JPH0672957B2 - Treatment method of radioactive ion exchange resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a method for inorganic stabilization treatment of a radioactive ion exchange resin (hereinafter simply referred to as a resin) stored in a nuclear facility.

[Conventional technology]

As a resin treatment method, there is no example of application to an actual machine at present, and therefore various technologies under development will be described.

1) Incineration method: This is literally a method of incinerating resin, but if the level of radioactivity contained in the resin is high, the amount of radioactivity contained in the incinerator exhaust gas will increase, so the exhaust gas treatment device will have an excessive amount of radioactivity removal performance. Will be required. That is,
Exhaust gas treatment equipment becomes complicated and large-scale. In addition, the radioactivity concentration of incinerated ash is high, and its handling is not easy.

2) Pyrolysis: This is a method of thermally decomposing at a high temperature in an inert atmosphere, and then burning the decomposed gas. Compared to the incineration method, it has less soot and dust, but requires an additional thermal decomposition step, and the product has a high radioactivity concentration.

3) Chemical decomposition method: A resin is acid-decomposed by a chemical reaction with a chemical agent, but since a strong acid and an oxidizer are handled at high temperatures, corrosion of equipment constituent materials becomes a problem.

4) Direct solidification method: This is a method of directly solidifying the resin with cement, asphalt, or plastic, but the high radioactivity level of the resin causes the resin to deteriorate due to radiation during long-term storage, lowering the pH and generating gas. As a result, damage to the solidified body and eventually damage to the container (drum can) will occur.

[Problems to be solved by the invention]

When solidifying a relatively high level of resin (using asphalt, plastic, cement, etc.) or HIC filling, 1) reduce the radioactivity concentration in the resin.

2) As a result, the radiation damage to the resin itself during storage is reduced.

3) From this, deterioration of the resin of the solidified body is prevented, and the soundness of the solidified body and the container is maintained.

In addition, in the case of rotating the resin, 1) the radioactivity concentration in the exhaust gas is reduced by reducing the radioactivity concentration in the resin.

2) As a result, it is possible to incinerate in an existing incinerator, and no new equipment is required.

3) The acid in the eluent is recovered in high yield to highly concentrate the nuclide and reduce the amount of the cement solidified product.

The present invention is intended to provide a method for treating a radioactive ion exchange resin capable of achieving the above-mentioned object.

[Means for solving problems]

The present invention is to elute a medium- or long-half-life radionuclide adsorbed on a radioactive ion exchange resin using an acid solution, and pass the eluate through a first diffusion dialysis tank to recover the acid, After the acid waste liquid containing is concentrated in the concentrator, it is passed through the second diffusion dialysis tank to recover the acid again, and the acid waste solution is concentrated, and then the step of recovering the acid through the diffusion dialysis tank is performed at least once. As a result, nuclides are collected from the eluent with high concentration to form a solidified product, and acids are collected and reused in high yield to reduce secondary waste, and the resin from which nuclides have been removed is incinerated. The method for treating a radioactive ion exchange resin is characterized by

In the present invention, first, an acid solution, for example, a H ₂ SO ₄ solution is passed through a resin that has adsorbed medium-long half-life nuclides (Co, Cs, etc.) to elute the nuclide from the resin. The resin can be treated as a low activity level material and the application of an incinerator for low activity level is possible. On the other hand, the eluent is passed through a diffusion dialysis tank provided in two or more stages to separate the nuclide and the acid in the eluent with high efficiency. By doing so, the acid in the eluent can be reused and secondary waste can be reduced. The nuclide is highly concentrated by a diffusion dialysis tank and stored in a relatively small amount as a cement solidified body in an inorganic state.

[Action]

By separating the resin and the radionuclide, the resin can be practically made into an inorganic substance only by a combination of known techniques in which the resin is incinerated and the nuclide is sealed in the inorganic material.

〔Example〕

One embodiment of the present invention will be described with reference to FIG. 1, and its mass balance is shown in Table 1.

In FIG. 1, first, a fixed amount of resin is taken out from a waste resin storage tank 1 and filled in a resin processing tank 2. Next, H ₂ SO ₄ having a constant concentration (about 2 N) is pressure-fed through the line 8 to pass the liquid. At this time, in the resin treatment tank 2, nuclides (Cs ⁺ , Co
²⁺ ) elutes and H ⁺ adsorbs. (H ₂ SO ₄ is consumed) A first stage diffusion dialysis tank 3 is installed downstream of this tank 2. An anion exchange membrane 10 is arranged in the tank 3 so that the tank 3 is divided into two chambers. When pure water and the eluent from the above process are flown through the anion exchange membrane 10 in a counter flow as shown in the figure, H ₂ SO ₄ moves to the right chamber, and the nuclide remains in the same chamber. Go out of the tank.

The liquid containing this nuclide is then concentrated in the concentrator 5, and the liquid amount is extremely reduced. Further, in this solution, there is H ₂ SO ₄ that has not moved to the right chamber in the first diffusion dialysis tank 3, and this is also concentrated in the concentrator 5.

Therefore, this concentrated liquid is guided to the second-stage diffusion dialysis tank 4 having the same structure as the first-stage diffusion dialysis tank 3, and further, H ₂ SO ₄ is moved to the right chamber and collected. In the second-stage diffusion dialysis tank 4, the nuclide in the left ventricle also flows out from the tank 4 as it is. By repeating this operation, the volume of the liquid containing the nuclide can be extremely reduced.

The material balance difference in Table-1 is the data of resin used 10 m ³ / year, and the symbol marked with ◯ in the table indicates the position of the symbol marked with ◯ in FIG. This is a tiered example.

Since the liquid containing the nuclide discharged from the second-stage diffusion dialysis tank 4 contains a small amount of H ₂ SO ₄ , it is neutralized in the neutralization tank 6 with NaOH and the solubility of Na ₂ SO _{4 in} the concentrator 7 (25 wt%) It is concentrated until it is solidified with cement.

On the other hand, the nuclide-free resin is incinerated in the incinerator 9 and collected as ash.

Also, the amount equivalent to H ₂ SO ₄ that could not be consumed and recovered was H
₂ SO ₄ Makeup line 8 is supplied.

Note that Na ₂ SO ₄ is cemented as it is. In this example, the number of cement solidifications is 78 / batch x 20 batch / year =
Since it is 1560 / year, if we put 100 in one drum, it will be 1560 / year / 100 / piece = 15.6 / year ≈ 16 / year, and if we put resin 10m ³ / year in 200 containers as it is, 50 /
Although it was necessary for a year, a considerable volume reduction effect can be obtained.

EFFECTS OF THE INVENTION In the treatment of the radioactive ion exchange resin, the present invention separates the nuclide and the resin by an acid solution, the resin from which the nuclide is separated and removed is incinerated, and the acid containing the nuclide is assembled in two stages. In the diffusion dialysis tank, the nuclide and the acid are separated with high efficiency, the acid is reused, and the nuclide is inorganic-stabilized as a small amount of cement solidified product, so that the radioactive ion exchange resin can be significantly reduced in volume.

[Brief description of drawings]

 FIG. 1 is an explanatory diagram of an embodiment of the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshio Funakoshi 2-1-1, Niihama, Arai-cho, Takasago, Hyogo Prefecture Mitsubishi Heavy Industries, Ltd. Takasago Laboratory (72) Inventor Wataru Kawamura 2--1, Niihama, Arai-cho, Takasago, Hyogo Prefecture No. 1 Mitsubishi Heavy Industries, Ltd. Takasago Research Institute (72) Inventor Yuzo Inagaki 5-16 Komatsudori, Hyogo-ku, Kobe, Hyogo Prefecture (56) Shinryo High-Tech Co., Ltd. (56) Reference JP-A-59-51399 A) JP-A-61-155898 (JP, A)

Claims (1)

[Claims] 1. Adsorbed on a radioactive ion exchange resin
The long half-life radionuclide is eluted with an acid solution, the eluate is passed through a first diffusion dialysis tank to recover the acid, and the acid waste solution containing the nuclide is concentrated in a concentrator, The acid is recovered again by passing it through the diffusion dialysis tank, and the step of concentrating the acid waste solution and then recovering the acid through the diffusion dialysis tank is carried out at least once, whereby highly concentrated nuclides are recovered from the eluent. A method for treating a radioactive ion exchange resin, which is characterized in that the resin is solidified, the acid is recovered in high yield and reused, secondary waste is reduced, and the resin from which the nuclide has been removed is incinerated.