The method of decontamination of radioactive waste

 

The invention relates to the field of nuclear energy, and more specifically to the technology of decontamination and disposal of radioactive waste from the activities of nuclear power plants, research institutions, industrial and medical facilities using various radioactive isotopes. The method consists in the fact that the liquid and/or solid waste is placed in a liquid environment and carry out their additional activation by exposure to waste cavitation. Cavitation is generated in the liquid medium by application of cyclic alternating loads. These loads generate the volume changes in the environment. Technical result: implementation of processing radioactive waste and recycling heat energy released in the process of decontamination. 9 C.p. f-crystals, 2 Il.

The invention relates to the field of nuclear physics, and more specifically to a method of processing radioactive waste that is a byproduct of nuclear energy.

Under radioactivity understand the spontaneous transformation of an unstable isotope of a chemical element into another isotope, usually another element. The essence of the radiation is the spontaneous change in the composition of the atomic nucleus in the ground state, or in fieldsteel fundamental interactions microcosm: strong effects (nuclear power) or weak interactions, the first is responsible for transformation, accompanied by the emission of nuclear particles-studies, or fission fragment nuclei, the latter appear in the-decay of nuclei. For the process of radioactive decay of nuclei is characterized by the exponential law decrease with time of the average number of active cores. Usually the lifespan of radioactive nuclei is characterized by the half - life is the period of time T/2, for which the number of radioactive nuclei will decrease on average by half. As a natural radioactive elements and artificial, have a life expectancy calculated from billions of years (238U) fractional seconds (T).

Radioactive waste includes solid, liquid and gaseous materials containing radioactive material in concentrations that exceed the standards approved in this country.

Liquid radioactive waste is generated during operation of nuclear power plants (NPP), regeneration nuclear fuel and spent fuel elements and the use of different radiation sources in science, engineering, and medicine. Liquid radioactive waste in its activity are divided into three categories: low in the odes - above 1 Curie/liter Over 99.9% of all problems arising in the process of NPP activity during regeneration nuclear fuel goes into the liquid high-level wastes, which can be concentrated to a small volume. For solid radioactive wastes are not amenable to wash contaminated material, in particular fragments of metal or concrete building structures, used clothing and others In the nuclear industry and nuclear power plants emissions containing volatile compounds, radioactive isotopes, such as 131J, 129J, as well as the formation of radioactive aerosols.

Under the influence of the initiating radiation emitted by radioactive elements (waste), changes in the activity and structure of living organisms - in this case, the main danger of all radioactive substances. Last pollute the biosphere penetrating the atmosphere, hydrosphere, soil as a result of nuclear explosions, development of radioactive ores, in case of accidents at nuclear power plants, etc. particularly dangerous accumulation of radioactive substances in biological objects, accompanied by an increase of their concentration in comparison with the content of these substances in the environment. Votestacking substances.

Currently set up and practically implemented dozens of technologies for the decontamination of radioactive waste, which can be divided into two main types: active and passive. The first are the methods of absorption, adsorption, ion exchange, biological, annealing, flocculation, distillation, etc., the second storage in tanks or sustainable solid medium by dissolution in sea currents, the disposal of solid radioactive waste into space.

All of these methods of dealing with radioactive waste does not fundamentally solve the problem of eliminating them.

It is known that, in passing through matter,-quantum or fast particles (-particles, electrons, protons, neutrons, and other), cause its ionization or excitation. Clash of fast charged particles with molecules of the substance, causing the kinetic energy of the particles is transferred to the molecules, which leads to changes in their energy state. There is a large number of activated molecules in different States of excitation. Excited molecules and atoms are unstable and they decay, or they interact with okrujayuschih reactions which are also unstable. The increase in the intensity of the excitation or ionization lead to decay and intermediate particles, increasing the degree of decontamination. Ultimately, the goal is to message the molecules and atoms of matter some excess energy (activation energy), which will allow them to overcome the so-called energy barrier of the internal connections. For the reactions of active particles or molecules, the energy barrier is very small. Particularly impressive reactions proceed with the recombination of electrons and positive ions of atoms and radicals with each other, and also the reactions of positive ions with molecules. These elementary processes, as a rule, lead to the collapse of the molecules or large ions.

Currently as sources of ionizing or exciting radiation uses radioactive cobalt, radiant-rays with energies above 1 MeV. Widely used accelerators of electrons, due to the high radiation intensity and control. Developed methods for direct use-radiation with energies up to 10 MeV nuclear reactors, consisting of generator active the tour of the working substance. As a result of neutron capture in the generator, located in the core of a nuclear reactor or close to it, the working substance is ionized andradiation isotopes formed, is then used in the irradiator to commit an act of transformation, or decomposition of the treated substance.

Thus, for carrying out the process of deactivation of excited molecules and atoms, which include radioactive waste, the required external energy source, in particular-radiation with energies up to 10 MeV. Most suitable for this purpose is the neutron nuclear reactor, the device described above. However, the complexity of the design of the reactor, an indirect method of obtainingradiation effects on the treated substance, problematic in the management of the process of excitation prevented its widespread use for mass decontamination of radioactive waste that considered promising source-radiation.

As the closest analogue of the claimed invention selected technical solution described in the patent of the Russian Federation 2075126. It relates to a method for recycling (disposal) radio perform consistently fragmentation of equipment and induction melted in the presence of oslakovic fluxes with the Department formed of radioactively contaminated slag from molten metal and curing of the latter. Before fragmentation produce equipment decontamination liquid in his collection, and after fragmentation - decontamination liquid fragments. Then carry out thermal decontamination of fragments by burning combustible materials, melting of these metals. The surface equipment calcined and separate the dross. After thermal deactivation fragments sorted and sent for induction melting. Formed during the processing gases is removed for disposal and cleanup [1].

Achievable technical effect cleanup of radioactively contaminated metal parts of the equipment to the level that allows the return of secondary metals in the economic turnover, and reduce the volume of radioactive waste to be disposed of.

The advantage of analog is that it can significantly reduce the volume of radioactive waste, by removing the metal part of the equipment for recycling, reducing them eventually to a small amount of radioactive slag, which kill by any known method.

Thus, solving the problem of recycling contaminated with radioactivity technological equipment described ways/p> The aim of the invention is to create conditions for receipt of ionizing radiation with the energy level sufficient to overcome the energy barrier for links inside the nuclei of the molecules and atoms of radioactive waste, destruction and recycling of heat energy released in the process of decontamination.

The purpose of the invention is achieved due to the fact that the liquid and/or solid radioactive waste is placed in a liquid environment, in which you can actually use liquid wastes, and activate them by exposure to cavitation generated by any known method. This cavitation is performed by changing the volume of a liquid medium by application thereto of cyclic alternating loads in the vibrational mode with a frequency of at least 1 Hz. The degree of activation of waste regulate the intensity of the cavitation process, adjusting the amplitude of change of volume of a liquid medium. The activation process wastes are recirculated liquid medium with its constant cooling. For regulation of the activation process in the liquid medium is injected radioactive substance (isotope) with a lower half-life than waste, or graphite powder. As the liquid medium may use the Institute of cavitation in a liquid medium, containing radioactive waste, in particular bulk cavitation, in which process fluid dilate, increasing its volume from the original so that bubbles with a diameter of 100-150 μm, which, upon removal of the tensile stresses dramatically, less than 1 µs, collapse. In the moment of the collapse of bubbles in the wall under the action of the pressure acting on the cavitation bubble inside and out, faster, gaining kinetic energy and collide in the center.

The value of the acquired kinetic energy is sufficient to sever the links between nucleons in the molecules and atoms of radioactive waste, overcome the forces of repulsion of the nuclei and the interactions between elementary particles in the nuclei of waste. The result is in the local scope of a substance at the time of disappearance of cavitation bubble (collapse) occur in nuclear reactions with the release of large amounts of energy. It should be noted that nuclear reactions are accompanied+-radiation [2], with the energy of up to 6.0 MeV [3].

The presence of a stream of elementary particles (protons, neutrons), which accompanied dostatni is transferred to the molecules and atoms of radioactive waste, located in the immediate vicinity of the cavitation bubble (in the zone of collapse) and having initially a high degree of excitation due to their nature. The sum of the internal energy with the energy of external ionizing exposure eventually led to the decay of radioactive molecules or atoms, or a transition to the ground state or to the formation of isotopes with a smaller half-life. Decaying molecules of radioactive waste, as generated isotopes are themselves sources of ionizing radiation than dramatically increase the excitation energy, influencing the type of chain reaction with other molecules and atoms waste.

In Fig. 1 shows a schematic representation of an installation for decontamination and disposal of radioactive waste.

In Fig.2 given an axial section of an element of the plant.

Process unit 1 includes a container 2, which is installed with a gap relative to each other alternately movable and fixed disks 3 and 4, respectively. First rigidly connected with the rod 5 power vibroisolating engine 6 and have an annular gap with the inner walls of the vessel 2. The latter are rigidly connected with these walls and have rmational system with the possibility of recycling it liquid medium. The pump is engaged in recycling, as loading and unloading openings not shown. In the output pipe 7 is installed detector of the radiometer 10, and in the inlet piping detector 11, the temperature of cooling water in the heat exchanger 12. Both detector electrically connected with the control unit vibroisolating engine 6.

Implemented the proposed method as follows.

Solid radioactive waste, pre-crushed to a fraction of not more than 1 mm, are connected with the liquid medium, for example water, forming a coarse suspension. As the liquid medium can be used and liquid waste, diluted with the same water up to a certain concentration. The number, and more precisely the volume of the prepared suspension should correspond to the total volume of all internal cavities of the installation 1, including the piping and coil. Initially, include vibropressovannye engine 6 and allow to it to work idling, then, without shutting down the installation, pour the suspension into the container 2 through the loading hole located at the top of this container.

After filling 2/3 of the volume of the suspension includes a pump, which is under pressure fills the tank completely and begins to work in Cai displayed on the resonant mode, making a reciprocating movement of the rod 5 and the associated movable disks 3. During the oscillatory movement of the latter in the cavities formed by the pairs of stationary disks 4, under certain values of the amplitude a (see Fig.2) these fluctuations above and below the movable disks 3, depending on the phase of movement of the vacuum is formed, which in liquid medium the growth of cavitation bubbles and their subsequent collapse.

Radioactive isotopes contained in the suspension, will be affected by the temperature and power factors cavitation, which in accordance with the above-described mechanism will cause the complete or partial destruction of the molecules and atoms of these isotopes, stimulating the emergence of a stream of elementary particles (-particles, protons, neutrons), and+-radiation [3]. As the path length-quantum to the nearest molecule or atom in a liquid medium minimum, all energyradiation in conjunction with a stream of elementary particles will create a powerful impulse excitation of nearby molecules and atoms of radioactive isotopes, causing them to collapse or intermediate maturing fields and high energy saturation, there is reason to believe that at least 50% of the radioactive waste will lose its activity due to decay and transition to more stable and less energy level. Ultimately, long-term waste treatment installation may reduce the level of residual radiation to a minimum.

In addition, the proposed design has significant technological flexibility, i.e. the ability of changing the amplitude And the oscillation drive 3 it is possible to regulate the amplitude changes of the volume of medium in the cavitation regime between discs 3 and 4, which gives the possibility, in turn, modify the intensity of the cavitation process, to change the size of the excitation or activation of waste. This is achieved by the control system vibroisolating engine 6 according to the results of measurement of radioactivity and output coolant temperature corresponding detectors 10 and 11.

In addition, the same result may be achieved by changing the frequency of application of cyclic alternating loads to the liquid medium from the side of the movable disk 3. This frequency can be adjusted from 1 to 400 Hz. Another method of regulation of the excitation process can serve as an introduction into the liquid medium, isoto which helps to reduce the level of cavitation effects to obtain the necessary ionizing flux of elementary particles and radiation. According to the authors, the use of a liquid medium of molten metal, such as lithium, may increase the effectiveness of cavitation by increasing the viscosity of the liquid phase.

As the decay of radioactive isotopes is associated with a large release of thermal energy, in conjunction with the installation 1 includes a heat exchanger 12, within which is placed the coil 9, washed by the flowing fluid, for example water. Selected heat can be used for domestic and industrial purposes. Due to the fact that the intensity of cavitation exposure to radioactive waste is great and the excitation energy can cause nuclear processes, similar to a chain, in a liquid environment, you can enter the moderator of these processes in the form of graphite powder.

Summarizing and evaluating the possible results of the proposed method can be argued that, in addition to the decontamination of radioactive waste and useful utilization of the released energy, the proposed method increases the efficiency of the use of nuclear fuel in General, "Doroga" after testing at nuclear power plants.

Currently, NPP "art" developed the technological basis and the basic design of the installation for decontamination and disposal of radioactive waste.

In energy, 20.02.1996.

3. Patent 2165054, CL F 24 J 3/00. The method of obtaining heat, 10.04.2001.

Claims

1. The method of decontamination of radioactive waste, consisting in the fact that the liquid and/or solid waste is placed in a liquid environment, and implement them by activating, creating the excitation energy with the help of cavitation generated in the liquid medium by application of cyclic alternating loads that create change its volume.

2. The method according to p. 1, characterized in that the magnitude of the excitation regulate the intensity of the cavitation process.

3. The method according to any of paragraphs.1 and 2, characterized in that the load changes are in the vibrational mode with a frequency of at least 1 Hz.

4. The method according to any of paragraphs.1-3, characterized in that the intensity of the cavitation process to regulate the amplitude of the volume changes of the environment.

5. The method according to p. 1, characterized in that in the process of decontamination disposed of released thermal energy by carrying out this process in a physically closed volume, which is constantly cooled.

6. The method according to p. 1, characterized in that the liquid medium is injected radioactive substance with a lower half-life than substance waste.

7. With>/p>8. The method according to p. 1, characterized in that the deactivation is carried out in the recirculated liquid medium.

9. The method according to p. 1, characterized in that as the liquid medium used for liquid radioactive waste.

10. The method according to p. 1, characterized in that the liquid medium is injected graphite in powder form.

 

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