Radioactive waste repository when contacted by water provides borates that absorb neutrons
11721448 · 2023-08-08
Assignee
Inventors
Cpc classification
G21F9/24
PHYSICS
G21C19/40
PHYSICS
Y02E30/30
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
International classification
Abstract
A container holds radioactive material. A sub-criticality controller protects the radioactive material from reaching a criticality from contact with the water. The sub-criticality controller includes a metallic composition having at least one metal component and at least one borate component bonded to the at least one metal component. The metallic composition forms borates when the metallic composition contacts the water.
Claims
1. A repository for storing radioactive material adjacent to water, the repository comprising: a container for holding the radioactive material; and a sub-criticality controller for protecting the radioactive material from reaching a criticality from contact with the water; wherein the sub-criticality controller includes a metallic composition having a metal component and a borate component bonded to the metal component; and wherein the metallic composition forms a second borate from the borate component reacting with the metal component when the metallic composition contacts the water.
2. The repository of claim 1, wherein the second borate is selected from the group consisting of lead borate, cadmium borate, zinc borate, manganese borate, iron borate, cobalt borate, nickel borate, copper borate, tin borate, bismuth borate, antimony borate, calcium borate, magnesium borate, lead metaborate hydrate, cadmium metaborate, zinc metaborate, manganese metaborate, iron metaborate, cobalt metaborate, nickel metaborate, copper metaborate, tin metaborate, bismuth metaborate, and antimony metaborate.
3. The repository of claim 1, wherein the borate component includes sodium tetraborate hydrate; and the metal component includes a metal-bearing compound.
4. The repository of claim 3, wherein the metal-bearing compound is selected from the group consisting of a lead-bearing compound, a cadmium-bearing compound, a zinc-bearing compound, a manganese-bearing compound, an iron-bearing compound, a cobalt-bearing compound, a nickel-bearing compound, a copper-bearing compound, a tin-bearing compound, an antimony-bearing compound, a bismuth-bearing compound, a calcium-bearing compound, and a magnesium-bearing compound.
5. The repository of claim 1, wherein the metal component includes a metal oxide comprising a metal, and the borate component comprises boric acid.
6. The repository of claim 5, wherein the metal is selected from the group consisting of lead, cadmium, zinc, manganese, iron, cobalt, nickel, copper, tin, antimony, bismuth, calcium, and magnesium.
7. The repository of claim 1, wherein the metal component includes a metal hydroxide for providing a metal, and the borate material include boric acid.
8. The repository of claim 7, wherein the metal is selected from the group consisting of lead, cadmium, zinc, manganese, iron, cobalt, nickel, copper, tin, antimony, bismuth, calcium, and magnesium.
9. The repository of claim 1, wherein the metal component includes a cation selected from the group consisting of a divalent cation, a trivalent cation, a mixture of divalent cations, a mixture of trivalent cations, and a mixture of both divalent and trivalent cations.
10. The repository of claim 1, wherein the sub-criticality controller is in the container.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) The application will become more fully understood from the following detailed description, taken in conjunction with the accompanying figures, wherein like reference numerals refer to like elements, in which:
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DETAILED DESCRIPTION OF THE INVENTION
(22) Before turning to the figures which illustrate the exemplary embodiments in detail, it should be understood that the application is not limited to the details or methodology set forth in the following description or illustrated in the figures. It should also be understood that the phraseology and terminology employed herein is for the purpose of description only and should not be regarded as limiting. Unless otherwise indicated percentages are expressed by weight.
(23) Exemplary embodiments of the invention relate to systems and methods for nuclear waste management and, in particular, to sub-criticality controllers that prevent criticalities that can occur during the storage of radioactive materials. The controllers can be adapted for long-term storage of nuclear waste or for the disposal of radioactive materials in geological repositories.
(24) The subject sub-critically controllers utilize materials that have a large cross-section for neutron capture, namely borate-containing materials. The borate-containing materials form compounds with various metals. These compounds have a low solubility in water, so that the compounds form borates when the compounds contact water that invades nuclear waste repositories or other containment systems that hold radioactive materials, or so that the compounds will not be readily dissolved nor moved away from the radioactive materials because of their low solubility, and therefore the compounds are always collocated with the radioactive materials.
(25) Turning to
(26) The repository 10 can include a container 14 therein. The container 14 includes a sub-criticality controller 16 and radioactive material 18 therein. The sub-criticality controller 16 protects the radioactive material 18 from reaching a criticality from contact with water from the water source 12.
(27) The container 14 holds the radioactive material 18 with the sub-criticality controller 16 being adjacent thereto. The sub-criticality controller 16 protects the radioactive material 18 from water flowing from the water source 12 to invade the container 14 when the container 14 is breached.
(28) The sub-criticality container 16 can be positioned in various configurations in relation to the container 14. In some embodiments, the sub-criticality controller 16 is positioned within the container 14 to protect the radioactive material 18 from the water after the container 14 is breached. In other embodiments, the sub-criticality controller 16 is positioned outside of the container 14 or incorporated into the container 14 to prevent the water from contacting the radioactive material 18 before the container 14 is breached.
(29) The sub-criticality controller 16 includes a metallic composition 20 that has a metal component 22 and a borate component 24. The metal component 22 is bonded to the borate component 24. In some embodiments, the bond between the metal component 22 and the borate component 24 is an ionic bond or primarily an ionic bond. In such embodiments, the bond has an ionic character that is greater than the covalent character. Such bonds have a large difference in electronegativity between the atoms that bond the metal component 22 to the borate component 24.
(30) The sub-criticality controller 16 can be positioned within the container 14. In other embodiments, the sub-criticality controller 16 can be positioned outside of the container 14 or incorporated into the walls of the container 14. The positioning of the sub-criticality controller 16 is not critical, as long as the sub-criticality controller 16 is positioned within a path 26 of water flowing from the water source 12. Additionally, the sub-criticality controller 16 must be positioned to absorb neutrons that radiate from the radioactive material 18.
(31) The metallic composition 20 has a low solubility in water. As a result, the metallic composition 20 forms borates from the borate component 24 when the metallic composition 20 contacts water from the water source 12. The borates remain in place to absorb radiation from the radioactive material 18.
(32) The borates that are formed from the borate component 24 include boron, which has a large cross-section for neutron capture. Neutron capture involves a nuclear reaction in which an atomic nucleus and one or more neutrons collide and merge to form a heavier nucleus. The formation of the heavier nucleus absorbs radiation, which can prevent a criticality. The neutron absorption cross-section, σ.sub.a, for elemental boron is 710±21 barns.
(33) As shown in
(34) In other embodiments, the metal component 22 can be a metal-bearing compound that forms a mixture with borate component 24. The metal-bearing compound can be any metal-bearing compound that forms a mixture with the borate component 24 that has a low solubility in water. Exemplary metal-bearing compounds can include a lead-bearing compound, a cadmium-bearing compound, a zinc-bearing compound, a manganese-bearing compound, an iron-bearing compound, a cobalt-bearing compound, a nickel-bearing compound, a copper-bearing compound, a tin-bearing compound, an antimony-bearing compound, a bismuth-bearing compound, a calcium-bearing compound, a calcium-sodium-bearing compound, and a magnesium-bearing compound.
(35) In yet other embodiments, the metal component 22 can be a metal oxide or a metal hydroxide. The metal oxide or metal hydroxide can be any metal oxide or metal hydroxide that forms a mixture with the borate component 24 that has a low solubility in water. Exemplary metal oxides include lead oxide, cadmium oxide, zinc oxide, manganese oxide, iron oxide, cobalt oxide, nickel oxide, copper oxide, tin oxide, antimony oxide, bismuth oxide, calcium oxide, and magnesium oxide. Exemplary metal hydroxides include lead hydroxide, cadmium hydroxide, zinc hydroxide, manganese hydroxide, iron hydroxide, cobalt hydroxide, nickel hydroxide, copper hydroxide, tin hydroxide, antimony hydroxide, bismuth hydroxide, calcium hydroxide, and magnesium hydroxide.
(36) Referring to
(37) Exemplary compositions for the borate component 24 that include metaborates include cadmium metaborate (Cd(BO.sub.2).sub.2), zinc metaborate (Zn(BO.sub.2).sub.2.1.5H.sub.2O), manganese metaborate (Mn(BO.sub.2).sub.2.2H.sub.2O), iron metaborate (Fe(BO.sub.2).sub.2), cobalt metaborate (Co(BO.sub.2).sub.2), nickel metaborate (Ni(BO.sub.2).sub.2.2NiO), copper metaborate (Cu(BO.sub.2).sub.2), tin metaborate (Sn(BO.sub.2).sub.2.2SnO), antimony metaborate (Sb(BO.sub.2).sub.2.2SbO), and bismuth metaborate (Bi(BO.sub.2).sub.2.2BiO).
(38) An exemplary metallic composition that includes a sodium tetraborate hydrate can form a mixture of a lead-bearing compound and sodium tetraborate hydrate (Na.sub.2B.sub.4O.sub.7.10H.sub.2O). Other exemplary metallic compositions form mixtures, such as a mixture of a cadmium-bearing compound and sodium tetraborate hydrate (Na.sub.2B.sub.4O.sub.7.10H.sub.2O), a mixture of a zinc-bearing compound and sodium tetraborate hydrate (Na.sub.2B.sub.4O.sub.7.10H.sub.2O), a mixture of a manganese-bearing compound and sodium tetraborate hydrate (Na.sub.2B.sub.4O.sub.7.10H.sub.2O), a mixture of an iron-bearing compound and sodium tetraborate hydrate (Na.sub.2B.sub.4O.sub.7.10H.sub.2O), a mixture of a cobalt-bearing compound and sodium tetraborate hydrate (Na.sub.2B.sub.4O.sub.7.10H.sub.2O), a mixture of a nickel-bearing compound and sodium tetraborate hydrate (Na.sub.2B.sub.4O.sub.7.10H.sub.2O), a mixture of a copper-bearing compound and sodium tetraborate hydrate (Na.sub.2B.sub.4O.sub.7.10H.sub.2O), a mixture of a tin-bearing compound and sodium tetraborate hydrate (Na.sub.2B.sub.4O.sub.7.10H.sub.2O), a mixture of a calcium-bearing compound and sodium tetraborate hydrate (Na.sub.2B.sub.4O.sub.7.10H.sub.2O), and a mixture of a magnesium-bearing compound and sodium tetraborate hydrate (Na.sub.2B.sub.4O.sub.7.10H.sub.2O).
(39) Exemplary mixtures that include borate-containing materials with boric acid can be a mixture of lead oxide or hydroxide and boric acid (H.sub.3BO.sub.3), a mixture of cadmium oxide or hydroxide and boric acid (H.sub.3BO.sub.3), a mixture of zinc oxide or hydroxide and boric acid (H.sub.3BO.sub.3), a mixture of manganese oxide or hydroxide and boric acid (H.sub.3BO.sub.3), a mixture of iron oxide or hydroxide and boric acid (H.sub.3BO.sub.3), a mixture of cobalt oxide or hydroxide and boric acid (H.sub.3BO.sub.3), a mixture of nickel oxide or hydroxide and boric acid (H.sub.3BO.sub.3), a mixture of copper oxide or hydroxide and boric acid (H.sub.3BO.sub.3), a mixture of tin oxide or hydroxide and boric acid (H.sub.3BO.sub.3), a mixture of calcium oxide or hydroxide and boric acid (H.sub.3BO.sub.3), and a mixture of magnesium oxide or hydroxide and boric acid (H.sub.3BO.sub.3).
(40) The metal component 22 can include one or more metals or metallic elements that form compounds or mixtures with metaborate hydrates, metaborates, sodium tetraborate hydrates, boric acid, or other borate-containing materials that have low solubility constants. An exemplary reaction for lead metaborate hydrate is set forth, as follows:
Pb(BO.sub.2).sub.2.H.sub.2O+3H.sub.2O(l)⇄Pb.sup.2++2B(OH).sub.4.sup.−, or
Pb.sub.5B.sub.3O.sub.8(OH).sub.3.H.sub.2O+7H.sup.+⇄5Pb.sup.2++3B(OH).sub.4
(41) The solubility constant, (log.sub.10 K.sup.0), for reaction can be −12, which represents a low solubility in water. Other exemplary borate-containing materials will have similar solubilities in water due to the chemical similarity between the materials.
(42) The metal component 22 can include any metal that forms a compound or mixture that has a solubility constant (log.sub.10 K.sup.0 of −4.0 or less. The metal can be a heavy metal and/or a transition metal, and/or an alkaline earth metal. Heavy metals can include metals having relatively high densities, high atomic weights, high atomic numbers, and/or certain chemical properties. As many as 96 of the known 118 chemical elements, including lead, bismuth, the transition elements, actinides, lanthanides, and the rare earth elements can be described as heavy metals.
(43) The metal component 22 can include any metal that bonds to borate containing materials in a similar manner as lead. Exemplary metals include cadmium, zinc, manganese, iron, cobalt, nickel, copper, tin, antimony, and bismuth. In some embodiments, the metal can be a divalent cation, a trivalent cation, a mixture of divalent cations, a mixture of trivalent cations, or a mixture of both divalent and trivalent cations. In other embodiments, the metal can be a soft acid or an intermediate acid, as understood under the Pearson acid-base concept.
(44) The use of cadmium, as part of the metal component, can have other benefits. Specifically, cadmium has a large cross-section for neutron capture (i.e., σ.sub.a=2410±110 barns).
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(64) The exemplary embodiments illustrated in the figures and described herein are presently preferred, it should be understood that these embodiments are offered by way of example only. Accordingly, the present application is not limited to a particular embodiment but extends to various modifications that nevertheless fall within the scope of the appended claims. The order or sequence of any processes or method steps can be varied or re-sequenced according to alternative embodiments.
(65) It is important to note that the construction and arrangement of the desalinization membranes as shown in the various exemplary embodiments is illustrative only. Although only a few embodiments have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited in the claims. For example, elements shown as integrally formed can be constructed of multiple parts or elements, the position of elements can be reversed or otherwise varied, and the nature or number of discrete elements or positions can be altered or varied. Accordingly, all such modifications are intended to be included within the scope of the present application. The order or sequence of any process or method steps can be varied or re-sequenced according to alternative embodiments. In the claims, any means-plus-function clause is intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Other substitutions, modifications, changes and omissions can be made in the design, operating conditions and arrangement of the exemplary embodiments without departing from the scope of the present application.