JPH0151957B2 - - Google Patents

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 fluid generated at boiling water nuclear power plants is sodium sulfate (Na ₂ SO ₄ ), but other minor components include Ca, Si, Fe, Co,
Often contains elements such as Ni and Cu,
In particular, it was found that the presence of Cu hydroxide significantly inhibits the polymerization reaction of thermosetting resins.

This is because copper hydroxide has amphoteric properties and dissociates as shown in the following formula, Cu(OH) ₂ Cu ⁺⁺ +2OH ^- Cu(OH) ₂ CuO ₂ ^-- +2H ^{+ H + generated} here This is thought to be due to the reaction with primary radicals generated by the polymerization initiator and polymerization accelerator and the radicals in the subsequent chain reaction, thereby inactivating the radicals.

Thermosetting resins that harden through radical polymerization are difficult to cure in the presence of sources of H ⁺ that react with radicals, such as copper hydroxide, and mixtures of radioactive waste and thermosetting resins are difficult to cure when they are not polymerized. Otherwise, it will be stored in a storage container with insufficient hardening. If this mixture remains unpolymerized, it can hardly be expected to have any radioactivity trapping ability, and the unpolymerized solidifying agent is classified as a dangerous substance under the Fire Service Act, making radioactive waste even more dangerous. There was a problem.

[Object of the Invention] The present invention was made to solve these problems, and is capable of sufficiently curing even if the radioactive waste contains substances that interfere with the curing reaction, such as copper hydroxide. The purpose is to provide a method for solidifying radioactive waste.

[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 solidified 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 the liquid substance, the mixing ratio is set to be alkaline substance:liquid substance=1:2. Further, the amount of the alkaline substance added is preferably approximately the same amount as the amount of copper hydroxide.

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

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

60% by weight of radioactive waste (sodium sulfate: copper hydroxide = 59:1) dried and powdered by the thin film dryer 1 is transferred to the mixing tank 3 by the dry powder transfer feeder 2.
At the same time, from the solidifying agent tank 4, 40% by weight of a solidifying agent such as a thermosetting resin, and from the polymerization initiator tank, 0.5% by weight of a polymerization initiator (methyl ethyl ketone peroxide) based on the solidifying agent, and a polymerization accelerator. From tank 6, a polymerization accelerator (cobalt naphthenate) is sent to mixing tank 3 at 0.5% by weight relative to the solidifying agent.
Furthermore, the alkaline substance slurry obtained by sending the alkaline substance and liquid substance from the alkaline substance storage hopper 7 and the liquid substance tank 8 to the mixing device 9 and mixing them is quantitatively charged into the mixing tank 3 at 3% by weight based on the solidifying agent. After mixing in the mixing tank 3, a certain amount was put into the drum can 10. When the drum 10 was left for a day and night, a strong plastic solidification was obtained.

[Effects of the Invention] As explained above, according to the method of the present invention, even if something that inhibits the polymerization curing reaction, such as copper hydroxide, is present in the radioactive waste, curing is sufficiently performed.
A strong plastic solidified body is obtained.

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.

Claims (1)

[Claims] 1. When mixing a thermosetting resin with radioactive waste containing copper hydroxide or a substance that dissociates to generate H ⁺ , polymerization and curing of an alkaline substance and a thermosetting resin that does not react with this alkaline substance A method for solidifying radioactive waste, comprising solidifying the radioactive waste by mixing a slurry with a liquid substance that does not inhibit the reaction.