WO2005045275A1 - Amortisseur - Google Patents

Amortisseur Download PDF

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Publication number
WO2005045275A1
WO2005045275A1 PCT/IB2004/002942 IB2004002942W WO2005045275A1 WO 2005045275 A1 WO2005045275 A1 WO 2005045275A1 IB 2004002942 W IB2004002942 W IB 2004002942W WO 2005045275 A1 WO2005045275 A1 WO 2005045275A1
Authority
WO
WIPO (PCT)
Prior art keywords
shock absorber
damping
transverse cross
section
hole
Prior art date
Application number
PCT/IB2004/002942
Other languages
English (en)
Inventor
Daniel Heyns
Jurie Johannes Van Wyk
Original Assignee
Pebble Bed Modular Reactor (Proprietary) Limited
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 Pebble Bed Modular Reactor (Proprietary) Limited filed Critical Pebble Bed Modular Reactor (Proprietary) Limited
Publication of WO2005045275A1 publication Critical patent/WO2005045275A1/fr

Links

Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16FSPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
    • F16F7/00Vibration-dampers; Shock-absorbers
    • F16F7/12Vibration-dampers; Shock-absorbers using plastic deformation of members
    • F16F7/125Units with a telescopic-like action as one member moves into, or out of a second member
    • GPHYSICS
    • G21NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21CNUCLEAR REACTORS
    • G21C7/00Control of nuclear reaction
    • G21C7/06Control of nuclear reaction by application of neutron-absorbing material, i.e. material with absorption cross-section very much in excess of reflection cross-section
    • G21C7/08Control of nuclear reaction by application of neutron-absorbing material, i.e. material with absorption cross-section very much in excess of reflection cross-section by displacement of solid control elements, e.g. control rods
    • G21C7/20Disposition of shock-absorbing devices ; Braking arrangements
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E30/00Energy generation of nuclear origin
    • Y02E30/30Nuclear fission reactors

Definitions

  • THIS INVENTION relates to a shock absorber.
  • the invention also extends to a nuclear reactor.
  • a shock absorber which includes at least one damping element having a hole therein; and a penetration element which is displaceable through the at least one damping element to deform the at least one damping element plastically in an energy absorbing manner when the penetration element is subjected to a load in excess of a predetermined load.
  • the penetration element may be elongate and may have, for at least a part of its length, a larger transverse cross-section than the hole in the at least one damping element such that the material of the damping element is caused to deform plastically when the penetration element is displaced through the hole.
  • the penetration element may have a leading end portion of reduced transverse cross-section relative to the hole of the at least one damping element such that the leading end portion may be receivable through the hole without deforming the damping element. ' This arrangement facilitates insertion of the leading end of the penetration element into the hole and compensates for small misalignments between the penetration element and the damping element.
  • the shock absorber may include a plurality of spaced apart damping elements arranged in series such that the holes are in register.
  • the shock absorber may include an elongate hollow housing in which the damping elements are located at longitudinally spaced apart positions. Spacer elements may be positioned between adjacent damping elements.
  • the shock absorber may include a guide for retaining the penetration element in register with the damping elements, which guide is typically positioned at one end of the housing.
  • the thickness of each of the damping elements and the transverse cross-section of each of the holes may be the same for all of the damping elements.
  • the hole in the or each damping element may have a diameter of between 15 mm and 30 mm. Preferably, each hole has a diameter of 20 mm.
  • the or each damping element may have a thickness of between 2 mm and 6 mm.
  • At least one of the thickness of the damping elements and/or the transverse cross-section of the holes may vary for at least some of the damping elements.
  • the hole in the or each damping element may have a diameter of between 15 mm and 30 mm.
  • the thickness of one or more of the damping elements may increase in a direction of displacement of the penetration element. The inventor believes that this arrangement will enable the shock absorber to operate at a range of temperatures. More particularly, at lower temperatures, the thinner damping elements, which are the elements with which the penetration element comes into contact first, will absorb the energy on impact. At higher temperature, where the damping elements are more readily deformable, both the thinner and thicker damping elements will absorb the energy.
  • the or each damping element may have a thickness of between 2 mm and 6 mm.
  • the uppermost damping element i.e. that element closest to the penetration element, has a thickness of 3 mm and the lowermost damping element, i.e. the element furthest from the penetration element, has a thickness of 6 mm.
  • the penetration element may have, for at least a part of its length, a transverse cross-section which is between 1.3 times and 4 times the transverse cross-section of the hole in the or each damping element.
  • the penetration element may have a maximum transverse cross- section of between 40 mm and 60 mm. Preferably the penetration element has a transverse cross-section of 50 mm.
  • the or each damping element may be in the form of a disc having a centrally disposed hole therethrough. Each spacer element may be tubular and a disc may be secured to an end thereof.
  • control rods of a neutron absorbing material are used to control the rate of fission reaction.
  • the control rods are displaceable within vertical bores in a side reflector.
  • Each control rod is connected to a control rod drive mechanism via a chain. If the chain fails, the control rod will fall under the influence of gravity within its associated bore in the side reflector and will impact on the base of the bore. This could lead to damage of the side reflector which, naturally, is undesirable.
  • a nuclear reactor which includes a graphite side reflector within which a plurality of circumferentially spaced bores is provided, and a plurality of control rods displaceable upwardly and downwardly within the bores between extended and retracted positions, which nuclear reactor includes; at least one shock absorber of the type described above associated with each of the control rods.
  • the shock absorber which is associated with each control rod may be located at the base of each bore.
  • a crash plate may be provided at the base of each bore on which the associated shock absorber is located and through which loads from the shock absorber are transmitted to the graphite reflector.
  • the crash plate and a lower end of the shock absorber may be provided with complementary locating formations whereby the shock absorber is beatable on the crash plate.
  • the shock absorber and associated crash plate may be loose such that the shock absorber is capable of independent removal from the bore, and the crash plate remains in position and serves to locate a replacement shock absorber inserted into the bore.
  • Figure 1 shows schematically part of a nuclear reactor in accordance with the invention
  • Figure 2 shows a three-dimensional partially exploded view of a shock absorber in accordance with the invention
  • Figure 3 shows a longitudinal sectional view of part of the shock absorber of Figure 2
  • Figure 4 shows a sectional elevation of a penetration element of the shock absorber of Figure 2
  • Figure 5 shows a graph of the damping characteristics of two shock absorbers in accordance with the invention as well as a prior art shock absorber of which the Inventor is aware.
  • reference numeral 10 refers generally to a shock absorber in accordance with the invention.
  • the shock absorber 10 includes housing, generally indicated by reference numeral 12.
  • the housing 12 includes a base 14 and an upwardly open circular cylindrical side wall 16 which extends operatively upwardly from the base 14.
  • the shock absorber 10 further includes a plurality of circular damping elements or plates 18 each of which has a centrally disposed hole 20 therethrough.
  • Each plate 18 is connected, e.g. by welding, to an end of a tubular spacer element 22.
  • the plates 18 are arranged within the housing 12 with a spacer element 22 positioned between each adjacent pair of plates 18.
  • the spacer elements 22 hence support the plates 18 in a desired spacial arrangement with the holes 20 in register.
  • the shock absorber 10 further includes a penetration element 24 and a guide 26.
  • the guide 26 is positioned in an upper end portion of the housing 12.
  • the guide 26 has a passage 28 extending axially therethrough, the passage 28 having, intermediate its ends, a neck portion, generally indicated by reference numeral 30.
  • the penetration element 24 has a leading end 32 and a trailing end 34.
  • a leading end portion, generally indicated by reference numeral 36, of the penetration element 24 is tapered such that the leading end 32 has a diameter which is smaller than that of the holes 20.
  • a cooling passage 37 extends longitudinally through the penetration element 24. Due to its proximity to the core, in use, the penetration element 24 is subject to neutronic heating. The provision of the passage 37 permits cooling gas to flow through the penetration element 24 .
  • each of the plates 18 has a thickness T of 3 mm.
  • Each hole 20 has a diameter D of approximately 20 mm.
  • the penetration element 24 has a diameter P of approximately 50 mm.
  • the various dimensions of the shock absorber 10 can vary depending upon the intended application.
  • the plates 18 further from the base 14 may have a thickness which is less than that of the plates closer to the base.
  • the shock absorber 10 will be subjected to a range of temperatures.
  • the plates 18 will deform more readily. Accordingly, the thinner plates with which the penetration element will come into contact first, will be suitable for use in absorbing load at low temperatures. In higher temperature applications, the penetration element will also come into contact with the thicker plates closer to the base plate 14.
  • the reactor 40 which is a high temperature gas cooled reactor which includes a pressure vessel 42 within which a core barrel 44 is contained. Contained within the core barrel are graphite reflectors within which the nuclear fuel is contained. A plurality of circumferentially spaced upwardly open bores 46 (one of which is shown in Figure 1 of the drawings) is provided in a side reflector.
  • the reactor 40 further includes a control rod assembly 48 associated with each of the bores 46.
  • a control rod drive mechanism 50 is mounted on the reactor pressure vessel 42 and connected to the associated core rod assembly by a chain 52.
  • a control rod guide tube 54 extends between the reactor pressure vessel 42 and the core barrel 44 to guide the control rod assembly 48 when in its raised position.
  • the control rods are used to control the neutronic power generated by the reactor by being raised and lowered in the bores 46 in the graphite side reflector by winding in and out of the chains 52. If, however, a chain 52 was to fail, the control rod assembly 48 would fall into the bore 46 within the graphite reflector and impact on the base of the bore thereby possibly damaging the graphite reflector.
  • a crash plate 56 ( Figure 2) is positioned at the base of the bore 46 and a shock absorber 10 is positioned on the crash plate 56.
  • the control rod assembly 48 will fall downwardly, under the influence of gravity into contact with the penetration element 24 of the shock absorber 10.
  • the penetration element 24 may be connected to the control rod assembly 48.
  • the weight of the falling control rod assembly 48 will drive the penetration element 24 downwardly, into contact with the uppermost plate 18.
  • the load of the falling control rod assembly 48 will cause the penetration element 24 to be driven through the plate 18 thereby deforming the plate plastically. This plastic deformation of the plate, naturally, serves to absorb energy.
  • the penetration element 24 will be driven downardly and deform plate after plate until the kinetic energy of the falling control rod assembly has been absorbed.
  • shock absorber 10 and crash plate 56 are separate so that the crash plate remains in the bore and serves as a guide to locate a replacement shock absorber in position. It also serves to transmit loads from the shock absorber housing 12 to the side reflector.
  • a tapered locating formation 58 protrudes upwardly from the crash plate 56 and cooperates with a complementary downwardly open recess (not shown) in the base 14.
  • the plot shown in solid lines marked B shows the load applied by a shock absorber 10 in accordance with the invention making use of plates 18 which were substantially identical.
  • the plot shown in chain-dotted lines marked C shows the use of a shock absorber 10 in accordance with the invention in which the thicknesses of the plates were varied.
  • the horizontal line indicates the maximum allowable force. From the graph it is readily apparent that the maximum force transmitted to the reflector is substantially reduced making use of a shock absorber in accordance with the invention.
  • the optimum arrangement for a particular application can be tailored by changing the thicknesses of the plate, the diameters of the holes 20 and/or the material properties of the plates.
  • the shock absorber in accordance with the invention will be capable of operating at a range of temperatures e.g. from 25°C to 1100°C. Naturally, however, the range of temperatures will depend on the materials used. Further, the Inventor believes that the shock absorber will provide consistent and repeatable impact properties.

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Plasma & Fusion (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Mechanical Engineering (AREA)
  • Vibration Dampers (AREA)

Abstract

Cet amortisseur (10) comporte une pluralité d'éléments d'amortissement circulaires ou disques (18) dont chacun est percé d'un trou (20) disposé centralement. Ces disques (18) sont agencés à l'intérieur d'un logement (12), un élément d'espacement (22) étant positionné entre chaque paire de disques (18) adjacents. Ces éléments d'espacement (22) soutiennent donc les disques (18) dans un agencement spatial souhaité, les trous (20) étant alignés. L'amortisseur (10) comprend également un élément de pénétration (24) et un guide (26). En service, cet élément de pénétration (24) s'enfonce successivement dans chaque disque qu'il déforme plastiquement jusqu'à absorption complète de l'énergie cinétique lui ayant été transmise.
PCT/IB2004/002942 2003-11-11 2004-09-10 Amortisseur WO2005045275A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ZA200308773 2003-11-11
ZA2003/8773 2003-11-11

Publications (1)

Publication Number Publication Date
WO2005045275A1 true WO2005045275A1 (fr) 2005-05-19

Family

ID=34574973

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB2004/002942 WO2005045275A1 (fr) 2003-11-11 2004-09-10 Amortisseur

Country Status (1)

Country Link
WO (1) WO2005045275A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114454788A (zh) * 2017-12-14 2022-05-10 宝钜儿童用品香港股份有限公司 缓冲结构及儿童安全座椅

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1286933A (fr) * 1961-02-16 1962-03-09 Atomic Energy Authority Uk Dispositifs d'absorption d'énergie
GB978443A (en) * 1961-05-05 1964-12-23 Alsacienne Atom Braking device for falling objects
DE2201952A1 (de) * 1972-01-15 1973-07-26 Hoesch Werke Ag Stossverzehrelement, insbesondere fuer kraftfahrzeuge

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1286933A (fr) * 1961-02-16 1962-03-09 Atomic Energy Authority Uk Dispositifs d'absorption d'énergie
GB978443A (en) * 1961-05-05 1964-12-23 Alsacienne Atom Braking device for falling objects
DE2201952A1 (de) * 1972-01-15 1973-07-26 Hoesch Werke Ag Stossverzehrelement, insbesondere fuer kraftfahrzeuge

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114454788A (zh) * 2017-12-14 2022-05-10 宝钜儿童用品香港股份有限公司 缓冲结构及儿童安全座椅
CN114454788B (zh) * 2017-12-14 2023-12-05 宝钜儿童用品香港股份有限公司 缓冲结构及儿童安全座椅

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