TECHNICAL FIELD OF THE INVENTION

The present invention relates in general to in-situ vitrification of waste material in human-made deeply located subterranean caverns and more specifically to management, treatment, and/or removal dangerous volatile materials produced during the vitrification processes.

COPYRIGHT AND TRADEMARK NOTICE

A portion of the disclosure of this patent application may contain material that is subject to copyright protection. The owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyrights whatsoever.

Certain marks referenced herein may be common law or registered trademarks of third parties affiliated or unaffiliated with the applicant or the assignee. Use of these marks is by way of example and should not be construed as descriptive or to limit the scope of this invention to material associated only with such marks.

BACKGROUND OF THE INVENTION

In the United States (U.S.) and other countries across the globe, the nuclear weapons production industry has left a massive and devastating legacy when the nuclear reactors were decommissioned. For example, the weapons manufacturing process left behind about 53 million U.S. gallons (or about 500,000 cubic meters [m3]) of high-level radioactive waste stored within 177 storage tanks. In addition, 25 million cubic feet (ft3) (or about 710,000 cubic meters [m3]) of solid radioactive waste and a resulting contamination zone covering several square miles of contaminated groundwater exists beneath the site. Much of this liquid waste has been leaking into the surrounding earth creating significant health and environmental problems. There is a tremendous safety and environmental need to store and/or dispose of such radioactive materials. Radioactive waste is generally categorized as high-level waste (HLW) or low-level waste (LLW).

In the past, radioactive and/or nuclear materials (such as waste materials) have been stored in barrels, individual capsular containers, as slurry material, in open pits and also within shallow mines which are very close to the surface of the Earth. In the past, it has been challenging, dangerous, and expensive to try to store radioactive and/or nuclear materials (such as waste materials) in underground cavern-like structures.

Many processes have been studied, proposed, and/or implemented in different forms to dispose of, get rid of, and/or contain these dangerous radioactive waste materials. For example, some form of vitrification has been tried in several countries.

Vitrification is a process in which a substance is transformed into a glass. Glass may be defined as a non-crystalline amorphous solid. Glass may also be defined in a broader sense to include solids that are amorphous in structure at the atomic scale and that exhibit a reversible change from a hard and relatively brittle state into a viscous or rubbery state when sufficiently heated. This reversible change point is defined as the glass transition point. Vitrification is usually achieved by heating materials to a liquid state, then cooling the liquid, often rapidly, so that it passes through the glass transition to form a glassy solid.

In practice, vitrification involves melting of waste materials with glass-forming additives, often called “frit,” so that the final vitreous product incorporates the waste contaminants macroscopically and microscopically. The vitrified glass material is often referred to as “melt” during the glass-forming process. In the macroscopic glass form, the waste material may be considered encapsulated while in a microscopic form such that the waste forms an integral structural part of the glass material.

The vitrification process may be implemented in two ways: by either a continuous feed operation in which the feed (waste) is introduced in a continuous or momentarily intermittent stream into the melter or by a batch type operation in which measured quanta (volumes/amounts) of waste or feed are introduced into a melter system and melted or vitrified over a period of time. The batch process may be repeated several times. In some embodiments herein the batch type system is contemplated. In the vitrification heating process, complex chemical reactions may occur and gases and other volatiles may be evolved during the chemical interactions between various constituents of the feed material. Some of the volatile products and gases may be dangerously radioactive and long lived with half-lives lasting tens of thousands of years. There is therefore a need to capture or keep these volatiles isolated and controllably removed from entering the environment. In the vitrification process after heating is established, a cold cap which consists of a finite layer of reacting material floating on the surface of the molten material at the top of the vitrification vessel or melter, is initiated and later becomes functional and fully developed. During the continued vitrification process this floating reaction zone or the “cold cap” by virtue of its temperature distribution and physical characteristics and foaming action occurring therein, may allow for complex reactions to occur in which the dangerous or radioactive volatiles which may be produced during the vitrification process may be modified by chemical interactions with chemical reagents which may be introduced into or added to the cold cap zone. The thickness of the cold cap region may vary depending on the ratio of the rate of heat flux generation from the melt zone and the heat loss above the cold cap. Published data indicates that the cold cap thickness may be between at least 2 cm to more than 15 cm depending on the heat generation rates in the melt. It is within this cold cap zone that the necessary reactions which provide the means to manage the volatile materials and products may be implemented by the embodiments taught by this patent application.

Glass has many physical and chemical properties and attributes that make such glass suitable and/or desirable for use in waste disposal, such as, being reliable in immobilizing the waste, being safe for long-term storage, being safer for handling and/or transportation operations. Glass is amorphous. Glass has been shown to be generally insensitive to the effects of radiation and radioactive decay. The finished glass material can chemically and physically incorporate many waste elements and products over wide composition ranges. The basic glassmaking process has been practiced for millennia, it is relatively simple and offers a means for waste disposal in radioactive operations in which massive volumes of HLW, LLW, and/or other dangerous wastes need to be safely disposed. The HLW that has to be disposed of, contains insufficient amount of glass precursors, e.g., silicon, and as such, to produce a long-lived glass product silica and other glass-forming must be added chemically and/or as a glass product called frit to vitrify HLW and/or other similar radioactive wastes.

The vitrification process applied to nuclear waste is attractive; flexible, and applicable to a variety of radioactive elements that may be incorporated in such glasses. In addition, the glass product is minimally leachable, resists corrosion, is durable; and the compactness, volume reduction, and ease of handling of the glass formed waste are all positive attributes. For example, natural analogues of vitrified products include silicate glasses found in the geologic record from volcanic glasses, these records have displayed minimal degradation processes over several million years.

Vitrification is a mature technology and has been used for HLW immobilization in many batch or continuous processes in limited volumes for more than 40 years in France, Germany, Belgium, Russia, the United Kingdom (UK), India, Japan, and in the U.S.

The prevailing and preexisting concepts in vitrification of nuclear waste, focus on the long-held view currently exhibited by the major U.S. companies disposing of nuclear waste. These companies are spending an enormous of money, e.g., up to $37 Billion projected for 2019 to: vitrify the waste in massive plants employing several thousand individual staff; storage of the vitrified products in stainless steel containers; transport of the vitrified products to a disposal location; entombing the vitrified products containers in shallow salt formations; and then waiting and hoping for mother nature to encapsulate the glass bearing containers to be subsumed by the salt encroachment over thousands of years of geologic time before leaching or surface contamination can occur via migration of radionuclides.

The prevailing and preexisting concepts in vitrification of nuclear waste are less than ideal and are in fact seriously problematic. This process has essentially spent billions of dollars to “kick the can down the road.” The waste may be temporarily contained but the waste has not been disposed, nor has the waste been sufficiently isolated from nearby ecosystems, environments, and ground waters.

Today (circa 2021), there is a well felt need for a better and more complete solution to the HLW and LLW waste problem.

It is at least one objective of this inventive application to solve the containment and disposal problem as completely as possible.

To this end, this patent application combines some existing prior art elements and introduces additional novel elements to attain a level of disposal and containment that hitherto has not been achieved by providing a subterranean deeply located in-situ vitrification process which may further manage, treat, and/or contain the evolved volatile radioactive constituents (which are dangerous byproducts of the vitrification process) in deeply located geological formations, from which no material can migrate over millions of years of geologic time.

Previously, there has not been any attempt to manage, treat, and/or contain the volatized (radioactive) effluents, from the vitrification, in-situ, in very deep human-made caverns as illustrated in the subject patent application. This may be because: (1) such caverns do not generally naturally exist in rock formations at very great depths; (2) it had been impossible to economically fabricate or produce large diameter caverns or to implement them in deep enough geological formations which are necessary to maintain a level of safety such that there would be no migration of radionuclides from the radioactive materials to the surface over geologic time; (3) the requisite technology to vitrify the waste material though available at the surface has only been tried in shallow surface pits and has not been extended to deep underground systems; (4) the electrical power systems needed to transmit, control and deliver sufficient electric power to deep downhole heaters had not been safely perfected; and/or the like.

The surface process of vitrification is quite simple (at or near the Earth's surface): (1) the waste is dried, then heated to convert the nitrates to oxides; (2) glass-forming additives or frit are added to the waste material and heated again to around 1000 degrees Celsius (° C.); (3) the molten liquid is poured into a suitable containment vessel to cool and form the solid glass; (4) the solidified vitreous product has incorporated the waste materials in its macro- and microstructures, and the hazardous waste constituents are immobilized.

Borosilicate and phosphate glasses are the two main types of glass frit currently used to immobilize nuclear waste in surface vitrification operations. Both of these materials can immobilize large amounts of radioactive products.

The ability to economically provide a human-made cavern, in a deep geologic formation, of sufficient size and volume, for efficient in-situ waste vitrification and also for safe disposal of substantial quantities of vitrified radioactive waste is now feasible today. What is required is more than just the ability to vitrify some small amounts of nuclear waste in a series of surface batch operations, there are real needs for the economic vitrification, disposal and storage of massive quantities of waste in the millions of gallons. To date (2021), the current best available technology at the Hanford site in the U.S. contemplates an expensive, single, stand-alone vitrification unit. If that unit fails, the whole vitrification industry stops; until a better solution is found. This current approach has no failsafe feature since there is only one plant contemplated to dispose of the HLW. A better means is needed.

Elements, systems and/or methods as proposed herein are different than the prior art. Embodiments of the present invention may provide elements, systems and/or methods to significantly multiply and scale these solutions to fit the need and demands. Embodiments of the present invention may run multiple systems in parallel as needed to meet the need and demands. Just like in the oil and gas industry where literally dozens of oil wells can be drilled by individual drilling rigs simultaneously to develop a given field, a plurality of vitrification systems can be implemented simultaneously to provide up to fifty or more simultaneous in-situ vitrification operations at the same location (or different locations). Embodiments of the present invention may provide a measurable economy of scale to resolve this seemingly intractable problem of disposing millions of gallons of waste.

Some of the technical drivers that have allowed the embodiments of present invention herein to be implemented may be as follows: (1) improvements in drilling rigs; (2) improvements to underreaming capabilities/operations using drilling rigs; (3) improvements in electrical power delivery/distribution, management, and/or control; (4) improvements in heating means; and/or the like.

Drilling rig design features have improved. Hydraulic pressure availability downhole in the wellbore at the drill bit has been increased. The available drilling rig horsepower has been increased up to as much as 4,000 hydraulic horsepower. Available pump horsepower has increased. Available rig capacity up to two million (2,000,000) pounds of dead weight lift is available. High downhole drilling fluid pressures can be maintained. Such drilling rig improvements provide for ease of implementation of deeply located human-made caverns for insitu vitrification and for loading or disposing of waste products into such deeply located human-made caverns.

Specific technological improvements that pertain to the drilling underreaming operations and underreaming equipment have allowed successful underreaming needed to make and manage large diameter human-made caverns that may be located with deeply located geological formation(s). Some of these underreaming improvements may include: hydraulically actuated reamer elements expandable and retractable with pump pressure and downhole RFID (radio frequency ID) triggering with injected RFID tags; cutter arms move upward and out simultaneously in the body; fail-safe cutter arm retraction; reverse actuating mechanism maintains that tool is open while drill string weight prohibits tool closure; unrestricted fluid flow through internal diameters of the wellbore tubular goods; roller cone cutters are specifically designed for the Drill Time Under-Reamers and are consistent with downhole diameters; reamer bodies machined from heat-treated steel bar, giving the reamer bodies exceptional strength; jet nozzles near the cutters allow for cutter washing and cooling; a variety of cutting structures are available to facilitate the reaming process; and/or the like.

Additionally, the electric power and applied industries have developed and implemented improved, surface facilities, control mechanisms and power cables which deliver electric power efficiently and controllably to the downhole heater equipment. Power cables have significant improvements and are now capable of transmitting megawatts of power over several thousand feet in a wellbore environment regularly and safely without accident. These computerized systems can minimize power losses in transmission, maximize energy deliverability, allow the types of temperature control needed to optimize the melt process and the annealing and cooling of the melt in the subterranean cavern during vitrification.

Today (2021), the understanding of vitrification processes and operational conditions have improved considerably. The compositions of the waste, the chemical and physical formulation of the frit and other physical descriptors have been studied by investigators across the globe. Additionally, the development and application of computational fluid dynamic modelling platforms for vitrification simulation have provided insights into and preconditions necessary for an optimal vitrification process without the need for hundreds of time consuming and ineffective laboratory or small-scale experiments.

Though most physical test efforts have been on small-scale experiments, it is generally accepted that larger batch operations can be more tolerant to compositional variations than small-scale laboratory tests. Embodiments of the present invention taught in this patent application may be for very large human-made cavern based waste systems in which several tons of waste are controllably vitrified in massive deeply located underground cylindrical human-made cavern(s) with heater(s) electrically powered and controlled from the Earth's surface.

In sum, some embodiments of the present invention may provide elements, devices, apparatus, products, machines, systems, mechanisms, means, and/or methods for the in-situ vitrification and/or disposal of radioactive materials within human-made subterranean caverns that are themselves located within deep geological formation(s); and wherein the dangerous volatiles produced from the vitrification may be managed, treated, and/or contained also within the given deep geological formation(s); in manners that may be safe (for humans and the environment), economically feasible, and efficient.

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.

It is to these ends that the present invention has been developed.

BRIEF SUMMARY OF THE INVENTION

To minimize the limitations in the prior art, and to minimize other limitations that will be apparent upon reading and understanding the present specification, embodiments of the present invention may describe elements, devices, apparatus, products, machines, systems, mechanisms, means, and/or methods for the management, treatment, and/or containment of at least some volatiles that may be evolved during vitrification of (radioactive) waste materials (including nuclear and non-nuclear materials) in deeply located underground human-made caverns, wherein such human-made caverns are located within deep geologic formation(s).

In light of the problems associated with the known methods of controlling these volatile vitrification byproducts and/or their derivatives, it may be an object of some embodiments, to provide at least one method for modifying or changing the vitrification process for nuclear waste and other materials in human-made caverns which is safe, with a high volumetric capacity, cost-effective, easily deployable, and may meet the regulatory requirements for safety and environmental protection. It may be another object of some embodiments to provide at least one method of the type described herein wherein the modified vitrification process occurs several thousand feet below the Earth's surface, below the water tables, away from potential contamination of the ecosphere by the evolved volatile byproducts and/or their derivative compounds.

Briefly, the modified vitrification method in accordance with some embodiments of this invention may achieve at least some of the intended objectives by comprising steps of: quantitively analyzing the chemical processes involved in the production of volatiles during the planned/proposed HLW vitrification operations (this may be an optional step); drilling a pilot well which intersects a deep geologic formation (with a drill rig); forming at least one human-made cavern within that deep geological formation (via underreaming operations with a drill rig); filling (to a predetermined level) that human-made cavern with waste (and frit) to be vitrified; implementing an electrically powered energizable heating system at the subject human-made cavern into which the waste products are disposed for subsequent vitrification for providing the necessary heat for the vitrification; while safely managing, treating, processing, fixing, containing and/or disposing of at least some of the volatile vitrification byproducts in a cold-cap section of the human-made cavern; and while allowing the melted vitrified waste and the solidified (fixed) products of the volatiles to remain sequestered in the human-made cavern above the glass products for thousands to millions of years. Some of these steps may be optional.

The present disclosure relates to methods for operating vitrification systems for the high-level waste disposal, and more particularly to methods for operating the in-situ vitrification of the high-level waste in deep underground geological human-made cavern systems utilizing a cold-cap system modified and operated to stabilize and immobilize at least some of the volatiles that are produced during the vitrification process.

Systems and methods are disclosed for the vitrification of waste materials such as radioactive wastes and particularly high-level radioactive wastes. The inventive methods herein improve the efficiency of the vitrification process by implementing chemical reactions which occur primarily in the cold-cap region of the human-made cavern to form compounds which remain incorporated (fixed) in the cold-cap and thereby prevent at least some of such volatiles from being disseminated away from the vitrification location that is within a deep geologic formation.

In one embodiment, a method of managing at least some of the volatiles formed during the vitrifying process may include steps of providing a high-level waste for vitrification; providing a glass frit additive or glass forming chemicals or both for mixing with the waste; providing a cold-cap; providing a source of volatile fixing additives (VFAs) (reagents); and, feeding the waste, the glass frit or glass forming chemicals or both, and VFAs to a melter system for vitrification of the waste so that formation of selected dangerous volatiles is managed. The VFAs are generally expected to be implemented in a cold-cap that is located within the human-made cavern.

In some embodiments, a method may comprise selecting the VFAs from a group comprising particular reagents which have been demonstrated to chemically and/or physically fix, combine, and/or react with the specific volatiles so that the modified compounds remain in or near the cold-cap region and/or melt region within the human-made cavern.

It is at least one objective of this inventive application to solve the containment and disposal problem with respect to radioactive wastes as completely as possible.

It is an objective of the present invention to provide for radioactive waste disposal that is safer, more efficient, more cost effective, cheaper, more easily built, more easily implemented, more easily maintained, more scalable, faster, handles greater volumes of waste, satisfies/meets regulatory requirements, as compared to prior art methods.

It is another objective of the present invention to provide for radioactive waste disposal that treats significantly larger volumes of waste products as compared to prior art methods.

It is another objective of the present invention to provide for radioactive waste disposal that is capable of operating for significantly longer times as compared to prior art methods.

It is another objective of the present invention to provide systems and/or methods for the in-situ vitrification of radioactive waste (or other waste materials) within human-made caverns that are located within deep geologic formation(s).

It is another objective of the present invention to provide systems and/or methods for managing, treating, and/or containment of at least some (radioactive) volatile byproducts produced from the in-situ vitrification of waste within human-made caverns that are located within deep geologic formation(s).

It is another objective of the present invention to provide a cold-cap with predetermined chemical(s)/compound(s)/reagent(s) for managing, treating, and/or containment of at least some (radioactive) volatile byproducts produced from the in-situ vitrification of waste, wherein the cold-cap is located within the human-made cavern.

It is another objective of the present invention to provide a cold-cap with volatile fixing additives (VFAs) for managing, treating, and/or containment of at least some (radioactive) volatile byproducts produced from the in-situ vitrification of waste, wherein the cold-cap is located within the human-made cavern.

It is another objective of the present invention to dispose of vitrified waste products in safe deep underground locations.

It is another objective of the present invention to provide a simple treatment solution to vitrification off-gases.

It is yet objective of the present invention to provide a safe deep underground location for (treated) off-gases disposal.

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.

