Capsule for disposal of radioactive waste

 

(57) Abstract:

The invention relates to nuclear power could be applied in other industries, for example, in the chemical, for output from the biosphere of dangerous toxins. The invention describes a capsule for the disposal of liquid radioactive waste. Capsule is a multilayer casing filled with porous ceramics installed inside and the fixed cartridge with a sorbent and shut-off covering over the sorbent, and on the surface of the Chuck holes. The capsule is suitable not only for irreversible disposal in deep strata of the earth radioactive waste, but can be used for safe storage in the near-surface mines with natural air cooling. The capsule's design provides improved environmental safety and reduce costs on the conclusion of toxicants broad composition of the biosphere. 2 C.p. f-crystals, 2 Il.

The invention relates to nuclear power and radioactive waste management (RW), but can be effectively used in other industries, for example, in the chemical industry for the output of the biosphere especially dangerous toxins.

Izvestnie cans [1], which should continuously for hundreds of years contained in the cooled storage of large volume.

The construction of the storage of vitrified radioactive waste and the appropriate technological equipment are characterized by high capital intensity in low level of environmental safety, due to the possible destruction over time of the glass under the action of radiation, natural disasters, terrorism and other force majeure factors.

The closest analogue is a multilayer capsule for the disposal of liquid radioactive waste described in patent SU N 1036257, G 21 F 9/32, 1983.

The purpose of the invention is to enhance reliability capsules for disposal of radioactive wastes, improvement of environmental safety of waste management and reducing costs at the conclusion of toxicants broad composition of the biosphere.

This objective is achieved in that capsule for the disposal of radioactive waste and other hazardous toxicants includes a housing and a filler, the body of the capsule is made of layered, inside of the last layer filled with filler of porous ceramics is placed and rigidly fixed to the cartridge with the sorbent and the locking cover over it, and on the surface of the cartridge slotted holes.

C. the Internal casing of the capsule is made of mild steel and outer made of heat-resistant and heat-resistant steel or alloy, and the surface of the capsules coated, of a thickness of 0.05-0.3 mm from compositions with melting temperature 2500-3500oC.

The design of the capsule, intended for disposal of radioactive wastes, mainly in the form of fuel solutions are presented in Fig. 1, in Fig. 2 shows the design of the cartridge, Fig. 3 photo capsule in the section, and General appearance.

The outer diameter of the ball capsule may vary within wide limits depending on the composition of materials storage, but the advantages of this device to the greatest extent implemented in the manufacture of capsules with a diameter from 50 to 250 mm, which is 50-80% of the diameter of a typical casing of boreholes, for only in this way ensures free movement of the capsules of the trunk to the underground cavern, the formation of which well-known techniques now technically possible at a depth of 4-5 km, and the many capsules in deep cavities drastically increases the security of stored toxins and does not require any additional maintenance costs.

The body of the capsule shown in Fig. 1 wipolo 2-8 mm made of cast or extruded heat-resistant and heat-resistant alloy alloy (steel) with a melting point of more than 1650oC, beats. weight of the alloy up to 9 t/m3moreover combining the hemispheres is carried out by welding.

The second layer (2) thickness of 3-5 mm of mild steel. Hemisphere this layer are interconnected by contact welding.

The third layer (3) made from carbon steel (1-2 mm) and forms a so-called "soft case", inside of which is placed and fixed by welding part, called a "cartridge".

The design of the cartridge shown in Fig. 2. The Chuck body (4) made of steel, and it has openings (slits). The portion of the cartridge, which is made with holes filled with special granules of adsorbent (7) to trap harmful sublimates, formed by heating and thermolysis RAO, for example, vapor of cesium and other radionuclides with high elasticity of steam.

Above the layer of sorbent is placed a layer of granules locking cover (5), for example, a mixture of granules of alloy systems Mn-Cu solder with a melting temperature of 900-950oC) or to save the solder - steel grit, coated with a layer of solder.

The main node of the capsules is filler 6 made of porous ceramics, for example, porous alumina, doped zirconium oxide, and the best properties in the region is thin (10-30 Ám) fibers alloy, Al-Zr.

The porosity of the filler is about 50-85%.

High porosity filler provides intensive absorption (absorption) of a mixture of raw and other toxicants in the amount of up to 1.0-1.5 kg/kg mass and spontaneous movement of the solution through the microchannels (wick effect), which is characteristic of the structure of the material used and proven experimentally.

The porosity of ceramics should not exceed 85% (for reasons of mechanical strength), at the same time when the porosity syroka less than 50% reduces the volume of radioactive waste that can be absorbed in a single capsule and consequently worsens the economy of the process of neutralization of toxins. With regard to the melting temperature of the filler, if it is less than 2000oC, it increases the danger of destruction of the capsules, and, if it is greater 2800oC, it increases its value.

The last item, which provide a capsule-funnel for draining solution RAO and impregnation of the filler lossless emitting materials.

Funnel (8) is made of solder foil, of a thickness of 0.5 mm, and through the funnel portion is successively poured solutions RAO (mainly nitrate solutions remaining after regeneracy and heated to full temperature thermolysis of dry residue with formation of a mixture of oxides of nuclides which over time under the influence of heat of radioactive decay interact with the oxide filler and form a thermally stable chemical composition.

In the process of heating RAO is the sublimation of volatile components, such as, Cs, Am and others who are caught by sorbent granules. Upon completion of thermolysis of solids - temperature increase up to 900-950oC, which leads to melting of the solder, a funnel and clogging of the cartridge trap.

Capsules are made of multilayer in order to weaken radiation hazard when handling radioactive waste and to increase the mechanical strength of the device for shock.

The external casing of heat-resistant and heat-resistant material, for example, from chromium alloys, doped tungsten, and coating the surface of the protective layer - provides the integrity of the shell of the capsules at high temperatures for a long time. In addition, alloying tungsten reduces the radiation intensity and, accordingly, radiation treatment capsules.

Further, the use of capsules of mass production involves moved the of time, required to heat the underlying rocks to the solid-liquid that provides spontaneous, environmentally safe movement of the array of capsules in the deep (30-40 km) layers of the lithosphere.

The proposed device in the form of capsules suitable not only for irreversible disposal in deep formations, but can also be used for safe storage groups capsules with fuel materials in a vertical, reinforced tubing trunks surface mines with natural air cooling, which allows you to utilize the heat of radioactive decay, reduce storage costs, improve reliability, and to be placed together with RAO capsules containing other hazardous toxins.

1. Capsule for the disposal of liquid radioactive waste containing multilayer body, characterized in that inside a capsule filled with a filler made of porous ceramics, placed and rigidly fixed to the cartridge with the sorbent and the locking cover over it, and on the surface of the cartridge slotted holes.

2. Capsule under item 1, characterized in that the filler is made of ceramics with a porosity of 50-85% and a melting point 2000-2800oC.

 

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