embodied in the same way. Various modifications and changes can be made that would be obvious to those skilled in the art who benefit from this disclosure. It is intended to encompass all such modifications and changes, and therefore the above description should be considered in an illustrative rather than restrictive sense. [Brief explanation of the drawing]
[0062] [Figure 1] A schematic representation shows one embodiment of a reaction and filtration apparatus that may be placed within a cover gas flow to carry out exemplary embodiments of the disclosed method.
Claims
1. A method for removing cesium from the cover gas flow inside a nuclear reactor, A step of providing a cover gas flow containing an inert cover gas and cesium vapor inside the reactor, To form cesium oxide particles, the process involves oxidizing the cesium vapor in the cover gas flow, To obtain a filtered cover gas flow, a step is taken to remove the cesium oxide particles from the cover gas flow using a particle filter placed within the cover gas flow, Methods that include...
2. The step of oxidizing the cesium vapor in the cover gas flow includes a step of reacting the cesium vapor with a metal oxide, The metal oxide has a first Gibbs free energy of formation, The method according to claim 1, wherein the cesium oxide has a second Gibbs free energy of formation that is lower than the first Gibbs free energy of formation.
3. The method according to claim 2, wherein the metal oxide comprises an oxide of at least one of copper, lead, nickel, selenium, tellurium, and cobalt.
4. The method according to claim 2, wherein the step of oxidizing the cesium vapor includes passing the cover gas flow through a porous material containing the metal oxide.
5. The method according to claim 4, wherein the porous material containing the metal oxide comprises at least one of a filler, wool, mesh, sieving material, powder, or granules.
6. The method according to claim 1, wherein the step of oxidizing the cesium vapor in the cover gas flow includes a step of reacting the cesium vapor with copper oxide to obtain cesium oxide particles and copper metal or reduced copper oxide.
7. The method according to claim 6, wherein the step of oxidizing the cesium vapor includes passing the cover gas flow through a porous material containing the copper oxide.
8. The method according to claim 7, wherein the porous material containing the copper oxide comprises at least one of a filler material, wool, mesh, sieving material, powder, or granules.
9. The method according to claim 1, wherein the step of oxidizing the cesium vapor in the cover gas flow includes a step of reacting the cesium vapor with oxygen gas to obtain cesium oxide particles.
10. The cover gas flow comprises the inert cover gas and the cesium vapor at a first molar concentration. The filtered cover gas stream contains the inert cover gas and the cesium vapor at a second molar concentration. The method according to claim 1, wherein the cesium vapor at the second molar concentration is 0% to 2% of the cesium vapor at the first molar concentration.
11. The method according to claim 10, wherein the cesium vapor at the second molar concentration is 0% to 0.2% of the cesium vapor at the first molar concentration.
12. The method according to claim 10, wherein the cesium vapor at the second molar concentration is 0% to 0.02% of the cesium vapor at the first molar concentration.
13. The method according to claim 10, wherein the cesium vapor at the second molar concentration is 0% to 0.002% of the cesium vapor at the first molar concentration.
14. The method according to claim 1, wherein the step of oxidizing the cesium vapor in the cover gas flow includes a step of reacting the cesium vapor with a metal oxide containing at least one of bismuth oxide and antimony oxide.
15. A method for removing cesium from the cover gas flow inside a nuclear reactor, A step of providing a cover gas flow containing an inert cover gas and cesium vapor inside the reactor, A step of oxidizing the cesium vapor in the cover gas flow by reacting the cesium vapor with at least one of a metal oxide and oxygen gas in order to form cesium oxide particles, To obtain a filtered cover gas flow, a step is taken to remove the cesium oxide particles from the cover gas flow using a particle filter placed within the cover gas flow, Methods that include...
16. The step of oxidizing the cesium vapor in the cover gas flow is, The process involves passing the cesium vapor through a porous metal oxide material placed within the cover gas flow, To form the cesium oxide particles, the process involves reacting the cesium vapor with the porous metal oxide material, The method according to claim 15, including the method described in claim 15.
17. The method according to claim 16, wherein the porous metal oxide material includes a copper oxide.
18. The particle filter comprises the porous metal oxide material, The method according to claim 16, wherein the porous metal oxide material acts as a first filter that removes at least a portion of the cesium oxide particles from the cover gas flow.
19. The particle filter further includes a second filter, The method according to claim 18, wherein the second filter removes residual cesium oxide particles from the cover gas flow.
20. The step of oxidizing the cesium vapor in the cover gas flow includes the step of adding oxygen gas to the cover gas flow, To form the cesium oxide particles, the process involves reacting the cesium vapor with the oxygen gas, The method according to claim 15, including the method described in claim 15.
21. The method according to claim 15, wherein the step of oxidizing the cesium vapor in the cover gas flow includes a step of reacting the cesium vapor with a metal oxide containing at least one of bismuth oxide and antimony oxide.
22. A method for removing cesium from the cover gas flow inside a nuclear reactor, A step of providing a cover gas flow containing an inert cover gas and cesium vapor inside the reactor, A step of providing a metal oxide having a first Gibbs free energy of formation within the cover gas flow, In order to form cesium oxide particles having a second Gibbs free energy of formation smaller than the first Gibbs free energy of formation, the process involves oxidizing the cesium vapor in the cover gas flow by a chemical reaction with the metal oxide, To obtain a filtered cover gas flow, the steps include: removing the cesium oxide particles from the cover gas flow using a filter placed within the cover gas flow; Methods that include...
23. The method according to claim 22, wherein the metal oxide includes at least one of copper oxide, lead oxide, nickel oxide, selenium oxide, tellurium oxide, and cobalt oxide.
24. The method according to claim 22, wherein the metal oxide comprises a copper oxide selected from the group consisting of cupric oxide, cuprous oxide, and combinations thereof.
25. The cover gas flow comprises the inert cover gas and the cesium vapor at a first molar concentration. The filtered cover gas stream contains the inert cover gas and the cesium vapor at a second molar concentration. The method according to claim 22, wherein the cesium vapor at the second molar concentration is 0% to 0.002% of the cesium vapor at the first molar concentration.