JPS6371691A - Core upper mechanism of fast breeder reactor - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) This invention provides a rectifying device for rectifying cold TJI material flowing out from the reactor; Regarding the mechanism.

(Conventional technology) The upper core mechanism of a fast breeder reactor consists of control rods, a subdivider drive mechanism,
Le II flit! Rod guide tube, jj and measuring finger
)) and is equipped with a rectifier, etc. As shown in FIG. 6, the rectifier 1 is attached to the lower part of the joint shell 3 of the upper core mechanism 2, and the other equipment mentioned above is housed inside the joint 1\43.

The rectifier 1 adjusts the flow of the coolant flowing out from the core by moving it along the surface of the guide plate 5 of the rectifier 1. The upper plate 7 of the rectifier 1 is fixed to the lower part of the joint shell 3 by bolts 9, as shown in detail in FIG. The rectifying device 1 is supported by the joint shell 3 by the upper plate 7.

(Problem to be solved by the invention) If the coolant temperature changes suddenly during reactor scram,
The temperature of the cold material outside the upper core machine v42 drops rapidly, but the cold material inside does not follow the temperature of the outside coolant and is maintained at a high temperature.

Therefore, a temperature difference of one level occurs in the coolant inside and outside of joints 1 & 43 and upper plate 7, respectively. This temperature difference causes thermal deformation in the thickness direction of the joint 11113 and the upper plate 7. However, since the joint 113 and the upper plate 7 are fixed by the bolts 9, the thermal deformation described above is restrained, and there is a possibility that a large thermal response may occur in the joint body 3 J3 and the upper plate 7.

In addition, the horizontal load that acts on the joint shell 3 from the upper plate 7 during an earthquake is transmitted to the joint shell 3 by the spigot part 11 of the joint shell 3, but this earthquake load is reliably transmitted to the joint 113. In order to do so, it is further necessary that the tightening force of the bolt 9 be maintained sufficiently.

However, in the case of a liquid metal cooled fast breeder reactor, since the coolant temperature exceeds 500°C, the behavior due to creep and stress relaxation that occurs in the joint shell 3, upper plate 7, and bolts 98 is ignored. I'm so lazy that I can't do it. Therefore, it is extremely important to maintain the tightness of the bolts 9 for a long period of time until the end of the reactor's life.
There is a risk that the # resistance of the upper core machine 4% 2 will decrease.

This invention was made in consideration of the above facts, and it is possible to maintain thermal stress at an appropriate value or less even when the temperature of cold 7'JL material changes suddenly, and it can be used for long periods of time at high temperatures. An object of the present invention is to provide an upper core mechanism for a fast breeder reactor that does not cause loosening of the mounting portion of a rectifier even when the rectifier is installed, and can improve seismic performance.

(Structure of the Invention) (Means for Solving the Problems) The present invention provides an upper core mechanism for a fast breeder reactor in which a rectifier is attached to the lower part of the joint shell containing a control rod drive mechanism, etc. The lower part consists of an inner shell and a thick-walled shell,
This thin wall is integrally connected to the upper plate of the rectifying device, and this upper plate is provided so as to be able to abut against the thick wall shell in the radial direction of the joint shell.

(Function) Therefore, the core upper mechanism of the fast breeder reactor according to the present invention reduces the thermal stress generated in the joint shell by the thin wall 154, and absorbs the thermal deformation generated in the upper plate of the rectifying root by the thin wall 154. Alleviates thermal stress generated in the plate. Also,
Since this upper core machine 424 has an integral structure of the thin wall y and the upper plate, the mounting part of the rectifier is 5. 7J] Even if it is immersed in a shrine for a long time, the attachment part will not loosen due to creep etc.

Further, in this core upper mechanism, the thick-walled shell supports horizontal loads on the upper plate caused by earthquakes and the like.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows the upper part of the core 1j of the fast breeder reactor according to the present invention!
! FIG. 3 is a cross-sectional view showing a fast breeder reactor to which the first practical example of FIG. 1 is applied.

As shown in FIG. 3, the fast breeder reactor 13 generally uses a liquid metal such as liquid nitrogen as the cold material 14. This coolant is filled into the atomic container 15. The upper end of this reactor vessel 15 is closed by a shielding plug 17, and a reactor core 19 is accommodated within the reactor vessel 15.

A cold UL material 14 such as liquid sodium flows into the reactor vessel 15 from the cold material inlet [] 21 at the bottom of the reactor vessel 15, flows upward in the reactor core 19, is heated, and flows out from the coolant outlet 23. .

A core upper mechanism 25 is attached to the a shield plug 17. This core upper mechanism 25 includes a control rod, a control rod drive side 27, a control rod guide tube 29, a measurement finger 31, and a rectifier 33. The measurement finger 31 measures the temperature, flow velocity, etc. of the coolant 14 flowing out from the core 19. Further, the rectifier 5A position 33 rectifies the coolant 14 flowing out from the core 19.

The control rod, the control rod drive mechanism 27, the υ1w rod guide tube 29, and the measurement finger 31 are connected to a cylindrical shielding body 3.
5 and is housed within the joint shell 37.

The shielding shell 35 is disposed within the shielding plug 17, and a connecting shell 37 is attached to the lower end of the shielding shell 35.

The joint shell 37 is covered and protected by a heat shield plate 39, as shown in FIG.

On the other hand, the rectifying device 33 is attached to the lower end of the joint body 37. This rectifying device 33 is connected to the upper plate 41 through an upper plate 41 attached to the joint shell 37, a conical guide plate 43 attached to the lower ends of the three heat shield plates, and a control rod guide tube 29. It is configured with a lower plate 45 connected to each other. This lower plate 45 has a large number of holes. Therefore, the flow straightening device 33 allows the coolant 14 flowing out from the core 19 (FIG. 3) to pass through the many holes in the lower plate 45 to form the guide plate 4.
3 and move it along the surface of this guide plate 43 to adjust the flow of the coolant 14.

The lower part of the joint body 37 and the upper plate 41, which serve as attachment parts for the rectifying device 33, are constructed as shown in FIG. 2.

In other words, the lower part t of the joint body 37, the outer body 47 as a meat body
It is formed by branching into an inner shell 49 as a thick-walled shell. The joints between the outer shell 47 and the inner shell 49 and the joint In 37 main body are as follows:
It is designed to prevent sudden changes in shape and to prevent stress concentration.

The outer shell 47 is integrally connected to the upper plate 41 by welding or the like. Therefore, the wall thickness of the outer shell 47 is sufficient as long as it can support the load of the V flow device 33 including the upper plate 41. It is not necessary to have a strength of 1.
7 is formed thinner than the main body of the joint body 37.

Furthermore, a plurality of communication holes 51 are opened in the outer shell 47 in the circumferential direction (see FIG. 1). This communication hole 51 has an outer g4
47 and the inner shell 49 and the outside of the outer shell 47 are communicated with each other, so that the temperature of the coolant inside the space 53 can follow the temperature of the coolant outside the outer JJ 147. The formation of the communication hole 51 also allows the outer shell 47 to maintain sufficient strength against the load of the adjustment equipment 33.

A ring-shaped steadying portion 55 is formed on the upper plate 41 near its periphery. The steadying portion 55 projects vertically upward and is provided so as to be able to come into contact with the inner circumferential surface of the lower end of the inner barrel 49 . Therefore, the horizontal earthquake load acting on the upper plate 41 is transmitted to the inner shell 49 via the steadying portion 55 . 1) Is 449 an earthquake like this? Constructed to be thick enough to withstand the weight of the iXi.

Next, the effect will be explained.

CI) When the coolant temperature changes suddenly during reactor scram, etc.

In this case, the temperature of the coolant outside the upper core mechanism 25 drops rapidly, but the crystallinity of the cold 01 material inside does not follow the temperature of the coolant outside, and the temperature of the coolant inside and outside of the upper core mechanism 25 decreases rapidly. The temperature difference in the coolant is strange.

Among these, since the outer shell 47 is thin and has the communication hole 51 formed therein, there is almost no temperature difference between the coolant outside the core upper mechanism 25 and the coolant inside the space 53. Therefore, the thermal stress generated in the outer shell 47 can be kept extremely low.

Further, the coolant inside the inner shell 49 has a higher temperature than the coolant in the space 53, and a temperature difference occurs between the two coolants. Due to this temperature difference, the inner yA49 is the outer or outer rk447.
thermal deformation in the direction of At this time, although the inner circumferential surface of the lower end of the inner Ij 149 is configured to be able to come into contact with the steady rest part 55, the outer circumferential surface is arranged with a space 53 between the outer Ij 149 and the inner Ij 149. The thermal deformation described above is not subject to any restrictions. Therefore, the thermal stress generated in the inner shell 49 is so low that it does not pose a problem.

Furthermore, due to the temperature difference between the cold IJl materials inside and outside of the upper core mechanism 25, the upper plate 41 is thermally deformed so that its central portion is curved convexly. However, since the outer shell 47 is formed thin, the outer shell 47 deforms in response to the above thermal deformation of the upper plate 41.

Therefore, thermal deformation of the upper plate 41 is not restricted in any way. Thermal stress generated in the frame and the upper plate 41 is gently relaxed. At this time, the outer shell 47 generates stress due to the above deformation, but since the outer shell 47 is thin, the stress generated is so low that it does not pose a problem.

(I[)i When immersed in hot and cold materials for a long period of time.

Since the outer shell 47 and the upper plate 41 are integrally connected by welding or the like, even if the outer shell 47 and the upper plate 41 are immersed in a high-temperature coolant for a long period of time, there will be no creep or stress relaxation at the joint between the upper plate 41 and the outer shell 47. (
No deformation occurs due to relaxation), etc. Therefore, the mounting portion of the rectifying device 33 does not become loose.

(DI) When a horizontal load such as ground force acts on the upper plate 41.

During an earthquake or the like, horizontal acceleration occurs in the flow straightener 21f33, and this acceleration applies a horizontal load to the upper plate 41. This load is applied to the inner II (49
transmitted to. Here, the inner shell 49 has a wall thickness that can withstand an excessive horizontal load, and the rectifier v! 33 does not become loose or the like, the horizontal load can be reliably supported by the inner Ju 49. As a result, the seismic strength can be reduced by 1 compared to the conventional structure. 4 is a sectional view of a main part showing a second practical example of the upper core mechanism of a fast breeder reactor according to the present invention.

In FIG. 4, the same parts as in FIG. 2 are designated by the same reference numerals, and their explanation will be omitted.

This second example differs from the first example in that a conical joint 1259 is formed at the peripheral edge of the upper plate 57, and the outer shell 61 is integrally connected to the conical joint portion 59. In other words, a conical joint 159 having a conical shape whose diameter increases vertically downward is formed on the outer peripheral edge of the steady stop portion 55 on the upper plate 57 . This conical shell 3-inch portion 59 is formed to have approximately the same thickness as the outer shell 'f161. On the other hand, the outer shell 61 extends to a lower surface position d in the figure of the upper plate 57, and its distal end is integrally joined to the distal end of the conical joint portion 59 by means such as welding.

Therefore, in this second embodiment, the thermal deformation of the upper plate 57 can be absorbed by the deformation of the outer shell 61 and the conical joint portion 59, so that the thermal stress caused by the thermal deformation of the upper plate 57 can be absorbed in the case of the first embodiment. It can be more relaxed compared to Furthermore, since the conical joint portion 59 is present, even if a horizontal load is applied to the upper plate 57, it can withstand this horizontal load and maintain seismic strength.

In the second embodiment, the conical joint portion 59 is conical in shape and expands downward in the vertical direction.
It may be a conical joint portion having a conical shape that expands upward in the vertical direction.

Furthermore, in the first and second embodiments, outside 11447.

Although the explanation has been made regarding the case in which the communication hole 51 is formed in the hole 61,
The communication hole 51 may not be formed. Also in this case, since the outer shells 47 and 61 are configured to have thin walls, the temperature difference between the coolant outside the outer shell 1147.61 and the coolant inside the air Gf 153 can be minimized. As a result, outside yA47
．． 61 can be reduced.

FIG. 5 is a sectional view of a main part showing a third practical example of the upper core I structure of a fast breeder reactor according to the present invention.

Even in FIG. 5, the same parts as in FIG. 2 are given the same reference numerals. In this third embodiment, the lower part of the joint 11137 is composed of a thick outer shell 63 and a thin inner shell 65, and the thin inner shell 65 is integrally joined to the upper plate 67 by welding or the like. The lower part of the thick outer body 63 serves as a steadying part 69, which is provided so as to be able to come into contact with the outer peripheral surface of the upper plate 67.

Therefore, according to this embodiment, even if the coolant temperature outside the core upper mechanism 25 drops rapidly and the lower part of the outer shell 63 thermally deforms outward, this thermal deformation is not restrained in any way. No thermal stress is generated in the outer shell 63. Further, since there is no temperature difference between the coolant in the space 71 surrounded by the outer shell 63 and the inner shell 65 and the inside of the inner shell 65, no thermal stress is generated in the inner shell 65. Even if the thermal deformation of the outer shell 63 causes a difference in the coolant humidity between the space 71 and the inner shell 65, the difference is not significant because the inner shell 65 is thin;
The thermal stress of No. 5 can be kept low.

Furthermore, since the inner part 1165 and the upper plate 67 are integrally connected, the mounting part of the rectifier 33 will not loosen even if it is in a high-temperature coolant for a long period of time, and the seismic load acting on the upper plate 67 Since horizontal loads such as the above are supported by the steadying portion 69, seismic performance can be maintained and improved.

In addition, in the first, second and third embodiments, the inner shell 49
Although the explanation has been made regarding the case where the steady rest part 55, the steady rest part 69, and the upper plate 67 are in contact with each other through a flat surface or an inclined surface,
The contact surfaces of these members may be formed in opposing convex shapes.

If this shape is used, the upper plate 41.57°67
Even if it is thermally deformed, a constant abutting surface can be formed at the abutting portions of the steadying part 55 and the inner barrel 65, etc.

Furthermore, the above-mentioned steady rest part 55 and inner body 65.1 arm rest part 6
A surface hardening treatment may be applied to the abutment surface between the upper plate 9 and the upper plate 67, or a sliding member may be installed to prevent these members from fusing together under high temperature conditions.

(Effects of the Invention) As described above, according to the upper core mechanism of a fast breeder reactor according to the present invention, the lower part of the I-barrel is composed of a thin-walled shell and a thick-walled bottom,
The thin-walled body is integrally connected to the upper plate of the rectifier, and
Since this upper plate is provided so that it can come into contact with the thick-walled shell in the radial direction of the joint shell, even if the temperature of the cold iJI material suddenly changes, it can be maintained at an appropriate value or below, and Even if the rectifier is used for a long period of time, the mounting part of the rectifier will not become jammed, resulting in improved seismic performance.

[Brief explanation of the drawing]

FIG. 1 is a cutaway side view of the main part of the first embodiment of the upper core mechanism of a fast breeder reactor according to the present invention, FIG. 2 is a sectional view of the main part of the first embodiment, and FIG. 1j is a sectional view showing a fast breeder reactor to which the first embodiment is applied, FIG. 4 is a sectional view of the main part showing the second embodiment, FIG. 5 is a sectional view of the main part showing the third embodiment, and FIG. FIG. 7 is a side view of a conventional fast breeder reactor in which the main parts are cut away next to the upper part of the reactor core, and FIG. 7 is a sectional view of the main parts of FIG. 6. 13... Fast breeder reactor, 25... Core upper mechanism, 27
... Control rod drive mechanism, 33... Rectifier, 37...
・Joint body, 41...Top plate, 47...Outer body, 49...
Inner barrel, 51...Communication hole, 55...Photo stop portion, 59.
・Conical joint part. Applicant's agent Hisashi Hatano Figure 8 Figure 7

Claims (1)

[Claims] 1. In a core upper mechanism of a fast breeder reactor in which a rectifier is attached to the lower part of a joint shell containing a control rod drive mechanism, etc.,
The lower part of the joint shell is composed of a thin-walled shell and a thick-walled shell, and the thin-walled shell is integrally connected to the upper plate of the rectifier, and this upper plate abuts against the thick-walled shell in the radial direction of the joint shell. An upper core mechanism of a fast breeder reactor characterized by being provided so as to be accessible. 2. The thin-walled body is the outer body, and the thick-walled body is the inner body, and a steadying part is provided protruding from the upper plate of the rectifier, and this steadying part can come into contact with the inner peripheral surface of the lower end of the inner body. Claim No. 1 provided
The upper core mechanism of the fast breeder reactor described in . 3. High-speed multiplication according to claim 1, wherein the thin-walled body is an inner body and the thick-walled body is an outer body, and the upper plate of the rectifier is provided so as to be able to come into contact with the inner peripheral surface of the lower end of the outer body. Upper core mechanism of the reactor. 4. The upper core mechanism of a fast breeder reactor as set forth in claim 2, wherein the outer shell has communication holes formed in its circumferential direction. 5. Claim 2 or 4, wherein the outer shell is integrally connected to the upper plate of the rectifier through a conical joint part.
The upper core mechanism of the fast breeder reactor described in .