RU2268514C2 - Method of melt-shutting of the dangerous materials and-or products - Google Patents

Abstract

FIELD: nuclear engineering; methods of processing of radioactive waste.

SUBSTANCE: the invention is pertaining to the field of processing of radioactive waste. The method of melt-shutting of dangerous materials and-or products provides for arrangement of the melt-shutting material, the subjected to the melt-shutting dangerous materials and-or products in a metal container and their heating by UHF-energy. In the capacity of the melt-shutting material use a loose radio-transparent material, in which dip the subjected to the melt-shutting dangerous materials and-or products till their complete surrounding by the radio-transparent loose material. Then using UHF-energy heat up the subjected to the melt-shutting dangerous materials and-or products, at least, to the melting point of the loose radio-transparent material contacting with the subjected to the melt-shutting dangerous materials and-or products for formation around the subjected to the melt-shutting dangerous materials and-or products of a monolithic shell. The technical result of the invention is a reliable fixation of the hazardous substances.

EFFECT: the invention ensures a reliable fixation of the hazardous substances.

3 cl, 4 dwg

Description

The invention relates to the field of isolation of hazardous materials and / or products from the environment and can be used, for example, to melt radioactive waste into a dense monolithic shell fused from various radio-transparent materials.

A known method of processing radioactive materials by melting in a furnace a mixture of a glass charge with a radioactive material, followed by pouring glass into a metal container, which is then sealed (V.I. Komarov and others. “Processing of radioactive waste using microwave energy.” Electronic technique, sulfur .1, Microwave Technology, issue 2 (476), 2000, GNPP “Istok”, Fryazino, Moscow Region, p.30-36).

The disadvantages of this method are the following:

- when conducting melting of the above mixture, secondary waste with high activity occurs, the decontamination of which is almost impossible;

- during the processing of a number of radioactive waste in the furnaces, a precipitate of the metal-like phase accumulates, which leads to emergency situations;

- when the process stops, leading to the solidification of the molten glass, it is no longer possible to continue the process.

These disadvantages are largely eliminated by using microwave heating.

A prototype is a method in which a glass charge mixed with radioactive waste is used. The mixture is placed in a replaceable metal container and heated by exposing it to microwave energy. As a result, the mixture is melted and glass is melted. The microwave energy is turned off and the glass melt cools. Thus, the vitrification of radioactive waste occurs. Then the metal container is sealed (V.I. Komarov et al. “Processing of radioactive waste using microwave energy.” Electronic equipment, ser.1, microwave equipment, issue 2 (476), 2000, GNPP “Istok”, Fryazino , Moscow Region, pp. 30-36).

However, this method also has disadvantages.

Since the glass mixture in the container mixed with radioactive waste must not only be melted, but also boiled, the resulting melt must be adjacent to the walls of the metal container. This leads to:

- the container is heated to the glass melting temperature and, in order to avoid deformation of the container, it is necessary to use glass with a melting temperature not exceeding 1000 ° C. Refractory glasses that are more reliable for the isolation of radioactive waste cannot be used;

- at high temperatures, there is a chemical interaction of the material of the molten mixture with radioactive waste and the material of the walls of the container, which is completely unacceptable;

- sharply increase heat loss;

- on the surface of the obtained glass ingot there are always radioactive substances;

- a fragile glass ingot is poorly protected from external mechanical influences, which can lead to cracking, crushing and loss of insulating properties.

The proposed method is intended to eliminate the above disadvantages.

The method consists in the fact that hazardous materials and / or articles to be melted are immersed in radiolucent bulk materials in a container, for example silica sand, aluminum oxide, etc., until they are completely surrounded by a radiolucent bulk material. Microwave energy is supplied to the container, which, passing through the radiolucent bulk material, heats the hazardous materials and / or products to a temperature at least sufficient to melt at least a layer of granular radiolucent material in contact with the hazardous materials being flooded and / or products and the formation of a monolithic shell around them. Then, microwave energy is immediately or gradually turned off, the melt cools, forming a dense monolithic shell. In this case, between the monolithic shell and the walls of the metal container, there always remains a layer of unmelted bulk radio-transparent material. Hazardous materials and / or products to be enclosed can be left in the same container or transferred to another. The container with molten hazardous materials and / or products is then sealed.

To reduce the volume and increase the density, hazardous materials to be filled and / or products can be pre-pressed and / or sintered.

If the fused hazardous materials and / or products, even at the first stages of heating, do not have sufficient microwave energy absorbing ability, they can be pre-mixed with absorbing substances to enhance the heating effect of hazardous materials and / or products.

To improve the insulating properties of the monolithic shell surrounding hazardous materials and / or products to be flooded, a radiolucent bulk material is formed from several at least two successive layers of different radiolucent materials, for example, aluminum oxide is used as one layer, and the second layer - quartz sand..

New in the proposed method of melting hazardous materials and / or products is that they are immersed in bulk radiolucent material until they are completely surrounded by bulk radiolucent material. When exposed to microwave energy, the fused hazardous materials and / or products are heated to a temperature at least sufficient to melt at least a layer of loose radiolucent material in contact with the heated fused dangerous materials and / or products, and to form a monolithic shell isolated from the walls of the container with a layer of unmelted radiolucent loose and therefore heat-insulating material.

The proposed method has obvious advantages:

- the temperature in the central part of the fused hazardous materials and / or products can reach 2500 ° C and above. Thus, to better isolate them, melting radiolucent bulk materials with high melting points can be used;

- the monolithic shell is completely surrounded by non-melting, loose radiolucent material, forming a “pillow” that protects the shell and molten hazardous materials and / or products from mechanical damage during storage, and the walls of the metal container from chemical and thermal effects; there is practically no heat loss;

- fused hazardous materials and / or products turn out to be completely isolated with a dense monolithic shell (s) and do not go to the surface of these shells.

Figure 1 shows the floating hazardous materials and / or products placed in a radio-transparent granular medium until they are completely surrounded.

Figure 2 shows hazardous materials melted into a shell of radiolucent material and surrounded by a layer of granular radiolucent material.

figure 3 shows the fused hazardous materials and / or products placed in a radio-transparent granular medium formed of two layers of different radio-transparent materials until they are completely surrounded.

- figure 4 shows the hazardous materials melted into a multilayer shell of various radio-transparent materials.

The method is as follows.

Floatable hazardous materials and / or articles 1 are immersed in a loose radiolucent transparent melting material 2 so that the hazardous materials and / or products are completely surrounded by a floatable bulk radiolucent. For this purpose, a melting material 2 is first placed in a metal container 3 and immersed in the material to be filled in hazardous materials and / or products, the container is closed with a lid 4 with an opening 5 through which microwave energy is passed into the container 3, passing through the radio-transparent bulk material 2 (Fig. one). Influencing microwave energy on hazardous materials and / or products 1 being melted, they are heated at least to the temperature necessary to melt the radiolucent material in contact with them 2 and forming a monolithic shell 6. In this case, the dangerous materials and / or products 1 may sinter or melt. Then the microwave energy is turned off (immediately or gradually, depending on the technology) and the contents of the container 3 cools down. As a result, hazardous materials and / or products 1 are enclosed in a dense monolithic protective shell 6, surrounded on all sides by an unmelted loose radiolucent material 2, which is a heat-insulating layer and at the same time a “cushion” that protects the molten hazardous materials and / or products 1 and their shell 6 from mechanical influences, and the walls of the metal container 3 - from thermal and chemical effects (figure 2). If necessary, floating hazardous materials and / or products 1 can be transferred to another container.

Hazardous materials and / or products 1 to be floated can be pre-pressed and / or sintered.

The radiolucent bulk material 2 can be formed from several, for example two, successive layers of different radiolucent materials (Fig. 3), for example, from aluminum oxide and silica sand, as a result of which the shell 6 is multilayer (Fig. 4).

Claims (3)

1. A method of melting hazardous materials and / or products, comprising placing melting material, fused hazardous materials and / or products in a metal container, heating with microwave energy to at least the melting temperature of the melting material and turning off microwave energy, characterized in that a loose radiolucent material is used as the melting material, into which dangerous hazardous materials and / or products are immersed until they are completely surrounded by a radiolucent granular material, the microwave energy is heated dangerous hazardous materials and / or products, at least up to the melting temperature of loose radiolucent material in contact with floating hazardous materials and / or products, for obtaining hazardous materials and / or articles of a monolithic shell around the melt. 2. The method according to claim 1, characterized in that the bulk radiolucent material consists of several layers, due to which a multilayer shell is obtained. 3. The method according to claim 1, characterized in that the fused material is pre-pressed and / or sintered.

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