Design basis accident. Accidents at radiation hazardous facilities Give a definition of design basis accident

Under design basis accident an accident is understood for which the initial events of emergency processes characteristic of a particular object are defined in the project.

Maximum design basis accidents are characterized by the most severe initiating events that cause the occurrence of an emergency process at this facility.

Under beyond design basis (hypothetical) accident an accident is understood that is caused by initiating events that are not considered for design basis accidents and is accompanied by additional failures of safety systems in comparison with design basis accidents.

66. Features and advantages of RUBREST:

natural radiation safety

long-term provision of fuel resources due to the efficient use of natural uranium;

elimination of weapons-grade plutonium production

environmental friendliness of energy production and waste disposal

economic competitiveness due to the natural safety of nuclear power plants and fuel cycle technologies, rejection of complex engineering safety systems

67. Environmental Consequences of NPP Operation

The main environmental problems of NPP operation. Compared to fresh fuel in its composition less content uranium-235 (since it burns out), but isotopes of plutonium, other transuranic elements, as well as fragments, or fission products - nuclei of medium masses, accumulate. The physical characteristics of the structural materials of the fuel assemblies also change over time.

Dismantling of a nuclear power plant at the end of its normal operation.

68. The main radionuclides formed during the operation of nuclear power plants and their effect on the body

Tritium -can enter the human body by inhalation, as well as through the skin. In the presence of tritium, the entire human body is exposed to β-radiation with a maximum energy of 18 keV.

Carbon-14- The effect of ionizing radiation on humans is mainly due to the consumption of food (milk, vegetables, meat).

Krypton - The radiological effect of 85 Kr on humans occurs mainly due to irradiation of the skin.

Strontium - 90 Sr enters the human body with food (milk, vegetables, fish, meat, drinking water). Like calcium, 90 Sr is deposited mainly in bone tissues containing vital hematopoietic organs.

Cesium- The radiological effect of cesium, like 90 Sr, on humans is associated with its penetration into the human body along with food. In living organisms, cesium can largely replace potassium and, like the latter, spread throughout the body in the form of highly soluble compounds.

69. Spent nuclear fuel - irradiated nuclear fuel, spent fuel elements (fuel rods) of nuclear reactors of nuclear power plants removed from the core.

RAW - Substances not intended for further use in any aggregate state, in which the content of radionuclides exceeds the levels.

70. Peculiarities of handling oyat:

Nuclear hazard (criticality);

Radiation safety;

Residual heat generation.

Ensuring subcriticality during the entire operation period;

Prevention of physical damage to the fuel assembly and / or TVEL;

Providing a reliable heat conduction;

Maintaining the level of radiation exposure and the release of radioactive substances when handling irradiated fuel at a reasonably achievable low level.

72. The list of technological operations for SNF management may include:

Intermediate storage of spent fuel assemblies in the spent fuel pool;

Transportation of spent fuel to a reprocessing plant, temporary storage or repository;

Intermediate storage before processing or disposal;

Reprocessing or preparation of spent fuel assemblies for temporary storage or disposal;

Temporary storage or burial.

73. Management of radioactive waste

A typical sequence of waste management operations is collection, separation, characterization, treatment, conditioning, transport, storage and disposal.

74. RW characteristics used for their classification + 75. RW classification

There are a number of criteria by which radioactive waste is classified.

By activity levels and heat release, with the definition of quantitative characteristics:

Waste high level activity; long rao

Medium activity waste;

Low activity waste; shortly rao

Very low activity waste.

Half-life of radionuclides, which determines the time of their potential danger:

Very short lived;

Short-lived;

Medium-living;

Long-lived.

By the nature of the predominant radiation:

α-emitters;

β-emitters;

Design-basis accident

an accident, the possibility of which is provided for by the current regulatory and technical documentation of this nuclear installation and for which the technical design provides for ensuring the radiation safety of personnel and the public.

• Civil protection. Conceptual and terminological dictionary

• - an industrial accident, for which the initial and final states are determined by the project and safety systems are provided for limiting the consequences of the accident to the established limits ...
• - Design-basis accident with the most severe consequences. Source: GOST R 12.3 ...

  Emergency Glossary

• - Accident for which the provision of a given level of safety is guaranteed by those provided for in the project industrial enterprise security systems. Source: GOST R 12.3 ...

  Emergency Glossary

• Emergency Glossary

• - see Industrial design accident ...

  Emergency Glossary

• - see Radiation design accident ...

  Emergency Glossary

• - an accident for which the project defines the initial and final states of the radiation situation and provides for safety systems ...

  Nuclear power terms

• - Design-basis accident an accident, the possibility of which is provided for by the current regulatory and technical documentation of this nuclear installation and for which the technical design provides for the provision of radiation ...

  Nuclear power terms

• - 1. temporary organizational structure, formed to achieve a specific, clearly defined goal 2.permanent organization developing construction, organizational, technical and technological projects ...

  Big Dictionary of Economics

• - see PROJECT Source: Terminological Dictionary of Construction at 12 ...

  Construction dictionary

• - line showing the position of the edge subgrade roads on a longitudinal profile ...

  Construction dictionary

• - the capacity provided by the design of this production, workshop, unit, installation ...

  Business glossary

• - production capacity, provided for by the approved project of the put into operation of the enterprise, workshop, unit, installation. During the development of the PM. is determined taking into account the standard terms of its development ...

  Big Dictionary of Economics

• - "... 1. Is an accident for which the project defines the initial and final states of the radiation situation and provides for safety systems ..." Source: "SP 2.6.1.799-99. OSPORB-99. 2.6.1 ...

  Official terminology

"Design accident" in books

Project democracy

From the author's book

Project Democracy The experience of the USSR shows that democracy has room for development in its technical application. However, in the 1985-1999 revolution, we refused to develop public power and institutionalize the management of society. We took a step back, unable to resist

5.3. Project group

From the book Investment projects: from modeling to implementation author Volkov Alexey Sergeevich

5.3. Project team The project team can be made up of people who are engaged on a temporary or permanent basis. Many members of the project team can combine this activity with any other. The project group is the core of the project, it includes all the main ones for the project

31. PROJECT STRUCTURE OF THE ORGANIZATION

From the book Organization Theory: The Cheat Sheet author author unknown

31. PROJECT STRUCTURE OF THE ORGANIZATION The project structure is used when a decision is made to focus maximum amount resources of the organization on a specific project for a specific period. Any process is considered a project

Project group

From the book HR in the Struggle for Competitive Advantage author Brockbank Wayne

Project team Create a project team that includes key stakeholders - line managers, HR employees from corporate services and departments, specialists, and, if necessary, external consultants. Challenge the group to: create a model

Research project activities

author Veraksa Nikolay Evgenievich

Research project activity Peculiarity of research project activities determined by its purpose: research involves obtaining an answer to the question of why a particular phenomenon exists and how it is explained from the point of view of modern

Creative project activities

From the book Project activity of preschoolers. A guide for educators preschool institutions author Veraksa Nikolay Evgenievich

Creative project activity In the course of creative project activity, a new creative product is created. If research project activity, as a rule, is of an individual nature, then creative project more often carried out collectively or

Regulatory design activities

From the book Project activity of preschoolers. A guide for preschool teachers author Veraksa Nikolay Evgenievich

Regulatory design activities Regulatory projects are extremely important focus in teaching activitiesas they develop positive socialization in children. These projects are always initiated by an educator who must clearly understand

RUSSIAN PROJECT ALTERNATIVITY - YESTERDAY, TODAY, TOMORROW

From the book Ark // №1 [Almanac of the direction "Alternative models of development" (ALMOR) movement "The essence of time"] author Kurginyan Sergei Ervandovich

RUSSIAN PROJECT ALTERNATIVITY - YESTERDAY, TODAY,

Project activities

From the book Modern Technologies of Teaching History at School author Studenikin Mikhail Timofeevich

Project activity At present, it is important to refer to project activity, when high school students create and defend their projects, as do university students their term papers and theses. A project is a prototype, a prototype of any kind of activity, object,

Project documentation

From the book How They Test on Google author Whittaker James

Project Documentation Every project on Google has a main project document. It is a living document, it develops along with the project. First, this document describes the purpose of the project, the prerequisites for its creation, the proposed list of participants and architectural solutions... On

2.5. DESIGN PROCEDURE FOR STATEMENT OF THE PROBLEM DEVELOPMENT OF THE PROGRAM

From the book Programming Technologies author Kamaev VA

2.5. DESIGN PROCEDURE FOR STATEMENT OF THE PROBLEM DEVELOPMENT OF THE PROGRAM The design procedure is based on ownership systematic approach in relation to analysis software systems... Initially, a system is considered - a person (people), a computer, a program, other objects, for example

Aircraft of Russia (project activity)

From the book Geometric Mosaic in Integrated Lessons. Summaries of classes with children 5-9 years old author Novikova Valentina Pavlovna

Aircraft of Russia (project activity) Purpose. Develop children's horizons, the ability to independently acquire knowledge, work with sources, convincingly substantiate what was conceived during the presentation of the project, work independently and in a team. Big set

Design capacity of Pushkin

From the book Literary Gazette 6305 (No. 4 2011) author Literary Newspaper

Design capacity of Pushkin Literature Design capacity of Pushkin STUDIES Marina KUDIMOVA Man, whether he is the king of nature or not a king, differs from other biological species in many ways. Too much. Including the desire for project activities. Design is inherent in

Land lease and project documentation

From the book Your business. Everything New Entrepreneurs Need to Know author Malitikov Pavel Nikolaevich

Land lease and project documentation Once you have selected a plot for parking, you should obtain the right to lease it. This is a rather difficult question, for the solution of which a number of approvals, documents and considerable cash... If a

55. Project documentation

From the book Instrumentation author Babaev MA

55. Project documentation Project documentation, which is the result of ATS design and control, usually consists of two parts. 1. At the “design assignment” stage, issues related to the object itself are studied; key performance issues

TEST TASKS FOR PREPARATION FOR GIA ON THE DISCIPLINE "RADIATION HYGIENE"

Choose one correct answer:

1. The main measures to ensure radiation safety include:

1) legal, epidemiological, sanitary and hygienic

2) legal, organizational, sanitary and hygienic

3) economic, organizational, epidemiological

4) operational, organizational, sanitary and hygienic

5) legal, organizational, epidemiological

2. Reduction of radiation exposure of patients during radiography is provided by:

1) the health of the device

2) compliance of the device with technical standards

3) the correct choice of the picture mode

4) filtration of the primary beam

5) all of the above is true

3. Weighting factors for certain types ionizing radiation is used when calculating:

1) exposure dose

2) absorbed dose

3) equivalent dose

4) effective dose

5) radiation output

A copy of the worker's radiation dose card should be kept in medical organization after his dismissal for ______ years

5. The following sources make the main contribution to population exposure:

1) global radioactive fallout

2) accidents at nuclear power plants

3) natural background radiation, technologically modified

natural background radiation, X-ray and radiological

diagnostics in medicine

4) nuclear power plants in normal operation

5) everything is true

6. Irradiation of patients during X-ray diagnostics is regulated by:

1) Radiation safety standards (NRB-99/2009)

2) Basic sanitary rules for ensuring radiation safety (OSPORB-2010)

3) SanPiN 2.6.1. 1192-03 "Hygienic requirements for the design and operation of X-ray rooms, apparatus and X-ray studies"

4) the federal law "On radiation safety of the population"

5) everything is correct

Planned radiation monitoring at enterprises,

using sources of ionizing radiation, includes:

1) determination of the levels of natural background radiation

2) estimate the duration technological processes

3) assessment of the dose rate at workplaces, determination of the content of radionuclides in the air working area, medical supervision of personnel

4) determination of the levels of technologically modified natural radiation background

6) everything is correct

8. Radiation monitoring devices are subdivided into:

1) customized

2) wearable

3) portable

4) stationary

5) everything is correct

Sanitary and dosimetric control in medical institutions

includes:

1) measuring the dose rate of external radiation

2) individual dosimetric control

3) determination of the concentrations of radioactive gases and aerosols in

4) control over the collection, storage and disposal of radioactive waste

5) everything is true

10. The level of radioactive contamination of surfaces is expressed in:

3) Frequency / cm 2 / min

4) MKR / hour

11. Weighting coefficients for tissues and organs are used when calculating:

1) exposure dose

2) absorbed dose

3) equivalent dose

4) effective dose

5) ambient dose equivalent

12. The principle of optimization of radiation safety during X-ray examinations assumes:

1) organization of a single X-ray department for a hospital and a polyclinic

2) carrying out X-ray examinations in the direction of the attending physician

3) establishment of reference levels of exposure for different types procedures and refusal of unjustified research

4) maintaining at the lowest possible level of radiation doses to patients while maintaining the quality of their examination and treatment

5) compliance with radiation safety standards

Solid radioactive waste is processed before disposal

methods:

1) burning

2) glass transition, bituminization, glass transition cementation,

cementing

3) grinding

4) pressing

5) everything is true

14. The activity of a radioactive substance is:

1) absorbed energy, calculated per unit mass

2) the amount of radiation emitted by radioactive atoms

3) the number of radioactive decays of atomic nuclei per unit time

4) the time of elimination of radionuclides from the body

5) dose created per unit of time

15. Radiation monitoring at personnel workplaces, adjacent rooms and areas adjacent to the X-ray room should be carried out at least 1 time in:

16. The highest concentration of radon is noted:

1) in the surface layer of air in winter

2) in the surface layer of air in summer

3) in the air over the ocean

4) in the soil air

5) in the upper atmosphere

17. Monitoring and control of the radiation situation outside the sanitary protection dose is carried out by:

1) radiation monitoring groups of the enterprise itself

2) organizations licensed to carry out such work

3) territorial offices of Rospotrebnadzor

4) regional bodies of Rostechnadzor

5) public organizations

Accident for which the project has defined the initial and end eventsis called:

2) design

3) actual

4) technical

5) hypothetical

19. The biological effect of radiation depends on:

1) dose received

2) body reactivity

3) exposure time, intervals between exposures

4) the size and location of the irradiated surface

5) all of the above is true

20. Radioactive waste in health care facilities includes:

1) radioactive aerosols removed from fume hoods and

2) liquid radioactive waste arising from

decontamination of equipment

3) radioactive waste excreted by patients

4) used tools, overalls, PPE from open source departments














Design basis accident

• Design basis accident - an accident for which initiating events and final states are defined by the project and safety systems are provided that, taking into account the principle of a single failure of safety systems or one personnel error independent of the initial event, limiting its consequences to the limits established for such accidents.

• Beyond design basis accident - an accident caused by initiating events not taken into account for design basis accidents or accompanied by additional failures of safety systems in excess of a single failure in comparison with design basis accidents, the implementation of erroneous decisions of personnel.

• Severe beyond design basis accident - beyond design basis accident with damage to fuel elements above the maximum design limit at which the maximum permissible accidental release of radioactive substances into the environment can be achieved.


















• Figure: 1. Schematic diagram of SPOT SG and SPO ZO

• 1 - tanks for emergency heat removal; 2 - steam lines; 3 - condensate pipelines; 4 - PHRS valves; 5 - heat exchangers-condensers SPOT-ZO; 6 - steam generators; 7 - shut-off valves








• 1 - reactor; 2 - melt localization device; 3 - fuel pool; 4 - shaft for revision of internals; 5 - pit tanks; 6 - pipeline for water supply to the melt surface; 7 - pipeline for water supply to heat exchanger ULR




Over the past four decades, nuclear power and the use of fission materials have become firmly established in the life of mankind. More than 450 nuclear reactors are currently in operation in the world. Nuclear power has made it possible to significantly reduce “energy hunger” and improve the environment in a number of countries. Thus, in France, more than 75% of electricity is obtained from nuclear power plants, and at the same time, the amount of carbon dioxide entering the atmosphere was reduced by 12 times. In the conditions of trouble-free operation of nuclear power plants, nuclear power is still the most economical and environmentally friendly energy production and no alternative to it is foreseen in the near future. At the same time, the rapid development nuclear industry and nuclear power industry, the expansion of the scope of application of radioactivity sources led to the emergence of radiation hazard and the risk of radiation accidents with the release of radioactive substances and pollution environment... Radiation hazard can arise in accidents at radiation hazardous facilities (ROO). ROO - an object where radioactive substances are stored, processed, used or transported, and in case of an accident, at which or its destruction may occur irradiation with ionizing radiation or radioactive contamination of people, farm animals and plants, objects of the national economy, as well as the environment.

At present, more than 700 large radiation hazardous facilities are operating in Russia, which to one degree or another pose a radiation hazard, but nuclear power plants are the objects of increased danger. Almost all operating nuclear power plants are located in a densely populated part of the country, and about 4 million people live in their 30-kilometer zones. The total area of \u200b\u200bthe radiation-destabilized territory of Russia exceeds 1 million km2; more than 10 million people live on it.

Accidents at the ROO can lead to radiation emergency (RFS). Radiation is understood as an unexpected hazardous radiation situation that has led or may lead to unplanned exposure of people or radioactive contamination of the environment in excess of established hygienic standards and requires urgent action to protect people and the environment.

Classification of radiation accidents

Accidents related to disruption of normal operation of the ROO are subdivided into design and beyond design basis.

Design basis accident - an accident for which the initial events and final states are defined by the project, in connection with which safety systems are provided.

Beyond design basis accident - is caused by initiating events not taken into account for design basis accidents and leads to serious consequences. This may result in the release of radioactive products in quantities leading to radioactive contamination of the adjacent territory, possible exposure of the population above the established standards. In severe cases, thermal and nuclear explosions can occur.

Potential accidents at nuclear power plants are divided into six types depending on the boundaries of the zones of distribution of radioactive substances and radiation consequences: local, local, territorial, regional, federal, and transboundary.

If, in a regional accident, the number of people who received a dose of radiation above the levels established for normal operation may exceed 500 people, or the number of people whose living conditions may be impaired exceeds 1,000 people, or material damage exceeds 5 million. minimum sizes wages, then such an accident will be federal.

In transboundary accidents, the radiation consequences of the accident go beyond the territory Russian Federationor given accident occurred abroad and affects the territory of the Russian Federation.

During the total operating life of all nuclear power plants in the world, equal to 6,000 years, only 3 major accidents occurred: in England (Windekale, 1957), in the USA (Three Mile Island, 1979) and in the USSR (Chernobyl , 1986). The accident at the Chernobyl nuclear power plant was the most severe. These accidents were accompanied by human casualties, radioactive contamination of large areas and enormous material damage. As a result of the accident in Windakale, 13 people died and an area of \u200b\u200b500 km2 was contaminated with radioactive substances. The direct damage to the Three Mile Island accident amounted to over $ 1 billion. The Chernobyl accident killed 30 people, over 500 were hospitalized and 115,000 people were evacuated.

The International Agency for nuclear power (IAEA) developed an international scale of events at nuclear power plants, which includes 7 levels. According to it, the accident in the USA belongs to the 5th level (with a risk to the environment), in the UK - to the 6th level (severe), the Chernobyl accident - to the 7th level (global).

General characteristics of the consequences of radiation accidents

The long-term consequences of accidents and disasters at facilities with nuclear technology, which are of an ecological nature, are assessed mainly by the amount of radiation damage caused to human health. In addition, an important quantitative measure of these consequences is the degree of deterioration in the living conditions and life of people. Of course, the level of mortality and deterioration in human health has a direct relationship with the living conditions and life activity, therefore, they are considered in conjunction with them.

The consequences of radiation accidents are caused by their damaging factors, which include ionizing radiation at the accident facility, both directly during release and during radioactive contamination of the facility territory; shock wave (in the presence of an explosion in an accident); thermal impact and impact of combustion products (in the presence of fires in an accident). Outside the accident object, the damaging factor is ionizing radiation due to radioactive contamination of the environment.

Medical consequences of radiation accidents

Any major radiation accident is accompanied by two fundamentally different types of possible medical consequences:
• radiological consequences resulting from direct exposure to ionizing radiation;
• various health disorders (general, or somatic disorders) caused by social, psychological or stress factors, that is, other damaging factors of the accident of a non-radiation nature.

Radiological consequences (effects) differ in the time of their manifestation: early (no more than a month after exposure) and long-term, arising after a long period (years) after radiation exposure.

The consequences of irradiation of the human body are the breaking of molecular bonds; changes in the chemical structure of compounds that make up the body; the formation of chemically active radicals with high toxicity; violation of the structure of the genetic apparatus of the cell. As a result, the hereditary code changes and mutagenic changes occur, leading to the emergence and development of malignant neoplasms, hereditary diseases, congenital malformations of children and the appearance of mutations in subsequent generations. They can be somatic (from the Greek soma - body), when the effect of radiation occurs in an irradiated person, and hereditary, if it manifests itself in offspring.

The most sensitive to radiation exposure are the hematopoietic organs (bone marrow, spleen, lymph nodes), the epithelium of the mucous membranes (in particular, the intestines), and the thyroid gland. As a result of the action of ionizing radiation, the most serious diseases arise: radiation sickness, malignant neoplasms and leukemia.

Environmental consequences of radiation accidents

Radioactive is the most important environmental consequence of radiation accidents with the release of radionuclides, the main factor affecting the health and living conditions of people in the territories exposed to radioactive contamination. The main specific phenomena and factors that determine the environmental consequences in radiation accidents and disasters are radioactive emissions from the accident zone, as well as from the cloud (clouds) of air contaminated with radionuclides formed during the accident and propagating in the surface layer; radioactive contamination of environmental components.

The air masses that moved westward on April 26, 1986, north and northwest on April 27, turned east, southeast from the north on April 28-29, and then south (to Kiev) on April 30.

Subsequent long-term intake of radionuclides into the atmosphere occurred due to the combustion of graphite in the reactor core. The main release of radioactive products lasted for 10 days. However, the outflow of radioactive substances from the destroyed reactor and the formation of contamination zones continued for a month. The long-term nature of exposure to radionuclides was determined by a significant half-life. The deposition of the radioactive cloud and the formation of the trail took a long time. During this time, the meteorological conditions changed and the trail of the radioactive cloud acquired a complex configuration. In fact, two radioactive traces were formed: the western and the northern. Most heavy radionuclides spread to the west, and the bulk of the lighter (iodine and cesium), having risen above 500-600 m (up to 1.5 km), was transferred to the northwest.

As a result of the accident, about 5% of the radioactive products accumulated over 3 years of operation in the reactor left the industrial site of the station. The volatile isotopes of cesium (134 and 137) have spread over great distances (significant amounts throughout Europe) and have been found in most countries and oceans of the Northern Hemisphere. The Chernobyl accident led to radioactive contamination of the territories of 17 European countries with a total area of \u200b\u200b207.5 thousand km2, with an area of \u200b\u200bcesium contamination above 1 Cu / km2.

If fallouts throughout Europe are taken as 100%, then 30% of them fell on the territory of Russia, Belarus - 23%, Ukraine - 19%, Finland - 5%, Sweden - 4.5%, Norway - 3.1%. On the territories of Russia, Belarus and Ukraine, the level of contamination of 1 Cu / km2 was taken as the lower boundary of the radioactive contamination zones.

Immediately after the accident, the greatest danger to the population was posed by radioactive isotopes of iodine. The maximum content of iodine-131 in milk and vegetation was observed from April 28 to May 9, 1986. However, during this period of “iodine danger”, almost no protective measures were taken.

Subsequently, the radiation situation was determined by long-lived radionuclides. Since June 1986, the radiation impact was formed mainly due to the radioactive isotopes of cesium, and in some regions of Ukraine and Belarus, also strontium. The most intense fallout of cesium is characteristic of the central 30-kilometer zone around the Chernobyl nuclear power plant. Another highly contaminated area is some areas of the Gomel and Mogilev regions of Belarus and the Bryansk region of Russia, which are located about 200 km from the nuclear power plant. Another, northeastern zone is located 500 km from the nuclear power plant, it includes some areas of the Kaluga, Tula and Oryol regions. Because of the rains, the fallout of cesium became "spots", so even in neighboring territories, the density of pollution could differ tens of times. Precipitation played a significant role in the formation of precipitation - in the zones of rainfall, pollution was 10 or more times higher than precipitation in dry places. At the same time, in Russia the fallout was “smeared” over a rather large area, therefore the total area of \u200b\u200bterritories contaminated above 1 Cu / km2 is the largest in Russia. And in Belarus, where the fallout turned out to be more concentrated, the largest area of \u200b\u200bterritories contaminated over 40 Kyu / km2 was formed in comparison with other countries. Plutonium-239, as a refractory element, did not spread in significant quantities (exceeding the permissible values \u200b\u200bof 0.1 Cu / km2) over long distances. Its fallout was practically limited to a 30-kilometer zone. However, this zone with an area of \u200b\u200babout 1,100 km2 (where strontium-90 in most cases dropped out more than 10 Cu / km2) became for a long time unsuitable for human habitation and management, since the half-life of plutonium-239 is 24.4 thousand years.

In Russia, the total area of \u200b\u200bradioactively contaminated territories with a pollution density above 1 Cu / km2 for cesium-137 reached 100 thousand km2, and over 5 Cu / km2 - 30 thousand km2. In the contaminated areas there were 7,608 settlements, in which about 3 million people lived. In general, the territories of 16 regions and 3 republics of Russia (Belgorod, Bryansk, Voronezh, Kaluga, Kursk, Lipetsk, Leningrad, Nizhny Novgorod, Oryol, Penza, Ryazan, Saratov, Smolensk, Tambov, Tula, Ulyanovsk, Mordovia, Tatarstan, ).

Radioactive contamination affected over 2 million hectares of farmland and about 1 million hectares of forest land. The territory with a contamination density of 15 Cu / km2 for cesium-137, as well as radioactive water bodies are located only in the Bryansk region, where the disappearance of contamination is predicted in about 100 years after the accident. When radionuclides propagate, the transport medium is air or water, and the role of the concentrating and depositing medium is played by the soil and bottom sediments. Areas of radioactive contamination are mainly agricultural areas. This means that radionuclides can enter the human body with food. Radioactive contamination of water bodies, as a rule, is dangerous only in the first months after the accident. The most accessible for assimilation by plants are “fresh” radionuclides when they enter the air route and during the initial period of stay in the soil (for example, for cesium-137, a decrease in the intake of plants into plants over time is noticeable, that is, during “aging” of the radionuclide).

Agricultural products (primarily milk), in the absence of appropriate bans on their use, became the main source of exposure of the population to radioactive iodine in the first month after the accident. Local foodstuffs made a significant contribution to radiation doses in all subsequent years. At present, 20 years later, the consumption of products subsidiary plots and forest gifts makes the main contribution to the radiation dose to the population. It is generally accepted that 85% of the total predicted internal dose for the next 50 years after the accident is the internal dose due to the consumption of food products grown in the contaminated area, and only 15% falls on the external dose. As a result of radioactive contamination of environmental components, radionuclides are included in the biomass, their biological accumulation, followed by a negative impact on the physiology of organisms, reproductive functions, etc.

At any stage of obtaining products and preparing food, it is possible to reduce the intake of radionuclides into the human body. If you thoroughly wash herbs, vegetables, berries, mushrooms and other products, radionuclides will not enter the body with soil particles. Effective ways reducing the flow of cesium from the soil into plants - deep plowing (makes cesium inaccessible to plant roots); application of mineral fertilizers (reduces the transition of cesium from soil to plant); selection of cultivated crops (replacement for species that accumulate cesium to a lesser extent). It is possible to reduce the supply of cesium to livestock products by selecting forage crops and using special food additives. Various processing and preparation methods can be used to reduce the cesium content of food. Cesium is soluble in water, therefore, due to soaking and cooking, its content decreases. If vegetables, meat, fish are cooked for 5-10 minutes, then 30-60% of cesium will go into the broth, which should then be drained. Pickling, pickling, salting reduces the cesium content by 20%. The same applies to mushrooms. Cleaning them from soil and moss residues, soaking in a saline solution and subsequent boiling for 30-45 minutes with the addition of vinegar or citric acid (change the water 2-3 times) can reduce the cesium content up to 20 times. In carrots and beets, cesium accumulates in the upper part of the fruit, if it is cut by 10-15 mm, its content will decrease 15-20 times. In cabbage, cesium is concentrated in the upper leaves, the removal of which will reduce its content up to 40 times. When processing milk for cream, cottage cheese, sour cream, the cesium content decreases by 4-6 times, for cheese, butter - 8-10 times, for ghee - 90-100 times.

The radiation situation depends not only on the half-life (for iodine-131 - 8 days, cesium-137 - 30 years). Over time, radioactive cesium goes into the lower layers of the soil and becomes less available to plants. At the same time, the dose rate above the earth's surface also decreases. The rate of these processes is estimated by the effective half-life. For cesium-137, it is about 25 years in forest ecosystems, 10-15 years in meadows and arable lands, 5-8 years in settlements. Therefore, the radiation situation is improving faster than the natural consumption of radioactive elements occurs. Over time, the density of pollution in all territories decreases, and their total area decreases.

The radiation situation has also improved as a result of protective measures. To prevent dust spreading, roads were paved and wells covered; roofs of residential buildings and public buildings were overlapped, where radionuclides accumulated as a result of fallout; soil cover was removed in places; in agriculture were held special events to reduce pollution of agricultural products.

Features of radiation protection of the population

Radiation protection- is a set of measures aimed at weakening or eliminating the impact of ionizing radiation on the population, personnel of radiation hazardous objects, biological objects of the natural environment, as well as protecting natural and man-made objects from radioactive contamination and removing these contaminants (decontamination).

Radiation protection measures, as a rule, are carried out in advance, and in the event of radiation accidents, upon detection of local radioactive contamination - promptly.

The following radiation protection measures are carried out in a preventive manner:
• radiation safety regimes are developed and implemented;
• systems for radiation monitoring of the radiation situation on the territories of nuclear power plants, in observation zones and sanitary protection zones of these stations are being created and operated;
• action plans are developed for the prevention and elimination of radiation accidents;
• personal protective equipment, iodine prophylaxis and decontamination are accumulated and kept in readiness;
• are maintained in readiness for use of protective structures on the territory of nuclear power plants, anti-radiation shelters in settlements near nuclear power plants;
• training of the population for actions in the conditions of radiation accidents, professional training of personnel of radiation hazardous facilities, personnel of emergency rescue forces, etc.
Measures, methods and means to ensure the protection of the population from radiation exposure in a radiation accident include:
• detection of the fact of a radiation accident and notification of it;
• identification of the radiation situation in the accident area;
• organization of radiation monitoring;
• establishment and maintenance of the radiation safety regime;
• carrying out, if necessary, at an early stage of the accident, iodine prophylaxis of the population, personnel of the emergency facility and participants in the liquidation of the consequences of the accident;
• providing the population, personnel, participants in the liquidation of the consequences of the accident with the necessary personal protective equipment and the use of these means;
• sheltering the population in shelters and anti-radiation shelters;
• sanitization;
• decontamination of the emergency facility, other facilities, technical means and etc;
• evacuation or resettlement of the population from areas in which the level of contamination or radiation doses exceed the permissible for the population.

The identification of the radiation situation is carried out to determine the scale of the accident, to establish the size of the zones of radioactive contamination, the dose rate and the level of radioactive contamination in the zones of optimal routes for the movement of people, transport, as well as to determine possible routes for the evacuation of the population and farm animals.

Radiation monitoring under conditions of a radiation accident is carried out in order to comply with the permissible time spent by people in the accident zone, to control radiation doses and levels of radioactive contamination.

The radiation safety regime is ensured by the establishment of a special procedure for access to the accident zone, zoning of the accident area; carrying out emergency rescue operations, carrying out radiation monitoring in the zones and at the exit to the “clean” zone, etc.

The use of personal protective equipment consists in the use of insulating skin protection (protective kits), as well as respiratory and eye protection (cotton-gauze bandages, different types respirators, filtering and isolating gas masks, goggles, etc.). They protect a person mainly from internal radiation.

To protect the thyroid gland adults and children from exposure to radioactive isotopes of iodine at an early stage of the accident, iodine prophylaxis is carried out. It consists in taking stable iodine, mainly potassium iodide, which is taken in tablets in the following doses: for children from two years of age and older, as well as for adults at 0.125 g, up to two years at 0.04 g, taken orally after meals with jelly, tea, water once a day for 7 days. A solution of iodine water-alcohol (5% iodine tincture) is indicated for children from two years of age and older, as well as for adults, 3-5 drops per glass of milk or water for 7 days. Children under two years old are given 1-2 drops per 100 ml of milk or nutritional formula for 7 days.

Maximum protective effect (reduction of the radiation dose by about 100 times) is achieved with the preliminary and simultaneous intake of radioactive iodine with its stable analogue. The protective effect of the drug is significantly reduced when it is taken more than two hours after the start of exposure. However, even in this case, effective protection against radiation occurs in the event of repeated inflows of radioactive iodine.

Protection from external exposure can only be provided by protective structures, which must be equipped with filters that absorb iodine radionuclides. Temporary shelters for the population prior to evacuation can be provided by almost any pressurized room.