CA1167176A - Fuel bundle with skewed elements - Google Patents
Fuel bundle with skewed elementsInfo
- Publication number
- CA1167176A CA1167176A CA000387727A CA387727A CA1167176A CA 1167176 A CA1167176 A CA 1167176A CA 000387727 A CA000387727 A CA 000387727A CA 387727 A CA387727 A CA 387727A CA 1167176 A CA1167176 A CA 1167176A
- Authority
- CA
- Canada
- Prior art keywords
- bundle
- rods
- fuel
- coolant
- end plates
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C3/00—Reactor fuel elements and their assemblies; Selection of substances for use as reactor fuel elements
- G21C3/30—Assemblies of a number of fuel elements in the form of a rigid unit
- G21C3/32—Bundles of parallel pin-, rod-, or tube-shaped fuel elements
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/30—Nuclear fission reactors
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- General Engineering & Computer Science (AREA)
- High Energy & Nuclear Physics (AREA)
- Monitoring And Testing Of Nuclear Reactors (AREA)
Abstract
FUEL BUNDLE WITH SKEWED ELEMENTS
ABSTRACT OF THE DISCLOSURE
A nuclear reactor having elongated pressure tube fuel channels containing rodded fuel elements assembled as discreate bundles arranged in end to end serial relation within the pressure tube, for the passage of liquid coolant therepast is provided with improved fuel bundles having the rodded elements skewed with respect to the pressure tube in order to promote swirling of the liquid or liquid and vapour mixture coolant in its passage along the fuel channel. In addition to the evident rotational effect due to the "twist", the effect of skewing the fuel rods in each bundle is to create a progressive change in flow area distribution between the interior subchannels and the subchannels surrounding the bundle, from both ends of each fuel bundle to its longitudinal centre, tending to promote uniform heating of the liquid or liquid and vapour coolant by flow deflection between the interior subchannels and the surrounding subchannels.
ABSTRACT OF THE DISCLOSURE
A nuclear reactor having elongated pressure tube fuel channels containing rodded fuel elements assembled as discreate bundles arranged in end to end serial relation within the pressure tube, for the passage of liquid coolant therepast is provided with improved fuel bundles having the rodded elements skewed with respect to the pressure tube in order to promote swirling of the liquid or liquid and vapour mixture coolant in its passage along the fuel channel. In addition to the evident rotational effect due to the "twist", the effect of skewing the fuel rods in each bundle is to create a progressive change in flow area distribution between the interior subchannels and the subchannels surrounding the bundle, from both ends of each fuel bundle to its longitudinal centre, tending to promote uniform heating of the liquid or liquid and vapour coolant by flow deflection between the interior subchannels and the surrounding subchannels.
Description
I ~ B'~
CASE-277~
FUEL BUNDLE WITX S:KEWED ELEM~NTS
This invention is directed to nuclear reactors, and to fuel for use in nuclear reactors, and methods of manufacturing such nuclear fuel.
In the Canadian Deuterium Uranium (acronym CANDU) type of reactor, use is made of fuel channels arranged within a calandria, somewhat in the manner of a boiler. The fuel channels each comprises a tube containing pressuriæed liquid and a so-called string of fuel bundles arranged in serial, end-to-end relation extending substantially the full length of the individual channel. Each fuel bundle has a plurality of clad fuel rods or elements, as many as but not limited to 37 rods per bundle each rod being about one half inch in diameter by about twenty inches long, being arranged in concentric rings and supported by welding of the rod end caps to a pair of spaced-apart end plates, with the polar axis of each rod being parallel with the bundle main axis and the end plates perpendicular to the bundle main axis.
In the CANDU type reactor the coolant is maintained usuall~ in liquid phase with a small proportion of vapour at the exit end of some channels, being pressurized in order to raise the maximum coolant temperature, the coolant liquid being deuterium-oxide i.e./ heavy water.
` One of the problems encountered is the matter of controlling coolant flow in a suitable condition to .. , .. ~ .... . .
.: .
. ~ .
.
.
I ~ 6 7~ 7~;
effect required heat transfer from the individual fuel rods to the liquid coolant. In accordance with prior art and practice, the ~uel rods extend parallel with the tube main axis, thereby ensuring minimal coolant pressure drop along the length of the fuel channel, to thereby minimize pumping requirement for the reactor.
In accordance with the present invention a nuclear reactor is provided having rodded fuel bundles wherein each bundle comprises a pluralit:y of fuel rods having the ends thereof secured to opposed end plates, the rods being skewed at angles in the typical range oE 0.3 to 0.5, but not restricted to this range, from an axis parallel with the principal axis of the bundle. A
centre rod lying on the bundle axis remains parallel to the bundle axis and the end plates perpendicular to the bundle axis.
One method by which the present invention may be practiced is to assemble the fuel rods and end plates, prior to final securement~ in a rectilinear axially aligned condition, and then rotate one of the end plates about its polar axis by a desired angle of displacement, in the typical range of 10 to ~0, but not restricted to this range from the other plate as to generate symmetrical skewing of all of the fuel rods. It will be understood that this method will produce differential axial skewing between respective rings of rods, with the radially outer ring of fuel rods being skewed at the greatest angle, and radially inner rings being progressively less skewed.
The effect of skewing is to shorten the projected length or distance between the ends of the fuel rods measured parallel to the bundle axis, but because of the differentiated skew angles, the outer ring of rods is shortened more than inner rings, which are progressively shortened by reduced amounts. A centre rod on the bundle a~is being not skewed maintains a projected length equal to its actual length.`
IJ~'~t 7~
A tabulated analysis given below in Table 1, shows the decreases in rod projected length resulting from varying degrees of skew, arrived at by respective relative rotations of the end plates. This length variation, according to the ring, can be compensated by appropriately increasing the fuel rod lengths, or by providing compensating annular steps or lands on the end plate.
One effect steming from the skewed construction is that the fuel bundle takes on a slightly waisted appearance, i.e., the bundle diameter diminishes progressively from a maximum value at the ends to a minimum value at the longitudinal mid point.
This has the effect of causing the interconnected coolant flow channels which exist in the in-terior of the fuel bundle, and those exterior to the bundle, to change in their relative cross sectional areas, thereby tending to cause a coolant transfer during coolant flow along the bundle from within the bundle to the outside of the bundle, and vice versa. This is complementary to the rotatory effect on coolant flow due to the handling effect of rod skewing (i.e~, twist).
Certain embodiments of the invention are described, reference being made to the accompanying drawings, wherein;
Figure 1 is a side view of a fuel bundle according to the present invention.
Figure 2 and Figure 3 are end views taken at 2-2 and 3-3 of Figure 1.
Figure 4 is a diametrical sectioned view of an end plate taken on line 4-4, a bundle having all rods of uniform length.
For illustratory purposes, a bundle having 37 rods is shown,arranged as three concentric rings of rods about a single rod lying on the bundle axis.
I ~ 6 ~ :? ~ ~;
Referring to the drawings, the bundle 20 is the same as a normal rectilinear bundle, but having a 40 counter clockwise twist applied between the ends thereof. Thus, in the illustratad embodiment, the respective rod positions for the rods 22 are displaced by two intervals in the case of the numbered, radially outer ring of rods, as shown in Figures 2 and 3.
The Figure 4 sectioned view is somewhat schematic, in that perforations of the end plate 24, which permit through-flow to assist coolant circulation~ have not been illustrated, to better show the provision of annular lands 26, 28 and 30 for the respective three annular rows of rods 22 contained in the bundle. The differences in the heights of the annular lands 26, 28 and 30 exaggerated for purposes of illustration, compensate for the differential axial shortening taking place in the equal length rods of the respective rings of rods, due to the different angles in inclination, as set forth below in Table I, with corresponding differences in effective axial length, as measured between the bundle end plates. Alternatively, a flat end plate of constant thickness, withou-t the annular lands 26, 28 and 30, may be used with rods having lengths that are increased to compensate for the differential axial shortening taking place due to the different angles of inclination in the respective rings as set forth in Table I.
- J ;1 ~;7 ~ 7~i .
_ 5 _ CASE 2774 SOME RELEVANT DIMENSIONS FOR THE ILLUSTRATED
Mid Length ¦ Mid Length Pitch Subchannel Area Circle Diam. Decrease End~ Change - inche.s Plate Rotary ___________________________ _ _ ______~_~
Angle Exterior Interior Outer Mid Inner Channels Channels Ring Ring Ring _~ .
00 O O o O O
10 +3.3 -2.1 .0133 .0086 .0046 20 -~12.7 -8.1 .0518 .0344 .0178 30 +28.3 -18.0 .1162 .0771 .0399 40 +49 -31.5 .2056 .1365 .0707 _______ _ _ ~ __ _~
End Rod Angle to Flow Porjected Axial RodLen9th Plate Change - inches Rotatory _ _ ~ _ _ ___~
Angle outer Mid Inner Outer Mid Inner _ Ring Ring Ring Ring Ring Ring O O O O O O
10 0.9 0.6 0.3 .0023 .0010 .0003 20 1.8 1.2 0.6 .0091 .0040 .0011 30 2.6 1.7 0.9 .0201 ~ .0089 .0024 40 3.5 2.3 1.2 .0351 .0155 .0041 :
__ ~ ~. __ ~' .
:' '7 ~
C~SE-277 ~ 6 --Referring to Table I, in the case of the 40 rotatory angle between the end plates, there is a projected rod length change, as measured axially between the end plates of the fuel bund:Le, amounting to approximately 35 thousandths of an inch ("thou."), in the case of the radially outer ring of rods, 15 thousandths of an inch in the case of the m:id ring of rods, and the 4 thousand-ths of an inch in the case of the inner ring of rods. These are the lengths by which the rods in the respective rings must be increased for the use of end plates without steps.
In the case where rods of uniform length are used throughout the bundle, both end plates 24 are approximately stepped, to compensate ~or axial projected length differences, the stepped differentials of the annular rings or lands 26, 28 and 30 would be halved to values of 17.5 thou., 7.5 thou., and 2 thou., approximately.
In the other three tabulated cases of a fuel bundle having a lesser angle of skew, the axial distance differentials are correspondingly reduced, to the extend that, for a ten degree skew (Table I) the difference to be made up at each'end would not exceed 1.15 thou., which could be accommodated in the welding of the rod end cap to the plate 24.
CASE-277~
FUEL BUNDLE WITX S:KEWED ELEM~NTS
This invention is directed to nuclear reactors, and to fuel for use in nuclear reactors, and methods of manufacturing such nuclear fuel.
In the Canadian Deuterium Uranium (acronym CANDU) type of reactor, use is made of fuel channels arranged within a calandria, somewhat in the manner of a boiler. The fuel channels each comprises a tube containing pressuriæed liquid and a so-called string of fuel bundles arranged in serial, end-to-end relation extending substantially the full length of the individual channel. Each fuel bundle has a plurality of clad fuel rods or elements, as many as but not limited to 37 rods per bundle each rod being about one half inch in diameter by about twenty inches long, being arranged in concentric rings and supported by welding of the rod end caps to a pair of spaced-apart end plates, with the polar axis of each rod being parallel with the bundle main axis and the end plates perpendicular to the bundle main axis.
In the CANDU type reactor the coolant is maintained usuall~ in liquid phase with a small proportion of vapour at the exit end of some channels, being pressurized in order to raise the maximum coolant temperature, the coolant liquid being deuterium-oxide i.e./ heavy water.
` One of the problems encountered is the matter of controlling coolant flow in a suitable condition to .. , .. ~ .... . .
.: .
. ~ .
.
.
I ~ 6 7~ 7~;
effect required heat transfer from the individual fuel rods to the liquid coolant. In accordance with prior art and practice, the ~uel rods extend parallel with the tube main axis, thereby ensuring minimal coolant pressure drop along the length of the fuel channel, to thereby minimize pumping requirement for the reactor.
In accordance with the present invention a nuclear reactor is provided having rodded fuel bundles wherein each bundle comprises a pluralit:y of fuel rods having the ends thereof secured to opposed end plates, the rods being skewed at angles in the typical range oE 0.3 to 0.5, but not restricted to this range, from an axis parallel with the principal axis of the bundle. A
centre rod lying on the bundle axis remains parallel to the bundle axis and the end plates perpendicular to the bundle axis.
One method by which the present invention may be practiced is to assemble the fuel rods and end plates, prior to final securement~ in a rectilinear axially aligned condition, and then rotate one of the end plates about its polar axis by a desired angle of displacement, in the typical range of 10 to ~0, but not restricted to this range from the other plate as to generate symmetrical skewing of all of the fuel rods. It will be understood that this method will produce differential axial skewing between respective rings of rods, with the radially outer ring of fuel rods being skewed at the greatest angle, and radially inner rings being progressively less skewed.
The effect of skewing is to shorten the projected length or distance between the ends of the fuel rods measured parallel to the bundle axis, but because of the differentiated skew angles, the outer ring of rods is shortened more than inner rings, which are progressively shortened by reduced amounts. A centre rod on the bundle a~is being not skewed maintains a projected length equal to its actual length.`
IJ~'~t 7~
A tabulated analysis given below in Table 1, shows the decreases in rod projected length resulting from varying degrees of skew, arrived at by respective relative rotations of the end plates. This length variation, according to the ring, can be compensated by appropriately increasing the fuel rod lengths, or by providing compensating annular steps or lands on the end plate.
One effect steming from the skewed construction is that the fuel bundle takes on a slightly waisted appearance, i.e., the bundle diameter diminishes progressively from a maximum value at the ends to a minimum value at the longitudinal mid point.
This has the effect of causing the interconnected coolant flow channels which exist in the in-terior of the fuel bundle, and those exterior to the bundle, to change in their relative cross sectional areas, thereby tending to cause a coolant transfer during coolant flow along the bundle from within the bundle to the outside of the bundle, and vice versa. This is complementary to the rotatory effect on coolant flow due to the handling effect of rod skewing (i.e~, twist).
Certain embodiments of the invention are described, reference being made to the accompanying drawings, wherein;
Figure 1 is a side view of a fuel bundle according to the present invention.
Figure 2 and Figure 3 are end views taken at 2-2 and 3-3 of Figure 1.
Figure 4 is a diametrical sectioned view of an end plate taken on line 4-4, a bundle having all rods of uniform length.
For illustratory purposes, a bundle having 37 rods is shown,arranged as three concentric rings of rods about a single rod lying on the bundle axis.
I ~ 6 ~ :? ~ ~;
Referring to the drawings, the bundle 20 is the same as a normal rectilinear bundle, but having a 40 counter clockwise twist applied between the ends thereof. Thus, in the illustratad embodiment, the respective rod positions for the rods 22 are displaced by two intervals in the case of the numbered, radially outer ring of rods, as shown in Figures 2 and 3.
The Figure 4 sectioned view is somewhat schematic, in that perforations of the end plate 24, which permit through-flow to assist coolant circulation~ have not been illustrated, to better show the provision of annular lands 26, 28 and 30 for the respective three annular rows of rods 22 contained in the bundle. The differences in the heights of the annular lands 26, 28 and 30 exaggerated for purposes of illustration, compensate for the differential axial shortening taking place in the equal length rods of the respective rings of rods, due to the different angles in inclination, as set forth below in Table I, with corresponding differences in effective axial length, as measured between the bundle end plates. Alternatively, a flat end plate of constant thickness, withou-t the annular lands 26, 28 and 30, may be used with rods having lengths that are increased to compensate for the differential axial shortening taking place due to the different angles of inclination in the respective rings as set forth in Table I.
- J ;1 ~;7 ~ 7~i .
_ 5 _ CASE 2774 SOME RELEVANT DIMENSIONS FOR THE ILLUSTRATED
Mid Length ¦ Mid Length Pitch Subchannel Area Circle Diam. Decrease End~ Change - inche.s Plate Rotary ___________________________ _ _ ______~_~
Angle Exterior Interior Outer Mid Inner Channels Channels Ring Ring Ring _~ .
00 O O o O O
10 +3.3 -2.1 .0133 .0086 .0046 20 -~12.7 -8.1 .0518 .0344 .0178 30 +28.3 -18.0 .1162 .0771 .0399 40 +49 -31.5 .2056 .1365 .0707 _______ _ _ ~ __ _~
End Rod Angle to Flow Porjected Axial RodLen9th Plate Change - inches Rotatory _ _ ~ _ _ ___~
Angle outer Mid Inner Outer Mid Inner _ Ring Ring Ring Ring Ring Ring O O O O O O
10 0.9 0.6 0.3 .0023 .0010 .0003 20 1.8 1.2 0.6 .0091 .0040 .0011 30 2.6 1.7 0.9 .0201 ~ .0089 .0024 40 3.5 2.3 1.2 .0351 .0155 .0041 :
__ ~ ~. __ ~' .
:' '7 ~
C~SE-277 ~ 6 --Referring to Table I, in the case of the 40 rotatory angle between the end plates, there is a projected rod length change, as measured axially between the end plates of the fuel bund:Le, amounting to approximately 35 thousandths of an inch ("thou."), in the case of the radially outer ring of rods, 15 thousandths of an inch in the case of the m:id ring of rods, and the 4 thousand-ths of an inch in the case of the inner ring of rods. These are the lengths by which the rods in the respective rings must be increased for the use of end plates without steps.
In the case where rods of uniform length are used throughout the bundle, both end plates 24 are approximately stepped, to compensate ~or axial projected length differences, the stepped differentials of the annular rings or lands 26, 28 and 30 would be halved to values of 17.5 thou., 7.5 thou., and 2 thou., approximately.
In the other three tabulated cases of a fuel bundle having a lesser angle of skew, the axial distance differentials are correspondingly reduced, to the extend that, for a ten degree skew (Table I) the difference to be made up at each'end would not exceed 1.15 thou., which could be accommodated in the welding of the rod end cap to the plate 24.
Claims (7)
1. In a nuclear reactor having pressurized fuel channels containing liquid coolant and a plurality of fuel bundles arranged in abutting serial relation, each fuel bundle having a plurality of cylindrical rods extending in attached relation between spaced end plates, arranged in at least one ring about the bundle axis the improvement comprising said rods extending in skewed relation between said end plates, to provide a plurality of interconnected coolant flow channels, wherein said coolant flow channels vary in their respective flow sections, progressively along the length of said bundle.
2. The nuclear fuel bundle as claimed in Claim 1 having an outer row of said rods and at least one inner row of said rods the angle inclination of said inner row rods being less than the angle of inclination of said outer row rods.
3. The nuclear fuel bundle as claimed in Claim 1 having flat end plates of constant thickness, each said ring of rods having the length of the respective rods compensated according to the respective angle of skew, such that welded attachment to said end plates is provided at both ends of all said rods.
4. The nuclear fuel bundle as claimed in Claim 1 at least one said end plate having raised annular rings therein to receive said rods in welded relation thereto.
5. The bundle as claimed in Claim 1, Claim 2 or Claim 3, an outer ring of said rods being inclined at a predetermined angle such that said end plates are in effect rotated from each other by an angle in the range 10° to 40°.
Case 2774
Case 2774
6. The bundle as claimed in Claim 1, claim 2 or Claim 3 in combination with a nuclear fuel reactor, said reactor having appropriate coolant circulation pumping capability, in order to promote circulation of said liquid coolant past said bundles.
7. The bundle as claimed in Claim 4 in combination with a nuclear fuel reactor, said reactor having appropriate coolant circulation pumping capability, in order to promote circulation of said liquid coolant past said bundles.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000387727A CA1167176A (en) | 1981-10-09 | 1981-10-09 | Fuel bundle with skewed elements |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000387727A CA1167176A (en) | 1981-10-09 | 1981-10-09 | Fuel bundle with skewed elements |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1167176A true CA1167176A (en) | 1984-05-08 |
Family
ID=4121142
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000387727A Expired CA1167176A (en) | 1981-10-09 | 1981-10-09 | Fuel bundle with skewed elements |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1167176A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2473986C1 (en) * | 2011-09-14 | 2013-01-27 | Государственное образовательное учреждение высшего профессионального образования "Московский энергетический институт (технический университет)" (ГОУВПО "МЭИ(ТУ)") | Technological steam-reheating channel of straight-flow water-water nuclear reactor |
-
1981
- 1981-10-09 CA CA000387727A patent/CA1167176A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2473986C1 (en) * | 2011-09-14 | 2013-01-27 | Государственное образовательное учреждение высшего профессионального образования "Московский энергетический институт (технический университет)" (ГОУВПО "МЭИ(ТУ)") | Technological steam-reheating channel of straight-flow water-water nuclear reactor |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |