JPH0368900A - Burnable powder oxine carbon filter being used for purification of water containing radioactive nuclides - Google Patents

Abstract

PURPOSE:To simplify a device for removing Co-60 in depleted heavy water as far as possible by putting oxine carbon powder which is an activated carbon on which oxine is deposited, into a cartridge, and by fitting filters to both of the inlet and the outlet for a raw liquid to be treated. CONSTITUTION:A raw liquid to be treated flows into a layer of an oxine carbon 2 from a part pre-filter 3 provided in a lower part of a cartridge. By this pre- filter 3, objects having large particle diameter, deposited on the surfaces of the oxine carbon, and causing clogging, are removed. Then, ionized Co-60 in the raw liquid flowing into the layer of the oxine carbon 2 is adsorbed producing a chelate compound O-M/n with the oxine. On the other hand, crud Co-60 is filtered by filtration of the powder oxine carbon 2. A treated liquid from which the Co-60 has been removed by adsorption of the layer of the oxine carbon 2 flows out to an outlet 6 through a post-filter 4.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a combustible powder oxine carbon filter.

(Prior art) When disposing of the ion exchange resin used in the heavy water system of a new converter reactor, an operation called light water conversion is required to recover the heavy water from the ion exchange resin and discharge tritium from the system. When this operation is performed, degraded heavy water (heavy water concentration 1 to 99%) diluted with light water is produced, but this heavy water is purified to 99.8% or more using a heavy water purification device called an upgrader.

This degraded heavy water contains Co-60, so after removing Co-60 from the degraded heavy water, it is transferred to the upgrader to prevent the dose from increasing due to the accumulation of Co-60 in the upgrader. However, studies are underway to make this removal device as simple and compact as possible.

1) - It is possible to treat the inside of the shell with a combination of an ion exchange resin and a filter.
It is thought that the DF of both ions and cladding in the liquid is about 10 due to the adsorption or filtration effect of ions and Co-60 cladding (particulate matter) in the filter.

2) On the other hand, it is known that activated carbon impregnated with oxine (hereinafter abbreviated as oxine carbon) is effective in adsorbing and removing Go-60. When using granular oxine charcoal, the oxine charcoal is usually used by filling it in a column. When powdered oxine charcoal is used, the filter is precoated and used for removing crud, but in this case a tank and pump for precoating are 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 from degraded heavy water as simple and compact as possible.

(Means for solving problems by the invention) A cartridge is filled with powdered oxine charcoal, which is made by impregnating activated carbon with oxine, which is effective for removing Go-60 ions, and whose particle size distribution is adjusted to 50 to 200 mesh. A pre-filter with a capacity of about 1 μl was installed at the outlet of the processing solution, and a post-filter with a capacity of several μl was installed at the outlet of the processing solution.

In addition, all or most of the cartridge filled with oxine charcoal and the housing in which the cartridge is loaded are made of flammable material, so that the housing can be incinerated together with the housing to reduce its volume when disposed of.

Furthermore, flammable materials include nylon, ABS, acrylic, and the like.

(Example) FIG. 1 is a sectional view of the first example of a cartridge filter element A filled with powdered oxine-impregnated carbon. 1 is a cylindrical cartridge with 100 to 150 particles inside.
Metush's powdered oxine charcoal 2 is filled in a dry state. 3 is a pre-filter, 4 is a post-filter, and powdered oxine charcoal is filled between these filters. The pre-filter 3 holds the powdered oxine charcoal in the cartridge 1 and prevents it from flowing out, but has a filtration accuracy of about 25 μm so as not to capture several micrometers of crud.

Similarly to the pre-filter 3, the post-filter 4 is intended to prevent the powdered oxine carbon 2 from flowing out and to remove crud as a final filtration layer, and has a filtration accuracy of several microns.

The diameter and height of the cartridge filter element A are approximately 70 φ x 250 fl, which are similar to a general cartridge filter, and are compatible with each other so that they can be incorporated into the housing.

FIG. 2 is a sectional view of a second embodiment of the cartridge filter element A. In this example, 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 processing solution is supplied from the upper and lower solution ports 5 of the cartridge outer pipe 1a, passes through the post filter 4 in the center, and passes through the processing solution outlet 6 provided in the cartridge inner pipe 1b.
is discharged from.

In the first example of Fig. 1, the filling height of oxine charcoal 2 is approximately 200 mm.
m, and the flow path area is an area corresponding to the cross-sectional area.

Further, in the second embodiment shown in FIG. 2, since the flow flows from the upper and lower parts, the flow path area can be increased, but the filling height is 1/2 that of the first embodiment. Note that the specifications can be arbitrarily determined depending on the required DF and flow rate.

Currently, wastewater generated in nuclear power plant waste treatment equipment is treated with filters and ion exchange resins, but by replacing the filter cartridge of the present invention with the conventional filter cartridge, radioactive C
Not only O-60 but also radioactive nuclides such as Ni and Fe can be removed at a higher DF.

When processing the heavy water system of a new converter reactor using the oxine charcoal cartridge filter as described above, handling of the cartridge with increased dose becomes a problem. To solve this problem, if the cartridge and housing are all made of flammable materials, the cartridge filter, which has been drained and dried after water treatment, can be incinerated together with the housing.

Figure 3 shows an example of a flammable filter housing, with ABS
Molded from resin.

The configuration described above operates as follows.

In the example shown in Fig. 1, the processing stock solution is supplied from the upper prefilter 3.
In the example shown in FIG. 2, the water passes through the upper and lower prefilters 3, 3 and flows into the oxine carbon layer 2.

This pre-filter 3 removes particles that have a large particle size (several tens of micrometers or more) and accumulate on the surface of the oxine charcoal, causing clogging.

Next, among the stock solutions that flowed into the layer of oxine charcoal 2, ionic Go-60 was mixed with oxine and chelate compound 0-M/
The cladding Co-60 is filtered by the filtration effect of the powdered oxine carbon layer.

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

(Effects) A cartridge was filled with powdered oxine charcoal in which oxin was impregnated with activated carbon, and filters were installed at the inlet and outlet of the processing stock solution. With this configuration, 1) Conventionally, Co-60 ions and cladding were treated with equipment with separate functions (for example, ion exchange resin and filter), but now it is possible to treat them simultaneously with one filter element, and It is now possible to have a higher DF (DF > 100).

2) Since it is not used as a pre-coat type, there is no need for a pre-coat tank or pump, and the equipment can be simplified. This is particularly effective when the amount of processing is small.

3) In the case of the conventional pre-coated type, the oxine carbon layer is dense, so the initial differential pressure and the differential pressure increase from blockage due to surface filtration are large, and a large processing flow rate cannot be obtained.However, in this cartridge, the pre-coated type Although the density of the oxine coal layer is inferior to that of the oxine carbon layer, the depth filtration effect is greater, so it has been demonstrated that the performance is sufficient for removing Go-60 crud.

4) When replacing the cartridge, radioactive nuclides such as Go-60 are retained in the oxine carbon layer inside the cartridge, which prevents them from scattering into the atmosphere and from being inhaled by workers.

5) Since both the cartridge and the housing are made of combustible materials, there is no need to remove the cartridge with increased radiation dose from the housing, making it possible to reduce the radiation exposure of workers.

[Brief explanation of drawings]

FIG. 1 shows a first diagram of a powdered oxine charcoal filter according to the present invention.
Example sectional view. FIG. 2 is a sectional view of the second embodiment. FIG. 3(a) shows an example of a combustible 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 Powdered oxine charcoal prefilter 4 Post filter SyK liquid population 6 Processing liquid outlet or above

Claims (3)

[Claims] (1) Powdered oxine carbon, which is effective in removing Co-60 ions, is impregnated with activated carbon and the particle size distribution is adjusted to 50 to 200 mesh, and the cartridge is filled with a pre-filter of several tens of μm at the inlet of the processing stock solution. A flammable powder oxine charcoal filter used for purifying water containing radionuclides, characterized in that a post filter of several μm is attached to the outlet of the treatment liquid. (2) Claim (1) characterized in that the cartridge filled with oxine charcoal and the housing in which the cartridge is loaded are all or most made of a combustible material, and the volume can be reduced by incinerating the entire housing at the time of disposal. combustible powder oxine charcoal filter used to purify water containing radionuclides. (3) The flammable powder oxine charcoal filter for use in purifying water containing radionuclides according to claim (2), wherein the flammable material is nylon, ABS, acrylic, or the like.