JPS646719B2 - - Google Patents

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a radioactive corrosion generation system that captures radioactive corrosion products contained in conductive liquids such as liquid sodium and liquid sodium potassium used as coolant in fast breeder reactors. Regarding object capturing devices.

[Technical background of the invention]

In fast breeder reactors, a conductive alkaline liquid metal, typically liquid sodium, is generally used as a coolant. After being heated in the reactor core inside the reactor vessel, such liquid metal coolant is led to the primary cooling system installed outside the vessel, and then returned to the reactor vessel, where it is circulated. do.

By the way, in the case of fast breeder reactors, the cladding tubes and core structures of the nuclear fuel elements are usually made of stainless steel, but when these constituent materials are irradiated with neutrons, they are Iron, cobalt, etc. cause a nuclear reaction, producing manganese-54 and cobalt-
Large amounts of radionuclides such as cobalt-60 and cobalt-58 are produced. On the other hand, since the alkali liquid metal is used as the coolant as described above, the stainless steel which is the constituent material mentioned above will still be corroded.
Therefore, so-called radioactive corrosion products containing the above-mentioned radionuclides are mixed into the coolant.

The radioactive corrosion products mixed into the coolant are carried to each part of the primary cooling system according to the flow of the coolant.
It deposits on the walls of this primary cooling system. In this way, the radioactivity of radioactive corrosion products deposited on the walls of the primary cooling system can be removed by maintenance and repair of equipment such as pumps, heat exchangers, valves, flow meters, etc., and the piping connected to these equipment. impede the work of In particular, manganese-54, cobalt-60, cobalt-58, etc. are produced in large amounts and have long half-lives, so their effects are large.

Therefore, in order to eliminate such problems,
Recently, a device for harvesting radioactive corrosion products has been installed inside the reactor vessel, taking advantage of the property of nickel to efficiently capture radionuclides such as manganese-54 and cobalt-60 in high-temperature liquid metal sodium. It is considered to be installed in This radioactive corrosion product capture device has a plurality of elements containing capture materials such as nickel placed opposite the coolant outlet of the reactor core, that is, above the core, and directs the coolant flowing out from the core to the capture materials. By contacting them, radionuclides are captured.

[Problems with background technology]

As mentioned above, in order to efficiently capture the nuclides of radioactive corrosion products in the equipment, the contact area between the capture material and the coolant must be increased to a certain extent, and all the coolant must come into uniform contact with the capture material. It is necessary to do so.

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 probability that the coolant flowing through the center of the channel formed between the capture materials comes into contact with the capture materials is small. Therefore, the radioactive corrosion products in the coolant flowing through the center diffuse exclusively through the boundary layer and are adsorbed by the trapping material, but the diffusion rate of the radioactive corrosion products in the boundary layer is is very slow and because of this,
There was a problem that the capture efficiency was low, resulting in a low efficiency of the entire device.

[Purpose of the invention]

The present invention was made in view of the above circumstances, and its purpose is to forcibly disturb the flow of conductive liquid such as liquid sodium flowing between the capture materials, and to Therefore, it is an object of the present invention to provide a radioactive corrosion product capturing device that can reduce the thickness and exfoliation of the boundary layer, and can efficiently capture radioactive corrosion products contained in a conductive liquid.

[Summary of the invention]

The radioactive corrosion product capture device of the present invention applies a magnetic field in a direction perpendicular to the flow direction to a conductive liquid such as liquid sodium flowing between capture materials, and also flows a current in a direction parallel to the flow direction. The feature is that the flow of conductive liquid is forcibly disturbed by the interaction between electric current and magnetic field.

〔Effect of the invention〕

With such a configuration, the flow of a conductive liquid such as liquid sodium flowing between the capture materials is forcibly disturbed by the interaction between the magnetic field and the current.
For this reason, the boundary layer formed near the surface of the capture material is also disturbed, and this boundary layer becomes thin or peels off. Therefore, it is possible to increase the probability that the radioactive corrosion products in the conductive liquid flowing in the center between the capture materials will come into contact with the capture materials, and the boundary layer can be made thinner, so that the cooling that flows in the center between the capture materials can be increased. The time required for the nuclide of the radioactive corrosion product in the material to diffuse through the boundary layer and reach the capture material can be shortened. Therefore, the nuclides of the radioactive corrosion products in the coolant flowing through the central part can be efficiently captured by the trapping material, and in the end, almost all of the radioactive corrosion products mixed into the coolant can be captured. be able to. Therefore, by installing this capture device at the coolant outlet of the reactor vessel of a fast breeder reactor, it is possible to prevent radioactive corrosion products from flowing to the primary cooling system, making maintenance and repair work of this system easier. It can contribute to making it easier.

[Embodiments of the invention]

The figure is a schematic diagram of a radioactive corrosion product capture device according to an embodiment of the present invention. This radioactive corrosion product capture device is roughly divided into a flow path through which a conductive liquid P such as liquid sodium, liquid sodium potassium, etc., which is a coolant for a fast breeder reactor, flows inside, for example, a stainless steel pipe 1. , a capture body 2 for capturing radionuclides disposed within the pipe 1, and a magnetic field generator that applies a magnetic field in a direction across the pipe 1 from the outside of the pipe 1 to a portion where the capture body 2 is located; In other words, it is composed of an electromagnet 3 and a current supply device 4 that allows a current to flow in a direction parallel to the flow direction of the conductive liquid P through the conductive liquid P flowing through the capture body 2.

The trapping body 2 is constructed by combining trapping materials 5 formed of a large number of thin nickel plates in a lattice shape, and the columnar gaps 6 formed by the trapping materials 5 are arranged in the direction of flow of the conductive liquid P. It is fixed to the inner surface of the pipe 1 by a ring-shaped stopper 7 in a state parallel to the pipe 1 .

The electromagnet 3 includes a U-shaped iron core 8 arranged so as to sandwich the portion of the pipe 1 where the capture body 2 is located between its magnetic pole faces, a coil 9 wound around the iron core 8, and a coil 9 wound around the iron core 8. and a DC power supply 10 that passes a DC current through.

On the other hand, the current supply device 4 includes ring-shaped electrodes 11 and 12 mounted at upstream and downstream positions, respectively, with respect to the position of the capture body 2 on the outer peripheral surface of the pipe 1, and these electrodes. 11 and 12, and an AC power supply 13 that causes an AC current to flow through them.

With such a configuration, with the DC power supply 10 and the AC power supply 13 turned on, liquid sodium, which is the coolant for the fast breeder reactor, is passed through the pipe 1 as the conductive liquid P as shown by the arrow in the figure. If you let
This liquid sodium will flow through the columnar gap 6 formed by the capture material 5, but at this time, a magnetic field in a direction perpendicular to the flow direction is applied by the electromagnet 3 at the position where the capture body 2 is provided. It is also supplied with an alternating current parallel to the flow direction by the current supply device 4. Therefore, the liquid sodium flowing at the location where the capture body 2 is installed is subjected to an electromagnetic force according to Fleming's left hand rule,
This force forces the flow to be disturbed. Therefore, the boundary layer formed near the surface of the capture material 5 is also inevitably disturbed, becoming thinner or peeled off. Therefore, the nuclides of the radioactive corrosion products mixed in the liquid sodium are absorbed by the capture body 2.
It is efficiently captured by the capture material 5 that forms a . Therefore, if this device is installed at the coolant outlet of the reactor vessel, it will be possible to prevent the radioactive corrosion products generated in the reactor core from flowing to the primary cooling system, making maintenance and repairs of this system easier. It can contribute to making work easier.

In particular, in this embodiment, since the capture body 2 is constructed by assembling a large number of capture materials 5 in a lattice shape so that a large number of columnar gaps 6 are formed, the capture material 5 and the coolant are It is possible to increase the contact area, and the above-mentioned trapping action can be performed more effectively.

Furthermore, since the electrodes 11 and 12 are formed into a ring shape, it is possible to obtain a more uniform current density over the entire cross section of the flow in the pipe 1, and a more uniform trapping effect can be obtained over the entire cross section of the flow. can.

Note that the present invention is not limited to the embodiments described above. In the embodiment, a direct current magnetic field was used as the magnetic field and an alternating current was used as the current, but this relationship may be reversed. Further, in the embodiment, nickel was used as the capture material, but it may be a nickel alloy, stainless steel with a nickel plating on the surface, a nickel alloy with a nickel plating on the surface, or a combination thereof. Furthermore, the structure of the capture body is not particularly limited either.

[Brief explanation of the drawing]

The figure is a partially cutaway schematic configuration diagram showing a radioactive corrosion product capture device according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Piping, 2... Capture body, 3... Electromagnet, 4... Current supply device, 5... Capture material, 8... Iron core, 9... Coil,
10... DC power supply, 11, 12... Electrode, 13... AC power supply, P... Conductive liquid.

Claims (1)

[Claims] 1. A channel for guiding a conductive liquid mixed with radioactive corrosion products, a capture body disposed within the channel to adsorb and capture nuclides of the radioactive corrosion products, and at least the capture body in the channel means for applying a magnetic field in a direction perpendicular to the flow direction of the conductive liquid to a region where the conductive liquid is located; A radioactive corrosion generation and capture device comprising means for passing an electric current that acts on the conductive liquid to strongly disturb the flow of the conductive liquid.