Channel box for boiling water reactor and method for manufacturing the same

Abstract

To provide a channel box for a boiling water reactor and a method for manufacturing the same that can prevent distortion, radiation-induced growth, and corrosion of the control box. [Solution] The channel box comprises a substrate and a first layer. The substrate has a tubular shape. The substrate contains silicon carbide fibers impregnated with silicon carbide. The first layer is attached to a first surface of the substrate and the first layer contains a corrosion-resistant metal composition. Each side of the channel box is exposed to radiation with a ejection count of at least 1 per atom.

Description

Technical Field

[0001] Cross - reference to related applications This application claims the benefit of U.S. Provisional Application No. 63 / 018,561, filed May 1, 2020, the entire content of which is incorporated herein by reference.

Background Art

[0002] A nuclear power plant equipped with a boiling water reactor (BWR) can include a channel box that surrounds the nuclear fuel rod bundles in the core. The channel box directs the coolant flow around the nuclear fuel rod bundles and prevents steam drift from the nuclear fuel rod bundles into the low - pressure bypass region between the channel boxes in order to maintain proper cooling within the BWR core. Typically, control blades slide around the outside of the channel box to control the neutron flux within the core.

[0003] Typically, the channel boxes within a BWR contain zirconium or zirconium alloys. In a radiation field, zirconium alloys grow anisotropically (e.g., grow to different lengths depending on the direction of growth). Additionally, zirconium channel boxes are susceptible to corrosion and hydrogen pickup within the BWR. Hydrogen pickup can produce zirconium hydride, which may form a second hard phase in the relatively soft zirconium alloy of the channel box, potentially serving as a crack initiation point or changing the direction of radiation - induced growth within the channel box. This can lead to distortion along the length of the channel box that interferes with the operation of the control blades. It has been an issue to prevent distortion, radiation - induced growth, and corrosion of the control boxes within a BWR.

Summary of the Invention

[0004] This disclosure provides a channel box for a boiling water reactor (BWR). The channel box comprises a substrate and a first layer. The substrate has a tubular shape. The substrate contains silicon carbide fibers impregnated with silicon carbide. The first layer is attached to a first surface of the substrate and the first layer contains a corrosion-resistant metal composition.

[0005] This disclosure also provides a pre-irradiated channel box for a BWR. The channel box comprises a substrate having a tubular shape. The substrate comprises silicon carbide fibers. A first layer is attached to the surface of the substrate and the first layer comprises a corrosion-resistant metal composition. Each side of the channel box is exposed to radiation with a ejection count of at least 1 per atom.

[0006] This disclosure also provides a method for fabricating a channel box for a boiling water reactor. The method includes creating a silicon carbide fiber preform by providing a layer of silicon carbide fibers to enclose a mold. An intermediate layer is attached to the silicon carbide fibers. A substrate is fabricated from the preform, and the substrate has a tubular shape. The substrate is removed from the mold. A first layer is attached to a first surface of the substrate, thereby forming a channel box. The first layer comprises a corrosion-resistant metal composition.

[0007] It should be understood that the present invention as described herein is not limited to the embodiments summarized in this summary. Various other embodiments are described and illustrated herein. [Brief explanation of the drawing]

[0008] The features and advantages of the embodiments, as well as the methods by which they are achieved, will become clearer, and the embodiments will be better understood by referring to the following description of embodiments used in conjunction with the accompanying drawings.

[0009] [Figure 1] This is a cross-sectional view showing an example of a channel box according to this disclosure. [Figure 2] This is a process diagram illustrating an example of a method for fabricating a channel box according to this disclosure.

[0010] Corresponding reference letters indicate the corresponding parts throughout some of the figures. The examples described herein illustrate specific embodiments in one form, and such examples should not be construed as limiting the scope of the embodiments in any way. [Modes for carrying out the invention]

[0011] Herein, specific exemplary embodiments of the present disclosure are described to provide an overall understanding of the composition, function, manufacture, and use principles of the compositions, articles, and methods disclosed herein. Examples of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will understand that the compositions, articles, and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments, and that the scope of the various embodiments of the invention is defined solely by the claims. Features illustrated or described in relation to one exemplary embodiment may be combined with features of other embodiments. Such modifications and variations are intended to fall within the scope of the invention.

[0012] Throughout this specification, references to “various embodiments,” “several embodiments,” “one embodiment,” “one embodiment,” or equivalents mean that a particular feature, structure, or characteristic described in relation to an embodiment is included in that embodiment. Therefore, the occurrences of phrases such as “various embodiments,” “several embodiments,” “one embodiment,” “one embodiment,” or equivalents throughout this specification do not necessarily all refer to the same embodiment. Furthermore, certain features, structures, or characteristics may be combined in any preferred manner in one or more embodiments. Thus, certain features, structures, or characteristics illustrated or described in relation to one embodiment may be combined, in whole or in part, with features, structures, or characteristics of another embodiment or other embodiments, without limitation. Such modifications and variations are intended to be included within the scope of these embodiments.

[0013] As used herein, particularly in relation to layers, the terms “on,” “onto,” and “over,” and their variations (e.g., “applied on,” “formed on,” “adhered on,” “provided on,” “placed on,” “electroplated on,” and equivalents) mean that an object is applied, formed on, adhered to, provided on, or otherwise placed on the surface of a substrate, but not necessarily in contact with the surface of the substrate. For example, a layer “applied on” of a substrate does not preclude the presence of another coating layer or other coating layer of the same or different composition placed between the applied coating layer and the substrate. Similarly, a second layer “applied on” a first layer does not preclude the presence of another layer or other layer of the same or different composition placed between the applied second layer and the applied first layer.

[0014] As used herein, “intermediate” means that the referenced element is located between two elements, but is not necessarily in contact with them. Therefore, unless otherwise stated herein, an element “intermediate” between the first and second elements may or may not be adjacent to or in contact with the first and / or second elements, and other elements may be located between the intermediate element and the first and / or second elements.

[0015] When channel boxes within a BWR become distorted, inserting control blades between the channel boxes can cause problems due to increased friction between the control blades and the channel boxes. Furthermore, zirconium or zirconium alloys in the BWR core generate hydrogen gas and heat when exposed to steam, which can lead to explosions like those seen in the Fukushima accident. Typical zirconium or zirconium alloy channel boxes can account for up to 40% of the zirconium material in the BWR core. Therefore, the inventors provide a channel box and a method for manufacturing the same that can withstand distortion and corrosion, minimize the presence of zirconium or zirconium alloys in the BWR core, and improve the accident resilience of the BWR.

[0016] Referring to Figure 1, a cross-section of a channel box 100 for a boiling water reactor is provided. The channel box 100 may have a tubular shape comprising a cavity 110 configured to receive a bundle of nuclear fuel rods and / or other reactor components as desired. In various embodiments, the channel box 100 may have a rectangular tubular shape as shown in Figure 1. In various other embodiments, the channel box 100 may have a different shape. The dimensions of the channel box 100 may be selected to suit the desired reactor type. For example, the channel box 100 may have a length in the range of 1 meter (m) to 4 m for a boiling water reactor. In certain embodiments, the channel box may have a first dimension d1 and a second dimension d2, which may be the same or different. Dimensions d1 and d2 may be in the range of 1 inch to 10 inches. For example, the channel box 100 may have a square cross-sectional shape with dimensions d1 and d2, which are 6 inches each. The channel box has a wall thickness t suitable for operation in a BWR. w It includes t w This could be, for example, within a range of 1 mm to 4 mm, such as 1 mm to 2 mm or 2 mm to 3 mm.

[0017] The channel box 100 may comprise a base material 102, a first layer 104 and / or a second layer 106, and optionally a third layer 108. The base material 102 may have a tubular shape. For example, as shown in Figure 1, the base material 102 may have a rectangular tubular shape.

[0018] The substrate 102 may include silicon carbide fibers impregnated with silicon carbide, zirconium, zirconium alloy, or a combination thereof, which provide rigidity to the channel box 100 and enable it to withstand strain caused by exposure to radiation such as neutrons, gamma rays, or a combination thereof. In some embodiments, the substrate 102 may consist of silicon carbide fibers impregnated with silicon carbide and optionally an intermediate layer. The substrate 102 may have a thickness t0 suitable for providing rigidity and / or withstanding strain during operation in a boiling water reactor ("BWR"). For example, the thickness t of the substrate 102 o This could be in the range of 1 mm to 4 mm, for example, 1 mm to 2 mm or 2 mm to 3 mm. For example, the thickness t of the base material 102 o It can be at least 1 mm.

[0019] The silicon carbide fibers of the substrate 102 can be impregnated by chemical vapor impregnation, chemical vapor deposition, or a combination thereof. Chemical vapor impregnation is a process of impregnating a porous preform with a gaseous material at high temperatures. For example, chemical vapor impregnation of silicon carbide fibers may include heating the silicon carbide fibers in a reactor to a high temperature (e.g., at least 1000 degrees Celsius) and introducing a gaseous material into the reactor containing the pores of the silicon carbide fibers. The gaseous material may include a silicon carbide precursor (e.g., trichloromethylsilane) and optionally a diluent (e.g., nitrogen). Trichloromethylsilane decomposes into silicon carbide and hydrogen chloride at high temperatures. The silicon carbide adheres to the silicon carbide fibers, including within and / or on the surface of the pores, and the hydrogen chloride can be removed from the reactor. In embodiments in which zirconium or a zirconium alloy is impregnated into silicon carbide fibers, the gaseous material may include zirconium or a zirconium alloy precursor (e.g., ZrI4).

[0020] In various embodiments, an intermediate layer may be formed on the silicon carbide fibers before introducing the gaseous material, so that the intermediate layer lies between the silicon carbide fibers and the silicon carbide impregnated within them. The intermediate layer may be a carbon-based material, such as graphite. The intermediate layer can be attached by heating the silicon carbide fibers in the reactor to a high temperature and injecting a carbon-based precursor (e.g., methane) into the reactor containing the pores of the silicon carbide fibers. Methane can decompose into elemental carbon and hydrogen at high temperatures. The intermediate layer can provide lubrication between the silicon carbide fibers and the silicon carbide impregnated within them so that the toughness and robustness of the substrate 102 are enhanced and it exhibits pseudoductility. In addition, providing lubrication between the silicon carbide fibers and the silicon carbide impregnated within them can prevent the initiation and / or propagation of cracks within the substrate 102.

[0021] Chemical vapor deposition is similar to chemical vapor permeation, except that in chemical vapor permeation, silicon carbide adheres to the pores of the silicon carbide fibers, whereas in chemical vapor permeation, silicon carbide adheres to the surface of the silicon carbide fibers rather than to the pores. In various examples, the desired porosity and / or thickness t0 of the substrate 102 can be achieved by combining chemical vapor permeation and chemical vapor deposition to permeate the silicon carbide fibers of the substrate 102.

[0022] The first layer 104 can be attached to the first surface 102a of the substrate 102, and the second layer 106 can be attached to the second surface 102b of the substrate. For example, the first layer 104 can be in direct contact with the substrate 102, and / or the second layer 106 can be in direct contact with the substrate 102. The first and second layers 104 and 106 may contain corrosion-resistant metal compositions. The corrosion-resistant metal composition of the first layer 104 may be the same as or different from the corrosion-resistant metal composition of the second layer 106. The corrosion-resistant metal compositions of the first layer 104 and the second layer 106 can be configured to withstand corrosion (e.g., dissolution, oxidation, chemical decomposition) under various operating conditions within the core of a BWR.

[0023] Attach the first and second layers 104 and 106 onto the substrate 102 to prevent contact between the substrate 102 and the coolant (e.g., water) within the core in a BWR, thereby preventing corrosion of the substrate 102 that could be caused by the coolant. Thus, the first and second layers 104 and 106 can prevent silicon carbide from the substrate 102 from reacting with the coolant (e.g., dissolved oxygen in water) to form silicon dioxide, which could dissolve into the coolant and deposit on the surfaces within the core of the BWR. In certain embodiments, the first and second layers 104 and 106 cover substantially all of the exposed surface of the substrate 102. In some other examples, the first and second layers 104 and 106 selectively cover the portions of the substrate 102 that would be immersed in the coolant within the BWR, and other portions of the substrate 102 that need not be immersed in the coolant within the core of the BWR may not be covered by the first and second layers 104 and 106.

[0024] The first layer 104 and the second layer 106 can include zirconium, zirconium alloys, titanium, titanium alloys, yttrium, yttrium alloys, or combinations thereof. In various embodiments, the zirconium alloy can further include niobium, such as a binary zirconium alloy containing niobium or a non-binary zirconium alloy containing niobium. The zirconium alloy can include reactor-grade zirconium alloys. The reactor-grade zirconium alloys can include Zircalloy-2 (trademark), Zircalloy-4 (trademark), ZIRLO (trademark), optimized ZIRLO (trademark), or combinations thereof. For example, the reactor-grade zirconium alloy can include a composition that, although for the total weight of all reactor-grade zirconium alloys, contains 0.5% - 2.0% niobium, 0.7% - 1.5% tin, 0.07% - 0.14% iron, up to 0.03% carbon, up to 0.2% oxygen, and zirconium remainder and incidental impurities.

[0025] The first layer 104 can have a thickness t1 suitable for preventing corrosion of the base material 102, and the second layer 106 can have a thickness t2 suitable for preventing corrosion of the base material 102. For example, the thickness t1 of the first layer 104 can be within the range of 1 micron to 20 microns, such as, for example, 5 microns to 10 microns, 10 microns to 20 microns, or 5 microns to 15 microns. The thickness t2 of the second layer 106 can be within the range of 1 micron to 20 microns, such as, for example, 5 microns to 10 microns, 10 microns to 20 microns, or 5 to 15 microns. Since the neutron absorption provided by silicon carbide is usually smaller than that by the corrosion-resistant metal composition of the first layer 104 and the second layer 106, it may be desirable to minimize the thicknesses t1 and t2 in order to increase the efficiency of the BWR during operation. Similarly, in embodiments where the first layer 104 and the second layer 106 include zirconium or a zirconium alloy, it may be desirable to minimize the thicknesses t1 and t2 in order to increase the accident tolerance of the BWR.

[0026] The channel box 100 can have the amounts of the first and second layers 104 and 106 be within the range of more than 0 wt% to 10 wt%, such as, for example, 0.1 wt% to 10 wt%, 0.5 wt% to 5 wt%, or 1 wt% to 2 wt%, etc., based on the total weight of the entire channel box 100. For example, the channel box 100 can include the first and second layers 104 and 106 in amounts within the range of more than 0 wt% to 10 wt% based on the total weight of the channel box 100, and the remaining base material 102, the third layer 106, and any other optional layers.

[0027] The third layer 108 can be attached to the intermediate layer 104 and the substrate 102, on the first layer 104, intermediate layer 106 and the substrate 102, on the second layer 106, or a combination thereof. In various embodiments, it may be desirable to attach the third layer 108 on the first layer 104 and the second layer 106. The third layer 108 can contain chromium or a chromium alloy. The third layer 108 can have a thickness t3 in the range of 0.1 to 5 microns, such as 0.5 to 2 microns, 0.5 to 1.5 microns, or 1 to 2 microns. The third layer 108 can be more corrosion-resistant than the first layer 104 or the second layer 106. However, the neutron cross-sectional area of ​​the third layer 108 may be larger than that of the first layer 104 or the second layer 106. Therefore, the thickness t3 should be sized to minimize the overall neutron cross-sectional area of ​​the channel box 100 while maintaining sufficient corrosion resistance.

[0028] In various embodiments, a BWR may be equipped with a channel box 100. For example, a bundle of nuclear fuel rods can be placed in a cavity 110 to operate a boiling water reactor. The channel box 100 is capable of withstanding corrosion and / or deformation within the BWR so that it does not deform even after receiving a fluence of at least 100 displacements per atom (dpa).

[0029] Silicon carbide can expand uniformly upon exposure to radiation. In addition, the expansion of silicon carbide can be suppressed, or at least it will stop after exposure to a predetermined level of radiation of 1 dpa. However, if a channel box containing silicon carbide, such as channel box 100, is subjected to a non-uniform high level of radiation, such as that present in the center of a BWR core, the channel box 100 may expand and deform non-uniformly. Therefore, this disclosure provides a method for pre-irradiating the channel box 100 to prevent non-uniform expansion and deformation. The method comprises exposing the channel box 100 to radiation at a first location in the core of a BWR, where the neutron gradient at the first location is lower than the neutron flux gradient at a second location in the core of the BWR. For example, the first location may be near the edge (e.g., a side and / or corner) of the core of the BWR, and the second location may be near the center of the core of the BWR. Pre-irradiating the channel box 100 may include exposing the channel box to radiation until a fluence of at least 1 dpa is reached, for example, at least 2 dpa or at least 5 dpa. In various embodiments, pre-irradiating the channel box 100 may include exposing the channel box 100 to radiation until a fluence in the range of 1 dpa to 2 dpa is reached. Pre-irradiation may also include uniformly exposing each side of the channel box 100 to radiation until a fluence of at least 1 dpa is reached so that uniform expansion of the channel box 100 is obtained. In embodiments where the channel box 100 is rectangular, all four sides 112a, 112b, 112c, and 112d can be uniformly exposed to radiation.

[0030] Referring to Figure 2, a method for fabricating a channel box for a BWR is provided. As illustrated, the method may include creating a silicon carbide fiber preform by providing a layer of silicon fibers to wrap around a mold (202). The mold (form) may be a tube (e.g., a square tube), a mandrel, or a similar object. The layering may be done by adhesion, wrapping, braiding, winding, or a combination thereof. An intermediate layer may be attached to the silicon carbide fibers (204).

[0031] The substrate is prepared from a silicon carbide fiber preform (206). For example, silicon carbide can be impregnated into the silicon carbide fiber preform by chemical vapor infiltration, chemical vapor deposition, or a combination thereof to form a substrate having a tubular shape. By impregnating the preform with silicon carbide, zirconium, zirconium alloy, or a combination thereof, the porosity of the silicon carbide preform can be reduced and the rigidity of the preform can be increased. In various embodiments, the impregnation process may include chemical vapor infiltration followed by chemical vapor deposition. In specific embodiments, the impregnation process may include chemical vapor deposition, chemical vapor infiltration, and subsequent chemical vapor deposition. In various embodiments, chemical vapor deposition is performed on the mold before a layer of silicon carbide fibers is provided to enclose the mold.

[0032] The substrate can be removed from the mold (208). A first layer can be attached to a first surface of the substrate, and the first layer contains a corrosion-resistant metal composition (210). A second layer can optionally be attached to a second surface of the substrate, and the second layer contains a corrosion-resistant metal composition. In various embodiments, a third layer containing chromium or a chromium alloy can be attached to the substrate. The first, second, and / or third layers can be attached by physical vapor deposition, cold spraying, thermal spraying, or a combination thereof.

[0033] Various aspects of the present invention as described herein include, but are not limited to, those listed in the following numbered clauses. 1. A channel box for a boiling water reactor, A tubular-shaped base material containing silicon carbide fibers, A first layer is attached to the first surface of the substrate and comprises a corrosion-resistant metal composition. A channel box equipped with the following features. 2. The channel box according to Clause 1, wherein silicon carbide fibers are impregnated with silicon carbide, zirconium, zirconium alloy, or a combination thereof by chemical vapor impregnation, chemical vapor deposition, or a combination thereof. 3. The channel box according to Clause 2, further comprising an intermediate layer between the silicon carbide fibers and the silicon carbide, zirconium, zirconium alloy, or combination thereof impregnated therein. 4. The channel box according to Clause 3, wherein the intermediate layer is carbon-based. 5. The channel box according to any one of Clauses 1 to 4, wherein the corrosion-resistant metal composition comprises zirconium, zirconium alloy, titanium, titanium alloy, yttrium, yttrium alloy, or a combination thereof. 6. The channel box according to any one of clauses 1 to 5, wherein the corrosion-resistant metal composition comprises a zirconium alloy containing niobium. 7. A channel box according to any one of the clauses 1 to 6, wherein the thickness of the first layer is in the range of 1 micron to 20 microns. 8. A channel box according to any one of claims 1 to 7, further comprising a second layer attached to a second surface of the substrate opposite to the first surface of the substrate, wherein the second layer comprises a second corrosion-resistant metal composition. 9. The channel box according to Clause 8, wherein the amount of the first and second layers of the channel box is within the range of more than 0% to 10% of the total weight of the channel box. 10. The channel box according to Clause 8, wherein the amount of the first and second layers of the channel box is within the range of 1% to 2% of the total weight of the channel box. 11. The channel box described in any one of the clauses 1 to 10, wherein the wall thickness of the channel box is in the range of 1 mm to 4 mm. 12. A channel box according to any one of the clauses 1 to 11, further comprising a third layer disposed on the first layer, wherein the third layer comprises chromium or a chromium alloy. 13. The channel box according to Clause 12, wherein the thickness of the third layer is in the range of 0.1 microns to 5 microns. 14. A boiling water reactor having a channel box as described in any one of clauses 1 to 13. 15. A method comprising pre-irradiating a channel box described in any one of the clauses 1 to 13 at a first location in the core of a boiling water reactor, characterized in that the neutron flux gradient at the first location is lower than that at a second location in the boiling water reactor. 16. The method according to Clause 15, wherein pre-irradiating the channel box includes exposing the channel box to radiation until the number of ejections per atom reaches a fluence of at least 1. 17. Pre-irradiated channel box for a boiling water reactor, A tubular-shaped base material containing silicon carbide fibers, The substrate comprises a first layer attached to the surface of the substrate and containing a corrosion-resistant metal composition, A channel box in which each side of the channel box is exposed to radiation until the number of ejections per atom reaches a fluence of at least 1. 18. A method for fabricating a channel box for a boiling water reactor, A layer of silicon fibers is created to enclose the mold, and a silicon carbide fiber preform is created. The process involves attaching an intermediate layer to the silicon carbide fibers, From the aforementioned preform, a substrate having a tubular shape is created, Removing the substrate from the mold, The channel box is formed by attaching a first layer containing a corrosion-resistant metal composition to the first surface of the substrate. Methods that include... 19. The method according to Clause 18, wherein the preparation of the substrate includes preparing the substrate by impregnating the preform with silicon carbide, zirconium, zirconium alloy, or a combination thereof using chemical vapor impregnation, chemical vapor deposition, or a combination thereof. 20. The method according to clause 18 or 19, further comprising exposing the channel box to radiation until the number of ejections per atom reaches a fluence of at least 1.

[0034] Those skilled in the art will recognize that the compositions, articles, methods, and accompanying considerations described herein are intended as illustrative examples to clarify concepts, and that various configuration modifications are intended. Therefore, when used herein, the specific examples and accompanying considerations described are intended to represent their more general class. Generally, the use of any particular example is intended to represent its class, and the exclusion of certain components (e.g., actions), devices, and objects is not considered limiting.

[0035] To provide an understanding of the compositions, structures, production, functions, and / or operations of the present invention, including the disclosed compositions, coatings, and methods, various features and properties are described herein. It is understood that the various features and properties of the present invention described herein may be combined in any preferred manner, whether or not such features and properties are expressly described herein in combination. The inventors and applicants expressly intend that any combination of such features and properties falls within the scope of the present invention as described herein. Accordingly, the claims may be amended to enumerate any combination of any features and properties that are expressly or essentially described herein, or otherwise expressly or essentially supported. Furthermore, the applicants reserve the right to amend the claims to positively waive any features and properties that may exist in the prior art, even if these features and properties are not expressly described herein. Accordingly, any such amendment shall not add any new matter to this specification or the claims and shall be subject to the requirements of description, sufficiency of description, and additions.

[0036] With respect to the attached claims, those skilled in the art will understand that the operations enumerated therein may generally be performed in any order. Furthermore, while various operation flows are presented in a certain order, it should be understood that various operations may be performed in orders other than those illustrated, or simultaneously. Examples of such alternative orderings include, unless otherwise indicated by the context, overlap, alternating, interruption, reordering, incremental, pre-emptive, supplementary, simultaneous, reverse, or various other orderings. Moreover, unless otherwise indicated by the context, terms such as “responding to,” “related to,” or other past tense adjectives are generally not intended to exclude such variations.

[0037] The present invention as described herein may include, consist of, or essentially consist of, the various features and properties described herein. The terms “comprise” (and any form of “comprise,” such as “comprises” or “comprising”), “have” (and any form of “have,” such as “has” or “having”), “include” (and any form of “include,” such as “includes” or “including”), and “contain” (and any form of “contains” or “containing”) are unrestricted linking verbs. Thus, a composition, nuclear fuel assembly, or method that “comprises,” “has,” “includes,” or “contains” one or more features and / or properties will possess, but will not be limited to possessing, only, those features or those features and / or properties. Similarly, any element of a composition, coating, or process that “possesses,” “has,” “includes,” or “contains” such features or those features and / or properties will have, but will not be limited to having only, such features or those features and / or properties, and may have additional features and / or properties.

[0038] As used herein, including in the claims, the grammatical articles “a,” “an,” and “the” are intended to include “at least one” or “one or more,” unless otherwise stated. Thus, the articles are used herein to refer to one or more of the grammatical objects of the articles (i.e., “at least one”). For example, “a component” means one or more components, and therefore, in some cases, two or more components may be conceived and employed or used in the implementation of the compositions, coatings, and processes described. Nevertheless, if the terms “at least one” or “one or more” are used in some cases and not in others, it is understood that the absence of these terms would not imply that the objects of the grammatical articles “a,” “an,” and “the” are limited to only one. Furthermore, unless otherwise required in the context in which they are used, the use of singular nouns includes the plural form, and the use of plural nouns includes the singular form.

[0039] In this specification, unless otherwise indicated, all numerical parameters should be understood, in all cases, to be prefaced and modified by the term “approximately,” meaning that the numerical parameter possesses the inherent variability characteristics of the underlying measurement technique used to determine the numerical value of the parameter. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the claims, each numerical parameter described herein should be interpreted at least in light of the reported number of significant figures and by applying common rounding techniques.

[0040] Any numerical range enumerated herein includes all subranges contained within the enumerated range. For example, the range "1 to 10" includes all subranges between the enumerated minimum value of 1 and the enumerated maximum value of 10 (including boundary values), i.e., all subranges where the minimum value is 1 or greater and the maximum value is 10 or less. Furthermore, all ranges enumerated herein include the endpoints of the enumerated range. For example, the range "1 to 10" includes endpoints 1 and 10. Any maximum numerical limit enumerated herein is intended to include all lower numerical limits contained within it, and any minimum numerical limit enumerated herein is intended to include all higher numerical limits contained within it. Accordingly, the applicant reserves the right to amend this specification, including the claims, to explicitly enumerate any subranges contained within the explicitly enumerated range. All such ranges are essentially described herein.

[0041] Any patent, publication, or other document identified herein is incorporated herein in whole by reference unless otherwise indicated, but only to the extent that the incorporated material does not contradict existing descriptions, definitions, statements, illustrations, or other disclosures expressly provided herein. Therefore, to the extent necessary, express disclosures provided herein take precedence over any contradictory material incorporated by reference. Any material or any part thereof incorporated herein by reference that contradicts existing definitions, statements, or other disclosures provided herein is incorporated only to the extent that the incorporated material does not contradict existing disclosures. The applicant reserves the right to amend this specification to expressly enumerate any subject matter or any part thereof incorporated by reference. Any amendment to this specification to add such incorporated subject matter shall be subject to the requirements of description, sufficiency of description, and additions.

[0042] While specific embodiments of the present invention are described above for illustrative purposes, it will be apparent to those skilled in the art that numerous modifications of the details of the present invention can be made without departing from the present invention as defined in the appended claims.

Claims

1. A channel box for a boiling water reactor, A tubular-shaped base material containing silicon carbide fibers, A first layer is attached to the first surface of the substrate and comprises a first corrosion-resistant metal composition, A second layer comprising a second corrosion-resistant metal composition is attached to the second surface of the substrate opposite to the first surface of the substrate. Equipped with, A channel box in which the amount of the first and second layers of the channel box is in the range of more than 0% to 10% of the total weight of the channel box.

2. The channel box according to claim 1, wherein silicon carbide fibers are impregnated with silicon carbide, zirconium, zirconium alloy, or a combination thereof by chemical vapor impregnation, chemical vapor deposition, or a combination thereof.

3. The channel box according to claim 2, further comprising an intermediate layer between the silicon carbide fibers and the silicon carbide, zirconium, zirconium alloy, or combination thereof impregnated therein.

4. The channel box according to claim 3, wherein the intermediate layer is carbon-based.

5. The channel box according to claim 1, wherein the first corrosion-resistant metal composition and the second corrosion-resistant metal composition comprise zirconium, zirconium alloy, titanium, titanium alloy, yttrium, yttrium alloy, or a combination thereof, and the first corrosion-resistant metal composition is identical to or different from the second corrosion-resistant metal composition.

6. The channel box according to claim 1, wherein at least one of the first and second corrosion-resistant metal compositions comprises a zirconium alloy containing niobium.

7. The channel box according to claim 1, wherein the thickness of the first layer is in the range of 1 micron to 20 microns.

8. The channel box according to claim 1, wherein the amount of the first and second layers of the channel box is within the range of 1% to 2% of the total weight of the channel box.

9. The channel box according to claim 1, wherein the wall thickness of the channel box is in the range of 1 mm to 4 mm.

10. The channel box according to claim 1, further comprising a third layer disposed on the first layer, wherein the third layer comprises chromium or a chromium alloy.

11. The channel box according to claim 10, wherein the thickness of the third layer is in the range of 0.1 microns to 5 microns.

12. A boiling water reactor comprising the channel box described in claim 1.

13. A method comprising pre-irradiating a channel box according to claim 1 at a first location in the core of a boiling water reactor, characterized in that the neutron flux gradient at the first location is lower than that at a second location in the boiling water reactor.

14. The method according to claim 13, wherein pre-irradiating the channel box includes exposing the channel box to radiation until the number of ejections per atom reaches a fluence of at least 1.

15. A channel box according to claim 1, which has been pre-irradiated, A channel box in which each side of the channel box is exposed to radiation until the number of ejections per atom reaches a fluence of at least 1.

16. A method for fabricating a channel box for a boiling water reactor, A layer of silicon carbide fibers is placed around the mold to create a silicon carbide fiber preform, The process involves attaching an intermediate layer to the silicon carbide fibers, From the aforementioned preform, a substrate having a tubular shape is created, Removing the substrate from the mold, A first layer containing a corrosion-resistant metal composition is attached to the first surface of the substrate, A second layer containing a second corrosion-resistant metal composition is attached to the second surface of the substrate opposite to the first surface of the substrate. Including, A method for manufacturing a channel box, wherein the amount of the first and second layers of the channel box is within the range of more than 0% to 10% of the total weight of the channel box.

17. The method according to claim 16, wherein the preparation of the substrate includes preparing the substrate by impregnating the preform with silicon carbide, zirconium, zirconium alloy, or a combination thereof using a chemical vapor impregnation method, a chemical vapor deposition method, or a combination thereof.

18. The method according to claim 16, further comprising exposing the channel box to radiation until the number of ejections per atom reaches a fluence of at least 1.

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