JP2017049170A - Atomic reactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an atomic reactor having a simple structure and capable of sufficiently suppressing the jumping of a reactor core component.SOLUTION: An atomic reactor 100 includes: a plurality of reactor core elements having an atomic core container filled inside with a liquid, a plurality of connecting pipes 30 having a vertically extended cylindrical shape and arranged in a horizontal direction, an entrance nozzle 22 inserted into each connecting pipe, an outer coat part 21 positioned above the entrance nozzle 22 and having a diameter larger than that of the entrance nozzle 22, a connection part for vertically connecting the entrance nozzles 22 and the outer coat part 21, and a pad part 24 provided at a lower end of the outer coat part 21 and having a diameter larger than that of the outer coat part 21. A narrowing part A smaller in vertical cross-section than the other area is formed between the pads 24 adjacent to each other.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a nuclear reactor.

In a nuclear power generation facility, power is generated by driving a turbine using heat from a fission reaction that proceeds in a core. Core components such as a nuclear fuel rod in which nuclear fuel is sealed and a control rod for controlling the progress of the fission reaction are stored inside the core.
An entrance nozzle is formed at the end of the core component. By inserting the entrance nozzle into the connecting pipe, the core components are supported in a self-supporting state. Therefore, when an earthquake occurs, the core components jump out of the connecting pipe. In this case, the core components can be dissipated in the core, which can hinder the insertion of control rods in particular.

  As a technique for suppressing the jumping of the core components as described above, a technique described in Patent Document 1 below is known. In the support structure described in Patent Document 1, a through hole is provided in a part of the connecting pipe, and a groove corresponding to the through hole is formed in the side wall of the entrance nozzle. Further, this device includes a shear rod that can move through the through hole and the groove.

JP-A-5-150075

  However, since the core and its surroundings reach a high temperature, there is a possibility that thermal expansion will occur in each member such as the core component and the connecting pipe. When such thermal elongation occurs, in the support structure described in Patent Document 1, the shear rod may not be properly fitted to the through hole and the groove, and the intended function may not be achieved. That is, there is room for improvement in the technique of Patent Document 1.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a nuclear reactor that has a simple configuration and can sufficiently suppress the jumping of core components.

  A nuclear reactor according to a first aspect of the present invention includes a nuclear reactor vessel filled with a liquid, and a connection provided in the nuclear reactor vessel and having a cylindrical shape extending in the vertical direction and arranged in the horizontal direction. A pipe, an entrance nozzle inserted in each of the connecting pipes, a jacket part positioned above the entrance nozzle and having a larger diameter than the entrance nozzle, and connecting the entrance nozzle and the jacket part in the vertical direction A plurality of core components having a connecting portion and a pad portion provided at a lower end of the mantle portion and having a diameter larger than that of the mantle portion, and the other between the pad portions adjacent to each other. A narrowed portion having a smaller vertical sectional area than the region is formed.

  According to this configuration, the pad portions in the plurality of core components adjacent to each other form a narrowed portion. Therefore, when an upward force is applied to the core component by the vertical vibration given from the outside, flow path resistance is generated when the liquid in the reactor vessel body flows through the constricted portion. By this flow path resistance, upward jumping of the core components can be suppressed.

  In the nuclear reactor according to the second aspect of the present invention, the pad portion may extend from a lower end of the mantle portion to a lower end of the connection portion.

  According to this configuration, the space between the pad portion and the upper end surface of the connecting pipe can be reduced. As a result, a squeeze effect is generated between the pad portion and the upper end surface of the connecting pipe, so that when a vertical vibration is applied from the outside, a force is applied in a direction to resist the core components. Therefore, the upward jump of the core component can be suppressed.

  In the nuclear reactor according to the third aspect of the present invention, the surface from the lower end of the connecting portion to the upper end of the entrance nozzle may have a shape corresponding to the shape of the upper end surface of the connecting pipe.

  According to this configuration, since a squeeze effect occurs between the surface from the lower end of the connecting portion to the upper end of the entrance nozzle and the upper end surface of the connecting pipe, even when vertical vibration is applied from the outside, A force can be applied in a direction that resists the core components. Therefore, the upward jump of the core component can be suppressed.

  According to the present invention, it is possible to provide a nuclear reactor that has a simple configuration and can sufficiently suppress jumping of core components.

1 is an overall view of a nuclear reactor according to each embodiment of the present invention. It is a figure which shows the core periphery of the reactor which concerns on each embodiment of this invention. It is a figure which shows the core component which concerns on embodiment of this invention. It is a figure which shows the modification of the core structural element which concerns on embodiment of this invention. It is a figure which shows the core component which concerns on embodiment of this invention. It is a figure which shows the modification of the core structural element which concerns on embodiment of this invention. It is a figure which shows the modification of the core structural element which concerns on embodiment of this invention.

  A first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a nuclear reactor 100 as a fast breeder reactor. The nuclear reactor 100 includes a nuclear reactor vessel 1, a core 2, a support structure 3, and an upper structure 4.

  The reactor vessel 1 includes a reactor vessel body 10, a shielding plug 11, a coolant inlet pipe 12 and a coolant outlet pipe 13, and a partition wall 14. An opening is formed in the upper part of the reactor vessel main body 10 and is stored in the reactor 100 containment vessel (not shown) with the bottom opposite to the upper part facing vertically downward. The shielding plug 11 is disposed in the opening in the reactor vessel body 10 to seal the opening. The coolant inlet pipe 12 and the coolant outlet pipe 13 form an inlet / outlet for the coolant (primary main coolant) into the reactor vessel 1. The partition wall 14 is a plate-like member having an opening at the center. The partition wall 14 extends in the horizontal direction inside the reactor vessel 1, thereby dividing the inside of the reactor vessel 1 in the vertical direction.

  The reactor core 2 mainly has a control rod assembly and a fuel rod assembly, and is disposed in the central portion of the reactor vessel 1. Here, elements constituting the core 2 such as a fuel assembly and a control rod assembly are collectively referred to as a core component 20. The support structure 3 is a structure for supporting the core component 20, and is disposed at the center of the reactor vessel 1 when viewed in the vertical direction. Further, the partition wall 14 is fixed to the reactor vessel 1 and the support structure 3.

  The support structure 3 has a plurality of connecting pipes 30. One core component 20 is arranged for each of the connecting pipes 30. The upper structure 4 includes, for example, a drive device for driving a control rod that is the core component 20. The upper structure 4 is disposed above the core 2, penetrates the shielding plug 11, and is fixed by the shielding plug 11.

  In the nuclear reactor 100 configured as described above, heat is generated by the fission reaction in the core 2. Further, after the coolant is supplied from the coolant inlet pipe 12 to the lower part in the reactor vessel 1, the coolant flows from the lower side to the upper side. Next, the coolant passes through the connecting pipe 30 and the inside of the core component 20 to absorb the heat of the core 2. Thereafter, the coolant that has reached a high temperature is delivered from the coolant outlet pipe 13 to the outside of the reactor vessel 1.

  Next, a support structure for the core component 20 and the connecting pipe 30 in the present embodiment will be described with reference to FIG. As shown in the figure, the core component 20 according to the present embodiment is a long member having a columnar shape. Specifically, the core component 20 includes a mantle portion 21, an entrance nozzle 22, a connection portion 23 that connects the mantle portion 21 and the entrance nozzle 22, and a pad provided on the outer peripheral side of the connection portion 23. Part 24.

  The outer jacket portion 21 is a trumpet tube or a guide tube having a hexagonal cross section when viewed in the vertical direction, and constitutes a main body portion of the core component 20. The entrance nozzle 22 is formed at an end portion of one side of the mantle portion 21 (particularly, the lower side when the core component 20 is disposed in the connecting pipe 30). Further, the interior of the core component 20 is hollow. Openings are respectively formed from the end portion on the entrance nozzle 22 side to the end portion on the mantle portion 21 side. That is, the inside and outside of the core component 20 communicate with each other through these end portions. Further, the region including the lower end of the outer jacket portion 21 is gradually reduced in diameter as it goes from the upper side to the lower side, and the transition portion 25 is formed by forming a circular cross section when viewed in the vertical direction.

  The connecting portion 23 connects the outer jacket portion 21 and the entrance nozzle 22 in the vertical direction. The outer diameter dimension of the connection portion 23 is set smaller than the outer diameter dimension of the outer jacket portion 21. Further, the outer cover portion 21 has a hexagonal cross-sectional shape as described above, whereas the connection portion 23 has a circular cross-sectional shape. The cross-sectional area of the connecting portion 23 is constant over the vertical direction. In other words, the connection part 23 has a straight tubular shape extending in the up-down direction. Furthermore, the part including the lower end of the connection part 23 is made into the contact part 26 by gradually reducing the diameter from the upper side to the lower side, like the transition part 25 described above.

  The pad portion 24 is an annular member provided on the outer peripheral side of the connection portion 23 described above. The cross section of the pad portion 24 viewed from the horizontal direction (direction perpendicular to the vertical direction) is generally rectangular. On the other hand, the outer peripheral surface of the cross section in the vertical direction of the pad portion 24 is generally hexagonal. Further, the central portion of this cross section is penetrated in a substantially circular shape corresponding to the outer peripheral surface of the connecting portion 23. This penetrating portion is a pad portion opening 241.

  In the cross section of the pad portion 24, the surface facing the pad portion opening 241 is a pad portion inner peripheral surface 242. On the other hand, the surface facing the outer peripheral side of the pad portion 24 is a pad portion outer peripheral surface 243. Furthermore, the upper side surface and the lower side surface are a pad portion upper surface 244 and a pad portion lower surface 245, respectively.

  The inner diameter dimension of the pad portion 24 (that is, the radial dimension of the pad inner peripheral surface 242) is substantially the same as the outer diameter dimension of the connection portion 23. As a result, the inner peripheral surface of the pad portion 24 is fixedly supported in a state of being in close contact with the outer peripheral surface of the connection portion 23 from the outer side in the radial direction of the connection portion 23 with substantially no gap.

  On the other hand, the radial dimension of the pad portion outer peripheral surface 243, that is, the length of the hexagonal diagonal line formed by the pad portion outer peripheral surface 243 is set to be larger than the diagonal length of the hexagonal shape of the outer cover portion 21. ing.

  Further, as shown in FIG. 3, the connecting pipe 30 includes a cylindrical connecting pipe main body 31 surrounding the entrance nozzle 22 from the outer peripheral side, and a plurality of connecting pipe main bodies 31 arranged at intervals in the horizontal direction. And a support plate portion 32 to be supported. The support plate part 32 supports the upper end part (flange part 31A) of the connecting pipe main body part 31 from below. The opening end at the upper end of the connecting pipe main body 31 is made into the connecting pipe insertion part 33 by gradually increasing the diameter from the lower side toward the upper side.

  As shown in FIGS. 2 and 3, a plurality of core components 20 configured as described above are arranged in a state of being adjacent to each other in the horizontal direction (along a horizontal plane) with respect to the connecting pipe 30. Each core component 20 is arranged in a state in which hexagonal sides having a cross section when viewed from above and below are opposed to each other. Further, a slight gap is formed in the horizontal direction between the opposing sides. During normal operation of the nuclear reactor 100, the gap is filled with a liquid coolant.

  Furthermore, as shown in FIG. 3, a narrowed portion A is formed by forming a gap also between the pad portion outer peripheral surfaces 243 facing each other in the horizontal direction. The constricted portion A is also filled with a coolant. Similarly, a slight gap is also formed between the pad portion lower surface 245 and the flange portion 31A. In particular, in the present embodiment, the pad portion lower surface 245 and the flange portion 31A extend in the horizontal direction in parallel with each other. In other words, the surface from the lower end of the connecting portion 23 to the upper end of the entrance nozzle 22 has a shape corresponding to the shape of the upper end surface (connecting tube insertion portion 33) of the connecting tube 30.

  On the other hand, the contact part 26 formed between the connection part 23 and the entrance nozzle 22 is in contact with the above-described connecting pipe insertion part 33. Thereby, the core component 20 is supported on the connecting pipe 30. In other words, the weight of the core component 20 is supported by the connecting pipe insertion portion 33.

  When vertical vibration is applied to the nuclear reactor 100 configured as described above, for example, due to an earthquake or the like, the core component 20 will be displaced away from the connecting pipe 30 (support plate portion 32) upward. And Here, since the outside of the core component 20 is filled with the coolant as described above, the coolant tends to flow downward as the core component 20 is displaced upward. (Conversely, when the core component 20 is displaced downward, the coolant tends to flow upward.)

  However, a flow path resistance is generated in the narrowed portion A with respect to the coolant that flows in this way. Furthermore, a squeeze film damper phenomenon occurs between the pad portion lower surface 245 and the flange portion 31A. Therefore, pressure loss occurs in the inflow and outflow of the coolant in the constricted portion A. Therefore, when the pad portion lower surface 245 is separated and displaced from the flange portion 31A, a damping force with respect to the relative speed is generated.

  Therefore, even when vertical vibrations are applied from the outside due to an earthquake or the like, a damping force with respect to the relative speed in the upward and downward directions is generated, so that jumping up of the core component 20 can be reduced.

  Further, when the core component 20 is exposed to a high temperature environment during the operation of the nuclear reactor 100, each member may be deformed due to thermal expansion. When such thermal elongation occurs, the gap between the pad portions 24, that is, the opening size of the narrowed portion A is further reduced, so that the flow path resistance in the narrowed portion A with respect to the coolant is increased. Thereby, it can fully maintain, without impairing the damping force with respect to the relative velocity of the core component 20. FIG.

  On the other hand, when moving parts are used for the purpose of suppressing the jumping of the core component 20 or when using other configurations that require relatively high accuracy, the expected function is achieved by the above-described thermal elongation. There is a possibility that you will not be able to fulfill. However, in the core component 20 of the present embodiment, not only such movable parts are used, but also processing accuracy and dimensional accuracy equivalent to those of other members are allowed, so that the influence of thermal elongation and the like is reduced. be able to.

  Furthermore, when the pad portion 24 is configured as a member different from the core component 20, it can be easily disposed with respect to the existing nuclear reactor 100.

  Further, as described above, the jumping can be sufficiently suppressed only by providing the pad portion 24, so that the number of parts of the core component 20 can be reduced, and the manufacturing cost and the construction cost can be reduced. . Therefore, according to the above configuration, it is possible to provide the nuclear reactor 100 that has a simple configuration and can sufficiently suppress the jumping of the core component 20.

  Further, as described above, since the core component 20 is supported by the connecting pipe 30 provided below, the pad portion 24 is provided on the side close to the entrance nozzle 22 (lower portion of the core component 20). Thus, the swing range caused by vibration such as an earthquake can be made extremely small. In other words, the core component 20 can be supported more stably by providing the pad portion 24 below.

  The embodiments of the present invention have been described above with reference to the drawings. However, the above embodiment is merely an example, and various modifications can be made without departing from the gist of the present invention.

  For example, in the above-described embodiment, the configuration in which the contact portion 26 in the core component 20 is formed in a straight line when viewed from the horizontal direction has been described. However, as shown in FIG. 4, the contact portion 260 may be formed by gradually bending from the lower end of the connection portion 23 toward the upper end of the entrance nozzle 22. More specifically, the contact portion 260 protrudes so as to curve from the radially inner side to the outer side of the core component 20.

  Thereby, the contact part 260 and the connection pipe insertion part 33 contact | abut at one point on a circular arc seeing from the horizontal direction, and can further make the clearance gap between the pad part lower surface 245 and the connection pipe 30 smaller. it can. Therefore, the above-described squeeze film damper phenomenon can be expressed more effectively. That is, even when vertical vibration is applied to the core component 20, the upward jump of the core component 20 can be suppressed.

  Furthermore, as shown in FIG. 5, the connecting pipe insertion portion 33 may have a curved shape corresponding to the contact portion 260. Thereby, the adhesiveness of the connection pipe insertion part 33 and the contact part 260 can be improved. Therefore, in addition to the squeeze film damper effect by the pad part 24 and the support plate part 32, the same effect can be expressed also between the connection pipe insertion part 33 and the contact part 260. Thereby, the jumping up of the core component 20 can be further suppressed.

  In addition, in the example of FIG. 5, the transition portion 25 and the connection portion 23 form a continuous surface, and the pad portion inner peripheral surface 242 has a shape corresponding to the shape of the connection portion 23. According to such a configuration, the cost and time required for processing and manufacturing the core component 20 can be further reduced. Furthermore, the volume of the space from the lower end of the mantle portion 21 to the flange portion 31 </ b> A can be made smaller than the volume of the space above the lower end of the mantle portion 21. Thereby, the above-mentioned squeeze film damper effect can be made to act more fully.

In addition, it is possible to adopt a configuration as shown in FIG. In the example shown in the figure, the pad portion 24 has a shape corresponding to the shape of the transition portion 25. More specifically, the pad portion 24 in this example corresponds to the transition portion 25 of the entrance nozzle 22 by forming the upper half portion so that the opening diameter gradually decreases from the upper side toward the lower side. It is made into a shape.
According to such a structure, the squeeze film damper phenomenon produced between the pad part 24 and the flange part 31A can be produced more effectively. That is, jumping up of the core component 20 can be further suppressed.

DESCRIPTION OF SYMBOLS 1 ... Reactor vessel 2 ... Core 3 ... Support structure 4 ... Superstructure 10 ... Reactor vessel main body 11 ... Shield plug 12 ... Coolant inlet piping 13 ... Coolant outlet piping 14 ... Bulkhead 20 ... Core component 21 ... Outer part 22 ... Entrance nozzle 23 ... Connection part 24 ... Pad part 25 ... Transition part 26 ... Abutting part 30 ... Connection pipe 31 ... Connection pipe body part 31A ... Flange part 32 ... Support plate part 33 ... Connection pipe insertion part 100 ... Reactor 241 ... Pad part opening 242 ... Pad part inner peripheral surface 243 ... Pad part outer peripheral surface 244 ... Pad part upper surface 245 ... Pad part lower surface 260 ... Contact part A ... Narrowed part

Claims (3)

A reactor vessel filled with a liquid,
A connecting pipe which is provided in the reactor vessel, has a cylindrical shape extending in the vertical direction, and is arranged in a plurality in the horizontal direction;
An entrance nozzle inserted into each of the connecting pipes;
A mantle that is located above the entrance nozzle and has a larger diameter than the entrance nozzle;
A connecting portion for connecting the entrance nozzle and the mantle portion in the vertical direction;
A pad portion provided at a lower end of the mantle portion and having a larger diameter than the mantle portion;
A plurality of core components having:
With
A nuclear reactor in which a constricted portion having a smaller vertical sectional area than other regions is formed between the pad portions adjacent to each other.   The nuclear reactor according to claim 1, wherein the pad portion extends from a lower end of the mantle portion to a lower end of the connection portion.   The nuclear reactor according to claim 1 or 2, wherein a surface from a lower end of the connection portion to an upper end of the entrance nozzle has a shape corresponding to a shape of an upper end surface of the connection pipe.

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