JPS5958396A - Radioactive waste solidifying method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a method for solidifying radioactive waste using a thermosetting resin.

[Technical background of the invention and its problems] In recent years, it has been considered to dry and powder radioactive waste fluid generated from nuclear power plants and other nuclear facilities, and to treat this powder by solidifying it with thermosetting resin, etc. It is being

However, radioactive waste may contain substances that inhibit the polymerization reaction of thermosetting resins. For example, the main component of concentrated waste liquid generated at boiling water nuclear power plants is sodium sulfate (Na2SO4). However, other trace components such as Ca, Si, Fe, Co, Ni, and Cu are often included, and the presence of Cu hydroxide significantly inhibits the polymerization reaction of thermosetting resins. It turned out that.

This is because the hydroxide in the shell has amphoteric properties and dissociates as shown in the following formula, Cu(OH)2■Cu+++2OH- Cu(OH)2CuO2--+2H+H+ generated here initiates polymerization. This is thought to be due to the reaction with the primary radicals generated by the polymerization promoter and the radicals in the subsequent chain reaction, thereby inactivating the radicals.

Thermosetting resins that harden through radical polymerization are difficult to harden in the presence of H+ sources that react with radicals, such as copper hydroxide, and mixtures of radioactive waste and thermosetting resins may be unpolymerized or It will be stored in a storage container with insufficient hardening. If this mixture remains unpolymerized, it can hardly be expected to have the ability to trap radioactivity, and furthermore, the unpolymerized solidifying agent is classified as a dangerous substance under the Fire Service Act, so it would leave radioactive waste in an even more dangerous state. There was a problem.

[Object of the Invention] The present invention has been made to solve these problems, and provides radioactive waste that can be sufficiently cured even if the radioactive waste liquid contains substances that interfere with the curing reaction, such as copper hydroxide. The purpose of this invention is to provide a method for solidifying materials.

[Summary of the Invention] That is, the method of the present invention involves mixing an alkaline substance and this alkaline substance when mixing additives such as a thermosetting resin and a polymerization initiator with radioactive waste containing copper hydroxide or other amphoteric substances. The method is characterized in that the radioactive waste is assimilated by mixing a slurry consisting of a liquid substance that does not react with the substance and does not inhibit the polymerization and curing reaction of the thermosetting resin.

Examples of the thermosetting resin used in the present invention include those obtained by mixing a monomer such as styrene with an unsaturated polyester obtained by condensing maleic anhydride and phthalic anhydride with propylene glycol. It will be done. This mixture exhibits a curing reaction at room temperature when a polymerization initiator such as methyl ethyl ketone peroxide and a polymerization accelerator such as cobalt naphthenate are added.

Examples of the alkaline substance used in the present invention include hydroxides or oxides of sodium, magnesium, calcium, and the like.

These are thought to function to neutralize amphoteric substances such as copper hydroxide that inhibit the polymerization reaction of thermosetting resins. This alkaline substance is mixed with a liquid substance such as a petroleum solvent that does not react with the alkaline substance and does not inhibit the polymerization and curing reaction of the thermosetting resin to form a slurry. The mixing ratio of the alkaline substance and the liquid substance varies slightly depending on the types of the alkaline substance and liquid substance used, and it is desirable that the alkaline substance slurry has a viscosity that makes it easy to transfer with the supply device. For example, when magnesium oxide is used as an alkaline substance and mineral spirits are used as a liquid substance, the mixing ratio should be 1:2 (alkaline substance:liquid substance).

Further, the amount of the alkaline substance added is preferably approximately equivalent to that of copper hydroxide.

In the present invention, dried and powdered radioactive waste,
After a thermosetting resin, a polymerization initiator, a Confucian accelerator, and a slurry of an alkaline substance are uniformly mixed, the mixture is allowed to stand at room temperature.

[Embodiments of the invention] Next, embodiments of the present invention will be described using the drawings.

Radioactive waste (sodium sulfate: copper hydroxide = 59:1) (60% by weight) dried and powdered by thin film dryer 1,
The dry powder is transferred to the mixing tank 3 by the dry powder transfer feeder 2, and 40% by weight of a solidifying agent such as a thermosetting resin is solidified from the solidifying agent tank 4, and the polymerization initiator (methyl ethyl ketone peroxide) is solidified from the polymerization initiator tank. 0.5 for agent
From the polymerization accelerator tank 6, the polymerization accelerator (cobalt naphthenate) is sent to the mixing tank 3 in an amount of 0.5% by weight based on the solidifying agent, and further, the alkaline substance storage hopper 7 and the liquid substance are sent to the mixing device 9. A fixed amount of the alkaline substance slurry obtained by mixing was put into the mixing tank 3 at a polymerization rate of 3% relative to the solidifying agent, and after mixing in the mixing tank 3, a fixed amount was put into the drum can 10. When the drum 10 was left for a day and night, a strong plastic solidified body was obtained.

[Effects of the Invention] As explained above, according to the method of the present invention, even if substances such as copper hydroxide that inhibit the polymerization curing reaction are present in the radioactive waste, curing is carried out sufficiently, and a strong plastic solidification is achieved. You get a body.

In addition, an alkaline substance that neutralizes copper hydroxide, which inhibits the polymerization and curing reaction of thermosetting resins, is added in the form of a slurry, which has the advantage of good dispersibility, resulting in uniformly hardened plastic solids. It will be done.

[Brief explanation of drawings]

The drawings are diagrams for explaining one embodiment of the present invention. １…………Thin film dryer ３…………Mixing tank ４…………Solidifying agent tank 5...Polymerization initiator tank 6...Polymerization accelerator tank 7……Alkaline substance storage hopper 8……Liquid substance tank 10……Drum can Representative Patent Attorney Saiichi Suyama

Claims (1)

[Claims] When mixing a thermosetting resin with radioactive waste containing a hydroxide cylinder or a substance that dissociates to generate H+, a polymerization curing reaction between an alkaline substance and a thermosetting resin that does not react with this alkaline substance is necessary. A method for solidifying radioactive waste, comprising solidifying the radioactive waste by mixing a slurry with a liquid substance that does not inhibit the radioactive waste.