Radioactive waste

Radioactive waste is unusable materials containing radioactive substance in excess of permissible concentrations of these substances to water. Radioactive waste is generated in the manufacture of nuclear fuel and fuel elements, the operation of nuclear reactors, reprocessing of irradiated fuel elements, production and use of artificial and natural radionuclides (see Isotopes).
Liquid R. O. include technological, decontamination and biological (from vivarium) drains, distillation residues from the evaporation of low-activity waste water, waste oils, organic solvents and other Solid R. O. usually consist of waste containing glass, paper, textiles, rubber, wood, plastics, unusable equipment, laboratory instruments, the corpses of laboratory animals. To solid R. O. is also clothing, contaminated with radioactive substances above the level of activity of group III (500 000 beta particles and 7000 alpha-particles in 1 min. from 150 cm - surface), as overalls with this level of radioactive contamination is not subject to decontamination (see). The amount of solid R. O. is about twice the amount of liquid R. O. Them this ratio usually come when designing disposal facilities R. O. Radioactive gases formed at the radiochemical enterprises in the operation of nuclear reactors and incineration of waste containing radioactive material, also belong to P. O. Gaseous emissions contain radioactive substances in the form of gases, mist or aerosol cleaners.
The degree of activity of radioactive wastes are divided into:
1) low activity concentrations of beta-izluchaya radioisotopes to 10-5 Curie/l;
2) intermediate level with the concentration of beta-emitters to 1 Curie/l; 3) high level
with the concentration of beta-active radioactive substances over 1 Curie/L. the Main source of highly active R. O. are nuclear reactors.
In the USA and England liquid radioactive waste is also divided into 3 categories: high-activity - with the content of radioactive substances (RS) in dozens Curie per 1 liter; intermediate level - with a concentration of PB in several millicurie or tenths of a Curie; mild - containing PB, 100-1000 times the MPC established for water.
Radioactive waste participate in local pollution by radioactive substances to air, water, soil and plants. Radioactive pollution of the external environment improves the level of natural radioactive background and creates the danger of receipt of PB in the body with water and food. The degree of radiation danger in turn is determined by the amount R. O. entering the biosphere, gamma-radiation, the dimensions of the contaminated territory and number of population living in the area. The main danger of radioactive waste is not in the external impact on human health and the penetration of radioactive substances in the body. There is a clear need for localization R. O. on the place of generation and to prevent the possibility of their migration through the food chain power of humans and animals.
Liquid R. O. small and medium activity, containing short-lived radioisotopes (T max 15 days), kept in special containers to reduce the level of activity, stipulated by the sanitary rules, then dumped into the sewer system or divert water. Maintaining high-level radioactive waste is economically unprofitable.
More common cleanup of radioactive waste water coagulation (see water Purification). For cleaning used conventional coagulants: Al2(SO4)3, Fe2(SO4)3 and FeCl3. Passed in the sediment (1-3% of the volume) PB will be transported for disposal facilities. The most complete decontamination of sewage waters is achieved by the method of ion exchange. In this way the concentration of radioactive substances in the wastewater can be reduced to the level of maximum permissible concentration.
Radioactive waste waters biological and medical facilities to decontaminate recycled in the biofilters scheme treatment of sanitary wastewater (see). After biological treatment of wastewater is typically concentrated method of evaporation and subsequent disposal of radioactive sludge. Decontamination of waste water after filtering through biological filters produced by ion-exchange filtration.
In practice, disposal of liquid radioactive waste widely used method of evaporation of waste water, allowing decontamination of radioactive water of any salt composition and any level activities and provide a high degree of decontamination and the production of concentrated residue of high activity. The effectiveness of this method is determined by the ratio of the volume of liquid R. O. to the volume of concentrate. The volume of liquid R. O. may be reduced after evaporation 1000 times. The method is unsuitable if the wastewater volatile radioactive substances (J131 and others).
To reduce the amount of hydrated after evaporation of precipitation are dehydration. The amount of sludge is reduced by 10-15 times. A more complete removal of moisture from hydrated precipitation is achieved by the use of drainage devices with the subsequent drying in the open air. To remove water sludge is dried in the drying units, packaged and sent to a landfill.
Combustible liquid Radioactive wastes consisting of lubricating oils, solvents and extractants (gasoline, kerosene, acetone, ether, alcohol), should be kept to a decline in accordance with the established norms. After the relevant keeping flammable R. O. disposed of or burnt. In the presence of long-lived radioisotopes used burning, drying, filtering and settling. Selected by filtration and sedimentation of solid radioactive impurities are buried, like solid R. O. They are mixed with sand or earth is Packed in a metal drum and pour a concrete solution. Purified oils and solvents are disposed of or burnt.
For collection, storage and transportation of solid R. O. apply rubber (plastic or paper bags disposable. A small amount of liquid R. O. sometimes subjected to hardening in bags of polyethylene or chloride gypsum, which is poured into the bag with a thick layer before filling radioactive liquid. Packed in such a way P. O. stored and transported in a negotiable transport containers. The gamma-radiation at a distance of 1 l of a container must not exceed 3,6 Mr/hour. In areas for storage of containers with radioactive waste containing gamma-emitting radioisotope should get protective screens or trench, and refrigerators for storage of corpses laboratory animals and organic materials). Containers and storage for keeping alpha - and beta-active R. O. can be more simple. Pulverized R. O. Packed in metal drums, after which the lid is sealed. Items of laboratory equipment and machine parts in order to avoid radioactive contamination of transport vehicles and roads covered with durable waterproof paint.
Solid R. O. for reducing activity and volume reduction withstand, crushed and pressed. Combustible waste is incinerated in special furnaces far from settlements. The burning process is associated with smoke, containing radioactive aerosols; to capture their need for complex cleaning system.
Burning to reduce the amount of solid R. O. 20-30 times, but this created additional waste in the form of exhaust nozzles, filtering fabrics and scrubbing liquid residues.
Solid radioactive waste containing long-lived radioisotopes, processed in the case, when a lot of them and place of education is far from the repository. Solid R. O. containing short-lived radioisotopes (T 15-60 days), it is expedient to sustain over time, equal to 10 polarizada (there is a slowdown in 210=1024 times). If the average half-life period is in the range 15-60 days., R. O. withstand 150-600 day.
Any removal system P. O. must meet basic hygiene standards: 1) to guarantee absolutely penetration of radioactive substances in food and water; 2) to eliminate any danger of external exposure of the population in doses exceeding the maximum permissible level; 3) to prevent adverse impact of radioactive waste on mineral deposits and difficulties of access to them; 4) to be economically viable.

Radioactive called waste, in which the concentration of radioactive substances exceed the norms established for a respective environments (for example, water, air, solid waste).
Sources of radioactive waste are the enterprises on extraction and processing of radioactive raw materials, production and use of radioactive materials, as well as agencies working with radioactive isotopes. The degree of health hazard of radioactive waste at uncontrolled removal of them, due to the possibility of contamination by radioactive substances in environmental media (air, water, soil, and so on), the result of which may be exposure of people. Essential in this sense the extent of the contaminated areas, the intensity and duration of the effects of ionizing radiation on people.
On the physical condition of radioactive waste is divided into liquid, gaseous and solid. In sanitation the most serious attention as potential factors of pollution of environmental objects deserve liquid and gaseous radioactive waste, due to their ability to be easily distributed environments.
For liquid radioactive waste includes waste technological solutions, the waste water from washing equipment, contaminated with radioactive substances, appropriate accommodations, overalls and so forth, water cooled nuclear reactors, etc. According to the recommendations of the International atomic energy 1971 liquid radioactive waste according to the degree of radioactivity are divided into high-level (with concentration of 10-4 Curie/l and above), the average activity (10-4 Curie/l to 10-8Curie/l) and mild (10-9 Curie/l and less). High-level radioactive wastes arise only on some of the radiochemical enterprises. They are stored in metal tanks. Liquid radioactive waste with average levels of activity are formed at a number of enterprises. Before removing they are appropriate decontamination. Low activity radioactive waste arise also in the institutions working with radioactive substances. The conditions of removal by sanitarian rules. Sanitary significance of contamination of water bodies as a result of uncontrolled descent into them of a liquid radioactive waste is due to the possibility of migration of radioactive isotopes from the reservoir into the body not only drinking water, but also through the chain of water - fish - human; when irrigation - circuit water - soil - plant - man and others
The main principles of the prevention of such pollution are reduced to the maximum decrease of the number (up to the total elimination) of liquid radioactive wastes awaiting disposal in the environment. This is achieved by improving the technological process of the production, the introduction of recycling of industrial water reuse (after cleaning) liquid radioactive waste. At impossibility of introduction of such systems of liquid radioactive waste inactivate. In cases where the radioactivity of the waste caused by the presence of short-lived isotopes, radioactive waste is kept in the time necessary for the decay of isotopes and reduce activity up to the required values. In the presence of radioactive waste is long-lived isotopes used methods to concentrate them in a small volume (e.g., coagulation, sedimentation, filtration, more effective residue and other), with further disposal concentrates (sludge, sediments). According to the sanitary legislation of the descent of wastewater in open waters is allowed only if the concentration of radioactive isotopes in the water at the place of their production do not exceed the standards set for water.
Gaseous radioactive wastes consist of radioactive gases and aerosols. They can occur when working nuclear reactors by irradiation with neutrons of airborne gases and impurities, due to the removal of radioactive gases and vapors of industrial premises, etc.

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