US3085965A - Supports for combustible elements in atomic piles or reactors having vertical channels - Google Patents

Supports for combustible elements in atomic piles or reactors having vertical channels Download PDF

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Publication number
US3085965A
US3085965A US43259A US4325959A US3085965A US 3085965 A US3085965 A US 3085965A US 43259 A US43259 A US 43259A US 4325959 A US4325959 A US 4325959A US 3085965 A US3085965 A US 3085965A
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US
United States
Prior art keywords
shell
bars
supports
reactors
vertical channels
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 - Lifetime
Application number
US43259A
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English (en)
Inventor
Aubert Michel
Roche Roland
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.)
Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
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Commissariat a lEnergie Atomique CEA
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    • 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
    • G21C3/38—Fuel units consisting of a single fuel element in a supporting sleeve or in another supporting element
    • 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 to an improved support for combustible elements, i.e. fuel elements in atomic piles or reactors having vertical channels.
  • the fuel elements In a number of types of atomic piles or reactors, the fuel elements have the form of cylindrical bars, of revolution or not, housed one above the other in vertical channels formed in the moderator pile.
  • the bars will rest one upon the other and the bar which is placed in the lower part of a channel is thus subjected to a compressive force equal to the weight of all the other bars contained in this channel.
  • the bars or fuel elements are associated with mechanisms which cooperate with housings in the channel walls to provide individual support for the bars.
  • Each bar is provided with a system of latches which latches, when the bar comes into contact with the bar immediately therebeneath, move apart and engage the housings provided in the channel walls.
  • a reinforcement which is resistant and not very absorbent is introduced inside each fuel element or bar, which reinforcement must be able to withstand the compressive forces exerted by the bars.
  • Such an arrangement gives rise to difiicult problems relating to the manufacture of the bars and relating to the mechanical behaviour of the bars during different thermal cycles (owing to differential contraction), and under radiation (owing to contraction, expansion and other deformations, resulting from neutron irradiation and fissions).
  • Each fuel element or bar is fixed to an external reinforcement which is not very absorbent and is capable of supporting the weight of the upper bars.
  • This reinforcement consists of an element which is arranged longitudinally of the axis of the bar and efiectively supports the upper bars, and of parts for booking the bar on to this element.
  • These parts which are rather complex, generally involve additional absorption, increase the spacing between the different bars of a channel which reduces reactivity, impede the cooling of the ends of the bars, and increase the load loss in the channel. Furthermore the cost of production of the parts is often high.
  • the fuel elements or bars are surrounded by an external reinforcement or shell the lower part of which carries on its internal face a throat or suitable shoulder on which rests the lower part of the bar connected thereto.
  • the reinforcements or shells which are mounted one on the other by means of suitable bearings.
  • These shells or reinforcements are also provided with annular throats disposed internally or externally which enable them to be handled by a remote-controlled device.
  • a space is left between the upper end of a bar and the lower end of the bar situated thereabove, in order to allow for deforma- 3,85,965 Patented Apr. 16, 1963 tion or contraction of the bars during the operation of the reactor.
  • This system has nevertheless the drawback that it impedes the cooling of the ends of the bars and gives rise to a substantial load loss.
  • the improvement which is the object of the present invention relates to supports of the type comprising a cylindrical reinforcement or shell which is capable of receiving and concentrically surrounding the fuel element and has internal supporting surfaces for this element.
  • the reinforcement or shell is provided on its internal wall with a ledge which forms a supporting surface for longitudinal extensions associated with the body of the fuel elements, and wherein a part overlies the ledge, which part, internally, is conical or nozzle-shaped, and is provided with indentations within which at least some of the longitudinal extensions fit.
  • the part may be annular and may be formed integrally with the shell or reinforcement, or alternatively may comprise a separate insert.
  • the arrangement of the ledge and the conical or nozzle shaped part which overlies it ensures that the cooling of the ends of the fuel elements is improved instead of being impeded or reduced by the support, whilst the load loss is reduced compared with previous support systems.
  • the longitudinal extensions of the body of the fuel elements are constituted by ribs. At their lower end these ribs are straight, that is to say radiallyextending or helical.
  • the pitch of the helices are made large relative to the diameter of the fuel element and are of the order of at least twice this diameter.
  • the parts of the ribs which are farthest from the longitudinal axis of the element rest on the ledge. All or some, for example a submultiple of the total number, of the ribs of each fuel element may rest on the ledge.
  • the improvement which is the object of the invention may be advantageously applied to fuel elements of heterogeneous atomic piles having vertical channels, to the support of samples to be irradiated in a channel and to the irradiation of small parts enclosed in a sheath.
  • FIGURE 1 is a vertical sectional view of one embodiment of the invention
  • FIGURE 2 is a horizontal sectional view along the line 11-11 of FIGURE 1 showing the longitudinal extensions of the sheath of the fuel element in section.
  • the fuel element 1 is in the form of a solid or hollow cylindrical bar of fissile material, such as uranium.
  • This element 1 is enveloped by a sheath 2 made of a metal which is not very absorbent, such as magnesium or aluminium.
  • This sheath 2 is provided with straight longitudinal extensions in the form of radially extending ribs or fins 3. As will be seen from FIGURE 2, there are shorter ribs 4 which solely serve to effect thermal exchanges, whilst ribs 3 jointly serve to effect these exchanges and also to support the element 1.
  • the support of the element 1 is ensured by a ledge which is machined from the base of a shell 6, and which is covered by a support ring 5.
  • the shell 6 is made of a material which is not very absorbent with respect to neutrons, such as for example graphite of so-called nuclear purity.
  • the lower portion 7 of this shell 6 is reduced in diameter and may thus penetrate within the top of a similar shell, shown in chain dotted lines in FIGURE 2, situated beneath the shell 6.
  • the various shells rest one on the other on spherical bearings 8 which tolerate slight nus-alignment between the shells.
  • the shell 6 has on its upper part an internal circular groove 9 permitting the assembled element 1 and shell 6 to be handled by means of a remote-controlled device,
  • the ring 5 supports an annular part 11, the internal surface of which is nozzle shaped or conical.
  • the annular part 11 fills the lower region 10 of the shell 6 and is provided with identations in the form of vertical radially extending slots corresponding to the larger ribs 3, Within which slots the tips of these ribs 3 are located.
  • said fins including a plurality of fins having the same greater radial dimension and a plurality of fins having the same reduced radial dimension, said fins having said greater radial dimension being received within corresponding ones of said indentations.
  • annular insert member and means locating said annular insert member within said shell over said ledge, said internal conical wall being formed in said member.
  • a support ring located between said ledge and said annular insert member.

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  • 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)
US43259A 1958-09-18 1959-09-16 Supports for combustible elements in atomic piles or reactors having vertical channels Expired - Lifetime US3085965A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR774763 1958-09-18

Publications (1)

Publication Number Publication Date
US3085965A true US3085965A (en) 1963-04-16

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US43259A Expired - Lifetime US3085965A (en) 1958-09-18 1959-09-16 Supports for combustible elements in atomic piles or reactors having vertical channels

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US (1) US3085965A (en))
BE (1) BE582757A (en))
CH (1) CH358165A (en))
DE (1) DE1093495B (en))
FR (1) FR1210319A (en))
GB (1) GB916871A (en))
LU (1) LU37662A1 (en))

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3325363A (en) * 1963-04-11 1967-06-13 Gen Dynamics Corp Carbon coated nuclear fuel and poison particles

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE631312A (en)) * 1962-04-20
GB2164195B (en) * 1984-09-03 1988-05-25 Nat Nuclear Corp Ltd Fuel element stringer construction
DE102019008538B3 (de) * 2019-12-10 2021-02-11 Westinghouse Electric Germany Gmbh Brennstabanbauelement, Brennelement und Kernbrennstoffanordnung

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE550790A (en)) * 1955-04-30
GB781648A (en) * 1953-07-23 1957-08-21 Atomic Energy Authority Uk Improvements in or relating to nuclear reactors
GB784890A (en) * 1955-08-25 1957-10-16 Atomic Energy Authority Uk Improvements in or relating to fuel elements for nuclear reactors
US2832732A (en) * 1953-06-08 1958-04-29 Eugene P Wigner Fuel assembly for a neutronic reactor
GB816124A (en) * 1956-11-23 1959-07-08 Atomic Energy Authority Uk Improvements in or relating to fuel elements
FR1186581A (fr) * 1956-11-23 1959-08-27 Atomic Energy Authority Uk Cartouches de combustible pour piles atomiques
US2968601A (en) * 1957-12-10 1961-01-17 Thomas C Evans Fuel element for neutronic reactors

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2832732A (en) * 1953-06-08 1958-04-29 Eugene P Wigner Fuel assembly for a neutronic reactor
GB781648A (en) * 1953-07-23 1957-08-21 Atomic Energy Authority Uk Improvements in or relating to nuclear reactors
BE550790A (en)) * 1955-04-30
GB784890A (en) * 1955-08-25 1957-10-16 Atomic Energy Authority Uk Improvements in or relating to fuel elements for nuclear reactors
GB816124A (en) * 1956-11-23 1959-07-08 Atomic Energy Authority Uk Improvements in or relating to fuel elements
FR1186581A (fr) * 1956-11-23 1959-08-27 Atomic Energy Authority Uk Cartouches de combustible pour piles atomiques
US2968601A (en) * 1957-12-10 1961-01-17 Thomas C Evans Fuel element for neutronic reactors

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3325363A (en) * 1963-04-11 1967-06-13 Gen Dynamics Corp Carbon coated nuclear fuel and poison particles

Also Published As

Publication number Publication date
GB916871A (en) 1963-01-30
LU37662A1 (en)) 1959-11-16
FR1210319A (fr) 1960-03-08
BE582757A (fr) 1960-01-18
DE1093495B (de) 1960-11-24
CH358165A (fr) 1961-11-15

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