Classifications

• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21C—NUCLEAR REACTORS
  • G21C5/00—Moderator or core structure; Selection of materials for use as moderator
  • G21C5/02—Details
  • G21C5/06—Means for locating or supporting fuel elements
• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21C—NUCLEAR REACTORS
  • G21C15/00—Cooling arrangements within the pressure vessel containing the core; Selection of specific coolants
  • G21C15/02—Arrangements or disposition of passages in which heat is transferred to the coolant; Coolant flow control devices
• • 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 nuclear reactors of the light water cooled type, such as those used for the production of electrical energy or naval propulsion.
• a nuclear reactor of this type consists of a cylindrical tank comprising a tank bottom of hemispherical shape and a removable cover, also of hemispherical shape, inside which is the core of the reactor made up of fuel assemblies.
• the core is contained in a structure internal to the vessel supported at the top thereof and essentially consisting of an upper flange, a ferrule and a support base receiving the fuel assemblies.
• the fuel assemblies are cooled by a heat transfer fluid, the primary fluid.
• the heart does not rest directly on the support bottom but on a lower heart plate located above the support bottom and connected to the latter by means of a number of columns.
• the support bottom is in the form of a thick plate pierced with a certain number of channels and the lower core plate is pierced with holes to the right of each fuel assembly.
• the primary fluid after having passed through the channels of the support bottom, is distributed in the core by means of the holes drilled in the lower core plate.
• This embodiment has a number of drawbacks. In particular, it does not allow optimal use of the interior volume of the reactor vessel since the space between the support bottom and the bottom core plate contains no fuel. In addition, this arrangement requires assembly, machining and adjustment of a large number of parts.
• the fuel assemblies rest directly on the support bottom.
• the support bottom plays, in this embodiment, both the support of the fuel assemblies and the distributor of the primary fluid, the latter consists of a thick plate pierced with channels made with throttling orifices allowing a fall of primary fluid pressure. The machining of these channels provided with such orifices can prove to be a delicate operation.
• the invention attempts to remedy the aforementioned drawbacks and shortcomings.
• the invention proposes a new lower core support which makes it possible to differentiate the support functions of the fuel assemblies and of distribution of the primary fluid while presenting a minimum bulk, by reducing the machining and assembly operations of the support bottom and by offering the possibility of better controlling the distribution of the fluid in the different regions of the heart.
• the invention applies to the lower support of the core of a nuclear reactor, intended to support each of the fuel assemblies of the core and to distribute the primary cooling fluid through these assemblies.
• the support consists of: - a first, thick plate, supporting the fuel assemblies and pierced at the right of each assembly, vertical channels intended for the passage of the primary fluid, - a second, thin plate, pierced with orifices, fixed under the first plate, with no space between the two plates, and positioned in such a way that each orifice is located in line with one of the channels, the section of each of the orifices being smaller than that of each of the channels and each of the channels being open to at least one orifice.
• the section of each channel drilled in the first plate is constant.
• the section of the orifices of the second plate varies according to their position on said plate.
• the cross section of these orifices decreases when one goes from the center of the plate towards the periphery thereof.
• the number of the orifices of the second plate at the right of each channel varies according to their position on said plate.
• the number of these orifices decreases when one goes from the center of the plate towards the periphery thereof.
• the first plate is pierced with vertical narrow channels and the second plate is pierced with small orifices in line with these narrow channels.
• These channels are extended below the second plate by columns which are centered on tank penetrations.
• the second plate comprises, as means of fixing to the first plate, fixing means which are specific to it, but also the means for fixing the base of the aforementioned columns to the assembly formed by the two plates.
• the second plate is constituted by a set of smaller plates juxtaposed, each small plate being fixed to the first plate independently of the neighboring plates.
• the small plates are formed by the bases themselves of the columns which extend said channels.
• Figure 1 is a sectional view of a nuclear reactor vessel coraportant a lower core support according to the invention.
• FIG. 2 is a section along A-A in FIG. 3.
• FIG. 3 is a view along B of FIG. 2.
• FIG. 4 is a section along CC of FIG. 5.
• FIG. 5 is a view along D of FIG. 4.
• FIG. 1 represents a nuclear reactor vessel comprising a cylindrical body 1 closed on the one hand by a hemispherically shaped vessel bottom 2 and by a removable cover, also hemispherical in shape, 3.
• the core 4 of the reactor is contained in an internal structure 5 which is suspended in the tank by resting on a shoulder 6 of the latter and the bottom of which is formed by a thick plate 7 pierced with vertical channels 8 .
• the fuel assemblies 9 rest directly on the thick plate 7, in line with the channels 8.
• a cooling fluid For the cooling of these assemblies, a cooling fluid, the primary fluid, enters the tank 1 through several inlet pipes 10, passes through an annular zone 11 comprised between the cylindrical body 1 of the tank and the wall of the internal structure 5 arrives in a chamber 12 delimited by the bottom of the tank 2 and the plate 7 then rises through the plate 7 to the fuel assemblies 9 to be finally evacuated by a plurality of outlet pipes 10 '.
• Under the thick plate 7 is fixed a thin plate 13 by means of screws 14. This plate is centered by means of pins 15.
• the thin plate 13 is pierced with orifices 16 comprising inlet chamfers 17 and located at the right of each channel 8. These orifices have a diameter smaller than that of the channels 8.
• the pressure of the primary fluid decreases during its passage from the chamber 12 to the heart of the reactor 4.
• the diameter of the orifices 16 can be constant for all the orifices or vary as a function of their position on the plate 13. Referring to FIG. 3 we see that the diameter of the orifices 16 decreases when we go from the center of the heart, which is a hot zone, towards the periphery of it, which is a less hot zone.
• FIGS. 2 and 3 Also shown in FIGS. 2 and 3 are the narrow channels 18 intended for the passage of instruments for controlling the fuel assemblies. These channels 18 are drilled in the thick plate 7. To the right of these channels, small orifices 19 are drilled in the plate 13. The channels 18 are extended below the plate 13 by columns 20 centered on tank penetrations 20 * and the base of which is fixed to all of the plates 7 and 13 by means of screws 21. The screws 21 participate not only to the fixing of the base of the columns 20 on the plate 1 but also to the maintenance of the plate 13 against the plate 7.
• FIGS. 4 and 5 represent a variant according to which the thin plate 13 is constituted by a set of independent plates 13 '.
• Each plate 13 ' has a square shape, is provided with four orifices 16' for distributing the fluid and is fixed to the plate 7 by screws 14 '.
• the plates 13 ′ which are located to the right of each channel 18 intended for the passage of the control instrumentation are in fact constituted by the base itself of the column 20. which extends each channel 18.
• the orifices 16 ′ have been represented in the same way as the orifices 16 in FIG. 3, that is to say with a section decreasing from the center towards the periphery of the plate 7.
• the following lower core support the invention has many advantages:
• the lower core support according to the invention offers the possibility of properly controlling the distribution of the primary fluid in the core. In particular, it makes it possible to increase the flow rate of the fluid at the center of the core and to decrease it at the periphery.
• the invention can be applied to any type of reactor cooled with light water, whatever the use made of it. Most often, the reactors according to the invention can be used for the production of electrical energy or naval propulsion.

Landscapes

• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Plasma & Fusion (AREA)
• General Engineering & Computer Science (AREA)
• High Energy & Nuclear Physics (AREA)
• Structure Of Emergency Protection For Nuclear Reactors (AREA)
• Monitoring And Testing Of Nuclear Reactors (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Adhesives Or Adhesive Processes (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=9232933

Family Applications (1)

Country Status (7)

Cited By (2)

Families Citing this family (1)

Citations (7)

• 1979
  • 1979-12-19 FR FR7931074A patent/FR2472249A1/fr active Granted
• 1980
  • 1980-12-18 WO PCT/FR1980/000183 patent/WO1981001908A1/fr unknown
  • 1980-12-18 ES ES497879A patent/ES8301050A1/es not_active Expired
  • 1980-12-18 JP JP81500237A patent/JPS56501774A/ja active Pending
  • 1980-12-18 EP EP80401819A patent/EP0031764B1/fr not_active Expired
  • 1980-12-18 AT AT80401819T patent/ATE9853T1/de not_active IP Right Cessation
  • 1980-12-18 DE DE8080401819T patent/DE3069430D1/de not_active Expired

Patent Citations (7)

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