Electrical penetration structure of sodium cooling fast reactor

Abstract

To provide an electrical penetration structure with excellent heat resistance and radiation shielding properties.SOLUTION: An electrical penetration structure S100 comprises: a sleeve 31 provided to penetrate a wall of a containment vessel 20 that houses a reactor vessel 10 or a wall of a room that houses a device or pipe that uses sodium as a coolant; a hollow cylindrical trunk 35 that is provided inside the sleeve 31, and has an inside end surface facing the inside of the containment vessel 20 and an outside end surface facing the outside of the containment vessel; an inorganic insulated cable 70 passed through the inside of the cylindrical trunk 35; and a radiation shielding plate 40 that is arranged in the cylindrical trunk 35, shields the passage of radiation from the inside end surface side to the outside end surface side, and is made of bismuth oxide.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an electric penetration structure for a sodium-cooled fast reactor. [Background technology]

[0002] Conventionally, electrical wiring that penetrates the bulkheads of a reactor containment vessel or a sodium coolant equipment room is routed through an electrical wiring penetration structure called an electrical penetration in order to shield against radiation and ensure airtightness. Patent Document 1 discloses a configuration in which the cable placed inside the hollow body is an inorganic insulated cable so as to maintain performance under high temperature and high pressure conditions. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-50859 Summary of the Invention [Problem to be solved by the invention]

[0004] For example, there was room for improvement in the conventional structure in terms of heat resistance and radiation shielding performance in the event that high-temperature coolant such as sodium leaks from the reactor vessel, sodium coolant equipment, or piping.

[0005] The present invention has been made in view of these points, and has as its object to provide an electrical penetration structure that is excellent in heat resistance and radiation shielding properties. [Means for solving the problem]

[0006] An electrical penetration structure of one form of the present invention comprises: a sleeve provided to penetrate the wall of a containment vessel that houses a reactor vessel or the wall of a room that houses equipment or piping that uses sodium as a coolant; a hollow cylindrical body provided inside the sleeve and having an inner end face facing the inside of the containment vessel and an outer end face facing the outside of the containment vessel; an inorganic insulated cable passed through the inside of the cylindrical body; and a radiation shielding plate made of bismuth oxide that is disposed in the cylindrical body and blocks radiation from passing from the inner end face side to the outer end face side.

[0007] The radiation shielding plates may include a first radiation shielding plate arranged closer to the inner end surface of the cylindrical body, and a second radiation shielding plate arranged at a position away from the first radiation shielding plate in the axial direction of the cylindrical body.

[0008] The first radiation shielding plate and the second radiation shielding plate may have a through hole through which the inorganic insulated cable is passed, and the through hole of the first radiation shielding plate and the through hole of the second radiation shielding plate may be positioned on the same straight line.

[0009] The tubular body may have an end plate arranged on the outer end surface, and the end plate may have a tubular sleeve formed thereon through which the mineral insulated cable is passed, and the end surface of the tubular sleeve may be fixed to the sheath of the mineral insulated cable by welding. [Effects of the Invention]

[0010] The present invention has the effect of providing an electrical penetration structure that is excellent in heat resistance and radiation shielding properties. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram illustrating a fast reactor including an electric penetration structure for a sodium-cooled fast reactor according to one embodiment of the present invention; [Figure 2] FIG. 1 is a cross-sectional view showing an electrical penetration structure. [Figure 3]FIG. 4 is a cross-sectional view showing the structure for fixing the cable to the end plate. [Figure 4] 10A and 10B are diagrams showing modified examples of the electrical penetration structure. [Figure 5] FIG. 10 shows an example of an end plate with multiple cables threaded through it. DETAILED DESCRIPTION OF THE INVENTION

[0012] Fig. 1 is a diagram schematically showing a fast reactor including an electric penetration structure for a sodium-cooled fast reactor according to one embodiment of the present invention, and Fig. 2 is a cross-sectional view showing the electric penetration structure.

[0013] 1 includes, as its main components, a reactor vessel 10, a containment vessel 20, and an electrical penetration structure S100. One of the features of the configuration of this embodiment is that the electrical penetration structure S100 is provided with a shielding material made of bismuth oxide to prevent sodium and radiation from being released to the outside even if sodium, which is the coolant of the reactor vessel 10, leaks.

[0014] The reactor vessel 10 is a vessel that houses the reactor core 11 together with a coolant 15. The reactor vessel 10 is also called a main vessel in a tank-type fast reactor 1, and has a diameter of, for example, about 15 m to 20 m.

[0015] The reactor core 11 has fuel assemblies, which are nuclear fuel, and control rods (neither of which is shown). The coolant 15, which is sodium in this embodiment, cools the reactor core 11. The coolant 15 circulates within the reactor vessel 10 by the action of a pump, not shown, arranged within the reactor vessel 10. The temperature of the sodium coolant during operation of the fast reactor 1 is, for example, 500°C or higher.

[0016] The reactor vessel 10 is provided with instruments 18. Although only one instrument 18 is illustrated in Fig. 1, the reactor vessel 10 is provided with a plurality of instruments 18 that measure various conditions of the reactor vessel 10 and the elements housed therein. Specifically, the instruments 18 include, for example, a thermometer, a flow meter, a pressure meter, and a liquid level meter. The instruments 18 transmit measurement signals to the outside via a cable 70.

[0017] The containment vessel 20 is a vessel that surrounds the reactor vessel 10. In FIG. 1 , the containment vessel 20 surrounds the reactor vessel 10, but the containment vessel 20 may be a vessel that houses other equipment that uses sodium as a coolant. The containment vessel 20 may house such other equipment that uses sodium as a coolant together with the reactor vessel 10. The containment vessel 20 may house, for example, a nitrogen atmosphere chamber in which other equipment that uses sodium as a coolant is arranged.

[0018] The electric penetration structure S100 is a structure through which cables 70 connected to the instruments 18 and cables for supplying power from the outside to equipment inside the containment vessel 20 are passed. The following description will be given using the cable 70 connected to the instruments 18 as an example. As shown in FIG. 2 , the electric penetration structure S100 has a sleeve 31, a cylindrical body 35, the cable 70, and a radiation shielding plate 40.

[0019] Both the sleeve 31 and the cylindrical body 35 are made of metal. The sleeve 31 is formed in a cylindrical shape. The sleeve 31 is, for example, a cylinder. The sleeve 31 is provided so as to penetrate the wall 21 of the containment vessel 20. As an example, the sleeve 31 is fixed to the wall 21 with its axis parallel to the thickness direction of the wall 21.

[0020] The cylindrical body 35 has a cylindrical body 36, and end plates 37A and 37B. The cylindrical body 35 is a hollow member provided inside the sleeve 31 and forms a sealed internal space. Nitrogen gas is sealed inside the cylindrical body 35, and the internal pressure is measured by a pressure gauge.

[0021] The cylindrical body 36 is formed to a size that allows it to be placed inside the sleeve 31. In the example of FIG.

[0022] The end plate 37A is fixed to the cylindrical body 36 so as to close the opening at one end (left side in the figure) of the cylindrical body 36. The end plate 37A forms the inner end surface of the cylindrical body 35 that faces the inside of the containment vessel 20. The end plate 37B has a structure similar to that of the end plate 37A. The end plate 37B is fixed to the cylindrical body 36 so as to close the opening at the other end (right side in the figure) of the cylindrical body 36. The end plate 37B forms the outer end surface of the cylindrical body 35 that faces the outside of the containment vessel 20.

[0023] The method of fixing the cylindrical body 35 to the sleeve 31 is not limited to a specific structure. As shown in Fig. 2, the cylindrical body 35 is fixed to the sleeve 31 by, for example, a fixing member 51 provided between the sleeve 31 and the cylindrical body 35. In this example, the fixing member 51 is provided near the end closer to the end plate 37B. An O-ring 52 is provided between the sleeve 31 and the cylindrical body 35 near the end closer to the end plate 37A.

[0024] As described above, the cable 70 is a cable connected to the instrument 18. The cable 70 is, for example, an inorganic insulation (MI) cable, and has a configuration in which an internal core wire is covered with an inorganic insulator such as magnesium oxide and further covered with a sheath that serves as a protective tube. The sheath is, for example, a metal sheath made of SUS304. The cable 70 is drawn from the inside to the outside of the containment vessel 20 through the electrical penetration structure S100. Although only one cable 70 is shown in FIG. 2, multiple cables formed similarly to the illustrated cable 70 may be passed through the tubular body 35.

[0025] 2, the cable 70 is passed through the inside of the cylindrical body 35 of the electric penetration structure S100. The cable 70 extends in a direction parallel to the extension direction of the cylindrical body 35. Specifically, the cable 70 penetrates one end plate 37A, extends inside the cylindrical body 36, and then penetrates the other end plate 37A to extend out to the outside of the containment vessel 20.

[0026] The cable 70 may extend straight inside the tubular body 35, but in this embodiment, the cable 70 extends in a partially curved manner. The cable 70 has a first portion 71, a bent portion 72, a second portion 73, a bent portion 74, and a third portion 75. The first portion 71, the second portion 73, and the third portion 75 are portions that extend straight. The first portion 71 passes through the end plate 37A.

[0027] The second portion 73 is connected to the first portion 71 via a bent portion 72. The second portion 73 extends at an offset position so as not to be located on the axis of the first portion 71. The third portion 75 is connected to the second portion 73 via a bent portion 74. The third portion 75 also extends at an offset position so as not to be located on the axis of the second portion 73. In this embodiment, the third portion 75 and the first portion 71 are located coaxially, as an example, but in the present invention, the third portion 75 and the first portion 71 do not have to be located coaxially.

[0028] The radiation shielding plate 40 is a member that blocks radiation from passing through. In this example, the radiation shielding plate 40 is arranged on a side of the cylindrical body 35 that is closer to the end plate 37A. The radiation shielding plate 40 is, for example, a disk-shaped member that is fitted inside the cylindrical body 35. The radiation shielding plate 40 has a through-hole 40h through which the first portion 71 of the cable 70 is passed. The through-hole 40h is formed to extend in the thickness direction of the radiation shielding plate 40.

[0029] The radiation shielding plate 40 is made of a material that has sufficient radiation shielding properties and heat resistance. In this embodiment, the radiation shielding plate 40 is made of bismuth oxide (Bi2O3). If the radiation shielding plate 40 is made of lead, for example, the melting point of lead is about 327.5°C, which is insufficient in heat resistance to the sodium coolant, which reaches temperatures of 500°C or higher. In contrast, if the radiation shielding plate 40 is made of bismuth oxide, the melting point of bismuth oxide is about 817°C, which is sufficient in heat resistance to the sodium coolant.

[0030] 2, in this example, the inner end face 40a of the radiation shielding plate 40 protrudes further toward the inside of the containment vessel 20 than the end face of the sleeve 31. The end face 40b of the radiation shielding plate 40 opposite to the end face 40a is located outside (to the right in the figure) the position where the O-ring 52 is disposed.

[0031] As described above, the electrical penetration structure S100 of this embodiment is provided with the radiation shielding plate 40, which is made of bismuth oxide and blocks radiation from passing from the end plate 37A side to the end plate 37B side. This radiation shielding plate 40 has sufficient radiation shielding properties and is also heat resistant to sodium coolant. Therefore, even if a high-temperature coolant such as sodium leaks, the electrical penetration structure S100 will not be damaged, and radiation will be prevented from leaking to the outside.

[0032] (Fixing structure of cable 70 on end plate) Fig. 3 is a cross-sectional view showing the fixing structure of cables 70 on an end plate. Note that Fig. 3 shows a configuration in which a plurality of cables 70 are provided. In this embodiment, such fixing structures are provided on both end plate 37A and end plate 37B, but the following description will be given using end plate 37B as an example.

[0033] The end plate 37B is provided with a tubular sleeve 39. The tubular sleeve 39 is, for example, a cylinder, and is fixed in a direction extending perpendicular to the end plate 37B. A cable 70 is passed through the inside of the tubular sleeve 39.

[0034] Although it is conceivable to fix the cable 70 to the tubular sleeve 39 by, for example, crimping the entire circumference of the tubular sleeve 39 or using a fastener, in this embodiment, the cable 70 and the tubular sleeve 39 are fixed together by welding. Specifically, the end face of the tubular sleeve 39 farther from the end plate 37B is fixed to the outer peripheral surface of the sheath of the cable 70 by welding.

[0035] In the case of such fixation by welding, the welded portion W is formed near the end face of the cylindrical sleeve 39, which allows for a more compact configuration compared to a method of crimping the cylindrical sleeve 39 or a method of using a fastener to fix the cable 70 to the cylindrical sleeve 39. In one embodiment, it is preferable that the welded portion W be formed with a diameter smaller than the diameter of the cylindrical sleeve 39.

[0036] (Effect of Electric Penetration Structure S100) As described above, according to the electrical penetration structure S100 of this embodiment, the radiation shielding plate 40 made of bismuth oxide is provided on the cylindrical body 35, thereby preventing radiation from being emitted to the outside, and even if high-temperature sodium coolant leaks, the radiation shielding plate 40 has sufficient heat resistance, preventing radiation from leaking outside the electrical penetration structure S100.

[0037] <Variation 1> Fig. 4 is a diagram showing a modified example of the electric penetration structure. The electric penetration structure S101 in Fig. 4 has a first radiation shielding plate 41 and a second radiation shielding plate 42 as the radiation shielding plate 40. The other structures are the same as those of the electric penetration structure S100 described above, so a duplicated description will be omitted.

[0038] The first radiation shielding plate 41 is disposed on the side closer to the end plate 37A. The first radiation shielding plate 41 has, for example, the same shape and material as the radiation shielding plate 40 described above. The second radiation shielding plate 42 is disposed at a position spaced apart from the first radiation shielding plate 41 in the axial direction of the cylindrical body 35. Like the first radiation shielding plate 41, the second radiation shielding plate 42 is made of bismuth oxide. The second radiation shielding plate 42 has a through-hole 42h formed therein, through which the cable 70 is passed. The space between the first radiation shielding plate 41 and the second radiation shielding plate 42 is filled with, for example, nitrogen.

[0039] The first radiation shielding plate 41 and the second radiation shielding plate 42 are provided so that the through hole 41h of the first radiation shielding plate 41 and the through hole 42h of the second radiation shielding plate 42 are not positioned on the same straight line. In this way, with a configuration in which the through hole of one shielding plate and the through hole of the other shielding plate are not positioned on the same straight line, the second radiation shielding plate 42 can effectively shield radiation that travels through a gap between the through hole 41h and the cable 70 in the extension direction of the through hole (here, the thickness direction of the shielding plate).

[0040] In assembling the electric penetration structure S101, for example, the cable 70 may first be passed through the second radiation shielding plate 42, and then, after the bent portions 72 and 74 are formed, the first portion 71 may be passed through the first radiation shielding plate 41 and the end plate 37A, and the third portion 75 may be passed through the end plate 37B. As a result of this procedure, for example, the bent portion 72 is located in the space between the first radiation shielding plate 41 and the second radiation shielding plate 42, and the bent portion 74 is located in the space between the second radiation shielding plate 44 and the end plate 37B.

[0041] In addition, even when the first radiation shielding plate 41 has a plurality of through holes 41h and the second radiation shielding plate 42 has a plurality of through holes 42h, it is preferable in one embodiment that the through holes 41h of the first radiation shielding plate 41 and the through holes 42h of the second radiation shielding plate 42 are not positioned on the same straight line. The first radiation shielding plate 41 may have the same thickness as the second radiation shielding plate 42, or may be thicker or thinner than the second radiation shielding plate 42.

[0042] <Variation 2> FIG. 5 is a diagram showing an example of an end plate through which multiple cables are passed. FIG. 5 illustrates end plate 37B. Multiple cables 70 may be arranged, for example, as shown in FIG. 5. In this example, one cable 70 is passed through the center of end plate 37B. A predetermined number of cables 70 are arranged in each of multiple concentric circles centered on the center of end plate 37B. By fixing cables 70 using welding as described with reference to FIG. 3, it is possible to arrange multiple cables 70 at high density as shown in FIG. 5.

[0043] (Other variations) 4 illustrates a structure in which two radiation shielding plates are provided, but the electrical penetration structure may have three or more radiation shielding plates. In the above embodiment, a configuration in which the electrical penetration structure is provided in the containment vessel is illustrated, but the electrical penetration structure may be provided in the wall of a room that houses piping through which the coolant, which is sodium, passes.

[0044] The present invention has been described above using embodiments, but the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. For example, all or part of the device can be configured by functionally or physically distributing or integrating any unit. Furthermore, new embodiments resulting from any combination of multiple embodiments are also included in the embodiments of the present invention. The effects of the new embodiments resulting from the combination also have the effects of the original embodiments. [Explanation of symbols]

[0045] 1 Fast reactor 10 Reactor vessel 11 Reactor Core 15 Coolant 18 Instruments 20 Containment Vessel 21 Wall 31 Sleeve 35 Cylindrical fuselage 36 Cylinder 37A End plate 37B End plate 39 Tubular sleeve 40 Radiation shielding plate 40a end face 40b end face 40h through hole 41 1st radiation shielding plate 41h through hole 42 Second radiation shielding plate 42h through hole 51 Fixing member 52 O-ring 70 Cable 71 Part 1 72 Bend 73 Part 2 74 Bend 75 Part 3 S100, S101 Electrical Penetration Structure W welded section

Claims

1. A sleeve provided to penetrate a wall of a containment vessel that contains a reactor vessel or a wall of a room that contains equipment or piping that uses sodium as a coolant; a hollow cylindrical body provided inside the sleeve and having an inner end surface facing the inside of the containment vessel and an outer end surface facing the outside of the containment vessel; an inorganic insulated cable passed through the inside of the cylindrical body; a radiation shielding plate made of bismuth oxide that is disposed on the cylindrical body and blocks radiation from passing from the inner end surface side to the outer end surface side; An electrical penetration structure having

2. The radiation shielding plate includes: A first radiation shielding plate disposed on a side closer to the inner end surface of the cylindrical body; a second radiation shielding plate disposed at a position spaced apart from the first radiation shielding plate in the axial direction of the cylindrical body; 2. The electrical penetration structure of claim 1.

3. the first radiation shielding plate and the second radiation shielding plate have a through hole through which the inorganic insulated cable is passed, The through hole of the first radiation shielding plate and the through hole of the second radiation shielding plate are not positioned on the same straight line.

3. The electrical penetration structure of claim 2.

4. The cylindrical body is an end plate disposed on the outer end surface, the end plate being formed with a tubular sleeve through which the mineral insulated cable is passed; The end surface of the cylindrical sleeve and the sheath of the inorganic insulated cable are fixed by welding.

3. An electrical penetration structure according to claim 1 or 2.

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