JPS59193187A - Adsorbing device for cobalt - Google Patents

Abstract

PURPOSE:To remove efficiently the cobalt dissolved in water by providing magnetically held powder manganese ferrite between magnetic holders and a piping which is connected to the lower part of a hollow column and introduces water contg. cobalt into the column, etc. CONSTITUTION:The filtrate from a water cleaning up system of a nuclear reactor is introduced through a piping 12 and an opened automatic two-way valve 13 into an adsorption column 14 from the bottom thereof. Powder manganese ferrite 17 is magnetically held in the spaces between the magnetic holders 16 disposed uniformly in the column 14, and when the reactor water introduced into the column ascends in the adsorption column, the water contacts the magnetically held ferrite 17 and the cobalt ions in the reactor water are adsorbed and removed. The insoluble corrosive components in the reactor water are removed as well by the contact filtration. Since the ferrite 17 is thoroughly held magnetically, there is no outflow at all.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a reactor for adsorbing and removing dissolved cobalt, which is a corrosion product contained in sub-reactor cooling water (hereinafter referred to as reactor water) of a nuclear power generation plant. This invention relates to a cobalt adsorption device as a water purification system.

[Technical background and problems of the invention]

Since cobalt becomes radioactive within the reactor and becomes a source of radiation exposure, a reactor water purification system is required. Conventional reactor water purification systems use the ion exchange resin method, in which reactor water is passed through a heat exchanger and water cooler to cool it down to the resin's heat resistance temperature of 60°C or less, and then passed through an ion exchange resin. Therefore, if the flow rate is increased in a conventional reactor water purification system, the heat loss of the plant will increase proportionally, and equipment such as heat exchangers will need to be strengthened.

FIG. 1 is a system diagram of a reactor water purification system for a conventional boiling water reactor plant. High-temperature, high-pressure reactor water of reactor I (280
°C1701cg/crl) is suctioned from the branch pipe 2 by the cleanup pump 3, introduced into the heat exchanger 4 and cooled. The cooled reactor water passes through piping 7 and enters ion exchange resin cylinder 8.
Cation and anion exchange resins remove cations such as cobalt ions and septa ions such as chloride ions.

The purified reactor water enters the heat exchanger 4, is heated by heat exchange, passes through the pipe 9, joins the water supply in the water supply system pipe 10, and is returned to the reactor 1.

In such a conventional reactor water purification system, as mentioned above,
There are limits to reducing cobalt exposure because increasing the processing flow rate directly affects heat loss in the plant.

Therefore, there is a need for a high-temperature cobalt adsorption device that can purify high-temperature, high-pressure reactor water without cooling the cobalt in the reactor water as in the conventional method, that is, can increase the amount of purified lightning without heat loss.

As the adsorbent in the high-temperature cobalt adsorption device, a heat-resistant inorganic material is used instead of an organic material, and for example, zirconium phosphate, zirconium oxide, titanium oxide, etc. are said to be promising.

In view of the above, the present inventors have made a number of inorganic material candidates.
As a result of comparative research on cobalt adsorption performance, hydrothermal stability, etc., we found that manganese ferrite has the best practical use as a high-temperature cobalt adsorbent.

Up until now, inorganic adsorbents that have been considered promising are in the form of fine powders, so they lack mechanical strength and cannot be applied directly to high-temperature cobalt adsorption equipment as door materials.
granular, linear, block-like, etc.).

The first method to prevent this solidification is to solidify by adding a binder or performing a sintering process, and the second method is to solidify by adding a binder or performing a sintering process.
One method is to use a carrier and coat the surface of the pressed body through impregnation or sintering, and the third method is to coat the surface of the pressed body by using a thin or fibrous metal and chemically treating the surface with an oxide film of the metal (adsorbent material). There are several methods for forming (having a function).

However, when solidifying the powdered inorganic adsorbent by the above method, the following problem occurs. That is, when a binder is added or a sintering treatment is performed, the effective surface area decreases and the adsorption activity deteriorates, and the cobalt adsorption ability of the powder inevitably deteriorates. In addition, the solidified inorganic adsorbent does not react in its entirety like a powder, and the inside does not participate in adsorption, so there is a risk that a large amount of radioactive waste will be generated. Furthermore, since solidified inorganic adsorbents cannot be handled as a fluid such as powder, they must be installed and removed from equipment using the IJ Soji method, which is not recommended for reliability when working in high-pressure vessels. It is extremely difficult to carry out this process unattended.

The present inventor has focused on the fact that manganese ferrite, which was discovered as a high-temperature cobalt adsorbent as mentioned above, is a ferromagnetic material, although the powdered inorganic adsorbent cannot be used as an F adsorbent due to its properties. The present invention has been made to solve technical problems.

[Purpose of the invention]

The purpose of the present invention is to directly fill and hold powdered manganese ferrite adsorbent into an adsorption column by making the most of the powder's excellent adsorption ability and workability without solidifying the powdered manganese ferrite, and to perform high-temperature purification of reactor water. The purpose of the present invention is to provide a cobalt adsorption device that can be used for commercial purposes.

[Summary of the invention]

The cobalt adsorption device according to the present invention includes a hollow column, a plurality of magnetic holding bodies that are cut in the direction of gravity and arranged at intervals within the effective magnetic region, and a plurality of magnetic holding bodies that are arranged in the column in the direction of gravity and spaced apart within the effective magnetic region. Powdered manganese ferrite magnetically held between the bodies, piping connected to the lower part of the column to introduce water containing cobalt into the column, and piping connected to the upper part of the column to lead out the water after absorbing cobalt. This equipment performs high-temperature purification of reactor water using powdered manganese cobalt.

[Embodiment name of the invention/l] The present invention will be described in detail below with reference to an embodiment shown in the drawings.
]. FIG. 2 is a system diagram of a high-temperature cobalt removal apparatus showing one embodiment of the present invention.

In FIG. 2, reference numeral 14 denotes an adsorption column made of a stainless steel pressure vessel, and a plurality of magnetic holding bodies 16 are provided inside. This magnetic holder 16 is made of stainless steel, titanium, or Zircaloy, which has good mechanical strength, and is placed inside a heat-resistant and corrosion-resistant non-magnetic insulator tube (approximately 10 mmφ) at the reactor water temperature (2
80″C) thermally stable permanent magnet block with little magnetic deterioration (alnico magnets such as MK steel, NKS steel, etc.)
15) are stacked in an expanded manner to obtain a homogeneous magnetic field along the entire length, and both yiA of this insulator tube! Even if it is sealed, there is 0'f. The magnetic holding body 16 of the octopus is arranged in the column 14 almost parallel to the direction of the vehicle force, and at a distance within the effective magnetic field of the head.
ヱIt can be fixed. 23 is the backwash water pipe and the acceleration pump 24.
Through the automatic two-way valve 25 - the water sprinkling pipe 2 in the upper part of the C cuff 14
It connects to 6. 27 is a powdered manganese noelite slurry liquid tank equipped with an agitator 28, an acceleration pump 24 and an automatic two-way valve 31? It is connected to the water sprinkler pipe 26 through the water pipe. Powdered manganese ferrite adsorbent slurry liquid 29 in the storage tank 27
) Inside the chamber 4 - Light is press-fitted from the upper water sprinkling pipe 26, and powdered manganese ferrite 117 is magnetically held uniformly over the entire space between the magnetic holding bodies 16. - Column 14r is also connected to the reactor water purification system by piping 12.19, as shown by the broken line in Figure 1. Note that 13, 18 and 20° 21 are automatic two-way valves, and 22 is a backwash liquid discharge pipe.

In the above configuration, the reactor water from the reactor water purification system is distributed to v1.
2, and is introduced into the adsorption column 14 from below via the automatic two-way valve 13 which is open.

Magnetic holding bodies 1 are evenly arranged inside the attraction ram 14.
Powdered manganese ferrite 17 is magnetically held in the mutual space of 6, and when the introduced reactor water moves up the adsorption column, the powdered manganese ferrite 17 is held magnetically.
Cobalt ions in the reactor water are adsorbed and removed.

At this time, non-corrosive components (crud) in the reactor water
The force is also removed by contact. During the adsorption process, the powdered manganese ferrite 17, which is the p-material, is sufficiently magnetically held, so there is no outflow at all. The purified reactor water is returned to the reactor through the self-excited two-way valve 18 which is opened from above the adsorption column 14. At this time, automatic two-way valves 20, 21, 2
5.31 is closed. The above is the purification of reactor water.

Next, an operation is performed to remove the powdered manganese ferrite 17 that has reached breakthrough through the purification process. First, automatic 2-square 13,1
After stopping the introduction of reactor water by closing the adsorption column 14
And allow the internal water to cool until it reaches room temperature. After cooling, the automatic two-way valve 20.21 is opened and the entire amount of water accumulated in the adsorption column 14 is drained from the bottom through the automatic two-way valve 20 and backwash liquid drain pipe 22.
discharge from. At this time, air flows into the adsorption column 14 through the automatic two-way valve 21 which is open to the atmosphere.

Next, the automatic two-way valve 25 is opened, the acceleration pump 24 is turned on, and a certain amount of backwash water is spouted from the backwash water pipe 23 through the sprinkler pipe 26, and then the automatic two-way valve 25 is closed and the acceleration pump is turned on. The injected backwash water falls in a straight line from top to bottom in the space between the magnetic holding bodies 16 arranged in the adsorption column 14, and the rapid falling impact causes the magnetic holding bodies 16 to fall in a straight line.
Peel off the powdered manganese ferrite that is magnetically attached to the surface and wash it away.

The backwashing liquid flows through an automatic two-way square 20 to the backwashing liquid drainage pipe 22.
is discharged from. After the discharge of the backwash liquid is completed, the automatic two-way valve 25 is opened again, the acceleration pump 24 is turned on, a constant amount of backwash water is supplied, and backwash is performed in the same manner as described above. This backwashing operation is repeated until the used powdered manganese ferrite is completely discharged, and after the discharge is completed, the automatic two-way valve 20.2
5 is closed and the acceleration pump 24 is turned off. The above is the process of removing spent powdered manganese ferrite from the adsorption column.

Next, an adsorption hoist holding operation is performed to magnetically hold the new powdered manganese ferrite adsorbent in the adsorption column 14. Fill the waste suction column 14 with water up to the lower end level of the magnetic 1 and H4 holder 16 in advance without separating it, and then close the automatic two-way valve 31.
I, the powdered manganese ferrite adsorbent slurry 29 with a specified concentration is evenly divided by the stirrer 28 from the slurry liquid storage tank 27, and the slurry pump 30 is turned on to within the upper limit level of the magnetic support 16 of the adsorption column 14. A certain amount is injected through the water sprinkler pipe 26. The powdered manganese ferrite in the injected slurry liquid (c) will be uniformly magnetically held 17 in the entire space between the magnetic holding bodies 16 under water. When the injection is completed, turn off the slurry pump 30 and close the automatic two-way valve 31. Next, open the automatic two-way valve 25, turn on the acceleration pump 24, inject water from the backwash piping 23 through the sprinkler pipe 26 into the adsorption column 14, and then turn the acceleration pump 24 OF'F' and the automatic 2-way valve 25. The valves 25 and 21 are closed. The above is the process of magnetically holding the powdered manganese ferrite adsorbent in the adsorption column 14.

After this process is completed, the automatic two-way valves 12 and 19 are opened, and the reactor water purification process described above begins.

In this way, cobalt in the reactor water is continuously removed by repeating the reactor water purification process, the removal process of spent manganese ferrite powder after adsorption/n, and the holding process of 1: New M powdered manganese ferrite adsorbent. Ions can be removed.

〔Effect of the invention〕

The high-width cobalt removal device of the present invention (1) has the following effects: Cobalt removal performance is obtained.

(,2) RC using easily reactive particulate adsorbent,
There are no unreacted parts and radioactive waste can be significantly reduced.

(3) Powder holding allows the porosity to be made more arbitrary and tighter than solid material, so the pressure loss of the device is small and the effective adsorption layer can be lengthened.

(4) Since a fluidized powder is used, it is easy to automate the adsorbent removal and filling process, and the device can be operated completely.

[Brief explanation of drawings]

FIG. 1 is a system diagram of the reactor water removal system of a general water reactor plant, and FIG. 2 is a system diagram showing an embodiment of the cobalt adsorption apparatus according to the present invention. 1... Nuclear reactor 3... Cleanag bomb 4... Heat exchanger 6... Water cooler 8... Ion exchange resin cylinder 14... Adsorption column 16... Magnetic holding body 24... Acceleration pump 27... Powdered manganese ferrite adsorbent slurry liquid storage tank 30... Slurry pump

Claims (2)

[Claims] (1) A hollow column, a plurality of magnetic holding bodies cut in the direction of gravity and arranged approximately parallel to each other and spaced apart within the effective magnetic region, and a magnetic holding body between these magnetic holding bodies. Cobalt adsorption comprising powdered manganese ferrite, a pipe connected to the lower part of the column to introduce cobalt-containing water into the column, and a pipe connected to the upper part of the column to lead out the water after adsorbing cobalt. Device. (2) Claim 1, characterized in that the magnetic holder is a thermostable permanent magnet block sealed in a non-magnetic insulator made of a heat-resistant and corrosion-resistant material.
Cobalt adsorption device as described in section.