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WO1994020962A1 - Grille d'espcacement melangeuse en zircaloy destinee a des applications dans des reacteurs a eau sous pression et des reacteurs a eau bouillante - Google Patents

Grille d'espcacement melangeuse en zircaloy destinee a des applications dans des reacteurs a eau sous pression et des reacteurs a eau bouillante Download PDF

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Publication number
WO1994020962A1
WO1994020962A1 PCT/US1993/008680 US9308680W WO9420962A1 WO 1994020962 A1 WO1994020962 A1 WO 1994020962A1 US 9308680 W US9308680 W US 9308680W WO 9420962 A1 WO9420962 A1 WO 9420962A1
Authority
WO
WIPO (PCT)
Prior art keywords
flow
strips
another
spacer grid
members
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.)
Ceased
Application number
PCT/US1993/008680
Other languages
English (en)
Inventor
Richard P. Broders
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Combustion Engineering Inc
Original Assignee
Combustion Engineering Inc
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Combustion Engineering Inc filed Critical Combustion Engineering Inc
Priority to AU49216/93A priority Critical patent/AU4921693A/en
Publication of WO1994020962A1 publication Critical patent/WO1994020962A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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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
    • G21C3/322—Means to influence the coolant flow through or around the bundles
    • 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
    • G21C3/34—Spacer grids
    • G21C3/352—Spacer grids formed of assembled intersecting strips
    • 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

Definitions

  • the present invention relates generally to a nuclear reactor and more specifically to an improved spacer grid which increases the coolant flow mixing within the nuclear reactor fuel assembly.
  • Nuclear fuel assemblies are customarily of the rod type where the fuel rods are held in a square array by a spacer grid assembly.
  • the spacer grid assemblies are typically made from relatively thin elongate strips arranged in an "egg crate" manner with the strips positioned at right angles to one another. Soft (springs) and hard (arches) support features are stamped into the strip and are used to position the fuel rods.
  • the grids are often equipped with vanes or other devices to enhance the Critical Heat Flux (CHF) and general heat transfer performance of the fuel. Since the projection of the grid into the flow stream causes pressure losses, spacer grid design optimization requires that the necessary structural support and CHF performance be provided with minimum pressure losses.
  • any CHF enhancement devices e.g. vanes
  • any CHF enhancement devices e.g. vanes
  • This spacer grid utilizes split vanes to improve CHF performance by mixing coolant between adjacent channels. and swirling the flow within sub-channels and around the rod.
  • the split vanes are optimized with respect to size, shape, and bend angle to enhance CHF performance and the top weld nugget is recessed with no cut-out in the vane so the turbulent wake produced by the nugget has less impact on vane performance.
  • This grid has been thoroughly tested to assess the mechanical, hydraulic and CHF performance. Results of these tests have shown that this type of split vane grid produces high CHF performance in the PWR operating space and that requirements of grid pressure drop, load-carrying strength, and handling performance are satisfied.
  • a spacer grid which supports nuclear reactor fuel rods includes an intersecting pattern of strips combined with cylindrical members which are slotted and fit onto the strips in a manner which encircles the intersections defined between the strips.
  • the tops of the cylindrical members can be shaped or formed with vanes to induce swirl within the flow channels defined between the fuel rods or deflect part of the flow in one channel into an adjacent one.
  • a first important aspect of the present invention resides in a spacer grid which features: a plurality of spaced first strips which are arranged essentially parallel to one another; a plurality of space second strips which are arranged essentially parallel to one another and which intersect the first strips at a predetermined angle to form a plurality of intersections; and a plurality of cylindrical members which are slotted and which fit onto the first and second strips so that each cylindrical member encloses an intersection therein.
  • An important feature of the above mentioned structure comes in that the top portion of at least one of the cylindrical members extends above the upper edges of the first and second strips and is provided with flow deflecting means which alters the direction of a flow of fluid which passes therepast.
  • a second important aspect of the invention resides in a spacer grid for supporting a plurality fuel rods in a nuclear reactor, which features: plurality of spaced first strips which are arranged essentially parallel to one another; a plurality of spaced second strips which are arranged essentially parallel to one another and which intersect the first strips at a predetermined angle to form a plurality of intersections; a plurality of cylindrical members which are slotted and which fit onto the first and second strips so that each cylindrical member encloses an intersection therein, the plurality of fuel rods being disposed between the plurality of cylindrical members so as to establish an essentially parallel relationship with one another and with the cylindrical members, the fuel rods defining a plurality of flow channels therebetween; and means defined at the upper portions of the plurality of cylindrical members for deflecting a flow of fluid passing between the fuel rods in a manner which induces a swirl in the flow within the flow channels and/or cause a portion of a flow in one flow channel to be deflected into an adjacent flow channel.
  • a further important aspect of the present invention resides in a structure for supporting a plurality of rods in a liquid which is characterized by first cross members which are arranged essentially parallel to one another; second cross members which are arranged essentially parallel to one another and which intersect the first cross members at a predetermined angle to form a grid; a plurality of tubular members which are slotted and which fit onto the first and second cross members so that each cylindrical member encloses a junction at which a first cross member and a second cross member intersect, the plurality of rods being disposed in the grid between the plurality of cylindrical members so as to establish an essentially parallel relationship with one another and with the cylindrical members; a plurality of flow channels defined between the plurality of rods; and means defined at the upper portions of the plurality of tubular members for deflecting a flow of fluid passing between the rods in a manner which induces a swirl in the flow within the flow channels and/or cause a portion of a flow in one flow channel to be deflected into an adjacent flow channel.
  • the design of the spacer grid offers advantages over existing designs because of its effective flow redistribution technique which minimizes pressure drop losses while maintaining component strength and compatibility with fuel assembly reconstitution. Since the flow redistribution technique should continue to work well at high coolant qualities, the spacer grid design is applicable to BWR applications as well as PWR applications.
  • Fig. 1 is a plan view showing a first embodiment of the invention
  • Figs. 2 and 3 show second and third embodiments of the invention, respectively; and Fig. 4 is a schematic drawing depicting axial velocity characteristics obtained with the second embodiment of the invention.
  • Fig. 1 shows a basic embodiments of the invention.
  • a distinctive feature of the basic spacer grid design is that, in addition to the thin strips that form the "egg crate", there is a thin-walled tube at each strip intersection that fits within the channel formed by four fuel rods. The tube is slotted on the bottom to fit over the straight strips and then is welded thereto.
  • the tops of the tubes which extends above the straight strips and can be shaped to redistribute the coolant flow in a variety of ways.
  • Figure 2 shows a second embodiment wherein the tops are flared in a manner which forms a "figure eight" type of configuration. This causes swirl around the fuel rods by moving flow from one channel to another.
  • Fig. 3 shows another configuration which causes swirl within the coolant flow channel itself. It will be understood that the present invention is not limited to the illustrated arrangement and that a different number of lobes or vanes can be used, as well as asymmetric lobe or vane geometries, without departing from the spirit of the invention.
  • the spacer grid is designed to enhance the CHF performance of the fuel without significantly increasing the pressure drop of the fuel assembly. This is done by using the overall pressure drop of the spacer grid to accomplish the flow mixing by channeling the flow captured within the tube into the desired patterns of swirl or redistribution. In this way the performance at high qualities can be expected and maintained. In addition, the channeled flow can be mixed more efficiently with shallower deflection angles, thus minimizing the pressure drop associated with a given increase in CHF performance.
  • the design lends itself to be used for the main structural spacer grid that supports the fuel rods, or as an intermediate (non-structural) grid positioned between the structural grids.
  • Any rod support features (arches and springs) can be formed in the slotted portion of the tubes. Since the outer diameter of the tubes are in close proximity to the fuel rod cladding, the projection of these support features into the coolant flow is minimal, thus minimizing any pressure drop increase associated with the features.
  • the spring supports are axially oriented. In addition to minimizing the grid's pressure drop by not having any leading edges, the axial spring can stay in closer proximity to the fuel rod cladding during operation due to differential growth between the spring and the tube.
  • the welding of the slotted tubes to the interlocking strips significantly reduces the column lengths of the spacer grid when loaded laterally.
  • the reduced lengths can be expected to significantly increase the buckling capability of the spacer grid.
  • the strips have no cutouts for springs and arches since they are formed into tubes. Therefore, the height and thickness of the strips can be reduced by while maintaining the required grid strength. Both of these height and thickness features help decrease the pressure drop of the spacer grid.
  • the spacer grid design is completely compatible with fuel assembly reconstitution from the top of the bundle.
  • the feature of the tubes that mix the flow are either no susceptible to damage from axial loads imposed by the fuel rod being reinserted (design shown in Fig. 2) or, if damaged would deflect away from the rod into a harmless position toward the center of tube (Design shown in Fig.
  • Fig. 2 which features flaring at the top of the tubes was fabricated, assembled and tested in a cold water flow loop.
  • Laser doppler velocimeter (LDV) measurements were taken.
  • the test setup was able to measure axial velocities and lateral velocities at right angles to the laser path.
  • the mixing between sub-channels for this grid design is done in the lateral plane and could not be measured using the LDV tests.
  • an evaluation of the axial velocity data as depicted in Fig. 4, verified that the separation angle of the high velocity lobes correspond to the sloped angle of the flared tube. This suggests that the flared tube design of the second embodiment was such as to redistribute the flow in the sub-channels.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)

Abstract

Un grille d'espacement qui supporte les barres de combustible dans les réacteurs nucléaires comprend une configuration composite de bandes combinées avec des éléments cylindriques qui portent des fentes et s'adaptent aux bandes de manière à entourer les intersections entre les bandes. Le haut des éléments cylindriques peut être formé ou pourvu d'ailettes pour provoquer un tourbillonnement dans les canaux d'écoulement délimités par les barres de combustible ou pour dévier une partie de l'écoulement d'un canal vers un canal adjacent.
PCT/US1993/008680 1993-03-08 1993-09-15 Grille d'espcacement melangeuse en zircaloy destinee a des applications dans des reacteurs a eau sous pression et des reacteurs a eau bouillante Ceased WO1994020962A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU49216/93A AU4921693A (en) 1993-03-08 1993-09-15 Mixing spacer grid for pwr and bwr applications

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US2775693A 1993-03-08 1993-03-08
US08/027,756 1993-03-08

Publications (1)

Publication Number Publication Date
WO1994020962A1 true WO1994020962A1 (fr) 1994-09-15

Family

ID=21839601

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1993/008680 Ceased WO1994020962A1 (fr) 1993-03-08 1993-09-15 Grille d'espcacement melangeuse en zircaloy destinee a des applications dans des reacteurs a eau sous pression et des reacteurs a eau bouillante

Country Status (2)

Country Link
AU (1) AU4921693A (fr)
WO (1) WO1994020962A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996019811A1 (fr) * 1994-12-21 1996-06-27 Abb Atom Ab Assemblage combustible et ecarteur pour reacteur nucleaire
CN109935365A (zh) * 2017-12-19 2019-06-25 中国原子能科学研究院 一种带圆管型栅元燃料组件定位格架

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2072154A1 (fr) * 1969-12-31 1971-09-24 Combustion Eng
FR2449324A1 (fr) * 1979-02-14 1980-09-12 Kraftwerk Union Ag Piece d'espacement pour elements combustibles de reacteurs nucleaires
GB2076102A (en) * 1980-05-10 1981-11-25 Rolls Royce Connecting strips to form a grid
US4725403A (en) * 1986-11-14 1988-02-16 Combustion Engineering, Inc. Box-type flow deflector for nuclear fuel grid
JPS6439592A (en) * 1987-08-06 1989-02-09 Mitsubishi Nuclear Fuel Supporting grid for nuclear fuel assembly
EP0456055A1 (fr) * 1990-05-11 1991-11-13 General Electric Company Dispositif d'espacement croisé modifié et sa construction

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2072154A1 (fr) * 1969-12-31 1971-09-24 Combustion Eng
FR2449324A1 (fr) * 1979-02-14 1980-09-12 Kraftwerk Union Ag Piece d'espacement pour elements combustibles de reacteurs nucleaires
GB2076102A (en) * 1980-05-10 1981-11-25 Rolls Royce Connecting strips to form a grid
US4725403A (en) * 1986-11-14 1988-02-16 Combustion Engineering, Inc. Box-type flow deflector for nuclear fuel grid
JPS6439592A (en) * 1987-08-06 1989-02-09 Mitsubishi Nuclear Fuel Supporting grid for nuclear fuel assembly
EP0456055A1 (fr) * 1990-05-11 1991-11-13 General Electric Company Dispositif d'espacement croisé modifié et sa construction

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 13, no. 231 (P - 878)<3579> 29 May 1989 (1989-05-29) *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996019811A1 (fr) * 1994-12-21 1996-06-27 Abb Atom Ab Assemblage combustible et ecarteur pour reacteur nucleaire
US5862196A (en) * 1994-12-21 1999-01-19 Abb Atom Ab Fuel assembly and spacer for a nuclear reactor
CN109935365A (zh) * 2017-12-19 2019-06-25 中国原子能科学研究院 一种带圆管型栅元燃料组件定位格架

Also Published As

Publication number Publication date
AU4921693A (en) 1994-09-26

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