Patent Application
20250062044
When operating conventional nuclear reactors, sometimes random transients or hot spots occur throughout the reactor fuel. Left unchecked, the number of hot spots and transients can exponentially increase. This increase can lead to an exponential increase in reactor power, quickly exceeding the reactor's design basis in regions near the hotspot or transient. The most severe power increases can meltdown of the fuel, the fuel-rod cladding, and the containment. Even much milder events can permanently and significantly damage fuel pellets. The unusual, transient and hotspot power increase damages fuel pellets. Commercial reactors produce xenon gas. The fuel pellets withstand and accommodate the steady-state amounts of xenon. But transient and hotspot power increases produce an unusual amount of xenon, which can fracture the fuel pellet as xenon overwhelms the pellet's xenon capacity.
The power spike can also thermally stress the fuel pellet leading to it cracking and fissuring, which also mechanically shortens the fuel pellet's life.
Transient numbers increase when the reactor power level increases or decreases—when the power level is changed. But the ability to change power output more safely would allow utilities to implement some degree of load following in the reactor. “Load following” is the ability to have power output from a power plant follow the grid's instantaneous power demands to one extent or another. Alternatively, “load following” is the ability to have a plant's output better follow the grids instantaneous demands.
Load following is a tool that nuclear-power-plant operators very much want. But implementing it using current technology unacceptably risks generating uncontrollable transients or hot spots as the operator varies reactor output. Current technology can't provide this tool; it remains out of reach.
Current control of transient or hotspot activity includes constructing the pellet to have a strong negative temperature coefficient of reactivity. A negative temperature coefficient of thermal reactivity means that the material in the pellet becomes less reactive as the pellet's temperature rises. This negative reactivity helps decrease the fission rate, but it happens on a thermal time scale. What is needed is a technique to combat the reaction rate increase caused by transients and hot spots on a time scale aligned with the increasing reaction rate.
The problem is too many neutrons. But the reactor needs neutrons, specifically thermal neutrons, to operate. One neutron for each fission event is needed to sustain the reaction. If this neutron flux increases, the reactor power increases, which generates even more prompt neutrons that cause even more fuel to fission and on and on. For this discussion, “prompt neutrons” are neutrons recently generated from a fission event. Prompt neutrons have much higher energies than energies useful for safely operating the reactor. And since they are excess neutrons, the reactor doesn't need them to function. But neutrons at these energies are vital because they moderate into thermal neutrons.
At its most basic level, the new fuel is a nuclear adjuvant material added to conventional nuclear fuel.
“Improve the reactor” means any one or any combination of factors that extend fuel life, lower the mechanical failure rate of the pellet, decrease the number of transients, decrease the density of transients, decrease the average number of hot spots, decrease the density of hot spots, prevent the increase in the average temperature of hot spots, decrease the average lifespan of hot spots, decrease the average lifespan of transients, decrease the propagation rate of transients, or decrease the propagation rate of hot spots.
Faster and more precise control over transients and transient dampening would give operators better load-following capability.
“Fissile material” is any material capable of undergoing fission to produce useful heat energy. “Fissile material” is a material commonly used as a fuel component in commercial nuclear power plants and that undergoes a fission reaction to produce heat. some embodiments, “useful heat energy” is over 25 kW.
“Transuranic atoms” are atoms produced in commercial nuclear fuel by reactor operation. Most of these come from neutrons colliding with uranium 238, which frequently captures the neutron and yields an element with a higher atomic number or atomic mass. In some embodiments, the term “transuranics” represents neptunium, plutonium, americium, curium, berkelium, and californium. In some embodiments, the term “transuranics” represents Np237, 238, and 239; Py238, 239,240,241,242, and 243; Am241,242,243, and 242.
“Nuclear adjuvant material” is any material that undergoes a nuclear reaction with a high-energy neutron or other radiation generated in nuclear reactor transients and yields products, none of which are neutrons. A nuclear adjuvant absorbs hardened neutrons during transient events in a commercial nuclear power plant or absorbs other types of radiation that result in dampening the transient.
In some versions, “nuclear adjuvant material” is any material that exhibits a nuclear adjuvant effect which means the material undergoes a nuclear reaction with a high-energy neutron or other radiation generated in nuclear reactor transients and yields products in which less than 50%, 40%, 30%, 20%, 10%, 5%, 1%, 2×10−2%, 4×10−3%, 8×10−4%, 1.6×10−4%, 3.2×10−5%, 6.4×10−6%, 1.28×10−6%, 2.56×10−7%, 5.12×10−8%, 1.02×10−8%, 2.05×10−9%, or 4.1×10−10% are neutrons. A nuclear adjuvant absorbs hardened neutrons during transient events in a commercial nuclear power plant or absorbs other types of radiation that result in dampening the transient.
Another characteristic of the nuclear adjuvant is that it undergoes a nuclear reaction with the incoming neutron and converts it into some other atomic particle. For instance, the nuclear reaction could yield a proton, Alpha particle, or gamma-ray. This absorption thwarts transient event propagation by removing high-energy, transient neutrons from the system, which normalizes the number of new fission events. So, enough high-energy neutrons must be absorbed to dampen the transient. Conversely, the material shouldn't absorb too many neutrons, or the steady-state operation of the reactor would be heavily affected.
The material comprises atoms or compounds containing atoms that exhibit the desired nuclear properties. In some embodiments, these atoms are chosen to provide neutron-energy-versus-neutron-absorption curves with as little a cross-section as possible in the low energy range. The cross-section's high-energy behavior yields a change in the cross-section that trims off enough high-energy neutrons to dampen the transient while maintaining the reactor's steady-state operation.
In some embodiments, the nuclear adjuvant material trims between 0.00001-110% or 0.00001-0.0001 of the excess high-energy neutrons. The material in various embodiments comprises atoms with 1-10, 1-5, 2-5, or 3-5 different atomic numbers or different atomic masses.
In nuclear and particle physics, the concept of a neutron cross section is used to express the likelihood of interaction between an incident neutron and a target nucleus. In conjunction with the neutron flux, it enables the calculation of the reaction rate. The standard unit for measuring the cross section is the barn, which is equal to 10-28 m2 or 10-24 cm2. The larger the neutron cross section, the more likely a neutron will react with the nucleus.
In some embodiments, suitable components include all isotopes or elements. More practical examples include mixtures selected from elements and isotopes that are substantially chemically and thermally stable inside the reactor. In some embodiments, the mixture's components are selected from materials easily handled in the fuel rod or fuel-production process. For this disclosure, easily handleable means that the cost involved and safely manipulating the materials does not exceed the economic benefit associated with using the material as a component of nuclear fuel rods. Other suitable but not mandatory characteristics include materials with low or very low neutron cross-sections in low energy ranges. Endothermic nuclear reactions are also a practical target because if the neutron energy is lower than the energy absorbed by the endothermic nuclear reaction, the relevant cross-section is theoretically zero. Having materials with low or zero neutron absorption in lower neutron energy ranges minimizes the adjuvant material's interaction with the thermal neutrons present in the reactor and necessary for the fission reaction to continue as normal.
In other embodiments, high-energy neutron absorption divided by low-energy neutron absorption is high. Low energy-range neutrons are neutrons with energies between 0-1 MeV, 0-500 KeV, or 0-300 KeV. High-energy neutrons are neutrons in energy ranges greater than 800 KeV, greater than 900 KeV, greater than 1 MeV, or greater than 1.2 MeV. In some embodiments, high-energy neutrons are neutrons with energies of 3 MeV up to 20 MeV.
Useful components of a nuclear adjuvant material include compounds or mixtures comprising two or more (alternatively, three, four, five, or six, or more) of Ba, As, Br, Ce, Cl, Co, F, Ga, Ge, K, La, Mo, Nd, Os, Pr, S, Sr, Ti, Tl, V, and Zr. Useful components of a nuclear adjuvant material include compounds or mixtures comprising two or more (alternatively, three, four, five, or six, or more) of As, Ce, Co, Ga, Ge, La, Mo, Nd, Os, Pr, Ti, V, and Zr. The compounds and mixtures can be created by combining the listed elements or combining other elements with the listed elements.
Useful adjuvant material includes mixtures or compounds comprising any one or any combination of F, K, Ti; of Ba, As, Br; of Ca, Cl, Co; of F, Ga, Ge; of K, La, Mo; of Nd, Os, Pr; of S, Sr, Tl; of Tl, V, Zr; of Ba, Br, Cl; of As, Ce, Cl; of Br, Cl, F; of Ce, Co, Ga; of Cl, F, Ge; of Co, Ga, K; of F, Ge, K; of Ga, K, Mo; of Ge La, Nd; of K, Mo, Os; of La, Nd, Pr; of Mo, Os, Pr; of Nd, Pr, St; of Os, S, Ti; of Tl, Zr, Ba; of F, Tl, V; of K, Ba, Br; and of Zr, Sr, Os—elements or compounds.
Useful components of a nuclear adjuvant material include compounds or mixtures consisting essentially of two or more (alternatively, three, four, five, or six, or more) of Ba, As, Br, Ce, Cl, Co, F, Ga, Ge, K, La, Mo, Nd, Os, Pr, S, Sr, Ti, Tl, V, and Zr. Useful components of a nuclear adjuvant material include compounds or mixtures consisting essentially of two or more (alternatively, three, four, five, or six, or more) of As, Ce, Co, Ga, Ge, La, Mo, Nd, Os, Pr, Ti, V, and Zr. The compounds and mixtures can combine the listed elements or combine other elements with the listed elements.
Useful adjuvant material includes mixtures or compounds consisting essentially of F, K, Ti; of Ba, As, Br; of Ca, Cl, Co; of F, Ga, Ge; of K, La, Mo; of Nd, Os, Pr; of S, Sr, Ti; of Tl, V, Zr; of Ba, Br, Cl; of As, Ce, Cl; of Br, Cl, F; of Ce, Co, Ga; of Cl, F, Ge; of Co, Ga, K; of F, Ge, K; of Ga, K, Mo; of Ge La, Nd; of K, Mo, Os; of La, Nd, Pr; of Mo, Os, Pr; of Nd, Pr, St; of Os, S, Ti; of Tl, Zr, Ba; of F, Tl, V; of K, Ba, Br; and of Zr, Sr, Os—elements or compounds.
In some versions, the nuclear adjuvant material has a coefficient of thermal expansion greater than or equal to that of commercial nuclear fuel. In some versions the nuclear adjuvant material has a coefficient of thermal expansion that is 10-200% or 50-150% of that of commercial nuclear fuel.
Group I isotopes useful as components in adjuvant material.
Group II isotopes useful as components in adjuvant material.
The following is a list of isotopes that absorb a neutron in a nuclear reaction and emit a nuclear particle that is not a neutron. Compositions comprising the isotopes are useful components in a nuclear adjuvant material.
These lists are by no means exhaustive.
In some embodiments, the placement of the nuclear adjuvant regarding nuclear fuel placement is important. The nuclear adjuvant can be mixed with the material of the fuel pellet in various particle sizes. In some embodiments, the adjuvant particle size can be on the same scale as the fuel particle size. In other embodiments, the adjuvant particle size is greater or much greater than the fuel particle size. In even other embodiments, the D adjuvant particle size is much smaller or much smaller than the fuel particle size.
In some embodiments, the adjuvant material is segregated from the fuel. For instance, in some fuel-rod embodiments, the fuel rod comprises standard nuclear fuel pellets separated by plates or pellets of the adjuvant material. Another way of segregating the adjuvant material from the nuclear fuel is by lining the fuel-rod cladding with a hollow structure of adjuvant material, such as a hollow cylinder. In some embodiments, the adjuvant material is a monolithic structure inside of the fuel rod.
Adding the adjuvant material as part of a primary-loop additive is another example of segregating the adjuvant material from nuclear fuel. Fuel pellets can also be prepared by sputter coating the fuel with the nuclear adjuvant material, ion implanting the fuel with the nuclear adjuvant material or any other way of making materials known to those of ordinary skill in the art.
The behavior of the nuclear adjuvant material combined with the fuel pellet is dependent or strongly dependent on the geometrical relationship between the pellet and the adjuvant material.
In
The combination of pellets 10 and nuclear adjuvant material need not be uniform. Some sections of fuel rod 40 may contain only nuclear fuel pellets 10; some may contain fuel pellets 10 interleaved with monolithic pieces of nuclear adjuvant material 101, 102; some may contain fuel pellets 10 in which some of the fuel pellets are interleaved with monolithic pieces of nuclear adjuvant material 101,102; and some may contain sections of fuel rod 40 only containing monolithic nuclear adjuvant material 101, 102.
Any of a variety of well-known processes yield monolithic adjuvant materials. For instance, subjecting the constituent powders to powder manipulating or pressing techniques produces the material with or without applying heat. Other ways of manufacturing monolithic ceramic materials can produce the monolithic adjuvant material. The monolithic materials can be sintered.
Another method of alleviating reactor transients uses the adjuvant material to soak up enough surplus high-energy neutrons or other radiation produced in reactor transient events to slow the transient growth rate. Slowing the growth rate allows enough time for the fuel's negative coefficient of thermal reactivity to act.
The above means the average of the assembly's high energy neutron absorption cross-sections adjusted for the relative volume composition of the overall material, including any uranium that is present.
In some exemplars, a “nuclear adjuvant material” replaces 50%, 40%, 30%, 20%, 10%, 5%, 1%, 2×10-2%, 4×10-3%, 8×10-4%, 1.6×10-4%, 3.2×10-5%, 6.4×10-6%, 1.28×10-6%, 2.56×10-7%, 5.12×10-8%, 1.02×10-8%, 2.05×10-9%, or 4.1×10-10% of the fissile material in a commercial fuel pellet.
The previous description of several embodiments describes non-limiting examples that further illustrate the invention. All titles of sections in this document, including those appearing above, are not to be construed as limitations on the invention, but instead, they are provided to structure the illustrative description of the invention provided by the specification.
Unless defined otherwise, all technical and scientific terms used in this document have the same meanings as commonly understood by one skilled in the art to which the disclosed invention pertains. Singular forms—a, an, and the—include plural referents unless the context indicates otherwise. Thus, for example, a reference to “fluid” refers to one or more fluids, such as two or more fluids, three or more fluids, etc. When an aspect is said to include a list of components, the list is representative. If the component choice is limited explicitly to the list, the disclosure will say so. Listing components acknowledges that embodiments exist for each component and any combination of the components—including combinations that specifically exclude any one or any combination of the listed components. For example, “component A is chosen from A, B, or C” discloses embodiments with A, B, C, AB, AC, BC, and ABC. It also discloses (AB but not C), (AC but not B), and (BC but not A) as embodiments, for example. Combinations that one of ordinary skill in the art knows to be incompatible with each other or with the components' function in the invention are excluded from the invention, in some embodiments.
The terminology used is to describe particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a”, “an”, and “the” may be intended to include the plural forms unless the context indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, or components but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or groups thereof. The method steps, processes, and operations described are not construed as requiring their performance in the particular order discussed or illustrated unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed,
When an element or layer is called being “on”, “engaged to”, “connected to” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. When an element is called being “directly on,” “directly engaged to”, “directly connected to”, or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). The term “or” includes any combinations of one or more of the associated listed items as used herein.
Although the terms first, second, third, etc. may be used to describe various moieties such as elements, components, regions, layers, or sections, these moieties should not be limited by these terms. These terms may only distinguish one element, component, region, layer, or section from another region, layer, or section. Terms such as “first,” “second,” and other numerical terms when used do not imply a sequence or order unless indicated by the context. Thus, a first element, component, region, layer, or section discussed below could be termed a second element, component, region, layer, or section without departing from the teachings of the example embodiments.
Spatially relative terms, such as “inner,” “outer,” “beneath”, “below”, “lower”, “above”, “upper” may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation besides the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations), and the spatially relative descriptors used interpreted.
The preceding description of the embodiments has been provided for illustration and description. It is not intended to be exhaustive or to limit the invention. Individual elements or features of a particular embodiment rarely are limited to that embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not explicitly shown or described. The same may also be varied. Such variations are not regarded as a departure from the invention, and all such modifications are intended to be included within the scope of the invention.
The embodiments of the invention described are exemplary. Numerous modifications, variations, and rearrangements can be readily envisioned to achieve substantially equivalent results, which are intended to be embraced within the invention's spirit and scope.
This application is related to and claims priority to U.S. Provisional Patent Application Nos., all of which are incorporated by reference. 62/935,98815-NOV-201962/936,23415-NOV-201962/936,31815-NOV-201962/937,00418-NOV-201962/936,70118-NOV-201962/936,88218-NOV-2019
| Number | Date | Country | |
|---|---|---|---|
| 62937004 | Nov 2019 | US | |
| 62936701 | Nov 2019 | US | |
| 62936882 | Nov 2019 | US | |
| 62936234 | Nov 2019 | US | |
| 62936318 | Nov 2019 | US | |
| 62935988 | Nov 2019 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 17099198 | Nov 2020 | US |
| Child | 18821291 | US |
