WO2005076769A2

WO2005076769A2 - Method and apparatus to absorb radiation from high level nuclear waste including fuel rods and use of that heat to produce electricity

Info

Publication number: WO2005076769A2
Application number: PCT/US2004/014816
Authority: WO
Inventors: Stuart Snyder
Original assignee: Stuart Snyder
Priority date: 2004-01-16
Filing date: 2004-05-12
Publication date: 2005-08-25
Also published as: WO2005076769A3

Abstract

A container (12) for radioactive waste, having a body member (14) including a cavity portion (16) for receiving and enclosing a quantity of radioactive waste, the body member comprising a composite material in the form of a mixture of heavy metals, cadmium (for absorbing neutrons emitted from fuel rods), and high thermal conductivity metals. This composite material will capture the particles emitted by the fuel rods, and approximately 80% of the emitted gamma rays. The container preferably includes at least one fin portion (18) extending from the body member to enhance heat transfer with the ambient atmosphere. Gas from the container is drawn into a sealed heat exchanger where it heats water or other fluid recruited to perform heat and/or power.

Description

METHOD AND APPARATUS TO ABSORB RADIATION FROM HIGH LEVEL NUCLEAR WASTE INCLUDING FUEL RODS AND USE OF THAT HEAT TO PRODUCE ELECTRICITY

BACKGROUND OF THE INVENTION

Technical Field

[0001] The present invention relates generally to methods and apparatus used to absorb most radiation from fuel rods and high level nuclear waste. This increases the available heat. The heat is used to create steam which drives a power generator.

Background Art

[0002] Some countries using nuclear reactors to produce electricity store radioactive solid waste in subterranean vaults. Others reprocess fuel rods to remove uranium and plutonium and store the residue.

[0003] Storage vaults may comprise deep vertical wells or horizontal tunnel corridors with tunnel rooms extending laterally from the corridors. The latter method is taught in Crichlow U.S. Pat. No. 5,850,614. Prior to deposition in vaults, the waste may be mixed with materials and converted into solid form having high chemical and structural stability. For example, radioactive oxides can be melted into a borosilicate glass or, alternatively, a lead iron phosphate glass, as taught by Boatner et al. U.S. Pat. No. 4,847,008, or a polymeric phosphate glass, as taught in Ropp U.S. Pat. No. 4,351,749. The glass mixture is typically poured into steel canisters or cylinders, solidified, sealed by welding or multiple lock systems, and overpacked with bentonite clay. The canisters are then placed into the subterranean storage chambers. [0004] U.S. Patent No. 6,183,243, entitled Method of Using Nuclear Waste to Produce Heat and Power, by applicant herein, and hereby incorporated by reference, provides a method for making practical and possibly temporary use of nuclear waste, while also ensuring environmental integrity and human safety. As described supra, it is well known in the art to incorporate nuclear waste products from nuclear production reactors into glass, ceramic, or cementitious blocks. The waste so incorporated may be solid nuclear waste, such as spent nuclear reactor fuel rods, or it may be liquid waste products reduced to solid form. Snyder U.S. Patent 6,183,243 discloses a method to exploit the heat generated by the decay of radioactive waste embodied in this fashion by placing cast blocks containing radioactive waste in a containment room where gas is circulated around the blocks as a heat exchange medium. The gas is drawn into a sealed heat exchanger where it heats water or other fluid recruited to perform some useful work such as the generation of heat and/or power. [0005] The containment room may be subterranean or above-ground and is bordered by a cement or earth fill wall engineered to reduce radioactivity to safe levels. When sealed, the room is gas tight.

[0006] The containers are then be transferred to the containment room through material handling means and arranged in columns and rows. An inlet port is provided to introduce a heat exchange gas. The gas is circulated among the containers and drawn through an outlet port into a sealed heat exchanger. Numerous uses may be made of the heated heat exchange fluid, including steam turbine power generation, building heat or warm water irrigation. Monitoring and inspection of the containers can be performed by shielded monitors and robots stored in an adjacent maze.

[0007] The foregoing patents reflect the current state of the art of which the present inventor is aware. Reference to, and discussion of, these patents is intended to aid in discharging Applicant's acknowledged duty of candor in disclosing information that may be relevant to the examination of claims to the present invention. However, it is respectfully submitted that none of the above-indicated patents disclose, teach, suggest, show, or otherwise render obvious, either singly or when considered in combination, the invention described and claimed herein.

Disclosure of Invention

[0008] The present invention provides a method and apparatus to absorb radiation from high level nuclear waste including nuclear fuel rods, and use of that heat to produce electricity. The inventive apparatus includes a container for radioactive waste, having a body member including a cavity portion for receiving and enclosing a quantity of radioactive waste, the body member comprising a mixture of heavy metals, cadmium (specifically for absorbing neutrons emitted from the subject rods), and high thermal conductivity metals.

This composite material will capture all of the particles emitted by the subject rods, and approximately 80% of the gamma rays emitted. The inventive container may be cylindrical in shape, and preferably includes at least one fin portion extending from the body member to enhance heat transfer with the ambient atmosphere. The gas is drawn into a sealed heat exchanger where it heats water or other fluid recruited to perform some useful work such as the generation of heat and/or power.

[0009] It is therefore an object of the present invention to provide a new and improved container for radioactive waste.

[0010] It is another object of the present invention to provide a new and improved container for radioactive waste that optimizes radiation absorption.

[0011] A further object or feature of the present invention is a new and improved container for radioactive waste that optimizes heat exchange.

[0012] An even further object of the present invention is to provide a novel container for radioactive waste that may be used in conjunction with a method to exploit the heat generated by the decay of radioactive waste embodied in this fashion by placing cast blocks containing radioactive waste in a containment room where gas is circulated around the blocks as a heat exchange medium.

[0013] Other novel features which are characteristic of the invention, as to organization and method of operation, together with further objects and advantages thereof will be better understood from the following description considered in connection with the accompanying drawing, in which preferred embodiments of the invention are illustrated by way of example. It is to be expressly understood, however, that the drawing is for illustration and description only and is not intended as a definition of the limits of the invention. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming part of this disclosure. The invention resides not in any one of these features taken alone, but rather in the particular combination of all of its structures for the functions specified.

[0014] There has thus been broadly outlined the more important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will form additional subject matter of the claims appended hereto. Those skilled in the art will appreciate that the conception upon which this disclosure is based readily may be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.

[0015] Further, the purpose of the Abstract is to enable the national and regional patent offices and the public generally, and especially the scientists, engineers and practitioners in the art who are not familiar with patent or legal terms or phraseology, to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application. The Abstract is neither intended to define the invention of this application, which is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way. [0016] Certain terminology and derivations thereof may be used in the following description for convenience in reference only, and will not be limiting. For example, words such as "upward," "downward," "left," and "right" would refer to directions in the drawings to which reference is made unless otherwise stated. Similarly, words such as "inward" and "outward" would refer to directions toward and away from, respectively, the geometric center of a device or area and designated parts thereof. References in the singular tense include the plural, and vice versa, unless otherwise noted.

Brief Description of the Drawings

[0017] The invention will be better understood and objects other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawing wherein: [0018] FIG. 1 is a perspective view of an apparatus to absorb radiation from high level nuclear waste including fuel rods, and use of that heat to produce electricity.

Best Mode for Carrying Out the Invention

[0019] Refereing to FIG. 1, there is illustrated therein a new and improved apparatus to absorb radiation from high level nuclear waste including fuel rods, and use of that heat to produce electricity, generally denominated 10 herein. The present invention includes a container 12 for radioactive waste, having a body member 14 including a cavity portion 16 for receiving and enclosing a quantity of radioactive waste. The composition of body member 14 preferably includes a mixture of heavy metals, cadmium (specifically for absorbing neutrons emitted from the subject rods), and high thermal conductivity metals. [0020] Snyder U.S. Patent 6,183,243 discloses a method to exploit the heat generated by radioactive decay from expended fuel rods and high level radioactive waste by reformatting high level waste to have the same geometry as expended fuel rods. These are placed into a vertical cavity in each column of material to absorb all particulate matter and at least eighty percent of gamma rays emitted by the expended fuel rods or waste configured in the same geometry as the fuel rods.

[0021] The enclosing columns shall have fins 18 to increase the transfer of heat to ambient gas. They shall also have a high degree of stiffness to prevent bending during an earthquake.

[0022] The columns shall be placed in a large array in a cut and cover facility 20.

[0023] The attachment of the columns to the floor of the cut and cover facility shall have a quick fit attachment system that ensures the columns will not escape from the attachment during an earthquake.

[0024] The cut and cover facility shall be gas tight and shall contain only non-reactive, oxygen free gas at 15 psi or higher.

[0025] Radiation resistant robots that are remotely operated by use of cables from control to robot, shall be used to place the columns in the cut and cover facility and to make the attachment of column to floor.

[0026] The interior of the facility shall have, at least, triply redundant heat exchangers 22, i.e., there shall be three sets of two heat exchangers in each set. The purpose is to maintain operation without removal and replacement of a failed heat exchanger set during the expected thirty year operating lifetime of the system. Only one set shall be operated at a time.

[0027] Radiation particle detectors shall be located at the input to each of the two heat exchangers in each set of three.

[0028] The ambient gas is maintained by triple gas tight entrance closures built into the entrance maze. The ambient gas shall be circulated by the heat exchanger set in use.

[0029] Visual inspection shall be through a staged system. At various locations within the facility front silvered reflecting mirrors shall be used for visual inspection. Well within the reinforced concrete, and away from direct or reflected gamma rays the image shall be reflected to a fiber optic system which carries the image to the surface. These shall be placed to provide complete visual monitoring as desired.

[0030] Entrance to the facility shall be by a maze which eliminates any radiation at the exterior door. [0031] The rows in the enclosed cut and cover facility shall be spaced so a remotely controlled robot can easily move through the row for initial installation of the columns, detailed inspection as well as subsequent removal and replacement of columns. The robots shall have radiation snifters for localized radiation leakage inspection. The robots shall be stored in a recess between the two stage pressure sealed access doors. Control shall be manual from the surface.

[0032] Heat shall be transferred to the ground surface where the heat is used to create steam which drives the generators 24 to produce electricity.

[0033] The present invention may be used in conjunction with the invention described in Snyder U.S. Patent 6, 183,243. As taught in that disclosure, the containment room may be subtenanean or above-ground. Preferably it is subtenanean and lined with a concrete or earth fill wall of sufficient thickness to minimize external radioactive levels according to accepted nuclear waste form engineering practices. When sealed, the room will also be gas tight. Dimensions of the containment room may be adapted to heat generation needs, disposal needs and schedules, rates of waste production, and monitoring capabilities, but one size could be roughly twenty feet in width and breadth and have a ten to twelve foot ceiling height.

[0034] Preliminary to placement in the containment room, radioactive waste may be stored in long-life containers such as described herein, preferably in the form of columns. It is well known that radioactive waste in solution may be evaporated until radioactive products are in the solid state. The solid products may be heated to maximize oxide production, and the products can be stored alone or in combination with other solid radioactive waste, such as spent nuclear fuel rods, be incorporated in a borosilicate glass, lead iron phosphate glass, polymeric phosphate glass, ceramic or cementitious forms. In the present method, any one or a combination of such materials and methods may be suitable, and such do not comprise an element of the present invention. However, the forms are preferably either cylindrical blocks or substantially flat plates. [0035] Once the radioactive waste is embodied as described, it will be placed (if solid) or poured (if still fluid) into heat absorbing containers such as described herein, and sealed. The configuration of the containers is of a design to facilitate heat transfer with the ambient atmosphere. Heat exchanging fins are preferably added for this reason. [0036] The containers will then be transfened to the containment room by suitable means, either manually or by other material handling means, such as a robot . The containers will be placed in rows for efficient heat transfer, monitoring, and future handling and transfer. At least one inlet port will be provided for the introduction of a heat exchange gas, such as molecular nitrogen. The nitrogen will be circulated among the containers and drawn through an outlet port into a sealed heat exchanger positioned immediately outside and adjacent to the containment room walls. A steam generator may be driven by water heated in the exchange, but numerous other applications are contemplated, including building heat and warm water rigation. In the event sufficient thermal energy can be generated from the cylinders, an electric power generator may derive the remaining electricity generating potential from the nuclear material. To eliminate the risk of radiation exposure, monitoring and inspection of the containers will be performed by shielded monitors and the previously mentioned robot, the latter protected from reflected radiation while not in use by being stored at the end of a maze extending outwardly from a containment room exit. The room exit is closed by an exit door having a metal seal or gasket. The maze terminates in a maze exit, which is also sealed closed by a maze exit door having a metal seal or gasket.

[0037] The above disclosure is sufficient to enable one of ordinary skill in the art to practice the invention, and provides the best mode of practicing the invention presently contemplated by the inventor. While there is provided herein a full and complete disclosure of the prefened embodiments of this invention, it is not desired to limit the invention to the exact construction, dimensional relationships, and operation shown and described. Various modifications, alternative constructions, changes and equivalents will readily occur to those skilled in the art and may be employed, as suitable, without departing from the true spirit and scope of the invention. Such changes might involve alternative materials, components, structural anangements, sizes, shapes, forms, functions, operational features or the like. [0038] Therefore, the above description and illustrations should not be construed as limiting the scope of the invention, which is defined by the appended claims.

Claims

What is claimed as invention is: 1. A container for radioactive waste, said container comprising: a body member including a cavity portion for receiving a quantity of radioactive waste, said body member comprising a mixture of heavy metals, cadmium, and high thermal conductivity metals.

2. The container for radioactive waste of claim 1 further including at least one fin portion extending from said body member to enliance heat transfer with the ambient atmosphere.

3. The container for radioactive waste of claim 1 wherein the radioactive waste is a solid.

4. The container for radioactive waste of claim 1 wherein the radioactive waste comprises spent nuclear fuel rods.

5. The container for radioactive waste of claim 1 wherein the radioactive waste is a liquid.

6. The container for radioactive waste of claim 1 wherein the radioactive waste is a liquid reduced to solid form and oxidized.

7. The container for radioactive waste of claim 1 wherein the radioactive waste is incorporated into cast glass.

8. The container for radioactive waste of claim 1 wherein the radioactive waste is incorporated into a ceramic.

9. The container for radioactive waste of claim 1 wherein the radioactive waste is incorporated into cementitious blocks.

10. The container for radioactive waste of claim 1 wherein said container is columnar in shape.

11. A method for containing radioactive waste, said method comprising the steps of: providing a body member including a cavity portion, the body member comprising a mixture of heavy metals, cadmium, and high thermal conductivity metals; placing a quantity of radioactive waste into the body member cavity portion.

12. The method of claim 11 further including the step of: providing at least one fin portion extending from the body member to enhance heat transfer with the ambient gas.

13. The method of claim 12 further including the step of: drawing the ambient gas into a sealed heat exchanger where it heats a fluid to perform useful work.

14. The method of claim 14 further including the step of: using the heat from the heat exchanger to create steam which drives a generator to produce electricity.