Patent Application
20250226122
The present disclosure is generally related to nuclear power and, more particularly, is directed toward a core component assembly having a rodlet including a capsule of material to be irradiated when the core component assembly is positioned in a fuel assembly of a nuclear reactor during operation.
The following summary is provided to facilitate an understanding of some of the innovative features unique to the aspects disclosed herein, and is not intended to be a full description. A full appreciation of the various aspects can be gained by taking the entire specification, claims, and abstract as a whole.
In various aspects, a rodlet for insertion into a fuel assembly guide tube of a fuel assembly in a pressurized water nuclear reactor is disclosed. The rodlet comprises a capsule for housing a material to be irradiated, a backfill region disposed between the capsule and the material, and an outer tube comprising a plurality of apertures defined therein. The capsule defines a wall that surrounds the material. The outer tube is to house the capsule. The outer tube defines a first annulus and a second annulus. The first annulus comprises a first width defined between the capsule and the outer tube. The second annulus comprises a second width defined between the outer tube and the fuel assembly guide tube.
In at least one aspect, the material has a first radial diameter. In at least one aspect, a radial thickness of the wall of the capsule is 0.05 to 0.10 times the first radial diameter of the material. In at least one aspect, the first width is 0.65 to 0.85 times greater than the second width. In at least one aspect, a diameter of each of the plurality of apertures is two to six times the first width. In at least one aspect, the material is 0.2 to 0.3 inches in diameter. In at least one aspect, the capsule comprises a material with a yield strength of between 60 kilopound per square inch (KSI) and 90 KSI. In at least one aspect, the outer tube comprises a material with a neutron cross section less than or equal to 0.3 barns. In at least one aspect, the outer tube comprises a material with a neutron cross section greater than or equal to 0.2 barns and less than or equal to 0.3 barns. In at least one aspect, the rodlet further comprises an end plug at an end of the outer tube and a spacer disposed between the end plug and the capsule to position the capsule at a desired axial location relative to the fuel assembly. In at least one aspect, a top end and a bottom end of the outer tube are sealed. In at least one aspect, the outer tube houses a plurality of capsules in a stacked configuration. In at least one aspect, the apertures allow coolant to flow through the apertures to cool the capsule and equalize pressure on either side of the outer tube. In at least one aspect, the backfill region is filled with air and/or helium. In at least one aspect, the material is cobalt 59. In at least one aspect, the capsule comprises one of SS304, Alloy 718, or Alloy 625. In at least one aspect, the outer tube comprises zirconium alloy. In at least one aspect, the plurality of apertures is disposed radially about the outer tube and at different vertical elevations. In at least one aspect, the plurality of apertures is greater than or equal to 4 and less than or equal to 20.
Various features of the aspects described herein are set forth with particularity in the appended claims. The various aspects, however, both as to organization and methods of operation, together with advantages thereof, may be understood in accordance with the following description taken in conjunction with the accompanying drawings as follows:
Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate various aspects of the invention, in one form, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.
Numerous specific details are set forth to provide a thorough understanding of the overall structure, function, manufacture, and use of the aspects as described in the disclosure and illustrated in the accompanying drawings. Well-known operations, components, and elements have not been described in detail so as not to obscure the aspects described in the specification. The reader will understand that the aspects described and illustrated herein are non-limiting examples, and thus it can be appreciated that the specific structural and functional details disclosed herein may be representative and illustrative. Variations and changes thereto may be made without departing from the scope of the claims. Furthermore, it is to be understood that such terms as “forward,” “rearward,” “left,” “right,” “upwardly,” “downwardly,” and the like are words of convenience and are not to be construed as limiting terms.
In the following description, reference characters designate like or corresponding parts throughout the several views of the drawings. Also in the following description, it is to be understood that such terms as “forward,” “rearward,” “left,” “right,” “upwardly,” “downwardly,” and the like are words of convenience and are not to be construed as limiting terms.
Before explaining various aspects of the core component rodlet in detail, it should be noted that the illustrative examples are not limited in application or use to the details of construction and arrangement of parts illustrated in the accompanying drawings and description. The illustrative examples may be implemented or incorporated in other aspects, variations, and modifications, and may be practiced or carried out in various ways. Further, unless otherwise indicated, the terms and expressions employed herein have been chosen for the purpose of describing the illustrative examples for the convenience of the reader and are not for the purpose of limitation thereof. Also, it will be appreciated that one or more of the following-described aspects, expressions of aspects, and/or examples, can be combined with any one or more of the other following-described aspects, expressions of aspects, and/or examples.
In general, various radioisotopes can be used for medical treatments, food sterilization and other processes requiring an alpha, beta, and/or gamma radiation source. Radioisotopes are produced by irradiating targets made of naturally occurring elements within a neutron flux. For industrial scale production of radioisotopes, irradiation of targets is currently performed in certain types of nuclear reactors where the neutron moderation and primary cooling systems are separate, such as CANDUs (e.g., heavy water moderated, light water cooled) and RBMKs (i.e., graphite moderated, light water cooled). However, increased demand for certain radioisotopes and the closure of some CANDUs and RMBKs have driven source suppliers to seek out irradiation of targets in the more common PWRs (e.g., pressurized water reactors) where the moderator and coolant are the same light water circuit.
In at least one aspect, in order to irradiate targets in a PWR, the targets are sealed within a set of capsules which are then placed into a group of core component rodlets or tubes, attached to a core component baseplate of a core component assembly, and inserted into the guide thimbles of a fuel assembly. After irradiation, the capsules containing the irradiated targets are removed from the core component rodlets and sent to a radiation source manufacturer. The source manufacturer then removes the irradiated targets from these capsules for further processing and shipment to the end-user.
Further to the above, because PWR irradiation exposes the target bearing capsules and core component assemblies to much higher operating temperatures and pressures than found in CANDUs or RBMKs, a PWR-specific target irradiation design is required. PWR-specific problems that need to be addressed for a successful irradiation strategy are the temperature and pressure induced creep of the capsules containing the targets, hydriding of the capsules and the core component tube holding the capsule stack within the fuel assembly guide tube, and boiling of the coolant in contact with the capsules, the core component tube, and the fuel assembly guide tube where the core component is installed. In addition, the PWR-specific design should seek to minimize parasitic neutron absorption by the support materials to maximize the amount of target material activation. The PWR-specific irradiated target producing core component which solves these problems is discussed in greater detail below.
Further to the above,
Further to the above,
Referring now to
Referring still to
Further to the above, the capsule tube 420 surrounds the target material 430 to fully encapsulate the target material 430. One or more than one target material 430 may be positioned within the capsule tube 420. In at least one aspect, the capsule tube 420 defines a wall having a radial wall thickness WT (see
Further to the above, the rodlet 400 further comprises a backfill region 440 defined between the capsule tube 420 and the target material 430. In at least one aspect, the backfill region 440 is an annulus defined between the capsule tube 420 and the target material 430 having a backfill annulus width BA as shown in
Referring primarily to
Referring again to
Further to the above, the diameter and wall thickness of the capsule tube 420 is sized to resist creep due to the temperature and pressure of the primary reactor coolant and to maintain sufficient clearance between the target material 430 and inner diameter of the capsule tube 420 to allow for ease of target material 430 removal by the radiation source manufacturer after the irradiation period is completed. The capsule tube 420 dimensions are also sized to minimize parasitic neutron absorption by the capsule tube 420 so that radioisotope production is enhanced. In at least one aspect, the target material diameter TD is 0.2 to 0.3 inches and the wall thickness WT of the capsule tube 420 is 0.05 to 0.10 times the target material diameter TD. In at least one aspect, the target material 430 comprises one or more than one slug having a slug diameter of 0.2 to 0.3 inches. In at least one aspect, the wall thickness WT of the capsule tube 420 is 0.05 to 0.10 times the slug diameter of the target material 430.
Further to the above, in at least one aspect, the capsule tube 420 comprises a material with a yield strength greater than or equal to 60 kilopound per square inch (KSI) and less than or equal to 90 KSI. In at least one aspect, the capsule tube 420 comprises a material with a yield strength of greater than or equal to 60 KSI and less than or equal to 70 KSI. In at least one aspect, the capsule comprises one of SS304, Alloy 718, Alloy 625, or combinations thereof. In any event, the capsule tube 420 is configured to keep the target material separate from the reactor coolant for the duration of the irradiation period (e.g., one or more than one PWR operating cycle).
Further to the above, the diameter and wall thickness of the core component outer tube 410 are sized to allow for sufficient coolant flow in the first annulus 450 between the capsule tube 420 and core component outer tube 410 and for sufficient flow in the second annulus 500 between the core component outer tube 410 and the fuel assembly thimble guide tube 210 to preclude boiling during reactor operation. Flow on the inside and outside of the core component outer tube 410 also equalizes pressure avoiding issues with the outer tube 410 creeping down and contacting the capsule tube 420 during operation. In at least one aspect, the first annulus width FAW is 0.65 to 0.85 times greater than the second annulus width SAW (see
Further to the above, the core component outer tube 410 is constructed of a low neutron absorbing material so that radioisotope production is enhanced. More specifically, in at least one aspect, the core component outer tube 410 comprises a material with a neutron cross section less than or equal to 0.3 barns. In at least one aspect, the core component outer tube 410 comprises a material with a neutron cross section greater than or equal to 0.1 barns and less than or equal to 0.3 barns. In at least one aspect, the core component outer tube 410 comprises zirconium. In at least one aspect, the core component outer tube 410 comprises zirconium alloy. In at least one aspect, the core component outer tube 410 comprises Zircalloy (ZIRLO). In at least one aspect, the core component outer tube 410 comprises optimized Zircalloy.
Further to the above, the combination of materials for the capsule tube 420 and the core component outer tube 410 and the design features of these individual core component parts have been chosen, at least in part, to preclude hydrogen embrittlement (e.g., hydriding) of either element over the lifetime of the core component assembly. Hydriding of these core component assembly parts would lead to swelling and potential failure during operation and/or during handing after the irradiation period. Further, the above described combination of the high strength capsule tube 420, the core component outer tube 410, and the apertures 460,470 in the outer tube 410 which provide flow into the first annulus 450 have been optimized to prevent creeping of the outer tube 410 onto the capsule tube 420, to prevent creep of the capsule tube 420 onto the target material 430, and to prevent boiling in the regions of the first annulus 450 and the second annulus 500.
Various aspects of the present disclosure include, but are not limited to, the aspects listed in the following numbered clauses.
All patents, patent applications, publications, or other disclosure material mentioned herein, are hereby incorporated by reference in their entirety as if each individual reference was expressly incorporated by reference respectively. All references, and any material, or portion thereof, that are said to be incorporated by reference herein are incorporated herein only to the extent that the incorporated material does not conflict with existing definitions, statements, or other disclosure material set forth in this disclosure. As such, and to the extent necessary, the disclosure as set forth herein supersedes any conflicting material incorporated herein by reference and the disclosure expressly set forth in the present application controls.
The present invention has been described with reference to various exemplary and illustrative aspects. The aspects described herein are understood as providing illustrative features of varying detail of various aspects of the disclosed invention; and therefore, unless otherwise specified, it is to be understood that, to the extent possible, one or more features, elements, components, constituents, ingredients, structures, modules, and/or aspects of the disclosed aspects may be combined, separated, interchanged, and/or rearranged with or relative to one or more other features, elements, components, constituents, ingredients, structures, modules, and/or aspects of the disclosed aspects without departing from the scope of the disclosed invention. Accordingly, it will be recognized by persons having ordinary skill in the art that various substitutions, modifications or combinations of any of the exemplary aspects may be made without departing from the scope of the invention. In addition, persons skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the various aspects of the invention described herein upon review of this specification. Thus, the invention is not limited by the description of the various aspects, but rather by the claims.
Those skilled in the art will recognize that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to claims containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations.
In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that typically a disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms unless context dictates otherwise. For example, the phrase “A or B” will be typically understood to include the possibilities of “A” or “B” or “A and B.”
With respect to the appended claims, those skilled in the art will appreciate that recited operations therein may generally be performed in any order. Also, although claim recitations are presented in a sequence(s), it should be understood that the various operations may be performed in other orders than those which are described, or may be performed concurrently. Examples of such alternate orderings may include overlapping, interleaved, interrupted, reordered, incremental, preparatory, supplemental, simultaneous, reverse, or other variant orderings, unless context dictates otherwise. Furthermore, terms like “responsive to,” “related to,” or other past-tense adjectives are generally not intended to exclude such variants, unless context dictates otherwise.
It is worthy to note that any reference to “one aspect,” “an aspect,” “an exemplification,” “one exemplification,” and the like means that a particular feature, structure, or characteristic described in connection with the aspect is included in at least one aspect. Thus, appearances of the phrases “in one aspect,” “in an aspect,” “in an exemplification,” and “in one exemplification” in various places throughout the specification are not necessarily all referring to the same aspect. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner in one or more aspects.
As used herein, the singular form of “a”, “an”, and “the” include the plural references unless the context clearly dictates otherwise.
Directional phrases used herein, such as, for example and without limitation, top, bottom, left, right, lower, upper, front, back, and variations thereof, shall relate to the orientation of the elements shown in the accompanying drawing and are not limiting upon the claims unless otherwise expressly stated.
The terms “about” or “approximately” as used in the present disclosure, unless otherwise specified, means an acceptable error for a particular value as determined by one of ordinary skill in the art, which depends in part on how the value is measured or determined. In certain aspects, the term “about” or “approximately” means within 1, 2, 3, or 4 standard deviations. In certain aspects, the term “about” or “approximately” means within 50%, 200%, 105%, 100%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, or 0.05% of a given value or range.
In this specification, unless otherwise indicated, all numerical parameters are to be understood as being prefaced and modified in all instances by the term “about,” in which the numerical parameters possess the inherent variability characteristic of the underlying measurement techniques 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 scope of the claims, each numerical parameter described herein should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.
Any numerical range recited herein includes all sub-ranges subsumed within the recited range. For example, a range of “1 to 100” includes all sub-ranges between (and including) the recited minimum value of 1 and the recited maximum value of 100, that is, having a minimum value equal to or greater than 1 and a maximum value equal to or less than 100. Also, all ranges recited herein are inclusive of the end points of the recited ranges. For example, a range of “1 to 100” includes the end points 1 and 100. Any maximum numerical limitation recited in this specification is intended to include all lower numerical limitations subsumed therein, and any minimum numerical limitation recited in this specification is intended to include all higher numerical limitations subsumed therein. Accordingly, Applicant reserves the right to amend this specification, including the claims, to expressly recite any sub-range subsumed within the ranges expressly recited. All such ranges are inherently described in this specification.
Any patent application, patent, non-patent publication, or other disclosure material referred to in this specification and/or listed in any Application Data Sheet is incorporated by reference herein, to the extent that the incorporated materials is not inconsistent herewith. As such, and to the extent necessary, the disclosure as explicitly set forth herein supersedes any conflicting material incorporated herein by reference. Any material, or portion thereof, that is said to be incorporated by reference herein, but which conflicts with existing definitions, statements, or other disclosure material set forth herein will only be incorporated to the extent that no conflict arises between that incorporated material and the existing disclosure material.
The terms “comprise” (and any form of comprise, such as “comprises” and “comprising”), “have” (and any form of have, such as “has” and “having”), “include” (and any form of include, such as “includes” and “including”) and “contain” (and any form of contain, such as “contains” and “containing”) are open-ended linking verbs. As a result, a system that “comprises,” “has,” “includes” or “contains” one or more elements possesses those one or more elements, but is not limited to possessing only those one or more elements. Likewise, an element of a system, device, or apparatus that “comprises,” “has,” “includes” or “contains” one or more features possesses those one or more features, but is not limited to possessing only those one or more features.
