Classifications

• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21C—NUCLEAR REACTORS
  • G21C13/00—Pressure vessels; Containment vessels; Containment in general
  • G21C13/02—Details
  • G21C13/032—Joints between tubes and vessel walls, e.g. taking into account thermal stresses
  • G21C13/036—Joints between tubes and vessel walls, e.g. taking into account thermal stresses the tube passing through the vessel wall, i.e. continuing on both sides of the wall
• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21C—NUCLEAR REACTORS
  • G21C7/00—Control of nuclear reaction
  • G21C7/06—Control of nuclear reaction by application of neutron-absorbing material, i.e. material with absorption cross-section very much in excess of reflection cross-section
  • G21C7/08—Control 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
  • G21C7/10—Construction of control elements
• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21C—NUCLEAR REACTORS
  • G21C7/00—Control of nuclear reaction
  • G21C7/06—Control of nuclear reaction by application of neutron-absorbing material, i.e. material with absorption cross-section very much in excess of reflection cross-section
  • G21C7/08—Control 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
  • G21C7/12—Means for moving control elements to desired position
  • G21C7/16—Hydraulic or pneumatic drive
• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21C—NUCLEAR REACTORS
  • G21C19/00—Arrangements for treating, for handling, or for facilitating the handling of, fuel or other materials which are used within the reactor, e.g. within its pressure vessel
  • G21C19/20—Arrangements for introducing objects into the pressure vessel; Arrangements for handling objects within the pressure vessel; Arrangements for removing objects from the pressure vessel
• • 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 generally relates to nuclear reactors with drive mechanisms of the reactivity control organs of the core located outside the vessel.
• a nuclear reactor may include:
• a tank having a substantially vertical central axis, the vessel having a lid having a plurality of orifices;
• lid vias each comprising a tubular adapter fixed in one of the orifices and delimiting an internal passage, each lid penetration further comprising a tubular sleeve engaged in the internal passage and extending axially in the extension of one of the tubes; guides;
• control rods secured to the control members and each extending through one of the cuffs
• Each cuff may be suspended by an upper axial end of the cuff, which rests on an upper bearing formed on the corresponding adapter.
• each sleeve is free relative to the corresponding tubular adapter, there may be wear of the tubular sleeve and / or the adapter, due to the relative movement between these two elements.
• the invention aims to propose a nuclear reactor in which this phenomenon of wear is better controlled.
• the invention relates to a nuclear reactor comprising:
• a tank having a substantially vertical central axis, the vessel having a lid having a plurality of orifices;
• each lug crossing further comprising a tubular sleeve engaged in the internal passage and extending axially in the extension of one of the tubes. guides;
• each mechanism being configured to axially drive one of the rods; each cuff being suspended by an upper axial end of the cuff resting on an upper bearing formed on the corresponding adapter;
• the sleeve then comes to rest by its lower axial end on the upper axial end of the guide tube.
• the sleeve is no longer suspended by its upper axial end, but instead bears axially at both ends.
• each lower axial end of the sleeve is separated from the upper axial end of the corresponding guide tube by a radial gap of radial width less than 20 millimeters; each lower axial end of the sleeve is of flared shape toward the guide tube, the upper axial end of the guide tube comprising an axially projecting portion engaged in the lower axial end of the sleeve, the said axial gap being defined between an internal surface of the sleeve; the lower axial end of flared cuff and the protruding portion;
• said radial gap is defined between the inner surface of the lower axial end of the flared-shaped cuff and the projecting portion;
• the lower axial end of the sleeve has a frustoconical shape, the projecting portion having a frustoconical shape conjugate with that of the lower axial end of the sleeve;
• the upper axial end of the guide tube has a lower bearing surface, a free edge of the lower axial end of the sleeve being situated axially above the lower bearing surface, the said axial gap being defined between the free edge and the lower bearing surface;
• the lower range is defined by a plurality of closed contour surfaces, separated from each other by passages, and distributed around the rod;
• the upper axial end of the guide tube comprises at least one radial abutment located radially inward and / or outward of the lower bearing surface, said radial interstice being defined between the free edge and the at least one radial abutment; ;
• each guide tube comprises a tubular guide structure and an end piece fastened to the guide structure and defining the upper end of the guide tube;
• the end piece has a central axial orifice through which the rod passes, and fluid circulation ducts opening into the central axial orifice;
• the guiding structure comprises an upper plate having a passage opening of the rod placed in coincidence with the central axial orifice, the end piece being fixed to the upper plate, the upper plate and the end piece presenting perpendicularly to the central axis of the substantially identical inner and / or outer sections.
• the invention relates to a method of maintenance of a nuclear reactor, comprising:
• a tank having a substantially vertical central axis, the vessel having a lid having a plurality of orifices;
• each guide tube comprising a tubular guide structure
• each lug crossing further comprising a tubular sleeve engaged in the internal passage and extending axially in the extension of one of the tubes. guides;
• each cuff being suspended by an upper axial end of the cuff resting on an upper bearing formed on the corresponding adapter;
• the method comprising at least the following step:
• an end piece to the guide structure of at least one guide tube, the end piece defining an upper axial end of the guide tube, the lower axial end of the sleeve being separated from the upper axial end of the guide tube; corresponding guide tube by an axial gap of axial height less than 50 millimeters.
• the method may further have the feature below:
• the lower axial end of the sleeve is separated from the upper axial end of the corresponding guide tube by a radial gap of radial width less than 20 millimeters.
• FIG. 1 is a sectional representation of the vessel of a nuclear reactor, taken in a vertical plane;
• FIG. 2 is a sectional view in a vertical plane of a cover crossing of the nuclear reactor of FIG. 1;
• FIG. 3 is a side view of the lower axial end of the sleeve of FIG. 2, and of the upper axial end of the corresponding guide tube for a nuclear reactor according to the invention;
• FIG. 4 is a sectional view in a vertical plane of the lower axial end of the sleeve of Figure 2, and the upper axial end of the corresponding guide tube for a nuclear reactor according to the invention;
• FIGS. 5 and 6 are perspective views, from above and below respectively, of the end piece shown in Figures 3 and 4; - Figures 7 and 8 illustrate an alternative embodiment of the end piece;
• FIG. 9 illustrates another variant embodiment of the end piece
• the nuclear reactor illustrated in FIG. 1 is a pressurized water or PWR type reactor.
• the reactor is of the boiling water type, or BWR.
• the nuclear reactor comprises a vessel 1 having a substantially vertical central axis.
• the vessel 1 comprises a substantially cylindrical shell 1a, closed at its lower end by a substantially hemispherical curved bottom 1b.
• the ferrule is open at its upper end.
• the tank further comprises a lid 2, having a plurality of orifices 2a.
• the cover 2 is substantially hemispherical and rests on a bearing surface at the upper end of the ferrule 1 a. It is typically fixed in a sealed manner on the ferrule 1a by clamping studs 3.
• the nuclear reactor still has a core 4 disposed inside the tank
• the core consists of nuclear fuel assemblies, typically of prismatic shape, arranged in a juxtaposed manner.
• the nuclear reactor further comprises guide tubes 12, arranged inside the tank, and a plurality of organs 14 for controlling the reactivity of the core, axially movable inside the guide tubes 12.
• the guide tubes are visible in FIG. 1, the upper part of the control members 14 being illustrated in FIG.
• the guide tubes 12 are of vertical orientation. They typically comprise guide cards (not shown) in which the rods 16 slide, and an outer cowl 20 of cylindrical shape.
• the rods 16 are engaged in the heart over at least part of their length when the control members are in the low position, and are extracted out of the heart when the control member is in the up position.
• the nuclear reactor further includes lid vias 22 shown in detail in FIG. 2.
• Each lid vias 22 comprise a tubular adapter 24 fixed in one of the orifices 2a.
• the adapter 24 typically comprises a running portion 26 whose diameter corresponds to the internal diameter of the orifice 2a, and which is typically firstly hooped into the lid and then fixed by an annular weld bead 28 on the lower inner face of the cover 2.
• the adapter 24 also has a diametrically enlarged upper portion 30 located outside and above the tank lid 2.
• a lower portion 32 of the adapter 24 protrudes from the lower inner surface of the lid 2.
• the adapter 24 delimits an internal passage 34.
• This passage is typically of vertical axis.
• Each bushing 22 also comprises a tubular sleeve 36 engaged in the internal passage 34 and extending axially in the extension of one of the guide tubes 12, as shown in FIG. 1.
• Each sleeve 36 is suspended by an upper axial end of the cuff. 38 which rests on an upper span 40 provided on the corresponding adapter 24 (see Figure 2).
• the sleeve 36 is typically coaxial with the adapter 24. It typically has a substantially cylindrical central portion 42 of substantially constant section over its entire height.
• the upper axial end 38 has an enlarged outer section relative to the central section 42 and constitutes a development coming to rest on the upper span 40.
• the internal passage 34 has a substantially constant inner section of current section, extending over almost the entire height of the adapter, this section being slightly greater than the outer section of the central section 42 of the sleeve so that a gap 44 exists between the central section 42 of the sleeve and the wall of the internal passage 34.
• the internal passage 34 has an upper end 46 of enlarged section.
• the upper span 40 constitutes a shoulder connecting the enlarged upper end 46 of the internal passage to the current section.
• the upper bearing surface 40 is turned upwards, the upper axial end 38 resting due to the weight of the sleeve on the upper bearing surface 40.
• the lower axial end 48 of the sleeve protrudes into the bowl beyond the tubular adapter 24.
• the sleeve 36 carries an outer surface of the pads 49, which ensure the spacing between the sleeve and the inner surface of the passage 34.
• the sleeve and the adapter are thus maintained in a substantially coaxial arrangement.
• the nuclear reactor further comprises control rods 50, integral with the control members 14.
• the spider 18 is rigidly attached to a lower end of the control rod 50, as shown in FIG.
• Each rod 50 extends axially through one of the cuffs 36.
• the nuclear reactor further comprises mechanisms 52 for driving the control members 14 located outside the tank 1.
• Each mechanism 52 is configured to axially drive one of the rods 50, and thus move the corresponding control member 14 .
• the mechanisms 52 are sealingly mounted on the upper parts 30 of the adapters.
• the lower axial end 48 of the sleeve 36 is separated from an upper axial end 54 of the corresponding guide tube 12 by an axial gap of height less than 50 millimeters.
• a gap 56 whose height, taken along the central axis, is less than 50 millimeters.
• this height is less than 30 millimeters and more preferably less than 10 millimeters.
• the lower axial end of the sleeve 48 is separated from the upper axial end of the corresponding guide tube 54 by a radial gap of width less than 20 millimeters.
• This radial interstice is preferably less than 10 millimeters wide and more preferably less than 5 millimeters
• the width of the gap 56 is less than the width stated above. This width is taken in a plane perpendicular to the central axis. It is taken in a radial direction relative to the axis X of the cuff.
• the lower axial end of the sleeve 48 is flared towards the guide tube 12, and the upper axial end of the guide tube 54 comprises a projecting part 58, engaged in the lower axial end of the sleeve 48.
• the gap 56 between the inner surface 60 of the lower axial end of the sleeve 48, and the outer surface 61 of the projecting portion 58 corresponds to both the axial gap and the interstice radial.
• the lower axial end of the sleeve 48 has a frustoconical shape.
• the projecting portion 58 also has a frustoconical shape, conjugated with that of the axial lower end of the sleeve. These frustoconical shapes are of axis coincident with the axis X of the cuff.
• each guide tube 12 comprises a tubular guide structure 62 and an end piece 64 fixed to the guide structure 62 and defining the upper axial end of the guide tube 54.
• the tubular guide structure 62 typically includes at least the guide cards and the shroud 20. It typically also includes an upper plate 66, closing an upper end of the shroud 20.
• the upper plate 66 is typically oriented perpendicular to the axis central. It has a through hole 68 (FIG. 4), through which the rod 50 passes.
• the end piece 64 comprises a base plate 70, having large lower faces 72 and upper 74.
• the large lower face 72 bears directly against the upper face 76 of the upper plate 66.
• the projecting portion 58 projects axially towards the sleeve 36 from the large upper face 74.
• the base plate 70 is oriented substantially perpendicular to the central axis.
• the end piece 64 has a central axial orifice 78, through which the rod 50 passes.
• the central axial orifice 78 and the through hole 68 are placed in register with each other.
• the upper plate 66 and the end piece 64 are perpendicular to the central axis of the substantially identical inner and / or outer sections.
• the internal section of the through hole 68 is substantially identical to the inner section of the central axial orifice 78.
• the outer section of the base plate 70 is substantially identical to the outer section of the upper plate 66.
• the base plate 70 and the upper plate 66 are circular.
• the end piece 64 has fluid circulation ducts opening into the central axial orifice 78.
• the ducts 80 extend radially from the wafer 82 of the base plate 70 to the central axial orifice 78.
• Other circulation ducts 86 extend radially from the outer surface 61 of the projecting portion 58 into the central axial orifice 78.
• the end piece 64 further comprises three recessed reliefs 88 (FIG. 5) intended to house fastening screws of the end piece 64 to the upper plate 66.
• These three recessed reliefs 88 are, in the example represented , partially formed in the base plate 64 and partially in the projecting portion 58.
• the bottoms 90 of the recessed reliefs 88 are pierced by orifices 92, visible in FIG. 6, provided for the passage of the fixing screws 93 (FIG. ).
• the heads of the fixing screws are housed in the recessed reliefs.
• the end piece 64 is not fixed to the guide structure 62 by screws but by any other suitable means, for example by welding.
• the guide tube 12 comprises anti-rotation bars 94 protruding from the upper face 76 of the upper plate 66.
• the end piece 64 has on its large lower face 72 housings 96 of reception of the protruding parts of these bars.
• the circulation ducts 80, 86 are replaced by large openings 97. These openings 97 are hollowed out in the projecting portion 58, and more precisely in the outer surface 61. They open into the central axial orifice 78. They are closed contour.
• the openings 97 are typically distributed circumferentially around the projecting portion 58, between the recessed reliefs 88.
• the openings 97 are not closed-contoured.
• the projecting portion 58 is delimited laterally towards the inner surface 60 of the lower axial end 48 by the outer surface 61, and axially by an annular surface 98.
• the annular surface 98 is perpendicular to the X axis and is turned upwards. .
• the openings 97 open each at the level of the annular surface 98, dividing it into three annular sections completely separated from one another.
• the upper axial end of the guide tube 54 has a lower bearing surface 99, a free edge 100 of the lower axial end of the sleeve 48 being situated axially above the bearing surface. lower 99.
• the axial gap 56 is defined between the free edge 100 and the lower bearing surface 99.
• the lower range 99 is for example defined by a plurality of closed contour surfaces, separated from each other by passages, and distributed around the rod 50.
• closed contour surfaces are for example defined by studs projecting axially.
• the lower range 99 typically falls in a surface perpendicular to the central axis.
• the passages separating the different closed contour surfaces allow the circulation of the primary fluid filling the tank.
• the lower bearing surface 99 is for example arranged on an end piece attached to the guide structure.
• This end piece comprises a plate carrying the pads.
• the lower scope is a continuous surface surrounding the shaft 50.
• the upper axial end of the guide tube 54 comprises at least one radially inward and / or outward radial stop 102, 104, as shown in FIGS. 10 and 11.
• the radial gap is defined between the free edge 100 and the outer radial stop 102 or inner 104.
• the stops 102, 104 are formed on the end piece defining the bottom span 99.
• the lower axial end of the sleeve 48 has a flared shape.
• the lower axial end of sleeve 48 may not have a frustoconical shape with circular sections perpendicular to the central axis. These sections may be oval, or have any other shape.
• the upper axial end of the guide tube 54 is defined by the tubular guide structure, and not by an end piece attached to the guide structure.
• the invention relates to a method of maintenance of a nuclear reactor comprising:
• a tank 1 having a substantially vertical central axis, the vessel 1 having a lid 2 having a plurality of orifices 2a;
• each guide tube 12 comprising a tubular guide structure 62; a plurality of organs for controlling the reactivity of the core 14, axially movable inside the guide tubes 12;
• each cover vias 22 comprising a tubular adapter 24 fixed in one of the orifices 2a and delimiting an internal passage 34, each cover vias 22 further comprising a tubular sleeve 36 engaged in the internal passage 34 and extending axially in the extension of one of the guide tubes 12;
• Control rods 50 integral with the control members 14 and each extending through one of the sleeves 36;
• Each sleeve 36 is suspended by an upper axial end of the sleeve 38 resting on an upper bearing surface 40 formed on the corresponding adapter 34.
• a lower axial end 48 of the sleeve protrudes axially into the vessel 1 beyond the passage 22, and is located above the corresponding guide tube 12.
• the method comprises at least the following step:
• an end piece 64 attaching an end piece 64 to the guide structure 62 of at least one guide tube 12, the end piece 64 defining an upper axial end of the guide tube 54, the lower axial end of the sleeve 48 being separated from the upper axial end of the corresponding guide tube 54 by an axial gap 56 of height less than 50 millimeters.
• the lower axial end of the sleeve 48 is separated from the upper axial end of the corresponding guide tube 54 by a radial gap of the width less than 20 millimeters.
• the end piece is advantageously of the type described above.
• the nuclear reactor is of the type described above.
• the maintenance process is typically implemented on reactors already in service. It can be implemented preventively, before significant wear of the sleeve or the adapter. Alternatively, the method can also be implemented correctively, while the sleeve has already descended due to the wear of the sleeve or the adapter.
• the maintenance method typically comprises the following steps, performed before the step of attaching the end piece to the guiding structure: - disassembly of the lid 2 and evacuation thereof;
• the attachment operation of the end piece 64 is preferably performed with the guide tubes 12 immersed in the reactor pool.
• the fixing step typically comprises the following substeps:
• the centering cap serves as a guide during the sub-step of placing the end piece on the guide structure, and prevents the falling of objects in the guide tubes 12.
• the central axial orifice 78 is threaded around centering plug.
• the maintenance method comprises the following steps:
• the invention makes it possible to stabilize the cuff 36 at a given altimetry, by means of the end piece 64 fixed on the guide structure 62.
• the cuff 36 retains all of its functions:
• the sleeve 36 has a function of a hydraulic valve in the sense that the sleeve 36 is raised from the upper bearing surface 40 to allow a flow of fluid from the inside of the tank 1 towards the inside of the mechanisms 52 in the event of rapid descent of the members control 14 of the reactivity of the heart.
• the establishment of the end piece 64 stops the wear of the sleeve 36 and the adapter 24, because the sleeve 36 is held at both ends, which limits its movement.
• the establishment of the end piece 64 has no impact on safety. It has little or no impact on the other maintenance operations provided on the guide tubes 12, and only requires adaptation of the grapple for gripping and handling the guide tubes 12.
• the installation time of the end pieces 64 is not critical for the wafer stop, this operation can be done in masked time compared to other work on the cover.
• the end pieces 64 are inexpensive and relatively simple to put in place. Attachment of the end piece 64 to the structure 62 typically requires only tapping operations.

Landscapes

• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Plasma & Fusion (AREA)
• General Engineering & Computer Science (AREA)
• High Energy & Nuclear Physics (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Monitoring And Testing Of Nuclear Reactors (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=62948224

Family Applications (1)

Country Status (9)

Families Citing this family (1)

Family Cites Families (16)

• 2018
  • 2018-04-05 FR FR1852975A patent/FR3079960B1/fr active Active
• 2019
  • 2019-04-04 KR KR1020207030102A patent/KR102649496B1/ko active IP Right Grant
  • 2019-04-04 WO PCT/EP2019/058487 patent/WO2019193088A1/fr active Application Filing
  • 2019-04-04 EP EP19714223.5A patent/EP3776595A1/fr active Pending
  • 2019-04-04 CN CN201980023011.2A patent/CN111919265A/zh active Pending
  • 2019-04-04 US US17/045,086 patent/US11557402B2/en active Active
  • 2019-04-04 JP JP2020554179A patent/JP7317041B2/ja active Active
  • 2019-04-08 TW TW108112204A patent/TW201944432A/zh unknown
• 2020
  • 2020-09-17 ZA ZA2020/05771A patent/ZA202005771B/en unknown

Also Published As

Similar Documents

Legal Events