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Debris filters

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20120273408 patent thumbnailZoom

Debris filters


A filter for reactor coolant may include a plurality of adjacent plates. Each of the plates may include a plurality of alternating peaks and valleys. The peaks of a first plate of the plurality of adjacent plates and the valleys of a second plate of the plurality of adjacent plates that is adjacent to the first plate may be aligned in parallel such that each peak of the first plate and an associated valley of the second plate define a closed channel. The closed channels may be at an angle to a flow path of the reactor coolant into the filter. The filter may be shaped such that the reactor coolant from the flow path enters the closed channels, flows at the angle, and does not flow between the closed channels.

Inventors: Robert Bruce Elkins, Richard Carl Longren
USPTO Applicaton #: #20120273408 - Class: 210343 (USPTO) - 11/01/12 - Class 210 
Liquid Purification Or Separation > Plural Distinct Separators >Filters >Alternating Oppositely Opening Liquid Distributors

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The Patent Description & Claims data below is from USPTO Patent Application 20120273408, Debris filters.

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PRIORITY STATEMENT

This application is a continuation application of U.S. patent application Ser. No. 11/024,953, filed on Dec. 30, 2004, and claims the associated benefit under 35 U.S.C. §120. The entire contents of parent U.S. patent application Ser. No. 11/024,953, entitled “DEBRIS FILTER”, are incorporated herein by reference.

BACKGROUND

1. Field

Example embodiments may relate to nuclear reactor cores. Example embodiments also may relate to debris filters for coolant entering cores of nuclear reactors.

2. Description of Related Art

In a nuclear reactor, a liquid coolant or moderator flows into the reactor core from the bottom and exits the core as a water/steam mixture from the top. The core includes a plurality of fuel bundles arranged in vertical side-by-side relation, each containing a plurality of fuel rods. The fuel bundles are each supported between an upper tie plate and a lower tie plate. The lower tie plate typically includes an upper grid, a lower inlet nozzle and a transition region between the inlet nozzle and the grid whereby coolant water entering the inlet nozzle flows through the transition region and through the grid generally upwardly and about the individual fuel rods of the fuel bundle supported by the lower tie plate.

Over time, debris accumulates in the reactor and can result in fuel bundle failures in the field by debris fretting through the fuel rod cladding. Such debris can include, for example, extraneous materials left over from reactor construction and various other materials employed during outages and repairs. The coolant moderator circulation system in a nuclear reactor is closed and debris accumulates over time with increasing age and use of the reactor. Many and various types of debris filters or catchers have been proposed and used in the past. One such system employs a series of curved plates extending substantially parallel to the direction of coolant flow interspersed with the webs and bosses of the lower tie plate grid to filter debris. While certain advantages accrue to this type of debris catcher, the various parts are difficult to manufacture and require complex assembly. Another type of debris filter uses a stacked wire concept perpendicular to the coolant flow. While this is effective in filtering out debris, the wires of the debris filter themselves have been known to generate debris, resulting in fuel bundle failures.

In other cases, reactor debris filters are cast integrally with the lower tie plate. The hole size and small ligament web between the holes, however, are very near the investment casting manufacturability limits and oftentimes require hand rework to produce the filter. Particularly, an integral cast plate containing multiple holes extending parallel to the direction of coolant flow at the bottom of the boss/web structure of the lower tie plate grid supporting the fuel rods has been employed as a debris filter. While this design is simple and robust and does not add additional piece parts to the lower tie plate, any reduction in size of the debris filtering holes would render the lower tie plate very difficult to cast.

SUMMARY

The various embodiments of the present invention provide a debris filter for filtering coolant entering the core of a nuclear reactor. The inventors hereof have designed a debris filter that provides, in various embodiments, for improved effectiveness in filtering debris, while simultaneously improving its manufacturability and assembly. Additionally, in some embodiments of the invention, the debris filter improves filtering effectiveness without substantially increasing the pressure drop and/or decreasing the pressure drop of the fluid flow in the lower tie plate assembly to enable flexibility in the overall fine-tuning of the bundle thermal hydraulic design.

According to one aspect of the invention, a debris filter for reactor coolant includes a plurality of adjacent plates defining a plurality of channels therebetween, each of said channels being at an angle to a flow path of the coolant into the filter.

According to another aspect of the invention, a multistage filter for reactor coolant including a first filter with a plurality of adjacent plates defining a plurality of first channels therebetween. Each of said first channels are at an angle to a flow path of the coolant into the first filter. A second filter includes a plurality of adjacent second plates defining a plurality of second channels therebetween. Each of the second channels are at an angle to the flow of the coolant from the first filter.

According to yet another aspect of the invention, a multistage filter for reactor coolant including a first filter with a plurality of adjacent plates defining a plurality of first channels therebetween. A second filter includes a plurality of adjacent second plates defining a plurality of second channels therebetween. Each second channel of the second filter is aligned to multiple first channels of the first filter.

Further aspects of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or other aspects and advantages will become more apparent and more readily appreciated from the following detailed description of example embodiments, taken in conjunction with the accompanying drawings, in which:

FIG. 1A is a perspective view of a debris filter according to some example embodiments.

FIG. 1B is a side view of a plate for a debris filter according to some example embodiments.

FIG. 1C is a close up perspective view of a debris filter illustrating the plate defining a plurality of flow channels according to some example embodiments.

FIG. 2A is a side perspective view of a debris filter having a multi-stage filter according to some example embodiments.

FIG. 2B is a perspective view of a multi-sage debris filter having first and second filter according to some example embodiments.

FIG. 2C is a close up perspective view of a multi-stage debris filter having first and second filters according to some example embodiments.

FIG. 3 is a cross sectional view of first and second flow channels for a debris filter according to some example embodiments.

FIG. 4 is a cross sectional view of how a lower tie plate is assembled with a separate debris filter and cover plate according to some example embodiments.

FIG. 5 is an illustration is a perspective view of a lower tie plate assembly according to some example embodiments.

FIG. 6 is a cross sectional view of a fuel assembly for a reactor according to some example embodiments.

DETAILED DESCRIPTION

OF EXAMPLE EMBODIMENTS

Example embodiments will now be described more fully with reference to the accompanying drawings. Embodiments, however, may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these example embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope to those skilled in the art. In the drawings, the thicknesses of layers and regions are exaggerated for clarity.

It will be understood that when an element is referred to as being “on,” “connected to,” “electrically connected to,” or “coupled to” to another component, it may be directly on, connected to, electrically connected to, or coupled to the other component or intervening components may be present. In contrast, when a component is referred to as being “directly on,” “directly connected to,” “directly electrically connected to,” or “directly coupled to” another component, there are no intervening components present. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

It will be understood that although the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers, and/or sections, these elements, components, regions, layers, and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, and/or section from another element, component, region, layer, and/or section. For example, a first element, component, region, layer, and/or section could be termed a second element, component, region, layer, and/or section without departing from the teachings of example embodiments.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper,” and the like may be used herein for ease of description to describe the relationship of one component and/or feature to another component and/or feature, or other component(s) and/or feature(s), as illustrated in the drawings. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes,” and/or “including,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

It should also be noted that in some alternative implementations, functions, and/or acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may in fact be executed substantially concurrently or may sometimes be executed in the reverse order, depending upon the functionality and/or acts involved.

Reference will now be made to example embodiments, which are illustrated in the accompanying drawings, wherein like reference numerals may refer to like components throughout.

In some example embodiments, a debris filter for reactor coolant includes a plurality of adjacent plates defining a plurality of channels therebetween, each of said channels being at an angle to a flow path of the coolant into the filter. One such example embodiment is illustrated in FIGS. 1A, 2B, and 1C.

Referring to FIG. 1A, a filter 100 includes a plurality of plates 102 defining a plurality of flow channels 104 therebetween. In this illustrated embodiment, the filter 100 is rectangular in shape; however, the filter 100 can be formed in any shape or size adaptable for use within a nuclear reactor. A single plate 102 of the filter 100 is shown in FIG. 1B. Each plate 102 has a plurality of alternating peaks 106 and valleys 108 spaced at a predetermined spacing from one another. The peaks 106 and valleys 108 are configured such that when spaced side by side, on a peak to valley arrangement, the flow channel 104 is defined therebetween. The peaks 106 and valleys 108 may be of any design including a triangular or wave pattern and in some embodiments, plates 102 are corrugated plates. In some embodiments, the peaks 106 and valleys 108 form the channel 104 having a substantially square cross sectional area. In some embodiments, the cross sectional area is less than or equal to about 0.04 inches, and in other embodiments the cross sectional area is greater than or equal to about 0.025 inches.

The peaks 106 and valleys 108 are formed at an angle 112 from a perpendicular path 110 to a lateral surface 114 of the corrugated plate 102. The angle 112 may be any angle, and in one preferred embodiment, angle 112 is greater or equal to about 15 degrees. In another preferred embodiment, angle 112 is less than or equal to about 60 degrees. In typical operation, reactor coolant (not shown) flows to the lateral surface 114 of the plates 102 and generally parallel to perpendicular path 110. As the peaks 106 and valleys 108 are an angle 112 to perpendicular path 110, coolant flowing in channels 104 defined by the peaks 106 and valleys 108 is forced to change flow direction to consistent with the angle 112.

This is further shown in FIG. 1C which provides a close-up perspective view of filter plate 100 illustrating the plurality of corrugated plates 102 (see 102 A-D by way of example) that are arranged side by side. Each plate 102 is aligned with its peaks 106 to the valleys 108 of the adjacent plates 102 (for example, plate 102A and plate 102B), to form channels 104 therebetween. As shown, peaks 106A and 106B of plate 102A are aligned to valleys 108A and 108B, respectively, of plate 102B to form channel 104N. In some embodiments, each plate 102 can be attached at some of these peaks 106 and valleys 108 at one or more connecting points 116. These connecting point attachments can be a weld, solder, or any other suitable means for attachment including an attaching filler or adhesive added by way of spraying or dipping. As can be seen from FIG. 1C, a plurality of substantially rectangular or square flow channels 104 are formed by the peaks 106 and valleys 108 of adjacent and connected corrugated plates 102. Additionally, as each plate 102 has the peaks 106 and valleys 108 formed at an angle 112, the channels 104 are positioned at an angle 112 to the perpendicular path 110 to the lateral face 114 of the filter 100. As noted, the perpendicular path 110 is the general direction of coolant or fluid flow into the filter 100 at the lateral face 114. As such, any coolant entering the channels 104 at filter surface 114 will flow through the channel 104 at an angular flow of angle 112 to that of the coolant flow 110 into the filter 100.

In other embodiments of the invention, a multistage filter for reactor coolant includes a first filter with a plurality of adjacent plates defining a plurality of first channels therebetween. Each of said first channels are at an angle to a flow path of the coolant into the first filter. A second filter includes a plurality of adjacent second plates defining a plurality of second channels therebetween. Each of the second channels are at an angle to the flow of the coolant from the first filter.

Some example embodiments of are illustrated in FIGS. 2A, 2B, and 2C of a filter 200 for a reactor coolant having a multi-stage filter arrangement with at least a first filter 202 and a second filter 204. In FIG. 1A, the second filter 204 is positioned adjacent to the first filter 202. In some example embodiments, additional filters can also include in such a multi-stage filter. Both the first filter 202 and the second filter 204 can have a plurality of flow channels 216 and 220 defined between a plurality of plates, 203 and 205, respectively. As shown, the first filter 202 includes a plurality of first plates 203 defining a plurality of first channels 216. The second filter 204 has a plurality of second plates 205 defining a plurality of second channels 220. One such embodiment for each of filter 202 and 204 is described above in reference to FIGS. 1A, 1B, and 1C. However, other embodiments are also within the scope of the disclosure.

In some example embodiments the second filter 204 is position directly adjacent to first filter 202. In other example embodiments the second filter 204 is spaced at a distance from the first filter 202 thereby by defining an intermediate zone 206 or gap therebetween. FIG. 2B illustrates an exemplary side view of the two side by side filters. As shown, the first filter 202 includes a surface 211 for receiving a flow of coolant (not shown). The first filter 202 includes a plurality of alternating peaks 106 and valleys 108 that are formed at an angle 218 to a perpendicular path 212 to surface 211.

The second filter 204 of the multi-stage filter 200 also includes a plurality of alternating peaks 106 and valleys 108. The second filter 204 is positioned adjacent to or side-by-side with the first filter 202 and can be separated by the intermediate zone 206. In such an embodiment, a plurality of connecting members 208 can be coupled to the first filter 202 and the second filter 204 and can fixedly couple the two filters 202 and 204 together thereby defining the intermediate zone having a gap or spacing 210. The peaks 106 and valleys 108 of the second filter 204 are positioned at a second angle 224 from the first angle 218. The second angle 224 can be, in some embodiments, less than or equal to 150 degrees. In another embodiment, the peaks 106 and valleys 108 of the second filter 204 can be a third angle 222 which is also defined from the perpendicular path 212. In such embodiments, the third angle 222 can be an angle that is in an opposite direction of the perpendicular path 212 than the first angle 218 of the peaks 106 and valleys 108 of the first filter. In one embodiment, the third angle 222 is equal in magnitude but opposite in sign with respect to the perpendicular path 212 as the first angle 218 of the first filter 202.

As shown in the close up perspective view of FIG. 2C, the first filter 202 and the second filter 204 are positioned side by side such that flow through the first channels 216 of the first filter 202 flow into the second channels 220 of the second filter 204. As described above, with the second angle 224 being less than or equal to 150 degrees from the first angle 218, coolant flowing into the first filter 202 flows at the first angle 218 from the perpendicular flow 212 of coolant into the first filter 202. The coolant then changes directions as the coolant flows from the first flow channels 216 into the second channels 220, e.g., changes directions equal to the second angle 224.

In FIG. 2C, it can also be shown that in some embodiments, the first flow channels 216 of the first filter 202 can interconnect with the second flow channels 220 of the second filter 204 on a one-to-one basis. In other embodiments, the peaks 106 of the first filter 202 can be aligned to the valleys 108 of the second filter 204. In some such embodiments, the first channels 216 provide coolant flow to a plurality of second channels 220. In other embodiments, the second flow channels 220 are aligned with the first flow channels 216 such that each second channel 220 is aligned to four or more first channels 216. In such embodiments, the coolant flow in the second channels 220 includes coolant received from four or more first channels 216. In some embodiments, about each ¼ of each second channel 220 is aligned with a different first channel 216.

As mentioned, the connecting members 208 can couple the first filter 202 and the second filter 204 together and can define the intermediate zone 206 between the two filters 202 and 204. The intermediate zone 206 can define the spacing 210 between the two filters 202 and 204, and in some embodiments, the spacing is about 0.04 inches. In other embodiments, the spacing 210 is less than or equal to 0.05 inches. In embodiments with the intermediate zone 206, the intermediate zone 206 provides for a mixing of flow from a plurality of first channels 216 being provided to each second channel 220. This also provides the multi-stage filter 200 with improved filtering characteristics. Various embodiments can include one or more of a) trapping debris with the multi-stage filter 200, b) trapping debris within the intermediate zone 206, and c) providing fluid flow around any trapped debris. Of course, other features or characteristics of the filter are also present although not described or particularly pointed out herein.

As discussed above, the alignment of the second filter 204 with the first filter 202 align the first channels 216 with one or more second channels 220. By way of example, some embodiments of a multistage filter for reactor coolant include a first filter 202 with the plurality of adjacent plates 203 defining the plurality of first channels 216 therebetween. The second filter 204 includes the plurality of adjacent second plates 205 defining a plurality of second channels 220 therebetween. Each second channel 220 of the second filter 204 is aligned to the multiple first channels 216 of the first filter 202. One such embodiment is shown in a close up perspective of FIG. 3.

In the illustrated example of FIG. 3 are a first filter 202 with first plates 203 and a second filter 204 with second plates 205. As can be seen, each peak of the first plates 203 are aligned with a valley of an adjacent plate thereby forming first channel 216 therebetween. For example, a plate 203A is aligned with a plate 203B and a first channel 216A is therebetween defined. Similarly, a plate 205A of second filter 204 defines a plurality of second channels 220 with an adjacent second plate 205B. For example, in FIG. 3 second plate 205A and second plate 205B form second channels 220A and 220B, second plate 205A and second plate 205C form another second channel 220D, and second plate 205B and second plate 205D form another second channel 220C.

The first filter 202 made up of first plates 203 that define the first channels 216 is aligned the second filter 204 made up of second plates 205 that define the second channels 220, in this example embodiment, such that multiple second channels 220 are aligned to each first channel 216. As shown, the first channel 216A is aligned to each of second channels 220A, 220B, 220C and 220D. In such an arrangement, coolant flows through each of the first channel 216 and is distributed and provided to multiple second channels 220, and in this example, to four second channels 220. In other embodiments, each first channel 216 can be aligned to two or more second channels 220. Additionally, in other embodiments and as discussed above an intermediate zone 206 may provide for additional mixing of coolant flow from first channels 216 to second channels 220.



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stats Patent Info
Application #
US 20120273408 A1
Publish Date
11/01/2012
Document #
13538067
File Date
06/29/2012
USPTO Class
210343
Other USPTO Classes
210417
International Class
/
Drawings
9



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