Radioactive contamination is ?
Radioactive contamination occurs when:
deposition of radioactive substances from the cloud of a nuclear explosion and induced radiation due to the formation of radioactive isotopes in the environment under the influence of instantaneous neutron and gamma radiation from a nuclear explosion; affects humans and animals mainly through external gamma and (to a lesser extent) beta-exposure, and through internal exposure (mainly to alpha-active nuclides) when radioisotopes enter the body with air, water and food.
technogenic accidents (leaks from nuclear reactors, leaks during transportation and storage of radioactive waste, accidental loss of industrial and medical radioactive sources, etc.) as a result of dispersion of radioactive substances; the nature of contamination of the area depends on the type of accident.
Natural sources of radioactive contamination
The causes of natural radioactive contamination include cosmic radiation and the formation of radioisotopes in the Earth’s crust. Natural radionuclides are divided into 4 groups: long-lived, short-lived, not forming families, formed as a result of interaction of cosmic particles with atomic nuclei.
The North and South Poles are most susceptible to cosmic radiation because of the magnetic field deflecting the radioactive particles. In mountainous areas and regions above 2,000 m above sea level the risk of exposure increases considerably. At the maximum altitude of passenger aircraft (12,000 m) the level of exposure increases by a factor of 25.
The greatest contribution to natural radioactive contamination comes from the dispersion of radioisotopes from rocks enriched in uranium, thorium, and radon. Hot spots include the beaches of Guarapari in Brazil and the southwest coast of India because of the high thorium content in the sands. Elevated radiation is also noted in parts of France, Nigeria, Madagascar, and Russia (Zauralye, Kamchatka, Northeast, and Western Siberia).
Radon and its daughter decay products pose the greatest danger. It accounts for more than 50% of the total radiation dose. It can migrate considerable distances, is widespread and has a high penetrating power. It has no characteristic odor or color, making it difficult to identify without special instruments.
Anthropogenic sources of radioactive contamination
The main share of contamination is accounted for by anthropogenic sources. These include the nuclear and thermal industries, nuclear testing grounds, man-made accidents, as well as medicine and science.
Radioactive Waste from the Nuclear Industry
During processing and enrichment of uranium ores radioactive aerosols containing xenon, strontium, cesium and krypton isotopes are released into the air through the ventilation systems of nuclear industry enterprises. Small amounts of nuclear reactor corrosion products as well as fission fragments of uranium, magnesium and cesium nuclei may be released. However, if the nuclear power plant operates properly, atmospheric radioactive emissions are insignificant compared to other industries.
Industrial effluents with elevated concentrations of certain isotopes are produced at plants producing uranium metal and at radiochemical production facilities. Part of the enterprises’ waste is emitted in the form of gases and aerosols: radon, thoron, iodine, and aerosol condensate.
Causes and consequences of radioactive contamination
The notion of radioactive contamination of terrain entered the world usage after discovering the consequences of nuclear explosions in Hiroshima and Nagasaki, and later – with the emergence of peaceful nuclear power – the results of accidents at nuclear power plants in Chernobyl and Fukushima-1. The results of the breakdown of nuclear devices were horrific both for the affected area and for the population living there.
Radiation comes from all materials that contain radioactive isotopes of various chemical elements. Such as astat, vanadium, tungsten, iodine, calcium, osmium and zirconium. The best known elements widely used in the military industry, geochemistry, medicine and energy are isotopes or nuclides of uranium and radium – uranium 235, 237, 238, 239 and radium 226, 228.
The most common cause of radioactive contamination of territories is the malfunctioning of systems that include units with these or those radionuclides. Both technological and human factors can lead to failures. Then, at some stage of system operation, the amount of isotopes reaches a critical mass. If there is a release of excess nuclides into the external environment, it will be contaminated.
Radioactive Contamination Problems
The main problems of radioactive contamination are the harmful effects of neutrons, alpha particles, beta particles, gamma rays from an explosion or other release of decay products of radioactive substances, and spilled fuel from a nuclear reactor on living organisms, clothing, plants, soil, water in water bodies and the surrounding air.
A feature of radioactive contamination is a long duration of the damaging effect, which directly depends on the decay time of the radionuclide that became the source of contamination.
Causes and sources of radiation contamination
Contamination of the area with radioactive products can occur for a number of reasons. The most well-known of them are the consequences of the use of nuclear weapons and explosions of power units at nuclear power plants. The time of radioactive contamination after a nuclear explosion is extremely long. For example, the half-life of depleted uranium-238, from which the bombs dropped on Japan were made, is several billion years.
- medical examination (fluorography, ultrasound, MRI, tomography);
- chemotherapy in the treatment of malignant tumors;
- work at nuclear power plants;
- uranium ore mining.
- medical equipment
- scientific instruments (flaw detectors, X-ray microscopes and lasers);
- pocket and cargo control frames in airports;
- all nuclear reactors;
- nuclear-powered ships;
- debris from spacecraft that fell to Earth;
- waste from nuclear power plants and thermal power plants;
- certain minerals;
- hard coal;
- nuclear-fueled ammunition;
- fuel for certain types of rockets.
The nuclear industry includes a range of ancillary industries that serve the needs of Russia’s military and civilian lines of business.
extraction of uranium-containing ores;
their reprocessing and enrichment to a level suitable for use;
Production of nuclear weapons and fuel for power plants;
disposal of industrial waste.
Part of radioactive particles at each stage of this industrial cycle inevitably finds its way into the environment, is deposited in people’s bodies, and contaminates soil, water and the atmosphere. Based on the fact that for the entire period of existence of the nuclear industry on the planet has produced over a thousand tons of plutonium (including weapons-grade) and about 10% of this amount ended up in the environment, about 10 tons of radioactive substance still cause environmental problems to mankind.
The long half-life of plutonium in all its nuclides prolongs the danger to the biosphere and humans for many millennia. The likelihood of cancer and genetic diseases, which shorten life and turn it into torture, increases many times over. Realization of this makes us strictly follow the rules of living in areas contaminated with radiation.
The USSR is home to atomic power plants. The first of them appeared in Obninsk, near Moscow. That was in 1954. Later, nuclear power plants began to appear all over the world. Their share in electrical power generation currently exceeds 17% of the total energy balance of the planet.
The first atomic bomb explosions stunned the world in August 1945. Two large Japanese cities were wiped out in an instant, with all their buildings and almost the entire population. The remaining inhabitants of Hiroshima and Nagasaki and the surrounding areas received severe burns, radiation sickness and various genetic pathologies. The consequences of these explosions are still affecting the descendants of the victims.
The testing of nuclear weapons continued in the future. The USSR conducted them in Semipalatinsk and Novaya Zemlya, the USA and Great Britain in the deserts of Nevada, France on Mururoa atoll in the Pacific Ocean, China on the Lobnor plateau on the site of a dried-up lake. By the end of 1992, all of these countries combined had detonated their bombs over 2,000 times.
The greatest harm to humans and the surrounding biosphere came from nuclear explosions detonated in the atmosphere. The air currents dispersed the radiation over vast distances from the epicenter. For example, the atmospheric explosion in China with a power of about three megatons, thanks to the wind, covered large areas in the Far East and Siberia, and in Central and Central Asia. The inhabitants of these places are still affected by the consequences of the Chinese experiment.
China ceased air tests in 1980. The USSR and the USA respectively – in 1962 and 1963. As a result of years of use of atomic weapons in the upper layers of the atmosphere, the dust particles formed there by the explosions have spread radiation to all corners of the globe. The contaminated nuclear dust penetrated into the soil, reservoirs, human and animal organisms together with precipitation. In all, about five tons of weapons-grade plutonium was released into nature in this manner.
Medicine and Science
The use of radiation in medicine is a widespread phenomenon. It is done both to diagnose diseases and to treat them. People who go through them become sources of radiation themselves. In order to avoid radioactive contamination of those around them, they need to follow certain rules of conduct.
Science also refers to those branches of human activity that affect health and the general state of the biosphere through the radioactive effects of their conventional nuclear reactors and specialized synchrophasotrons. By early 1992, there were about 500 of them in all economically developed countries of the planet. All of them pose a significant threat to the outside world.
In first place was the U.S., they had 94 reactors. THE SOVIET UNION HAD 66. Then came Germany (25), France (19), Japan (19), Canada (14) and China (12). In 2008, the LHC – the Large Hadron Collider – was built near Geneva. Thousands of scientists from over a hundred countries were involved in its construction and maintenance. China is now set to surpass this scientific achievement.
Nuclides are considered to be the main radioactive contaminants that pose a danger to living beings and the biosphere as a whole:
- strontium-90, which selectively affects bone tissue;
- amercium-241, cobalt-60, cesium-137 – the most dangerous contaminants of flora and fauna;
- Thorium – in large doses may provoke cancer of the blood, lungs, and pancreas;
- Radium, which in high doses causes skin burns, destroys red blood cells and weakens the immune function of white blood cells;
- uranium, whose effects are detrimental to the nervous system, kidneys, liver and spleen.
Another no less dangerous factor affecting both living and nonliving nature is cosmic radiation. It is scattered radiation coming from the sun. Under normal weather conditions, the atmosphere acts as a barrier against it. If it becomes thin for one reason or another, the threat from the sun’s rays increases.