JPH0740079B2 - Combustible powder oxine charcoal filter used for purification of water containing radionuclide - Google Patents

Description

TECHNICAL FIELD The present invention relates to a combustible powder oxine charcoal filter.

(Prior Art) When discarding the ion exchange resin used in the heavy water system of the new converter, it is necessary to perform operations called light water recovery for the purpose of recovering heavy water from the ion exchange resin and discharging tritium out of the system. When this operation is performed, deteriorated heavy water diluted with light water (heavy water concentration of 1 to 99%) is generated, but this heavy water is separately purified to 99.8% or more by a heavy water purification device called an upgrader. Since Co-60 is contained in this deteriorated heavy water, after removing Co-60 in the deteriorated heavy water, it is transferred to an upgrader to prevent an increase in dose due to the accumulation of Co-60 in the upgrader. It has been studied to simplify this removal device as much as possible and to make it compact.

1) Generally, it is considered to treat with a combination of an ion exchange resin and a filter. In the liquid, Co-60 ions are adsorbed by the ion exchange resin and Co-60 clad (particulate matter) is adsorbed or filtered by the filter. To remove from. For general performance Therefore, DF is considered to be about 10 for both ions and cladding.

2) On the other hand, it is known that activated carbon impregnated with oxine (hereinafter abbreviated as oxine charcoal) is effective for adsorption and removal of Co-60. As a method of using the oxine charcoal, when granular oxine charcoal is used, the column is packed and used. When powdered oxine charcoal is used, it is precoated on a filter and used for removing the clad. In this case, a tank or pump for precoating is required.

(Problems to be solved by the invention) In view of the problems of the prior art, it is an object of the present invention to make a device for removing Co-60 in deteriorated heavy water as simple and compact as possible.

(Means for Solving the Problems According to the Invention) A cartridge was filled with powdered oxine charcoal in which oxine effective for Co-60 ion removal was impregnated with activated carbon, and the particle size distribution was adjusted to 50 to 200 mesh. A prefilter of about μm and a postfilter of several μm were attached to the outlet of the treatment liquid.

Further, all or most of the cartridge filled with oxine charcoal and the housing loaded with the cartridge are made of a combustible material, and the entire housing is incinerated at the time of disposal so that the volume can be reduced.

Furthermore, the flammable substance is nylon, ABS, acrylic or the like.

(Example) FIG. 1 is a sectional view of a cartridge filter element A of Example 1 filled with powdered oxine impregnated carbon. Reference numeral 1 is a cylindrical cartridge in which 100-150 mesh powder oxine carbon 2 is filled in a dry state. Three
Is a prefilter, and 4 is a postfilter, and powdered oxine charcoal is filled between these filters. The prefilter 3 holds the powdered oxine charcoal in the cartridge 1 to prevent it from flowing out, but 25 μm so as not to capture the clad of several μm.
The filtration accuracy is about m.

Like the prefilter 3, the postfilter 4 has a filtration accuracy of about several μm for the purpose of preventing the outflow of the powdered oxine carbon 2 and removing the clad as the final filtration layer.

The cartridge filter element A has a diameter and height of about 70φ × 250, which is similar to that of a general-purpose cartridge filter and has compatibility so that it can be incorporated into a housing.

FIG. 2 is a sectional view of a cartridge filter element A according to a second embodiment. In this example, the powdered oxine charcoal 2 is filled in the annular space between the cartridge outer tube 1a and the cartridge inner tube 1b.

In this example, the stock solution for treatment is supplied from the stock solution inlets 5 at the top and bottom of the cartridge outer tube 1a, and the post filter 4 is provided at the center.
Through the treatment liquid outlet 6 provided in the cartridge inner tube 1b.

In the first example of FIG. 1, the filling height of the oxine charcoal 2 is about 200 mm.
However, the flow path area is an area corresponding to the cross-sectional area. Further, in the second embodiment shown in FIG. 2, since it flows from the upper and lower parts,
The flow passage area can be made large, but the filling height is 1/1 of that of the first embodiment.
It becomes 2. The specifications can be arbitrarily determined according to the required DF and flow rate.

At present, the wastewater generated in the waste treatment facility of a nuclear power plant is treated with a filter and an ion exchange resin, but by replacing the filter cartridge of the present invention with a conventional filter cartridge, radioactive Co
Not only -60, but also removal of radionuclides such as Ni and Fe can be treated with higher DF.

When the new converter heavy water system is treated with the oxine charcoal cartridge filter as explained above, handling of the cartridge with increased dose becomes a problem. In order to solve this point, if the cartridge and the housing are all made of a combustible material, it is possible to incinerate the cartridge filter, which has been drained and dried after the passage of water, together with the housing.

FIG. 3 shows an example of a flammable filter housing, which is molded from ABS resin.

With the above-mentioned configuration, it operates as follows.

In the example of FIG. 1, the processing stock solution is supplied from the upper prefilter 3,
Further, in the example of FIG. 2, it passes through the upper and lower prefilters 3, 3 and flows into the bed of oxine coal 2. The prefilter 3 removes particles having a large particle size (several tens of μm or more) and accumulating on the surface of oxine charcoal and causing blockage (clogging).

Next, in the stock solution that has flowed into the layer of oxine charcoal 2, ionic Co-60 forms oxine and a chelate compound O-M / n and is adsorbed, and clad Co-60 is filtered of powdered oxine charcoal 2. It is filtered by the effect.

The treated liquid from which Co-60 has been adsorbed and removed in the layer of oxine charcoal 2 flows out to the outlet 6 through the post filter 4.

(Effect) A powdered oxine charcoal in which oxine was impregnated on activated carbon was filled in a cartridge, and filters were attached to the inlet and outlet of the stock solution for treatment. With such a configuration, 1) Conventionally, Co-60 ions and the clad were treated with equipment having different functions (for example, ion exchange resin and filter), but they can be treated with one filter element at the same time, and It is now possible to have a higher DF (DF> 100).

2) Since it is not used as a pre-coat type, a pre-coat tank and pump are unnecessary, and the equipment can be simplified. It is especially effective when the processing amount is small.

3) In the case of the conventional precoat type, since the oxine charcoal layer is dense, the differential pressure rise due to the initial differential pressure and blockage due to surface filtration is large, and the processing flow rate cannot be made large. Although it is inferior to that of oxine in terms of the denseness of the oxine coal layer, it has been proved that the Co-60 clad removal performance is sufficient because the deep layer filtration action is large.

4) When replacing the cartridge, radionuclides such as Co-60 are retained in the oxine carbon layer inside the cartridge,
It is possible to prevent the radiation from being scattered into these atmospheres and inhaled by an operator.

5) Since both the cartridge and the housing are made of a flammable material, it is not necessary to extract the cartridge with the increased dose from the housing, and it is possible to reduce the exposure of workers.

[Brief description of drawings]

FIG. 1 is a first view of a powder oxine charcoal filter according to the present invention.
FIG. FIG. 2 is a sectional view of the second embodiment. FIG. 3 (a) shows an example of a flammable housing, and FIG. 3 (b) is a plan view thereof. In the figure; A ... Cartridge filter element 1 ... Cartridge, 1a ... Cartridge outer tube 1b ... Cartridge inner tube, 2 ... Powder oxine carbon 3 ... Prefilter, 4 ... Postfilter 5 ... Undiluted solution inlet, 6 ...... Processing liquid outlet

Front Page Continuation (72) Inventor Mikiya Fujii 2-1-1 Yatocho, Tanashi City, Tokyo Metropolitan Area Sumitomo Heavy Industries, Ltd. Tanashi Factory (56) Reference JP-A-57-144080 (JP, A) 53-38926 (JP, Y1)

Claims (3)

[Claims] 1. A cartridge is filled with a powdered oxine powder in which oxine effective for removing Co-60 ions is impregnated with activated carbon and the particle size distribution is adjusted to 50 to 200 mesh. A flammable powder oxine charcoal filter used for purification of water containing a radionuclide, characterized in that a prefilter is equipped with a post filter of several μm at the outlet of the treatment liquid. 2. A cartridge filled with oxine charcoal and a housing in which the cartridge is loaded are wholly or almost entirely made of a combustible substance, and can be incinerated together with the housing at the time of disposal to reduce the volume. ) A flammable powder oxine charcoal filter used for purification of water containing a radionuclide as described above. 3. A flammable powder oxine charcoal filter used for purification of water containing a radionuclide according to claim 2, wherein the flammable substance is nylon, ABS, acrylic or the like.