JPS61215999A - Solidifying agent for radioactive waste - 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] [Field of sedentary use] The present invention is an assimilating agent for radioactive waste, specifically a cementitious material, an ultrafine powder, a water reducing agent, and water as the product components, and the treatment capacity is comparable to that of a dog. This invention relates to a safe radioactive waste assimilation agent that can be stored permanently and has a low tendency to release radioactive materials.

[Prior art]

Radioactive waste generated from nuclear facilities such as nuclear power plants and nuclear fuel reprocessing plants includes slag waste, ion exchange resin for toilet use, filter sludge, incineration ash, miscellaneous solids, various i-sludges, and nuclear power plant waste. These include so-called low- and medium-level radioactive waste, such as concrete scraps that are disposed of during demolition, as well as high-level radioactive materials.

The cement solidification method, the bitumen solidification method, and the plastic assimilation method are in practical use as methods for solidifying these radioactive PA residues, especially low- and medium-level radioactive wastes.

[Problem that the invention seeks to solve]

However, although the cement solidification method has excellent durability, it has disadvantages such as low processing capacity and relatively high leachability. Further, although the bitumen solidification method and the plastic solidification method have high processing capacity, they have drawbacks such as complicated processing methods and safety problems in terms of weather resistance and the like.

Based on the above, there is a strong need for a radioactive waste disposal method that has large processing capacity, low leachability, and excellent weather resistance.
There is.

In order to eliminate the above-mentioned drawbacks, the present inventors have made extensive studies and have discovered that the above-mentioned drawbacks can be improved by using a solidifying agent containing a specific component as a product, thereby completing the present invention. reached.

[Means for solving problems]

That is, the invention is a solidifying agent for a radioactive Xfi substance whose product components are a cement substance, an ultrafine powder, a high-performance water reducer, and water.

Hereinafter, the non-invention will be explained in detail.

The cementitious materials referred to in the present invention include various types of portland cement such as Shintsu, early strength, ultra early strength, white or salt-resistant,
Furthermore, blast furnace slag and fly ash! #Commonly used are mixed cement containing admixtures, and mixed cement obtained by pulverizing the mixed material and/or the cement to be mixed.

In addition, we can use expanding cement to compensate for shrinkage, and use rapid hardening cement to develop the required strength in a short time.
A gypsum-based high-strength admixture can also be used.

As the expanding component of the expanding cement, ettringite-based ones such as those manufactured by Denki Kagaku Kogyo Co., Ltd. [rcsA#:20j
or calcined CaO is preferable, and among calcined CaO, 1100~
Particularly preferred are those which are fired at 1600°C and have an average crystal diameter of 10μ or less.

Rapid hardening cement is one that contains a calcium aluminate-based rapid hardening component, such as calcium aluminate alone or a mixture of calcium aluminate and calcium sulfate. -Product name [Denka E8
There are cements containing J and the product name ``Jet Cement'' manufactured by Onoda Cement (now closed).

In addition, high-strength admixtures include gypsum-based ones, such as "Denka Σ-1000J" manufactured by Denki Kagaku Kogyo Co., Ltd., "Asano Super Mix" manufactured by Nippon Cement Co., Ltd., and "Non-Non" manufactured by Osaka Cement Co., Ltd. Crepes, etc.

The ultrafine powder conveniently used in the present invention has an average particle size that is at least one order of magnitude lower than that of the above-mentioned cementitious material, and preferably one that has an average particle diameter of two orders of magnitude lower from the viewpoint of the fluidity of the kneaded product. Specifically, silica dust (silica hume) and silica powder, which are used for manufacturing silicon, silicon-containing materials, and zirconia, are particularly suitable.In addition, calcium carbonate, silica sol, opalescent silica, fly ash, slag, titanium oxide,
Ultrafine powders such as aluminum oxide can also be used. In particular, the use of ultrafine powder obtained by pulverizing opalescent silica or fly ash 1 slag using a shet mill equipped with a classifier or the like is effective from the standpoint of improving hardening shrinkage.

The amount of ultrafine powder used is preferably 60 to 9
5'jL] is 5 to 40 parts by weight, more preferably 10 to 65 parts by weight relative to 65 to 90x'Ik parts, and if it is less than 5TLt parts, high strength (@tightness) cannot be obtained. Moreover, if the amount exceeds 40 parts by weight, the fluidity of the kneaded product will be significantly reduced, making it difficult to mold it and developing insufficient strength.

The high-performance water reducing agent (hereinafter referred to as water reducing agent) used in the present invention is a surfactant with a large dispersion ability that does not cause too much delay in setting or excessive air entrainment even when added in a large amount compared to cement, and is Examples include salts of sulfonic acid formaldehyde condensed metals, salts of melamine sulfonic acid formaldehyde condensed metals, high molecular weight lignin sulfonates, polycarboxylic acid salts, and the like. Water reducing agents are necessary to obtain mixed materials at low water ratios, and the conventional usage amount is
0.5 to 1 as solid content for cement purchase '1821 purchase
Although Higashi Sumirechi is used, in the present invention, it is preferable to add it in a larger amount. Specifically, a mixture of a cementitious material and an ultrafine powder is used up to about 10 parts by weight as a solid content for x parts, and if it is added in a larger amount, it will adversely affect the curing reaction. A particularly preferable addition amount is 1 to 5 I Dobe. By using such a water reducing agent in combination with ultrafine powder, it is possible to obtain a fluid kneaded material that can be molded by a conventional method even if the ratio of water cementitious material to ultrafine powder is 25% or less.

The water used when preparing the mixture in the present invention is necessary for molding, but in order to obtain a high-strength hardened product, it is advisable to use as little water as possible. 12.5 to 50 N jt for 100 children
m and Luno are preferable, and 15 to 28 and a weight part are more preferable. When the amount of water is more than 60 parts by weight, it is difficult to obtain a high-strength cured product, and when it is less than 12.5 parts by weight, it is difficult to perform normal molding such as pouring. Note that pressure molding, etc. is not limited to this. 12.5
Molding is possible even when the amount is less than parts by weight.

Conventional cement solidification methods can be used to treat radioactive waste (hereinafter referred to as waste) using the solidification agent according to the present invention. These methods include mixing the waste in a disposal container such as a drum or concrete container, filling the disposal container with a mixture that has been mixed in advance, and filling the waste into the disposal container and then solidifying it in the void space. A method of filling the disposal container with an assimilating agent, or conversely, a method of filling the disposal container with an assimilating agent in advance, reducing the pressure there, or pressurizing the waste and injecting it into the disposal container, etc. are applied. At this time, the addition rate of assimilation agent varies greatly depending on whether the waste is solid or water-containing, but for every 100 tons of waste, 10 to 500
It is generally about parts by weight. From the viewpoint of increasing processing capacity, it is preferable to use as little solidifying agent as possible, but if the amount is less than 10:a parts by weight, solidifying is difficult and the effect of suppressing the release of radioactive substances is poor.

〔Example〕

This will be explained in more detail below with reference to Examples.

Example 1 0.2μc1”CJ, -/ in the formulation shown in Table-1y162
Mix radioactive isotope to obtain α3, φ5X5t,
A specimen of M was prepared and cured in a sealed container until the material age was 6.
After a day, a leaching test was carried out in a NaCj solution of Q, lMo1, and the effective diffusion coefficient De was determined from the relationship between the number of days of immersion and the amount of bathing. Furthermore, with the formulation shown in Table 144, the thickness is 1c! ! A thin film of L was prepared, and one side was separated by 134
Add 1Q-' Mol of C5CJ containing C8+ and add 1
The diffusion coefficient of 34 CS+ was determined. The results are shown to public-2.

I-1 Table-2 Materials used> Cement: Manufactured by Denki Kagaku Kogyo (closed), ordinary Portland cement, Zhao Weisong Nihon Arashi Kaimo Kogyo (closed), silica hume Water reducer: Manufactured by Dai-Kogyo (closed), [ Cellflow 10PJ Comparative Example 1 The same procedure as Example 1 was carried out except that the symbol /161 and its blend /166 were used. The results are shown in Table-2.

Example 2 Waste consisting of ion exchange resin regeneration waste liquid, filter sludge, used new ion exchange resin, etc. discharged from a boiling water nuclear reactor was evaporated, dehydrated, and then sampled.
It was treated using a solidifying agent having the formulation shown in Table 6. In addition, the moisture content of the waste is 80%, and this waste is 100%!
Solidifying agent is 200 for Dobe! It is expressed as a quantity part. The compressive strength and leaching rate in water of the wood at 6 days old were measured and shown in Table 6.

Isa-6 Comparative Example 2 The same procedure as in Example 2 was carried out except that the blend of 1 mA3 was used. The results are shown in Table-6.

Example 6 Concrete waste generated during the demolition of a nuclear power plant building was packed in advance into a drum pipe, and experiment/1 of Example 2 was carried out.
Inject anabolic agent using the formulation of 66, φ15X3011
A specimen of No. 711 was prepared and the compressive strength at 28 days of age was determined to be 1,077 icgt7c, -ml. For comparison, a similar test was conducted using a solidifying agent with the formulation of Experiment/I65, and the compressive strength was 586 f.
/f/(7+2″L), and moreover, there were noticeable voids due to breathing water on the underside of the concrete waste.

〔Effect of the invention〕

As described above, the hardening method using the hardening agent of the present invention has a larger processing capacity than the conventional cement hardening method, and has superior chemical resistance and durability compared to the bitumen assimilation method and the plastic hardening method. In addition, the treatment method is simple, has excellent heat resistance, and is safe even during transportation due to its compressive strength, making it possible not only to store waste kettle but also to permanently store it.

Claims (1)

[Claims] Solidifying agent for radioactive waste containing cementitious materials, ultrafine powder, high performance water reducer, and water.