EP0429445A1 - Arrangement for centering components of a nuclear reactor - Google Patents
Arrangement for centering components of a nuclear reactorInfo
- Publication number
- EP0429445A1 EP0429445A1 EP88909299A EP88909299A EP0429445A1 EP 0429445 A1 EP0429445 A1 EP 0429445A1 EP 88909299 A EP88909299 A EP 88909299A EP 88909299 A EP88909299 A EP 88909299A EP 0429445 A1 EP0429445 A1 EP 0429445A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- centering
- centering pins
- fuel
- pins
- head
- 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- Withdrawn
Links
- 239000000446 fuel Substances 0.000 claims abstract description 54
- 238000003780 insertion Methods 0.000 claims description 4
- 230000037431 insertion Effects 0.000 claims description 4
- 230000000712 assembly Effects 0.000 description 12
- 238000000429 assembly Methods 0.000 description 12
- 239000000463 material Substances 0.000 description 4
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 239000002826 coolant Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 125000006850 spacer group Chemical group 0.000 description 2
- 241000863032 Trieres Species 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 239000002915 spent fuel radioactive waste Substances 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
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
- G21C3/02—Fuel elements
- G21C3/04—Constructional details
- G21C3/06—Casings; Jackets
- G21C3/12—Means forming part of the element for locating it within the reactor core
-
- 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
-
- 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 an arrangement for centering components of a nuclear reactor and is applicable for fixing the position of fuel elements.
- the reactor core which is arranged in a reactor pressure vessel, consists of a large number of fuel elements with a square cross section, which are arranged in a core vessel.
- fuel rods are held in a supporting structure, which is formed from a fuel element head and a fuel element foot and intermediate guide tubes for control rods. Spacers are attached to the guide tubes, which bundle the fuel rods and hold them in such a way that they can expand freely.
- a coolant flows through the fuel elements from bottom to top.
- a scaffold insert is arranged in the core container above the fuel elements.
- centering pins are attached in the grid plate of the scaffold insert in order to keep the fuel elements in the core container as close as possible to one another and to fix them in this position.
- these centering pins are threaded into openings in the heads of the fuel assemblies.
- the centering pins are located in an area where there is a very high neutron flux, which leads to changes in the material properties, in particular embrittlement.
- the centering pins With horizontal loading, in particular with vibrations, the centering pins can loosen or break, which can lead to a washing away of the loose pin or a part of the centering pin, which then gets into the coolant circuits, which has a disadvantageous effect.
- the centering pins are therefore checked for their condition during breaks in operation of the reactor and - if necessary - replaced. The review and exchange in the event However, a defect in the known designs is difficult and only possible with great effort.
- the invention is based on the object of specifying an arrangement which offers a simple test option and easy interchangeability of the centering pins and ensures greater security.
- This object is divided by an arrangement for centering ' ⁇ au- a nuclear reactor dissolved, fuel assemblies are arranged in which in a core container, the heads of which use by a Gerüst ⁇ are fixable, wherein trier pins at the top of the fuel assemblies centering are arranged on the frame insertion holes are brought into which the centering pins can be inserted.
- centering pins are easily accessible each time the fuel element is changed and can be easily checked from above using a test device.
- the stability is no longer primarily decisive for the material selection of the centering pins, since these are exchanged with the spent fuel elements after a relatively short dwell time in the nesutron flow.
- the choice of material can therefore be made essentially without being influenced by the neutron radiation or by the wear resistance,
- the centering pins can have a conical neck with a threaded end and can be inserted into a corresponding conical opening in the frame and screwed tight by a nut.
- centering pins resiliently in the fuel assembly heads.
- the resilient arrangement only two instead of four diagonally opposite openings need to be provided in the lower lattice plate of the scaffold insert for each fuel element if the structural conditions make this necessary.
- the resilient arrangement of the centering pins also causes damage to the fuel assemblies when threading the Use of scaffolding avoided.
- FIG. 1 shows a plan view of a lower grid plate of a core insert of a nuclear reactor arranged above the fuel elements
- FIG. 2 shows a plan view of the fuel elements arranged within a core enclosure
- FIG. 3 shows a longitudinal section through a reactor core which is arranged in a reactor pressure vessel
- FIG. 4 shows a fastening possibility for a centering pin in a frame of the head of a fuel assembly
- FIG. 5 shows a fastening of a centering pin, which is provided with a conical neck, on a fuel assembly
- FIG. 6 shows a fastening of a centering pin by a weld seam
- 7 shows a fastening of a stepped centering pin in the lower head region of a fuel assembly
- FIG. 8 shows a centering pin spring-mounted in the head of a fuel assembly
- FIG. 9 shows a plan view of FIG. 8.
- each fuel assembly 1 contains fuel rods, which are held in a support structure, which has a head 2 and a foot. In between are arranged guide tubes for control rods, to which spacers are attached, which bundle the fuel rods.
- a large number of fuel elements 1 closely arranged in a row form the reactor core, which is accommodated in the reactor pressure vessel.
- a scaffold insert 5 is arranged above the fuel element 1, on the lower grid plate 4 of which four openings 7 of a fictitious square are provided (FIG. 1). Centering pins 3 each protrude into two diagonally opposite openings 7.
- holes 4 are provided in the frame 6 according to FIG. 4, into which the centering pins 3 provided with a stepped neck 3a are inserted and held by a centering pin 10 inserted into a transverse bore 11.
- the seat of the centering pin 3 in the cylinder opening 7 of the grid plate 4 of the scaffold insert 5 can be seen from FIG. It protrudes from the opening 7 with its tip 3b.
- the cylinder pin is secured by a caulking edge 12.
- 5 shows a fastening of a cylindrical pin 3, which has a conical neck 3c with a threaded end 3d and is inserted into a corresponding conical opening 13 in the frame 6 and is screwed tight by a nut 14.
- a spreading notch 15 serves to secure it.
- FIG. 7 shows a fastening of a centering pin 3 on a base plate 17 of the head 2 of a fuel assembly.
- a threaded bore 19 is provided in this base plate 17, into which centering pin 3 is screwed and fixed by a locking screw 20a.
- the centering pin 3 is offset in diameter in a predetermined centering area, the thinner end 3e provided with an insertion tip 3b penetrating a corresponding bore 18a in structures 18 of the grid plate 4.
- FIGS. 4 ' to 7 show designs in which the centering pins 3 are inserted rigidly and interchangeably into the head 2 of the fuel elements 1.
- FIG. 8 shows a spring-loaded interchangeable arrangement of the centering pins 3. While the rigid centering pins 3 require four openings 7 in the base plate 4 when there are two centering pins in the head 2, in the spring-loaded version of the centering pins 3 four centering pins - each one in the four corner areas of the head of a fuel assembly - which then only need two openings in the grid plate. The two centering pins, which are not in engagement, are in the pressed-in position during operation and participate in the spring-loaded floating protection of the fuel assemblies through the framework insert 5.
- FIG. 8 A design which is shown in FIG. 8 is particularly advantageous, in which the centering pin has a conical centering region 3f which must not have a self-locking effect (ie the angle of inclination c of the conical surface to the central axis must be greater than the friction angle o) essentially depends on the material).
- the opening 7 in the grid plate 4 of the scaffold insert 5 is correspondingly conical. This results in a play-free engagement of the centering pin in the opening 7, whereby it does not protrude from the top 4a of the grid plate 4 or only slightly so that any structures 18 present on the grid plate 4 do not interfere.
- two pins can thus be arranged at the head of the fuel assemblies 1 and four openings in the grid plate 4 of the scaffold structure, as well as four pins at the head of the fuel assemblies and two centering openings 7 in the grid plate 4 of the scaffold insert 5.
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- General Engineering & Computer Science (AREA)
- High Energy & Nuclear Physics (AREA)
- Fuel-Injection Apparatus (AREA)
Abstract
Un réacteur nucléaire contient des éléments de combustible (1) dont les têtes (2) peuvent être fixées par un insert en forme de cadre (5). Un dispositif de centrage avec des chevilles de centrage (3) sert à tenir serrées les uns contre les autres les éléments de combustible (1) dans le réacteur nucléaire et à les immobiliser dans cette position. Pour pouvoir facilement vérifier et changer les chevilles de centrage (3) tout en améliorant la sécurité du dispositif, lesdites chevilles de centrage (3) sont agencées au niveau de la tête (2) des éléments de combustible (1) et des ouvertures (7) dans lesquelles s'insèrent les chevilles de centrage (3) sont agencées sur l'insert en forme de cadre (5).A nuclear reactor contains fuel elements (1) whose heads (2) can be fixed by a frame-shaped insert (5). A centering device with centering pins (3) serves to hold the fuel elements (1) tight against each other in the nuclear reactor and to immobilize them in this position. In order to be able to easily check and change the centering pins (3) while improving the safety of the device, said centering pins (3) are arranged at the head (2) of the fuel elements (1) and openings (7). ) in which are inserted the centering pins (3) are arranged on the insert in the form of a frame (5).
Description
Anordnung zum Zentrieren von Bauteilen eines KernreaktorsArrangement for centering components of a nuclear reactor
Die Erfindung bezieht sich auf eine Anordnung zum Zentrieren von Bauteilen eines Kernreaktors und ist zum Fixieren der Lage von Brennelementen anwendbar.The invention relates to an arrangement for centering components of a nuclear reactor and is applicable for fixing the position of fuel elements.
Der Reaktorkern, der in einem Reaktordruckbehälter angeordnet ist, besteht aus einer Vielzahl von Brennelementen mit quadrati¬ schem Querschnitt, die in einem Kernbehälter angeordnet sind. In den einzelnen Brennelementen sind Brennstäbe in einer Tragstruk¬ tur gehalten, die aus einem Brennelemente-Kopf und einem Brenn¬ elemente-Fuß und dazwischenliegenden Führungsrohren für Steuer¬ stäbe gebildet ist. An den Führungsrohren sind Abstandshalter befestigt, welche die Brennstäbe bündeln und derart halten, daß sie sich frei ausdehnen können. Die Brennelemente werden von unten nach oben von einem Kühlmittel durchströmt. Um dabei ein Aufschwimmen der Brennelemente zu verhindern, ist im Kernbehäl¬ ter über den Brennelementen ein Gerüsteinsatz angeordnet.The reactor core, which is arranged in a reactor pressure vessel, consists of a large number of fuel elements with a square cross section, which are arranged in a core vessel. In the individual fuel elements, fuel rods are held in a supporting structure, which is formed from a fuel element head and a fuel element foot and intermediate guide tubes for control rods. Spacers are attached to the guide tubes, which bundle the fuel rods and hold them in such a way that they can expand freely. A coolant flows through the fuel elements from bottom to top. In order to prevent the fuel elements from floating, a scaffold insert is arranged in the core container above the fuel elements.
Bei bekannten Ausführungen dieser Art sind in der Gitterplatte des Gerüsteinsatzes Zentrierstifte angebracht, um die Brennele¬ mente im Kernbehälter möglichst dicht beieinander zu halten und in dieser Lage zu fixieren. Beim Einsetzen des oberen Gerüstein¬ satzes fädeln sich diese Zentrierstifte in Öffnungen der Köpfe der Brennelemente ein. Dadurch sind die Brennelemente in ihrer Quer- und Drehlage im Kernbehälter fixiert. Die Zentrierstifte befinden sich in einem Bereich, wo ein sehr hoher Neutronenfluß herrscht, der zu Veränderungen der Materialeigenschaften, ins¬ besondere zu Versprödungen führt. Bei horizontaler Belastung, insbesondere bei Vibrationen, können sich die Zentrierstifte lösen oder sie können brechen, was zu einem Fortschwemmen des losen Stiftes bzw. eines Teiles des Zentrierstiftes führen kann, der dann in die Kühlmittelkreisläufe gelangt, was sich nachtei¬ lig auswirkt. Daher werden die Zentrierstifte bei Betriebspausen des Reaktors auf ihren Zustand überprüft und - falls erforder¬ lich - ausgewechselt. Die Überprüfung und der Austausch im Falle eines Defekts ist bei den bekannten Ausführungen jedoch schwie¬ rig und nur unter großem Aufwand möglich.In known designs of this type, centering pins are attached in the grid plate of the scaffold insert in order to keep the fuel elements in the core container as close as possible to one another and to fix them in this position. When the upper scaffold insert is inserted, these centering pins are threaded into openings in the heads of the fuel assemblies. As a result, the fuel elements are fixed in their transverse and rotational positions in the core container. The centering pins are located in an area where there is a very high neutron flux, which leads to changes in the material properties, in particular embrittlement. With horizontal loading, in particular with vibrations, the centering pins can loosen or break, which can lead to a washing away of the loose pin or a part of the centering pin, which then gets into the coolant circuits, which has a disadvantageous effect. The centering pins are therefore checked for their condition during breaks in operation of the reactor and - if necessary - replaced. The review and exchange in the event However, a defect in the known designs is difficult and only possible with great effort.
Der Erfindung liegt die Aufgabe zugrunde, eine Anordnung anzu- geben, die eine einfache Prüfmöglichkeit und leichte Austausch¬ barkeit der Zentrierstifte bietet und eine höhere Sicherheit ge¬ währleistet.The invention is based on the object of specifying an arrangement which offers a simple test option and easy interchangeability of the centering pins and ensures greater security.
Diese Aufgabe wird durch eine Anordnung zum Zentrieren von'βau- teilen eines Kernreaktors gelöst, bei der in einem Kernbehälter Brennelemente angeordnet sind, deren Köpfe durch einen Gerüst¬ einsatz fixierbar sind, wobei am Kopf der Brennelemente Zen- trierstifte angeordnet sind und am Gerüsteinsatz Öffnungen an¬ gebracht sind, in welche die Zentrierstifte einführbar sind.This object is divided by an arrangement for centering 'βau- a nuclear reactor dissolved, fuel assemblies are arranged in which in a core container, the heads of which use by a Gerüst¬ are fixable, wherein trier pins at the top of the fuel assemblies centering are arranged on the frame insertion holes are brought into which the centering pins can be inserted.
Auf diese Weise sind die Zentrierstifte bei jedem Brennelement¬ wechsel leicht zugänglich und mit einem Prüfgerät von oben auf einfache Weise prüfbar. Die Standfestigkkeit ist nicht mehr in erster Linie bestimmend für die Materialauswahl der Zentrier- stifte, da diese nach relativ kurzer Verweilzeit im Nεutronen- fluß mit den verbrauchten Brennelementen ausgewechselt werden. Es kann deshalb die Materialauswahl im wesentlichen ohne Beein¬ flussung durch die Neutronenstrahlung bzw. durch die Verschlei߬ festigkeit getroffen werden,In this way, the centering pins are easily accessible each time the fuel element is changed and can be easily checked from above using a test device. The stability is no longer primarily decisive for the material selection of the centering pins, since these are exchanged with the spent fuel elements after a relatively short dwell time in the nesutron flow. The choice of material can therefore be made essentially without being influenced by the neutron radiation or by the wear resistance,
Auf der Gitterplatte des Gerüsteinsatzes können Aufbauten vorge¬ sehen sein, welche die Anbringung von vier Öffnungen erschweren, In diesem Fall ist es vorteilhaft, die Zentrierstift in einem vorgegebenen Zentrierbereich im Durchmesser abzusetzen, wobei das mit einer Einführungsspitze versehen dünnere Ende eine im Durchmesser kleinere Bohrung als die Öffnung in Aufbauten der Gitterplatte durchdringt.On the grid plate of the scaffold insert, structures can be provided which make it difficult to make four openings. In this case, it is advantageous to reduce the diameter of the centering pin in a predetermined centering area, the thinner end provided with an insertion tip having a smaller diameter bore as the opening penetrates in structures of the grid plate.
Bei Brennelementen, deren Kopf mit einem Rahmen versehen ist, ist es zweckmäßig, im Rahmen mindestens zwei diagonal gegen- überliegende Öffnungen anzuordnen, in denen die Zentrierstifte eingesetzt und verankert sind.In the case of fuel assemblies whose head is provided with a frame, it is expedient to place at least two diagonally Arrange overlying openings in which the centering pins are inserted and anchored.
Die Zentrierstifte können dabei einen kegelförmigen Hals mit ei- nem Gewindeende besitzen und in eine entsprechende konische Öff¬ nung im Rahmen eingesetzt und durch eine Mutter festgeschraubt sein.The centering pins can have a conical neck with a threaded end and can be inserted into a corresponding conical opening in the frame and screwed tight by a nut.
Es ist besonders günstig, die Zentrierstifte federnd in den Brennelementköpfen anzuordnen. Durch die federnde Anordnung brauchen in der unteren Gitterplatte des Gerüsteinsatzes für jedes Brennelement nur zwei anstatt vier diagonal gegenüberlie¬ gende Öffnungen vorgesehen zu werden, wenn die konstruktiven Verhältnisse dazu zwingen. Dies bedingt allerdings, daß im Brennelementkopf je ein Zentrierstift in den vier Eckbereichen angeordnet werden muß, um eine Zentrierung auch bei einer Dre¬ hung des Brennelementes um 90" zu gestatten. Durch die federnde Anordnung der Zentrierstifte wird auch eine Beschädigung der Brennelemente beim Auffädeln des Gerüsteinsatzes vermieden.It is particularly expedient to arrange the centering pins resiliently in the fuel assembly heads. As a result of the resilient arrangement, only two instead of four diagonally opposite openings need to be provided in the lower lattice plate of the scaffold insert for each fuel element if the structural conditions make this necessary. However, this means that a centering pin must be arranged in each of the four corner areas in the fuel assembly head in order to allow centering even when the fuel assembly is rotated by 90 ". The resilient arrangement of the centering pins also causes damage to the fuel assemblies when threading the Use of scaffolding avoided.
Anhand der Zeichnung wird die Erfindung näher erläutert. Es zeigt:The invention is explained in more detail with reference to the drawing. It shows:
FIG 1 eine Draufsicht auf eine untere Gitterplatte eines über den Brennelementen angeordneten Gerüsteinsatzes eines Kernreaktors, FIG 2 eine Draufsicht auf die innerhalb einer Kernumfassung an¬ geordneten Brennelemente, FIG 3 einen Längsschnitt durch einen Reaktorkern, der in einem Reaktordurckbehälter angeordnet ist,1 shows a plan view of a lower grid plate of a core insert of a nuclear reactor arranged above the fuel elements, FIG. 2 shows a plan view of the fuel elements arranged within a core enclosure, FIG. 3 shows a longitudinal section through a reactor core which is arranged in a reactor pressure vessel,
FIG 4 eine Befestigungsmöglichkeit für einen Zentrierstift in einem Rahmen des Kopfes eines Brennelementes, FIG 5 eine Befestigung eines Zentrierstiftes, der mit einem ke¬ gelförmigen Hals versehen ist, an einem Brennelement, FIG 6 eine Befestigung eines Zentrierstiftes durch eine Schwei߬ naht, FIG 7 eine Befestigung eines stufenförmig abgesetzten Zentrier¬ stiftes im unteren Kopfbereich eines Brennelementes, FIG 8 einen im Kopf eines Brennelementes gefedert angebrachten Zentrierstift und FIG 9 eine Draufsicht zu FIG 8.4 shows a fastening possibility for a centering pin in a frame of the head of a fuel assembly, FIG. 5 shows a fastening of a centering pin, which is provided with a conical neck, on a fuel assembly, FIG. 6 shows a fastening of a centering pin by a weld seam, 7 shows a fastening of a stepped centering pin in the lower head region of a fuel assembly, FIG. 8 shows a centering pin spring-mounted in the head of a fuel assembly, and FIG. 9 shows a plan view of FIG. 8.
In der in FIG 1 gezeigten Draufsicht auf eine untere Gitterplat¬ te 4 eines Gerüsteinsatzes 5 sind die in einem Reaktorkern ange¬ ordneten Brennelemente 1 gestrichelt dargestellt. Wie FIG 3 zeigt, enthält jedes Brennelement 1 Brennstäbe, die in einer Tragstruktur gehalten sind, welchen einen Kopf 2 und einen Fuß besitzt. Dazwischen sind Führungsrohre für Steuerstäbe angeord¬ net, an denen Abstandshalter befestigt sind, welche die Brenn¬ stäbe bündeln. Eine Vielzahl von eng aneinandergereihten Brenn- elementen 1 bilden den Reaktorkern, der im Reaktordruckbehälter untergebracht ist. Über dem Brennelement 1 ist ein Gerüstein¬ satz 5 angeordnet, an dessen unten angebrachter Gitterplatte 4 vier Öffnungen 7 eines fiktiven Quadrates angebracht sind (FIG 1). In zwei diagonal gegenüberliegenden Öffnungen 7 ragen jeweils Zentrierstifte 3 hinein. Diese beiden Zentrierstifte 3 sind am Kopf 2 der Brennelemente 1 diagonal gegenüberliegend be¬ festigt, wie auch aus FIG 2 ersichtlich ist. In dieser FIG 2 kann man erkennen, daß die Brennelemente 1 in der Kernumfassung 8 eng aneinandergerückt angeordnet sind und daß die am Rand stehenden Brennelemente um 90" gedreht eingesetzt sind.In the plan view shown in FIG. 1 on a lower grid plate 4 of a framework insert 5, the fuel elements 1 arranged in a reactor core are shown in dashed lines. As FIG 3 shows, each fuel assembly 1 contains fuel rods, which are held in a support structure, which has a head 2 and a foot. In between are arranged guide tubes for control rods, to which spacers are attached, which bundle the fuel rods. A large number of fuel elements 1 closely arranged in a row form the reactor core, which is accommodated in the reactor pressure vessel. A scaffold insert 5 is arranged above the fuel element 1, on the lower grid plate 4 of which four openings 7 of a fictitious square are provided (FIG. 1). Centering pins 3 each protrude into two diagonally opposite openings 7. These two centering pins 3 are fastened diagonally opposite one another on the head 2 of the fuel assemblies 1, as can also be seen from FIG. In this FIG 2 can be seen that the fuel assemblies 1 are arranged close together in the core 8 and that the fuel assemblies standing on the edge are inserted rotated by 90 ".
Zum Befestigen der Zentrierstifte 3 im Kopf 2 der Brennelemente 1 sind gemäß FIG 4 im Rahmen 6 Bohrungen 9 angebracht, in welche die mit einem abgesetzten Hals 3a versehenen Zentrierstifte 3 eingesetzt und durch einen in eine Querbohrung 11 eingeführten Zentrierstift 10 gehalten sind. Aus der FIG 4 ist der Sitz des Zentrierstiftes 3 in der Zylinderöffnung 7 der Gitterplatte 4 des Gerüsteinsatzes 5 zu ersehen. Er ragt mit seiner Spitze 3b aus der Öffnung 7 heraus. Der Zylinderstift ist durch eine Stemmkante 12 gesichert. FIG 5 zeigt eine Befestigung eines Zylinderstiftes 3, der einen kegelförmigen Hals 3c mit Gewindeende 3d hat und in eine ent¬ sprechende konische Öffnung 13 im Rahmen 6 eingesetzt und durch eine Mutter 14 festgeschraubt ist. Zur Sicherung dient eine Spreizkerbe 15.To fix the centering pins 3 in the head 2 of the fuel assemblies 1, holes 4 are provided in the frame 6 according to FIG. 4, into which the centering pins 3 provided with a stepped neck 3a are inserted and held by a centering pin 10 inserted into a transverse bore 11. The seat of the centering pin 3 in the cylinder opening 7 of the grid plate 4 of the scaffold insert 5 can be seen from FIG. It protrudes from the opening 7 with its tip 3b. The cylinder pin is secured by a caulking edge 12. 5 shows a fastening of a cylindrical pin 3, which has a conical neck 3c with a threaded end 3d and is inserted into a corresponding conical opening 13 in the frame 6 and is screwed tight by a nut 14. A spreading notch 15 serves to secure it.
In FIG 6 ist ein Zentrierstift 3 dargestellt, der am Kopf 2 eines Brennelementes 1 durch eine Schweißnaht 16 befestigt ist.6 shows a centering pin 3 which is fastened to the head 2 of a fuel assembly 1 by a weld 16.
Aus FIG 7 geht eine Befestigung eines Zentrierstiftes 3 an einer Grundplatte 17 des Kopfes 2 eines Brennelementes hervor. In die¬ ser Grundplatte 17 ist eine Gewindebohrung 19 vorgesehen, in die Zentrierstift 3 eingedreht und durch eine Sicherungsschraube 20a fixiert ist. Der Zentrierstift 3 ist in einem vorgegebenen Zentrierbereich im Durchmesser abgesetzt, wobei das mit einer Einführspitze 3b versehene dünnere Ende 3e eine entsprechende Bohrung 18a in Aufbauten 18 der Gitterplatte 4 durchdringt.7 shows a fastening of a centering pin 3 on a base plate 17 of the head 2 of a fuel assembly. A threaded bore 19 is provided in this base plate 17, into which centering pin 3 is screwed and fixed by a locking screw 20a. The centering pin 3 is offset in diameter in a predetermined centering area, the thinner end 3e provided with an insertion tip 3b penetrating a corresponding bore 18a in structures 18 of the grid plate 4.
In den Figuren 4' bis 7 sind Ausführungen gezeigt, bei denen die Zentrierstifte 3 starr und austauschbar in den Kopf 2 der Brennelemente 1 eingesetzt sind.FIGS. 4 ' to 7 show designs in which the centering pins 3 are inserted rigidly and interchangeably into the head 2 of the fuel elements 1.
FIG 8 zeigt eine gefederte austauschbare Anordnung der Zentrier¬ stifte 3. Während die starren Zentrierstifte 3 bei einer Anord- nung von zwei Zentrierstiften im Kopf 2 vier Öffnungen 7 in der Grundplatte 4 benötigen, können bei der gefederten Ausführung der Zentrierstifte 3 vier Zentrierstifte - je einer in den vier Eckbereichen des Kopfes eines Brennelementes - angeordnet sein, die dann nur zwei Öffnungen in der Gitterplatte benötigen. Die dabei nicht in Eingriff befindlichen zwei Zentrierstifte sind während des Betriebes in eingedrückter Stellung und beteiligen sich an der gefederten Aufschwimmsicherung der Brennelemente durch den Gerüsteinsatz 5.8 shows a spring-loaded interchangeable arrangement of the centering pins 3. While the rigid centering pins 3 require four openings 7 in the base plate 4 when there are two centering pins in the head 2, in the spring-loaded version of the centering pins 3 four centering pins - each one in the four corner areas of the head of a fuel assembly - which then only need two openings in the grid plate. The two centering pins, which are not in engagement, are in the pressed-in position during operation and participate in the spring-loaded floating protection of the fuel assemblies through the framework insert 5.
In üblicher Weise sind auch bei gefederter Ausbildung der Zen¬ trierstifte zwei Zentrierstifte im Kopf der Brennelemente und vier Öffnungen in der Gitterplatte 4 vorgesehen. Sind zwei Stifte im Kopf und vier Öffnungen in der Gitterplatte 4 vorge¬ sehen, so kann es zu Schwierigkeiten kommen, wie dies z.B. bei Niederhaltebrücken 20 - an zwei Brennelementeposition in FIG 1 gezeigt - der Fall ist. Die Befestigungspunkte 21 dieser Nieder¬ haltebrücken 20 müssen dann zur Umgehung dieser Schwierigkeiten so angeordnet werden, daß sie neben dem Bereichen der Öffnungen 7 zu liegen kommen, d.h. neben zwei Öffnungen 7 sind jeweils mindestens zwei Befestigungspunkte 21 für die Niederhaltebrücken 20 vorgesehen.In the usual way there are two centering pins in the head of the fuel elements and, even if the centering pins are sprung four openings are provided in the grid plate 4. If two pins are provided in the head and four openings in the grid plate 4, difficulties can arise, as is the case, for example, with hold-down bridges 20 - shown at two fuel element positions in FIG. 1. To avoid these difficulties, the fastening points 21 of these hold-down bridges 20 must then be arranged such that they come to lie next to the region of the openings 7, ie in addition to two openings 7, at least two fastening points 21 are provided for the hold-down bridges 20.
Besonders vorteilhaft ist eine Ausbildung, die in FIG 8 darge¬ stellt ist, bei welcher der Zentrierstift einen kegelförmigen Zentrierbereich 3f aufweist, der keine selbsthemmende Wirkung haben darf (d.h. der Neigungswinkelc der Kegelfläche zur Mit¬ tenachse muß größer sein als der Reibungswinkel o , der im wesentlichen abhängig ist vom Werkstoff). Bei der dargestellten Zentrierstift-Gestaltung sind die Öffnung 7 in der Gitterplatte 4 des Gerüsteinsatzes 5 entsprechend konisch ausgebildet. Da- durch ergibt sich ein spielfreier Eingriff des Zentrierstiftes in die Öffnung 7, wobei er die Oberseite 4a der Gitterplatte 4 nicht bzw. nur unwesentlich überragt, so daß eventuell vorhande¬ ne Aufbauten 18 an der Gitterplatte 4 nicht stören.A design which is shown in FIG. 8 is particularly advantageous, in which the centering pin has a conical centering region 3f which must not have a self-locking effect (ie the angle of inclination c of the conical surface to the central axis must be greater than the friction angle o) essentially depends on the material). In the centering pin design shown, the opening 7 in the grid plate 4 of the scaffold insert 5 is correspondingly conical. This results in a play-free engagement of the centering pin in the opening 7, whereby it does not protrude from the top 4a of the grid plate 4 or only slightly so that any structures 18 present on the grid plate 4 do not interfere.
Bei der gefederten Ausführung können also sowohl zwei Stifte am Kopf der Brennelemente 1 und vier Öffnungen in der Gitterplatte 4 des Gerüstaufbaues angeordnet sein, sowie vier Stifte am Kopf der Brennelemente und zwei Zentrieröffnungen 7 in der Gitter- platte 4 des Gerüsteinsatzes 5 vorgesehen sein.In the sprung version, two pins can thus be arranged at the head of the fuel assemblies 1 and four openings in the grid plate 4 of the scaffold structure, as well as four pins at the head of the fuel assemblies and two centering openings 7 in the grid plate 4 of the scaffold insert 5.
Diese letztere Lösung ist in der Draufsicht in der FIG 9 dar¬ gestellt. In den Eckbereichen des Kopfes 2 sind Aufnahmeboh¬ rungen 21 angeordnet, in welche die Zentrierstifte eingesetzt werden. Zwischen dem Zentrierstift 3 und der Grundplatte 17 eine Druckfeder 22 angebracht, welche den Zentrierstift 3 einem Anschlagbund 23 in die dargestellte Position drückt, der Grundplatte ist ein Zentrierteil 24 für die Druckfeder befestigt. This latter solution is shown in the top view in FIG. In the corner areas of the head 2 there are receiving bores 21 in which the centering pins are inserted. Between the centering pin 3 and the base plate 17th a compression spring 22 is attached, which presses the centering pin 3 a stop collar 23 in the position shown, the base plate is a centering part 24 for the compression spring attached.
Claims
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/DE1988/000604 WO1990003647A1 (en) | 1988-09-30 | 1988-09-30 | Arrangement for centering components of a nuclear reactor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| EP0429445A1 true EP0429445A1 (en) | 1991-06-05 |
Family
ID=6819734
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP88909299A Withdrawn EP0429445A1 (en) | 1988-09-30 | 1988-09-30 | Arrangement for centering components of a nuclear reactor |
Country Status (2)
| Country | Link |
|---|---|
| EP (1) | EP0429445A1 (en) |
| WO (1) | WO1990003647A1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102013113523B3 (en) * | 2013-10-29 | 2015-04-30 | Areva Gmbh | Method for connecting a centering pin with a core grid |
| ITUA20163713A1 (en) * | 2016-05-04 | 2017-11-04 | Luciano Cinotti | NUCLEAR REACTOR WITH SELF-SUPPORTING HAZELNUT |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4030975A (en) * | 1973-06-25 | 1977-06-21 | Combustion Engineering, Inc. | Fuel assembly for a nuclear reactor |
| SE387766B (en) * | 1974-12-30 | 1976-09-13 | Asea Atom Ab | FUEL CARTRIDGE WITH EASY REMOVABLE COMPONENTS |
| US4560532A (en) * | 1982-04-15 | 1985-12-24 | Westinghouse Electric Corp. | Nuclear fuel assembly |
-
1988
- 1988-09-30 EP EP88909299A patent/EP0429445A1/en not_active Withdrawn
- 1988-09-30 WO PCT/DE1988/000604 patent/WO1990003647A1/en not_active Application Discontinuation
Non-Patent Citations (1)
| Title |
|---|
| See references of WO9003647A1 * |
Also Published As
| Publication number | Publication date |
|---|---|
| WO1990003647A1 (en) | 1990-04-05 |
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