U.S. patent application number 13/538067 was filed with the patent office on 2012-11-01 for debris filters.
Invention is credited to Robert Bruce Elkins, Richard Carl Longren.
Application Number | 20120273408 13/538067 |
Document ID | / |
Family ID | 36096286 |
Filed Date | 2012-11-01 |
United States Patent
Application |
20120273408 |
Kind Code |
A1 |
Elkins; Robert Bruce ; et
al. |
November 1, 2012 |
DEBRIS FILTERS
Abstract
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: |
Elkins; Robert Bruce;
(Wilmington, NC) ; Longren; Richard Carl;
(Wilmington, NC) |
Family ID: |
36096286 |
Appl. No.: |
13/538067 |
Filed: |
June 29, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11024953 |
Dec 30, 2004 |
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13538067 |
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Current U.S.
Class: |
210/343 ;
210/417 |
Current CPC
Class: |
Y02E 30/30 20130101;
G21C 3/3206 20130101; Y02E 30/40 20130101 |
Class at
Publication: |
210/343 ;
210/417 |
International
Class: |
B01D 29/88 20060101
B01D029/88; B01D 29/50 20060101 B01D029/50 |
Claims
1. A filter for reactor coolant, the filter comprising: a plurality
of adjacent plates; wherein each of the plates includes a plurality
of alternating peaks and valleys, wherein 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 are aligned in parallel such that each peak of
the first plate and an associated valley of the second plate define
a closed channel, wherein the closed channels are at an angle to a
flow path of the reactor coolant into the filter, and wherein the
filter is 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.
2. The filter of claim 1, wherein each plate is a corrugated
plate.
3. The filter of claim 1, wherein the angle is greater than or
equal to 15 degrees.
4. The filter of claim 1, wherein each closed channel has a
substantially rectangular cross-section.
5. The filter of claim 1, wherein each closed channel has a
substantially square cross-section.
6. The filter of claim 1, wherein each closed channel has a
cross-sectional area that is less than or equal to about 0.04
square inches.
7. A multistage filter for reactor coolant, the filter comprising:
a first filter including a plurality of adjacent first plates; and
a second filter, adjacent to the first filter, including a
plurality of adjacent second plates; wherein each of the first
plates includes a plurality of alternating peaks and valleys,
wherein the peaks of one plate of the plurality of adjacent first
plates and the valleys of another plate of the plurality of
adjacent first plates that is adjacent to the one plate of the
plurality of adjacent first plates are aligned in parallel such
that each peak of the one plate of the plurality of adjacent first
plates and an associated valley of the another plate of the
plurality of adjacent first plates define a first closed channel,
wherein the first closed channels are at a first angle to a flow
path of the reactor coolant into the first filter, wherein the
first filter is shaped such that the reactor coolant from the flow
path into the first filter enters the first closed channels, flows
at the first angle, and does not flow between the first closed
channels, wherein each of the second plates includes a plurality of
alternating peaks and valleys, wherein the peaks of one plate of
the plurality of adjacent second plates and the valleys of another
plate of the plurality of adjacent second plates that is adjacent
to the one plate of the plurality of adjacent second plates are
aligned in parallel such that each peak of the one plate of the
plurality of adjacent second plates and an associated valley of the
another plate of the plurality of adjacent second plates define a
second closed channel, wherein the second closed channels are at a
second angle to a flow path of the reactor coolant into the second
filter, and wherein the second filter is shaped such that the
reactor coolant from the flow path into the second filter enters
the second closed channels, flows at the second angle, and does not
flow between the second closed channels.
8. The multistage filter of claim 7, wherein the second closed
channels are offset from the first closed channels such that the
reactor coolant flow in each second closed channel includes reactor
coolant from multiple first closed channels.
9. The multistage filter of claim 8, wherein each first closed
channel is aligned to four or more second closed channels such that
about 1/4 of each second closed channel cross-sectional area is
aligned to four different first closed channels.
10. The multistage filter of claim 7, further comprising: a
plurality of connecting members configured to fixedly connect the
second filter to the first filter; wherein the connecting members
are configured to create a substantially unobstructed intermediate
zone between the first filter and the second filter.
11. The multistage filter of claim 10, wherein when the plurality
of connecting members fixedly connect the second filter to the
first filter, the second filter is spaced apart from the first
filter by about 0.04 inches.
12. The multistage filter of claim 7, wherein a peak of the one
plate of the plurality of adjacent first plates is aligned to a
valley of the another plate of the plurality of adjacent second
plates.
13. The multistage filter of claim 7, wherein the first angle is
greater than or equal to 15 degrees, wherein the second angle is
greater than or equal to about 150 degrees from the first angle,
and wherein the first angle and the second angle are of opposite
signs.
14. The multistage filter of claim 7, wherein the second angle is
less than or equal to about 150 degrees from the first angle.
15. The multistage filter of claim 7, wherein each first plate is a
corrugated plate, or wherein each second plate is a corrugated
plate.
16. The multistage filter of claim 7, wherein each first plate is a
corrugated plate, and wherein each second plate is a corrugated
plate.
17. The multistage filter of claim 7, wherein each first closed
channel has a substantially rectangular cross-section, or wherein
each second closed channel has a substantially rectangular
cross-section.
18. The multistage filter of claim 7, wherein each first closed
channel has a substantially square cross-section, or wherein each
second closed channel has a substantially square cross-section.
19. The multistage filter of claim 7, each first closed channel has
a cross-sectional area that is less than or equal to about 0.04
square inches, or each second closed channel has a cross-sectional
area that is less than or equal to about 0.04 square inches.
20. The multistage filter of claim 7, each first closed channel has
a cross-sectional area that is less than or equal to about 0.04
square inches, and each second closed channel has a cross-sectional
area that is less than or equal to about 0.04 square inches.
Description
PRIORITY STATEMENT
[0001] 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. .sctn.120. The entire
contents of parent U.S. patent application Ser. No. 11/024,953,
entitled "DEBRIS FILTER", are incorporated herein by reference.
BACKGROUND
[0002] 1. Field
[0003] Example embodiments may relate to nuclear reactor cores.
Example embodiments also may relate to debris filters for coolant
entering cores of nuclear reactors.
[0004] 2. Description of Related Art
[0005] 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.
[0006] 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.
[0007] 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
[0008] 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.
[0009] 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.
[0010] 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.
[0011] 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.
[0012] 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
[0013] 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:
[0014] FIG. 1A is a perspective view of a debris filter according
to some example embodiments.
[0015] FIG. 1B is a side view of a plate for a debris filter
according to some example embodiments.
[0016] 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.
[0017] FIG. 2A is a side perspective view of a debris filter having
a multi-stage filter according to some example embodiments.
[0018] FIG. 2B is a perspective view of a multi-sage debris filter
having first and second filter according to some example
embodiments.
[0019] FIG. 2C is a close up perspective view of a multi-stage
debris filter having first and second filters according to some
example embodiments.
[0020] FIG. 3 is a cross sectional view of first and second flow
channels for a debris filter according to some example
embodiments.
[0021] 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.
[0022] FIG. 5 is an illustration is a perspective view of a lower
tie plate assembly according to some example embodiments.
[0023] FIG. 6 is a cross sectional view of a fuel assembly for a
reactor according to some example embodiments.
DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS
[0024] 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.
[0025] 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.
[0026] 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.
[0027] 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.
[0028] 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.
[0029] 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.
[0030] 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.
[0031] 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.
[0032] 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.
[0033] 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.
[0034] 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.
[0035] 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.
[0036] 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.
[0037] 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.
[0038] 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.
[0039] 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.
[0040] 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.
[0041] 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 1/4 of each second channel 220 is aligned with a
different first channel 216.
[0042] 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.
[0043] 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.
[0044] 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.
[0045] 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.
[0046] In operation, debris filters according to the various
embodiments of the invention described herein are adapted for
filtering debris in the coolant circulating within a nuclear
reactor. As such, other embodiments of the invention include a
lower tie plate assembly for a nuclear reactor that includes a
casing having an inlet opening for conducting coolant into the
lower tie plate assembly. A rod support member is configured for
receiving a plurality of fuel rods. A debris filter is positioned
adjacent to the rod support member. Various embodiments of the
debris filter, as discussed above and by way of the above examples,
can be utilized in such a lower tie plate assembly. For example, in
some embodiments the debris filter can include at least a first
filter and a second filter. The first filter can have a plurality
of adjacent plates defining a plurality of first channels
therebetween. Each of the first channels is at an angle to a flow
path of the coolant into the first filter. The second filter can
have a plurality of adjacent plates that define a plurality of
second channels therebetween. Each of the second channels is at an
angle to the flow of the coolant from the first filter. The second
channels of the second filter can be offset from the first channels
of the first filter such that the coolant flow in each second
channel includes coolant flow from multiple first channels. Each of
the first channels and the second channels can have a cross section
less than or equal to about 0.04 square inches in some preferred
embodiments. Such flow channels cross sections can be of any shape
and in one embodiment is substantially square in shape.
[0047] In some embodiments, a plurality of connecting members
coupling the second filter to the first filter to create a
substantially unobstructed intermediate zone between the first
filter and the second filter. In other embodiment, an angle of the
first channels is greater than or equal to about 15 degrees from a
coolant flow entering the first filter. Additionally, the angle of
the second channels is less than or equal to about 150 degrees from
the coolant flow from the first filter.
[0048] The casing can be dimensioned to provide a higher flow rate
in a center portion of the filter than a flow rate along a
perimeter portion of the filter. In such cases, the flow rate
arrangement provides for washing filtered debris from the center of
the multi-stage filter into the corners of the casing between the
casing and the multi-stage filter. The casing can also be
configured to include a filter placement opening that is adapted
for insertion of the multi-stage filter into the casing adjacent to
the rod support member and a closure plate. The multi-stage filter
can generally be dimensioned to substantially fill the casing such
that substantially all of the coolant flows through both the first
filter and the second filter.
[0049] Two such example embodiments are illustrated in FIGS. 4 and
5. Referring first to FIG. 4, a lower tie plate assembly 400 for a
nuclear reactor is illustrated with a plurality of fuel rods 408
coupled thereto. The lower tie plate assembly 400 includes a lower
tie plate casing 402 defining an inlet opening 404 and a flow
chamber 420. Coolant flows as shown as 414 into the reactor core
through this inlet 404 and chamber 420. A rod support member 406
includes rod holes 412 for receiving and supporting the plurality
of fuel rods 408, which may include non-fuel rods such as water
rods. Some of the fuel rods 408 can have end caps 410 for attaching
the fuel rods to the rod support member 406. The rod support member
406 can also include a plurality of openings 407 to allow for the
passage of coolant from below the rod support member 406 up to and
around the fuel rods 408. A filter cover plate 418 can provide
access to the filter 200 and can be adjacent to rod support member
406. In some embodiments, the filter cover plate 418 and/or lower
end plate casing 402 can be adapted to support or fixedly couple
the filter 200 into a position adjacent the rod support member
406.
[0050] As illustrated, the filter 200 receives coolant flow 414
from inlet 404 through chamber 420. The coolant entering the filter
200 can be substantially parallel to perpendicular path 212. The
coolant flow through the filter 200 and directly into the lower
portion of the rod support member 406 and up and through the rod
support member 406 to the fuel rods 408.
[0051] The lower tie plate casing 402 can be configured to provide
a higher flow rate of coolant near the center portion of the filter
200 and a lower flow rate at or near the perimeter of the filter
200. As such, at least a portion of the debris in the coolant
filtered by the filter 200 can be forced by the difference in flow
rates and associated pressures to one or more of the corners 416 of
the chamber 420.
[0052] Referring now to FIG. 5, a lower tie plate assembly 500 is
exploded to illustrate the separate parts according to some example
embodiments. In this example embodiment, the casing 402 defines a
filter access opening 502 for receiving the filter 200 into the
casing 402. After the filter 200 is inserted into the filter access
opening 502 of casing 402, the filter cover plate 418 closes the
opening 502. Typically, the filter cover plate 418 is welded or
otherwise fixedly attached to seal the lower tie plate casing
402.
[0053] In some example embodiments, a fuel assembly for a boiling
coolant reactor includes a lower tie plate with a rod support
member and an upper tie plate. A plurality of fuel rods extend
between the upper tie plate and the lower tie plate. A casing
surrounds the lower tie plate, the upper tie plate, and the fuel
rods and defines an inlet opening through the lower tie plate
assembly for conducting coolant into a reactor core. A debris
filter is position positioned adjacent to the rod support
member.
[0054] In some example embodiments, the debris filter is one of the
debris filters described above, by way of example. In one
embodiment, the filter includes a first filter, a second filter,
and a plurality of connecting members. The first filter has a
plurality of first plates defining a plurality of first flow
channels. Each of the first flow channels are at a first angle to a
flow path of the coolant into the first filter. The second filter
has a plurality of second plates defining a plurality of second
flow channels. Each of the second flow channels is at a second
angle to the flow of the coolant into the first filter. The second
angle is in an opposite direction to the first angle. Each of the
second flow channels can be offset from each of the first flow
channels. The connecting members can fixedly connect the second
filter to the first filter and can create an intermediate zone
therebetween. In some example embodiments, the intermediate zone is
substantially unobstructed.
[0055] One example of such a portion of a nuclear reactor fuel
assembly is shown in FIG. 6. In this example, a partial fuel
assembly 600 includes a lower tie casing 402 that includes a
coolant inlet 404 and a rod support member 406. The rod support
member 406 includes rod holes 412 for receiving a plurality of fuel
rods 408. A filter 200 is positioned adjacent to the rod support
member 406 and a filter cover plate 418. The filter 200 can be any
embodiment of the filter described above and herein.
[0056] One or more spacers 604 supports and spaces the upper
portions of the fuel rods 408. A fuel assembly casing 602 can
surround the fuel rods 408, the spacers 604, the rod support member
406, the lower tie plate casing 402, and an upper tie plate (not
shown).
[0057] When introducing aspects of the invention or embodiments
thereof, the articles "a", "an", "the", and "said" are intended to
mean that there are one or more of the elements. The terms
"comprising", "including", and "having" are intended to be
inclusive and mean that there may be additional elements other than
the listed elements.
[0058] In view of the above, it will be seen that several aspects
of the invention are achieved and other advantageous results
attained. As various changes could be made in the above exemplary
constructions and methods without departing from the scope of the
invention, it is intended that all matter contained in the above
description or shown in the accompanying drawings shall be
interpreted as illustrative and not in a limiting sense.
[0059] It is further to be understood that the steps described
herein are not to be construed as necessarily requiring their
performance in the particular order discussed or illustrated. It is
also to be understood that additional or alternative steps may be
employed.
[0060] While example embodiments have been particularly shown and
described, it will be understood by those of ordinary skill in the
art that various changes in form and details may be made therein
without departing from the spirit and scope of the present
invention as defined by the following claims.
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