EP1472700A2 - Element combustible pour reacteur a eau bouillante - Google Patents

Element combustible pour reacteur a eau bouillante

Info

Publication number
EP1472700A2
EP1472700A2 EP03704459A EP03704459A EP1472700A2 EP 1472700 A2 EP1472700 A2 EP 1472700A2 EP 03704459 A EP03704459 A EP 03704459A EP 03704459 A EP03704459 A EP 03704459A EP 1472700 A2 EP1472700 A2 EP 1472700A2
Authority
EP
European Patent Office
Prior art keywords
fuel
spacers
fuel element
spacer
fuel rods
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.)
Withdrawn
Application number
EP03704459A
Other languages
German (de)
English (en)
Inventor
Dieter Kreuter
Peter Rau
Reinhart Zimmermann
Dieter Bender
Walter Uebelhack
Werner Meier
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.)
Areva GmbH
Original Assignee
Framatome ANP GmbH
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 Framatome ANP GmbH filed Critical Framatome ANP GmbH
Publication of EP1472700A2 publication Critical patent/EP1472700A2/fr
Withdrawn legal-status Critical Current

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
    • G21C3/326—Bundles of parallel pin-, rod-, or tube-shaped fuel elements comprising fuel elements of different composition; comprising, in addition to the fuel elements, other pin-, rod-, or tube-shaped elements, e.g. control rods, grid support rods, fertile rods, poison rods or dummy rods
    • G21C3/328—Relative disposition of the elements in the bundle lattice
    • 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
    • G21C1/00—Reactor types
    • G21C1/04—Thermal reactors ; Epithermal reactors
    • G21C1/06—Heterogeneous reactors, i.e. in which fuel and moderator are separated
    • G21C1/08—Heterogeneous reactors, i.e. in which fuel and moderator are separated moderator being highly pressurised, e.g. boiling water reactor, integral super-heat reactor, pressurised water reactor
    • G21C1/084—Boiling water reactors
    • 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
    • G21C3/3432—Grids designed to influence the coolant, i.e. coolant mixing function
    • 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 invention relates to a fuel assembly for a boiling water reactor containing a number of part-length fuel rods.
  • a fuel assembly which also has part-length fuel rods to reduce the pressure drop in the two-phase area.
  • a fuel element known from WO 99/17299 provides for spacers to be arranged in the lower region of the fuel element at a distance from one another which is smaller than the spacing of the spacers in the upper region.
  • the boiling transfer power is the power at which the water film on the fuel rod evaporates, which leads to significantly poorer heat transfer (dry out). If the boiling transfer power is exceeded, a vapor film or a vapor layer is formed on the surface of fuel rods contained in the fuel element, which represents a heat transfer resistance. Since the amount of heat generated in the fuel rod is then temporarily no longer completely dissipated, the temperature of the fuel rod rises until a new thermal equilibrium is established. This can lead to overheating of the fuel rod and thus to thermal overload of a fuel rod cladding tube. Such overheating must be avoided at all costs because it would shorten the life of the fuel rod and thus the fuel assembly.
  • the invention is based on the object of specifying a fuel assembly for a boiling water reactor which is improved both in terms of its dry-out behavior and in terms of its thermohydraulic properties.
  • a fuel element for a boiling water reactor has these features, in which a plurality of fuel rods are mounted in a plurality of spacers spaced apart from one another in the axial direction of the fuel element, of which at least one fuel rod is partially long, and which is provided with deflection elements arranged at least in the upper region of the fuel element, Means to reduce the pressure loss caused by the baffles in this area.
  • the invention is based on the finding that, contrary to the restoration of a pressure drop in the upper region, which is aimed for in US Pat. No. 5,229,068, it is rather advantageous to keep the pressure drop as low as possible in order to avoid thermohydraulic instabilities.
  • measures are provided to reduce or compensate for the increase in the flow resistance caused by the deflection elements in the upper region by means of suitable fluidic measures.
  • upper area or “lower area” are to be understood in the following in such a way that the fuel element is mentally divided into two partial areas with respect to their axial extension, which adjoin one another.
  • the "upper range” can, but does not have to, coincide with the two-phase range, i.e. the boundary between the upper and the lower range does not necessarily coincide with the two-phase boundary and the "upper range” can be smaller or larger than the two-phase range.
  • this reduction in pressure loss takes place in that at least one of the spacers arranged in the upper region has a reduced pressure loss.
  • This can be achieved by using spacers made of a nickel-based alloy in the upper area of the fuel element, preferably in the area above the part-length rods, the web thickness of which is significantly lower than the web thickness of the spacers made of a zirconium alloy usually used.
  • This construction also means that the axial range of the good moderation is not impaired in its neutron economy by using spacers made of a zirconium alloy.
  • This measure is based on the consideration that the use of spacers made of a nickel-based alloy is not critical in spite of the inherently unfavorable corrosion properties in the upper area of the fuel element, since shadow corrosion, which essentially determines the corrosion behavior, occurs mainly in the lower area of the fuel element.
  • the flow resistance of the deflection elements arranged in the upper region of the fuel element can also be reduced upwards.
  • the uppermost spacer can also be designed without deflection elements.
  • This measure is based on the consideration that the pressure drop in the upper area of the fuel assembly increases exponentially, so that measures to reduce the pressure drop are particularly useful in the uppermost area of the fuel assembly. In other words: it has been found to be particularly advantageous to reduce the flow resistance within the combustion element in the uppermost zone of the upper area more than in the lower zone of the upper area.
  • FIGS. 2, 3 each show a section of a spacer with square or round meshes for receiving fuel rods, as are used in a lower region of the fuel assembly,
  • FIG. 4 shows a spacer in a lower section of the upper region of the fuel assembly
  • FIG. 5 shows a spacer which is arranged above the spacer shown in FIG. 4
  • FIGS. 6 to 8 each show alternative configurations of a spacer in the upper region of the fuel assembly.
  • a fuel assembly contains a plurality (a bundle) of fuel rods 1 to 3 which, in the operating state, extend vertically between a lower rod holding plate 4 and an upper rod holding plate 6.
  • the fuel rods 1 to 3 are arranged parallel to one another and clamped in spacers 11 to 18.
  • the fuel rods 1 and 2 are designed as part-long fuel rods and are shortened compared to the fuel rods 3, which extend over the entire length of the fuel element. The figure shows that the part-length fuel rods 1 are shorter than the part-length fuel rods 2. While the fuel rods 3 of normal length are not or only loosely Stand up on the lower rod holding plate 4, the part-long fuel rods 1, 2 are firmly anchored with their lower end in the rod holding plate 4.
  • a fuel element box 20 open at the top and bottom surrounds the bundle of fuel rods 1 to 3 and forms a closed channel for a liquid coolant entering through the lower rod holding plate 4.
  • the coolant - preferably water - is heated on its way through the fuel assembly 20 by the fuel rods 1 to 3 and begins to evaporate, so that a mixture of liquid and vaporous coolant is present in the upper region of the fuel assembly.
  • part-long fuel rods 1, 2 increases the clear channel cross section in the upper area of the fuel element than in the lower area, so that the higher flow velocity occurring in the two-phase area is counteracted.
  • the spacers 11 to 18 are divided into a lower group A (11 to 14) and an upper group B (15 to 18), the spacings of the spacers being equal to one another, at least in group A.
  • group B the spacing of the spacers 15 to 18 can also be smaller.
  • the increase in pressure loss caused by a reduction in the spacing of the spacers 15 to 18 can be compensated for by a larger number of part-length fuel rods 1, 2.
  • the boundary between the lower group A and the upper group B may, but does not have to correspond to the two-phase boundary or the end of the shortest part-long fuel rods 1. 2 shows, on a greatly enlarged scale, one of the spacers in group A (11 to 14) or the lowest of the upper spacers 16 in group B.
  • the spacer is made up of webs 40 which intersect at right angles and penetrate one another.
  • the webs 40 form approximately square meshes 42 for receiving the fuel rods 1 to 3, which are firmly clamped in the meshes 42 by knobs 44 and springs 46.
  • Deflection elements 48 are arranged on the webs 40 of the spacer and, in the exemplary embodiment of the figure, are swirl vanes which are bent laterally.
  • the swirl vanes are arranged at the intersection points such that coolant flowing in the axial direction (parallel to the fuel rods) is deflected between the fuel rods by the spacers and a speed component directed perpendicularly to the axial direction, a swirl pulse in the specifically illustrated embodiment D receives.
  • the rotary movement caused by the swirl vanes generates a centrifugal acceleration which throws the liquid phase of the coolant against the fuel rods 1 to 3, increases their cooling and accordingly reduces the risk of film breakage.
  • a spacer according to FIG. 3 acts in the same way, in which the dimensions provided for receiving the fuel rods 1 to 3 are formed by hollow cylindrical sleeves 50, which also have swirl vanes bent to the side as deflection elements 48 and impose a swirl pulse on the coolant flowing past.
  • FIG. 4 shows a spacer from group B, which is arranged above the spacer according to FIG. 2. It can be seen from the figure that part of the crossing points (indicated by hatching in the figure) are free of deflection elements 48 is. In the example of the figure, provision is now made to design one of 4 intersection points without deflection elements. Suitable crossing points are above all the crossing points in the corner points of such meshes, which lie above the free end of part-length fuel rods.
  • FIG. 5 shows a spacer which is arranged above the spacer according to FIG. 4 and in which every second crossing point is free of deflection elements 48.
  • the number of deflection elements is correspondingly reduced up to the uppermost spacer 18, which in principle can also be free of deflection elements.
  • FIGS. 6 and 7 Further alternative configurations are shown in FIGS. 6 and 7, in which the number of deflecting elements per crossing point is reduced (missing deflecting elements, highlighted by hatching, FIG. 6) or in which webs 40a (FIG. 7) are used which have no bent swirl flags.
  • the swirl vanes which would produce a cross-flow of the coolant directed into the interior of a mesh, which is not penetrated by a fuel rod, that is to say is located above the end of a part-length rod, are above all eliminated.
  • a mesh 43 is completely free of deflection elements pointing into its interior.
  • Such deflector-free meshes 43 preferably form empty positions, i.e. are located above the end of part-length fuel rods 1, 2 in the mesh positions assumed by them.
  • part of the deflection elements 48 in the embodiment Example, the swirl tabs 48b formed on the web 40b either have to be shaped shorter or bent less so that their flow deflecting effect and thus also their flow resistance is reduced.
  • the sum of the projection surfaces of all deflection elements 48, 48b of an upper spacer is smaller than the sum of the projection surfaces of all deflection elements 48, 48b of an upper spacer arranged underneath.
  • At least the uppermost or the upper spacers of the upper group B are made up of webs which consist of a nickel-based alloy, in particular Inconel. With the same mechanical stability, this allows a reduction in the. Wall thickness of the webs and thus causes a reduction in the pressure loss occurring at the spacers.
  • it can also be provided in the upper group that two adjacent spacers are constructed identically, but the flow resistance of the top spacer is always smaller than the flow resistance of the bottom of the top spacer in order to counteract the increase in pressure drop.

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)
  • Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
  • Feeding And Controlling Fuel (AREA)

Abstract

L'invention concerne un élément combustible destiné à un réacteur à eau bouillante. Cet élément comprend plusieurs crayons combustibles (1 à 3) disposés entre plusieurs séparateurs (11 à 18) placés à distance les uns des autres dans le sens axial de l'élément combustible, au moins un de ces crayons combustibles (1, 2) présentant une longueur réduite. Des éléments de déviation (48) sont disposés au moins dans la partie supérieure (B) de l'élément combustible pour améliorer les caractéristiques d'assèchement. Selon l'invention, cet élément combustible comprend en outre des moyens permettant de réduire la perte de pression occasionnée dans cette partie supérieure (B) par les éléments de déviation (48) en vue d'améliorer la stabilité thermohydraulique et les caractéristiques d'arrêt.
EP03704459A 2002-02-08 2003-01-24 Element combustible pour reacteur a eau bouillante Withdrawn EP1472700A2 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE10205202A DE10205202A1 (de) 2002-02-08 2002-02-08 Brennelement für einen Siedewasserreaktor
DE10205202 2002-02-08
PCT/EP2003/000708 WO2003067606A2 (fr) 2002-02-08 2003-01-24 Element combustible pour reacteur a eau bouillante

Publications (1)

Publication Number Publication Date
EP1472700A2 true EP1472700A2 (fr) 2004-11-03

Family

ID=27634806

Family Applications (1)

Application Number Title Priority Date Filing Date
EP03704459A Withdrawn EP1472700A2 (fr) 2002-02-08 2003-01-24 Element combustible pour reacteur a eau bouillante

Country Status (5)

Country Link
EP (1) EP1472700A2 (fr)
JP (1) JP2005525542A (fr)
DE (1) DE10205202A1 (fr)
TW (1) TW574711B (fr)
WO (1) WO2003067606A2 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102004014499B3 (de) * 2004-03-25 2005-09-01 Framatome Anp Gmbh Brennelement für einen Druckwasserkernreaktor
DE102004059195B3 (de) 2004-12-09 2006-02-23 Framatome Anp Gmbh Brennelement für einen Siedewasserreaktor

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4357298A (en) * 1980-10-10 1982-11-02 General Electric Company Nuclear fuel assembly space arrangement
US4418036A (en) * 1980-12-16 1983-11-29 Westinghouse Electric Corp. Fuel assembly for a nuclear reactor
US4744942A (en) * 1986-06-11 1988-05-17 Westinghouse Electric Corp. Nuclear reactor spacer grid loading
US5112570A (en) * 1988-04-04 1992-05-12 Hewlett-Packard Company Two-phase pressure drop reduction bwr assembly design
US5229068A (en) * 1991-05-17 1993-07-20 General Electric Company Optimized critical power in a fuel bundle with part length rods
US5371768A (en) * 1992-12-14 1994-12-06 General Electric Company Swirl type spacer for boiling water reactor fuel
SE505739C2 (sv) * 1996-01-25 1997-10-06 Asea Atom Ab Bränslepatron för kokarvattenreaktor
SE510656C2 (sv) * 1997-10-01 1999-06-14 Asea Brown Boveri Bränslepatron för kärnreaktor
JP3906009B2 (ja) * 2000-02-28 2007-04-18 原子燃料工業株式会社 過渡事象でのドライアウト性能を改善した沸騰水型原子炉用燃料集合体

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO03067606A2 *

Also Published As

Publication number Publication date
TW574711B (en) 2004-02-01
WO2003067606A3 (fr) 2004-04-01
TW200305171A (en) 2003-10-16
WO2003067606A2 (fr) 2003-08-14
JP2005525542A (ja) 2005-08-25
DE10205202A1 (de) 2003-08-28

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