JPS581400B2 - AEON CO., LTD. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for selectively separating radioactive substances in water using an ion exchange resin, and in particular to a method for separating radioactive substances in water in nuclear power plants, such as short and long half-life components in reactor cooling water systems. This is highly effective in reducing the amount of radioactive waste that is subject to permanent treatment.

In order to prevent the danger of cooling water contaminated by metal corrosion products in the reactor cooling water system activated in the reactor core or nuclear fission products due to fuel rod breakage, the cooling water is As shown in Figure 2, various radionuclides are adsorbed and purified through ion-exchange resins, and used ion-exchange resins or recycled waste liquids are stored as radioactive waste and permanently disposed of.

By the way, the amount of radioactive waste is increasing year by year as the number of nuclear power plants increases, and according to the current treatment method, the amount was approximately 70,000 drums per year in 1970, and 70,000 drums per year in 1980. It is estimated that there are about 200,000 trees, and countermeasures are currently being seriously discussed.

The present invention provides a method for treating radioactive substances in water using an ion exchange resin, which is significantly effective in reducing the amount of radioactive waste that is subject to permanent disposal, and will be described in detail below with reference to the drawings.

Nuclides contained in reactor cooling water have half-lives of several hours or tens of days, such as iodine-132 (half-life 2.26 hours), iodine-133 (20.3 hours), copper-64 (12
．． 8 hours), iron-59 (45.6 days), cobalt-60 (5.3 years), and cesium-137 (
30 years), strontium-90 (277 years), and intermediate half-lives of several hundred days, such as zinc-64 (245 days) and manganese-54 (303 days). Consists of things.

Therefore, instead of adsorbing and removing all of these nuclides using ion exchange resins as in the past, we have to remove nuclides with long half-lives, for example, from several hundred days to several decades, and comparatively those with half-lives of several tens of days or less. The idea was that the amount of radioactive waste (processed resin) could be reduced by making it possible to separate and adsorb nuclides with shorter half-lives and subjecting only nuclides with long half-lives to permanent disposal.

The present invention takes advantage of the fact that a special resin has the property of selectively adsorbing only nuclides with a specific half-life, and can adsorb a large amount or all of the nuclides with relatively short half-lives. A special resin selected as above was placed in front of the conventional ion exchange resin (hereinafter referred to as ordinary resin) that has the property of adsorbing all nuclides, and the halved ion exchange resin that penetrated the special resin without being adsorbed was used. By adsorbing relatively long-lived nuclides onto ordinary resin, the amount of radioactive waste can be significantly reduced.

Next, the present invention will be explained by examples.

Example (1) Separation of chelating agent adsorption anion exchange resin and ordinary resin Chelating agent adsorption anion exchange resin For example, the resins shown in Table 1 have the ability to adsorb short half-life nuclides.

In this example, the resin name (product name) and particle size shown in Table 1 are prefixed to the ordinary resin (1) as special resin (2), and contain various cations as shown in Table 2. When an aqueous solution was prepared using commercially available reagents and allowed to pass through the resin, a flow-through curve as shown in FIG. 3 was obtained.

The complete outflow point (3rd point) of long-half-life nuclides in this flow-through curve
As shown in Table 1, the adsorption rate of short half-life nuclides such as iron and copper to the special resin at point A in the figure is 92% for iron, as shown in Table 1.
~97%, and as high as 78~93% for copper, and it can be considered that short half-life nuclides and long half-life nuclides are practically separated into special resins and ordinary resins.

It should be noted that some amount of iron, copper, etc. leaked out from the special resin is adsorbed by the subsequent ordinary resin, that is, the ordinary resin that adsorbs nuclides with both long and short half-lives, so there is no problem.

Example (2) Separation using a special selective cation exchange resin The cation exchange resins shown in Table 3 have selective adsorption properties for short half-life nuclides.

In this example, a special resin with the resin name and particle size shown in Table 3 is placed in front of a regular resin, and an aqueous solution containing various cations is prepared using commercially available reagents and passed through the resin as shown in Table 4. As a result, the adsorption rate of copper, for example, at the complete outflow point of long-half-life nuclides in the flow-through curve is 74 to 82%, as shown in Table 3, and for practical purposes it can be considered that they are separated into short-half-life nuclides and long-half-life nuclides. That's it.

Note that short half-life nuclides flowing out from the special resin do not cause any problems because they are adsorbed by the subsequent ordinary resin which does not have selective adsorption properties for both long and short half-life nuclides.

Therefore, only resins that have adsorbed long-half-life components that do not become non-radioactive within a short period of time will be subject to permanent disposal, and the amount of radioactive waste will be significantly reduced compared to current disposal methods.

Although the present invention has been described above by way of example, the present invention is applicable to the treatment of recycled waste liquid from condensate desalination equipment, which accounts for the majority of radioactive waste in power plants using boiling water reactors (so-called BWR reactors), and other applications. Needless to say, it can also be applied to the separation of short and long half-life nuclides in general radioactive waste liquid treatment.

As is clear from the above explanation, according to the present invention, the amount of radioactive waste at nuclear power plants can be greatly reduced compared to the treatment method based on the current law, and it is a practical method that can significantly reduce the difficulties of permanent disposal. It has excellent effects.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the conventional method, Fig. 2 is an explanatory diagram of the present invention,
FIG. 3 is a flow curve diagram.

Claims (1)

[Claims] 1. A special ion exchange resin that selectively adsorbs steel, a nuclide with a relatively short half-life, is placed in front of a regular ion exchange resin,
A method for selectively separating radioactive substances in water using an ion exchange resin, characterized in that the nuclide that has flowed through the special ion exchange resin is adsorbed onto a normal ion exchange resin, thereby reducing the amount of radioactive waste that is subject to permanent disposal.