Cement-polymeric composition for preserving radioactive wastes of medium reactivity

FIELD: nuclear engineering; preservation of dry, wet, and liquid radioactive wastes.

SUBSTANCE: proposed composition has resin portion of cold-cured compound ATOMIK and filler. Resin portion ingredients are as follows, parts by weight: epoxy oligomer, 100;, curing agent (aromatic amines), 38-50 furfural, 9-11. Used as filler is composition incorporating following ingredients, parts by weight: cement, 50-100; marshalite, 50-100 or bentonite, 50-100, or when they are jointly used: marshalite, 90-100 and bentonite, 90-100. Such composition provides for desired radiation resistance in absence of leaching of alpha-, beta-, and gamma-active radionuclides from preserved specimens of reactor graphite.

EFFECT: enhanced radiation stability of preserved specimens free from pits and voids, and adequate lifetime of preserved wastes; ability of their depreservation.

1 cl, 2 dwg, 2 tbl, 2 ex

 

The invention relates to polymeric compositions of cold hardening used in nuclear engineering for the preservation of intermediate level radioactive waste (RW), in dry, wet and liquid state.

Known polymer composition is cold-curing, resistant to radiation, which includes a resin part (100 parts by weight) (patent RF №2239643, IPC 08 L 63/00, 2001). The resin portion further comprises an aliphatic epoxy resin and a low volatile ester of phthalic acid and aliphatic alcohol with a mass ratio of 90:5:5 to 30:25:45, and as the amine hardener is a product of the interaction of aromatic di - or polyamine (K), salicylic acid (L), benzyl alcohol (M) and furfural (N) in the ratio K:L:M:N 88:2:8:2 44:10:30:16. If this composition contains, in parts by weight:

The resin part100
The hardener12-60
Filler30-400

The disadvantage of this polymer composition is that it is not possible at room temperature monolithic pour contained in the vessel shattered fragments of graphite reactor of the rings. When sawing these samples were found shells and cavities, and to reduce the viscosity of the composition by heating below the consequently, as this increases the rate of the curing reaction and shortens the time of her life. When the curing of the composition may occur in the tank mixing of the resin part with hardener. In addition, this method of preservation is to provide a monolithic casting RAO composition it is necessary that the temperature of the tank waste was not lower than the temperature of the composition, otherwise the heated compound in contact with preserved material has cooled and the viscosity will decrease. In real conditions subject to conservation materials can be in the wet state. In this case, as well as for liquid radwaste using this resin composition is not suitable.

Also known polymer composition to isolate the solid radioactive waste (patent RU №2251561, 10.05.2005,). The composition comprises, in parts by weight: 100 epoxy Dianova resin as a resin part, 40-95 polyamide resin as a hardener, 25-45 furfural, 0-380 filler. In use as a filler bentonite, cement and Marsala.

Its disadvantages include insufficient radiation resistance evolution, complexity and duration of the technical process of making composition (the necessity of heating the mixture, the daily exposure of the mixture), lack of life of the mixture. When using such a composition when the room is Noah temperature in preserved samples were observed unfilled cavity, shell. The composition was aterials, not able to impregnate conserved graphite blocks, which led to poor sealing and consequently not sufficiently reduced the leaching of radionuclides.

The technical objective of the claimed invention to provide a resin composition for a simple and reliable conservation intermediate level radioactive waste in dry, wet and liquid state, in the absence of a conserved RAO shells and cavities.

The technical result of the present invention is the increased radiation resistance, in the absence of leaching of alpha-, beta - and gamma-active radionuclides from preserved samples of reactor graphite, in the absence of shells and cavities in canned RAO with sufficient lifetime and raskonservirovana.

To achieve the specified result of the proposed cement-polymer composition for conservation intermediate level radioactive wastes containing resin part of the compound of cold hardening "atomic"consisting of epoxy oligomer, hardener, and aromatic amines, and furfural, and fillers cement Marsala and/or bentonite, in the following ratio of components, parts by weight:

epoxy oligomer100
the above curing agent38-50
the furfural9-11
cement50-100
Marsala or bentonite50-100

or

Marsala90-100
and bentonite90-100

As the resin and hardener were used compound of cold hardening "atomic", manufactured by CJSC "ENPC APICAL" beyond 2257-998-18826195-01. It contains as a resin part, for example, Dianov a type resin ED-20, aliphatic epoxy resin deg-1 (100 parts by weight)as a hardener, such as a hardener based on polyamide resin L-19 (38-50 parts by weight), (see figure 1). Cement was used stamps 500.

As RAO used samples of reactor grade graphite GR-280, manufactured from a block of graphite columns of the 3rd unit of Leningrad NPP after 18 years of operation. In the study of radiation gas reactor graphite was discovered that it, in comparison with the source material that contains significantly more gaseous products, which include radioactive gases. Consequently, when developing the conservation of graphite blocks and rings, extracted from the reactor, it was suggested not to use the method in chumney impregnation with preservative, in order not to pollute the environment with radioactive gases, takuminokami from the pores of reactor graphite, and to carry out the impregnation of a low viscosity compositions.

For the manufacture of cement-polymer composition (CPC) in the capacity of the injected resin part of the compound of cold hardening "atomic", add the furfural 11 parts by weight, the filler (cement, Marsala or cement, bentonite), stirred for getting ready CTC. For execution of works on preservation of the crushed fragments of the reactor graphite blocks, rings, graphite spillages and other radioactive wastes generated during the dismantling of the reactor (both dry and wet), as well as sorbents for the purification of liquids containing radionuclides, these materials are loaded into metal barrels for conservation and fill them ready CTC. After curing the CPC formed monolithic blocks with high radiation resistance of the binder and the absence of leaching of radionuclides.

Table 1 presents examples of CTC (compounds No. 1, 2), and table 2 summarizes the main properties of the CTC.

Table 1
Cement-polymer composition for conservation intermediate level radioactive waste
Name of the component Composition 1 (for dry RAO), parts by weightComposition 2 (for wet and liquid waste), parts by weight
The resin part of the compound "atomic"100100
The hardener compound "atomic"4050
The furfural1111
Cement50
Marsala10050
and / or bentonite9050

Table 2
IndexThe composition according to the patent of Russian Federation №2251561The proposed composition.
The limit of compressive strength, MPa75-8060-89
Radiation resistance, Mrad11·103About 30·103
Radiation-chemical yield of gaseous products of radiolysis, cm3/g·happy7·10-1010-10
(at doses up to 11·103Mrad)(at doses up to 30·103Mrad)
The curing time under water a day.5
RMSE is the awn leaching Cs 137(α,β-activity),

g/cm3·d
1·10-7Was not observed
The rate of leaching Cs137(γ-activity), g/cm3·d1·10-71·10-8
Time life hours0.5 to 3Around 12

When creating a center that could be used for conservation splintered fragments of graphite reactor rings, spillages and other small radioactive fragments, located in the tank, by impregnation their compound without mixing, it is necessary that the viscosity of the compound was minimal. To reduce the viscosity of the compound was proposed to be part of an active diluent - furfural, as it has high wettability, the ability of chemical combination with the epoxy resin and contains heterocycles with radiation resistance. The addition of furfural (9-11 parts by weight per 100 parts by weight of resin) significantly reduces the viscosity and slows the curing of the compound (see figure 2).

The introduction of cement into the polymer composition contributes to a significant increase of tensile strength, yield strength and elastic modulus. The magnitude of this increase depends on the number of input marshalite and / or bentonite. Limit flowed the honor, tensile strength CTC equal to 500 and 600 kg/cm2. Introduction to CTC 50 parts by weight of marshalite leads to a significant increase in the elastic modulus (from 1200 to 1500 kg/cm2). Supplement CTC more cement and maralita (on 100 parts by weight, respectively) leads to an even more significant increase in yield strength (830 kg/cm2), tensile strength (930 kg/cm2) and elastic modulus (33000 kg/cm2). For CTC with increasing doses there is a continuous growth of the above physico-mechanical parameters to a dose of 3600 Mrad.

However, increasing the amount of mineral filler compressive strength increases up to a certain limit. Supplement CTC cement and maralita (150 parts by weight) leads to a decrease of the yield strength and tensile strength up to 550 and 700 kg/cm2.

CTC, containing in its composition 100 parts of cement and 100 parts of bentonite, has a yield strength of 480 kg/cm2the tensile strength of 560 kg/cm2the modulus of elasticity under compression of 1600 kg/cm2.

Use as filler cheaper than maralita bentonite prevents the leaching of Cs137from canned RAO, and not reduced mechanical strength.

In the patent of Russian Federation №2239643 not specified about the use of bentonite as a filler, the filler is used quartz sand (Margalit 215 mA is C).

If necessary, the removal of solid raw (precious metals, stainless steel, zirconium, non-ferrous metals etc) canned products may be exempt from CTC by heating to temperatures above 300°C.

In addition, CTC has a relatively low cost (no more than 50 rubles per 1 kg). The cost of the compound "atomic" depends on the party purchased material and an average of about 100 rubles per 1 kg of CTC can be recommended:

for conservation of reactor graphite rings in wet or dry);

- as a protective coating for metal surfaces and sealing of objects in the water, including those exposed to gamma irradiation;

for conservation of the reactor compartments of nuclear submarines (including flooded);

for preservation of aqueous solutions (containing radionuclides), mixing them with CTC with the formation of solid material;

- for preparation of concrete, which in dry condition different from the usual concrete ductility and high strength;

- to eliminate defects and repair of concrete structures and products (fill cracks, holes, cavities).

Cement-polymer composition for conservation intermediate level radioactive wastes containing resin part of the compound of cold overiden what I "atomic", consisting of epoxy oligomer, hardener - aromatic amines and furfural, and fillers cement, Marsala and/or bentonite, in the following ratio of components, parts by weight:

Epoxy oligomer100
The above curing agent38-50
The furfural9-11
Cement50-100
Marsala or bentonite50-100
Or Marsala90-100
And bentonite90-100



 

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The invention relates to the field of processing of liquid radioactive waste, in particular, to methods of extraction of precious metals
The invention relates to the field of processing of liquid radioactive waste

The invention relates to the field of processing of liquid radioactive waste

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