JPS58160895A - Device for capturing radioactive corrosion product - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a radioactive corrosion product capture device for capturing radioactive corrosion products contained in the coolant of a nuclear reactor.

[Technical background of the invention]

In fast breeder reactors, alkaline earth metals represented by liquid sodium are generally used as coolants. After being heated in the reactor core inside the reactor vessel, such liquid metal coolant is guided to the primary cooling system provided outside the vessel, and then returned to the reactor vessel. circulate.

By the way, in the case of fast breeder reactors, the cladding tubes and core structures of the nuclear and payload elements are usually made of stainless steel, but when these constituent materials are irradiated with neutrons, they are Iron, cobalt, etc. that are present cause a nuclear reaction (,
Large amounts of radionuclides such as Mann-54° Copal)-60 and Co-Gourteau-58 are produced. This material is corroded by the aforementioned alkaline earth metal used as a coolant and is released into the coolant. At this time, the aforementioned radionuclides are also released into the coolant, and so-called radioactive corrosion products are mixed into the coolant.

The radioactive corrosion products mixed into the coolant are carried to the primary cooling system according to the flow of the coolant, and are deposited on the surfaces of the pipes of primary cooling system equipment such as intermediate heat exchangers. In this way, the radioactivity of the radioactive corrosion products deposited on the walls of the primary cooling system is removed from equipment such as pumps, heat exchangers, heat exchangers, and fi meter, and maintenance of nine piping systems connected to these equipments. , causing trouble to repair work, etc. In particular, Mann is No. 54. Cobalt-60, Co-Harto-58, etc. are produced in large amounts and have long half-lives, so they are
That has a big impact.

Therefore, in order to solve this problem, recently, two Kels have been working on y-
It is being considered that a radioactive corrosion product trapping device can be installed inside the reactor vessel by taking advantage of its ability to efficiently capture 54, 60% O radionuclides.

This radioactive corrosion product capture device has a plurality of elements containing capture materials such as the above-mentioned 2, Kel, etc. arranged opposite to the coolant outlet of the reactor core, that is, above the reactor core, and collects the above-mentioned type i type of coolant flowing out from the reactor. Radioactive nuclides are captured by direct contact with the material.

[Problems with background technology]

In order to efficiently remove the nuclides of radioactive corrosion products using the above-mentioned lid, the contact area between the capture material and the coolant must be increased by at least a certain degree, and all of the coolant must be removed from the capture material. It is necessary to make uniform contact with the

However, when the coolant flows between the capture materials, a so-called boundary layer, which forms a laminar flow near the surface of the capture materials, is formed due to the viscous effect of the coolant. There is little exchange of position between the coolant forming this boundary layer and the coolant flowing outside the boundary layer. Therefore, the coolant flowing in the center of the flow path formed between the captured materials The radioactive corrosion products in the coolant flowing in the central part are only likely to come into contact with KrI, and the radioactive corrosion products in the coolant flowing through the center will diffuse through the boundary layer and be deposited on the trapping material KrI. The diffusion rate of radioactive corrosion products is very slow, which often leads to low capture efficiency and ultimately low overall efficiency of the device.

[Purpose of the invention]

The present invention was developed in view of the above circumstances, and its purpose is to efficiently bring the coolant into contact with the captured material, despite its simple structure, and thereby to reduce the captured material. It is an object of the present invention to provide a radioactive corrosion product trapping mat capable of improving efficiency.

[Summary of the invention]

The radioactive corrosion product trapping device of the present invention is a device that actively creates turbulence in the trailing region of the coolant that moves along the surface of the reactor coolant mixed with radioactive corrosion products in the flow path. It is characterized by having a plurality of radionuclide capture bodies each having a transparent surface.

〔Effect of the invention〕

Generally, the flow form of a viscous fluid that flows around an object placed in a flow channel is given by the Navier-Stokes solution, and this solution consists of the kinematic viscosity r of the fluid, the flow velocity V of the fluid, and the representative dimensions of the object. (diameter in the case of a sphere) L is greatly influenced by the value of the Reynolds number R. defined as the following equation.

L R@W.

That is, when the above-mentioned Reynolds number 8. is above a certain level or when a steady flow called turbulent flow is formed, it becomes K.

In this way, when an unsteady flow is formed, the boundary layer formed on the downstream surface of the object is disturbed, and this boundary layer becomes thin or peels off.6 The present invention takes advantage of this phenomenon. After that, the flow area of the coolant is actively injected into the flow path of the coolant.
A plurality of capture bodies with a uniform surface for L-hawking are provided.

Therefore, the probability that the coolant comes into contact with the capture body can be increased, and the thinning of the boundary layer allows the nuclides of the radioactive corrosion products in the coolant flowing in the center to diffuse through the boundary layer and the capture body. Therefore, the nuclides of the radioactive corrosion products in the coolant flowing through the central part can be efficiently captured by the plurality of capture bodies, and in the end, It is possible to capture a large amount of radioactive corrosion products in the coolant, and if this device is installed at the coolant outlet of the reactor vessel, the radioactive corrosion products will be captured in the middle. Since it can be prevented from flowing to equipment such as heat exchangers, it can contribute to facilitating maintenance and repair work of this system.

[Embodiments of the invention]

FIG. 11i11 is a vertical cross-sectional view showing a schematic configuration of a radioactive corrosion product capture device according to an embodiment of the present invention. A cylindrical body 2, a first capture body S disposed upstream within the cylindrical body 2 with respect to the flow direction of the coolant 1, and a first capture body S disposed downstream of the first capture body 3. second
A third capture body 5 is disposed further downstream of the second capture body 4.

The cylindrical body 2 is made of stainless steel, and openings 6 at both ends thereof are connected to piping r for guiding the coolant 1t.

Said first capture body 3. The second capture body 4 and the third capture body 5 are all of the same configuration, and each capture body includes a stainless steel ball 8 arranged on the axis of the cylindrical body 2, and a stainless steel ball 8 disposed on the axis of the cylindrical body 2. In the plane perpendicular to the above-mentioned center alKm, as shown in FIG. 8.9 and a round support 10 fixedly supported on the m* inner surface of the cylindrical body 2.

Note that the minimum cross-sectional area of the flow path of the coolant 1 in the portion where the first to third capture bodies 3.4.5 are installed, that is, the sphere 8. in the cylindrical body 2 in FIG. The diameters of the area 8.9 and the cylindrical body 2 are set so that the total area of the section 11 excluding # and the support 10 is smaller than the cross-sectional area of the pipe 1 through which the coolant 1 flows. There is.

With such a configuration, during reactor operation, the coolant 1
As shown by the arrows in Figure 1, the first to eleventh captured bodies are the third! , 4.5.

In this case, a boundary layer due to laminar flow is formed on the surface of the sphere 8.9 constituting the capture body as described above, but if the Reynolds number in this flow path system is sufficiently large (R・〉2)
, the boundary layer has the above area 8.9 at the maximum width position in the flow direction.
as a result of which a thin or turbulent flow occurs in the downstream region of the region 8.9. Therefore, the above coolant 1
The nuclides of the radioactive corrosion products mixed in are efficiently captured by the stainless steel balls 8.9 that serve as radionuclide capture materials, and the radioactive corrosion products eventually flow to equipment such as intermediate heat exchangers. This can contribute to facilitating maintenance, repair, etc. of this system.

In particular, in the embodiment, five balls 89 as trapping materials are distributed over the entire cross section of the cylindrical body 2, which is the flow path for the coolant 1, so that the thin flow formed by the area 8.9 or The turbulent flow is distributed over the entire cross section of the cylinder 2, resulting in a very uniform trapping effect over the entire flow cross section of the coolant 1.

In addition, the coolant 10 in the part where the capture body is installed
Since the cross-sectional area of the pipe 1 is made smaller than the cross-sectional area of the pipe 1, the flow velocity of the coolant 1 increases in the part where the above-mentioned capture body is installed. However, since the above-mentioned Ray nozzle number R. increases, the thin flow or turbulent flow of the coolant 1 becomes more likely to occur, and the above-mentioned trapping effect can be further improved.

It should be noted that the present invention is not limited to the embodiments described above; in the embodiments, stainless steel was used as the capture material;
2. It may be made of Kel or a nickel alloy. Also, the shape of the capture material may not be spherical, but may be an ellipsoid or other shape.

Furthermore, the number of balls constituting one catcher and the number of catchers distributed in the flow direction of the coolant are not particularly limited.

[Brief explanation of drawings]

The first factor is a vertical cross-sectional view showing the schematic configuration of a radioactive corrosion product capture device according to an embodiment of the present invention, and FIG.
It is a sectional view taken along A@ and viewed in the direction of the arrow. Figure 1 Figure 2 1 So-1

Claims (1)

[Claims] a channel for guiding reactor coolant mixed with radioactive corrosion products; and a plurality of capture bodies arranged in the flow channels to adsorb and capture the radioactive corrosion products; A radioactive corrosion product trapping device, characterized in that the trapping body is formed with a curved surface that actively creates turbulence in the trailing region of the flow of the coolant moving along the surface i[K.