JPS6035037B2 - Waste liquid treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for the complete treatment of waste liquids containing radioactive substances.

Conventionally, attempts have been made to immediately incinerate waste liquids containing radioactive materials, such as organic scintillator waste liquids, but since most waste liquids contain large amounts of water, direct combustion is difficult. Requires large-scale combustion equipment and dedicated engineers.

Therefore, it is possible to carry out treatment at each facility in most cases, but even in the case of centralized treatment, it is difficult to safely transport organic solvents and waste liquids containing radioisotopes. Due to the difficulty of treatment, waste liquid is currently stored in piles without being treated. This condition is extremely dangerous from the standpoint of preventing disasters caused by radioactive materials and fire prevention, and to avoid this, there are cases where direct use of liquid scintillation measurement equipment is prohibited. In order to improve the current situation, the present inventors conducted aeration distillation of the organic scintillator waste liquid to obtain a distillate fraction consisting of an organic solvent and water that contains almost no radioisotopes, and a distillation residue that contains most of the radioisotopes. Divide into
As a result of devising a method for treating each of these separately and conducting further intensive studies, we have arrived at the present invention.

In the present invention, waste liquid containing radioactive substances is separated into a distillation part and a residual part by aerated distillation, and while the distillation part is treated by an appropriate means, a methacrylic acid ester syrup is added to the residual part and polymerized and solidified. This is a complete treatment method for radioactive waste liquid, which is characterized in that the residual portion is sealed in methacrylic acid ester syrup and then incinerated together with the above-mentioned polymer.

According to the treatment method of the present invention, radioactive substance-containing waste liquid, which requires great consideration in its treatment, is first divided into a distillation part that contains almost no radioactive substances and a residual part that contains most of the radioactive substances. Since certain organic solvents and water can be disposed of in the usual manner, such as by incineration or as wastewater, the problem remains how to dispose of the residual portion, which is extremely small compared to the amount of the raw solution. The remaining parts containing most of the radioactive materials will be stored on the premise that they will be intensively incinerated.
We considered solidifying the material to prevent the scattering and leakage of radioactive materials during handling, transportation, and incineration.

As a result, by adding and mixing methacrylic acid ester syrup to the residual part and then polymerizing and solidifying it to seal in the residual part, the residual part can be easily solidified without emitting black smoke or leaving a residue. Then, they found that the solidified material could be incinerated, so they released it. The methacrylic acid ester syrup used in the present invention is mainly composed of a liquid mixture of polymethyl methacrylate and methyl methacrylate. In the present invention, a small amount of other methacrylic acid ester and/or acrylic acid ester is added to methyl methacrylate instead of polymethyl methacrylate within a range that does not impair the polymerizability of the syrup and the combustibility of the polymer. A copolymer obtained by polymerization may also be used.

Similarly, a small amount of other methacrylic ester and/or acrylic ester may be added to the methacrylic ester syrup.

As a method for producing the above-mentioned taacrylate syrup, for example, a method of dissolving polymethyl methacrylate in methyl methacrylate, or a partially polymerized syrup is produced by stopping the polymerization in a state where methyl methacrylate is partially polymerized. There are several methods.

The solidification treatment involves mixing the distillation residue containing most of the radioactive substances with the methacrylate syrup, adding a polymerization catalyst thereto, and solidifying the mixture.

At this time, it is okay for a small amount of organic solvent that has not been fractionated by aerated distillation to remain in the distillation residue, but if a large amount remains, it may cause softening of the molded product or
This is not preferable because the organic solvent will volatilize. Further, although it is acceptable for a small amount of water to be present in the distillation residue, it is not preferable for the water to be present in such a large amount that it inhibits the polymerization reaction or the combustion of the solidified product. As the polymerization catalyst, an oil-soluble peroxide such as penzoyl peroxide is most suitable, but it is also possible to use an azobis-based polymerization catalyst or to use heat, ultraviolet rays, or electron beams as an activation energy source.

Further, in order to promote the polymerization reaction by peroxide, it is possible to use a promoter such as a tertiary amine in combination. Furthermore, in order to reduce the influence of oxygen in the air on the polymerization reaction, paraffin or an air-blocking film can be used in combination. Example 1,000 pieces of radioactive organic scintillator waste liquid containing tritium, a radioactive substance, were subjected to aeration distillation, and 310 pieces of an easily volatile organic solvent containing almost no radioactive substances and 49 pieces of water were extracted.
Distilled residual light containing 0' and most radioactive materials was separated into 200 I.

The amount of radioactive substances in the separated organic solvent, water, and distillation residue was 4.1 × 10-3 microcuries (mountain C
i), 2.7 x 10-2 French Ci, 9.4 French Ci, and the amount of radioactive substances present in the separated organic solvent and water is that if these are removed by normal methods such as incineration or drainage, Most of the radioactive substances present in the waste liquid were contained in the distillation residue, which was within a range that would pose no problem for treatment.

Therefore, by this aerated distillation separation, the amount of radioactive materials that require special treatment can be reduced to 20% of the initial waste liquid.
It was reduced to %. 150 parts by weight of polymethyl methacrylate, 35 parts by weight of methyl methacrylate monomer, and N,N
When a syrup consisting of 1 part by weight of -dimethyl-paratoluidine was mixed with 5 parts by weight of penzoyl peroxide, the polymerization reaction was completed after about 30 minutes at room temperature, and the mixture of distillation residue and syrup was mixed with a mixture of distillation residue and syrup. I became a monster.

Claims (1)

[Claims] 1 Separate the waste liquid containing radioactive substances into a distillate part and a residual part by aerated distillation, treat the distillate part by appropriate means, and add methacrylic acid ester syrup to the residual part to polymerize and solidify it. A method for completely disposing of radioactive waste liquid, which comprises: trapping the residual portion in a polymer of methacrylic acid ester syrup, and then incinerating the residual portion together with the polymer.