Tell us about the features of radioactive contamination during accidents at nuclear facilities. What is the difference between radioactive contamination of the terrain during accidents at nuclear power plants and contamination of the terrain during a ground nuclear explosion?
Radioactive contamination during an accident at a nuclear power plant (facility) has the following features:
• radioactive products (dust, aerosols) in such cases easily penetrate inside the premises;
• a relatively small elevation of the radioactive cloud leads to pollution of settlements and forests to a much greater extent than open areas;
• with a significant duration of the radioactive release, when the direction of the wind can change many times, there is a likelihood of radioactive contamination of the area in almost all directions from the source of the accident.
Radioactive contamination of the area during accidents at nuclear power plants is somewhat different from radioactive contamination during nuclear explosions.
In a ground-based nuclear explosion, tens of thousands of tons of soil are drawn into its cloud. Radioactive particles are mixed with mineral dust, melted and deposited on the ground. The air is slightly polluted. The formation of a trace of a radioactive cloud is completed in a few hours. During this time, meteorological conditions, as a rule, do not change sharply, and therefore the cloud footprint usually has specific geometric dimensions and outlines. The main danger for people on this trail is external exposure (90–95% of the total radiation dose). The dose of internal exposure due to the ingestion of radioactive substances through the respiratory system and with food is insignificant.
In accidents at nuclear power plants, a significant part of the fission products of nuclear fuel is in a vaporous or aerosol state. Their release into the atmosphere can last from several days to several weeks. The impact of radioactive pollution on people in the first hours and days after the accident is determined by external exposure from a radioactive cloud and radioactive fallout on the ground and internal exposure from inhalation of radionuclides. In the future, for many years, the harmful effects and accumulation of the dose in humans will be due to the involvement of fallen radionuclides in the biological chain and the consumption of contaminated food and water. The total radiation dose predicted for the 50 years following the accident, in this case, it is customary to calculate as follows: 15% falls on external exposure, and 85% on internal.
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