Library                   Topics

Radioactivity          

Radioactivity

We are constantly exposed to natural radiation, although it can be neither seen nor felt. But how much background radiation is there?

The word "radiation" immediately conjures up images of nuclear weapons, nuclear power stations and radioactive waste, the terrifying consequences of a nuclear explosion and the devastating effects of radioactivity on humans and the environment. However, background radiation is found throughout nature. Human beings are exposed to natural radiation (e.g. cosmic radiation and radiation from rocks, soil, water, air and vegetation) and radiation from artificial sources (human activity).


Natural background radiation

Natural ionising radiation is the spontaneous transformation of unstable atomic nuclei in the nuclei of other elements, which is accompanied by the emission of nuclear radiation.

Natural radiation has always existed — before the appearance of human beings, and even before our planet. Depending on where you are in the world, the level of natural radiation ranges between 5 and 20 microroentgens per hour. It is generally believed that this level of radiation is not dangerous for humans or animals, although some scientists argue that even small doses of radiation can cause cancer and mutations. We may be unable to prevent exposure to natural radiation, but we should try to protect ourselves from the possibility of excessive exposure.

There are three main sources of natural radiation:

Solar radiation — Cosmic rays are a source of great power and could obliterate all life on Earth in the briefest moment. Fortunately, we have a reliable defence against this type of radiation: the atmosphere. However, human activities are leading to the thinning of the natural ozone layer and creating holes in this natural shield. The intensity of cosmic radiation depends on altitude and latitude. The higher you are above sea level, the greater the intensity of the cosmic radiation. With every thousand metres of height, the intensity of the impact doubles, and radiation levels at the equator are far stronger than at the poles.

Radiation from the Earth's crust — In addition to cosmic radiation, our planet is also radioactive. There are a lot of minerals beneath the Earth's surface, including granite and clay, that retain traces of past radioactivity. By themselves, they are dangerous only near their point of origin. However, radioactive particles are brought into our homes in the form of building materials, enter the atmosphere when coal is burned, are applied to the soil in the form of phosphate fertilisers, and then reach our tables in the food we eat. Radiation levels in a brick or panel house, for example, can be several times higher than in natural surroundings. Although buildings protect us from cosmic radiation, hazardous construction materials pose a new kind of radioactive threat.

Radon — A radioactive inert gas without colour, taste or smell, radon is 7.5 times heavier than air and is a source of radioactivity in building materials. Radon accumulates below the ground in large quantities and escapes where there are cracks in the Earth’s crust — as a result of mining, for example. Radon may enter our homes via cooking gas or tap water (especially if extracted from very deep wells), or may simply seep through cracks in the soil and accumulate in basements and ground floors. The best way to reduce the amount of radon in the home is by regular ventilation.


Artificial radioactivity

Artificial radioactivity is the result of human activities: the primary sources are nuclear weapons, industrial waste, nuclear power plants, medical equipment and, in Belarus, personal heirlooms (including precious gems) retrieved from the forbidden zone following the accident at the Chernobyl nuclear power plant.


The impact of space technology on the environment

Space technology affects almost the entire geosphere — from the solid Earth up to near-Earth space. Its impacts on the environment are very diverse. Liquid rocket fuel (LRF) is often spilled, accidentally or otherwise, near launch pads and other areas. As LRF contains carcinogenic and mutagenic compounds, these sites are contaminated with acute and life-threatening pollution and require rigorous containment and decontamination procedures.

Until the advent of space technology, humankind’s interactions with nature took place strictly within the boundaries of the Earth. Space exploration, however, has led to transformations that are extra-terrestrial in magnitude. Social ecology can no longer be seen as limited to the Earth; we also need to take into account the impacts of space travel on our atmosphere and outer space.

From space, the consequences of major military operationsin the form of smoke pollution, forest fires, the destruction of large swathes of jungle and other vast tracts of decimated land — are all clearly visible. The military assault on nature is becoming more and more severe and wreaking profound and extensive changes on our surroundings. In general, anthropogenic impacts on the environment are global. Even strictly localised activities may affect the interests of many countries — either directly or further down the road. This in turn leads to international conflicts, the prevention and resolution of which may depend on information obtained from satellite observations.


Most of the radioactive contamination in Belarus is the legacy of the Chernobyl nuclear power plant disaster. The radioactive contamination of the environment began immediately after the Chernobyl reactor exploded on April 26, 1986. The complex nature of contamination in Belarus is the result of the meteorological conditions between April 26 and May 10, 1986, and the compositional dynamics of the radioactive substances that were released.

About 35 percent of the fallout of radioactive cesium-137 (Cs-137) from Chernobyl is in Belarus. Contamination from this radionuclide poses a health hazard over 23 percent of the total area of Belarus (compared to 5 percent of Ukraine and 0.6 percent of Russia).

Large amounts of radioactive iodine-131 were also emitted immediately following the explosion at the Chernobyl plant. The highest levels of contamination from this isotope were observed in Chacherski, Karmianski and Dobrushski districts. Although iodine-131 had completely dispersed a few months after the disaster, the isotope had already triggered significant thyroid damage in the many people — especially children — unlucky enough to receive a dose of radiation.

The area is still contaminated today. Strontium-90 has been recorded on 10 percent of the territory, and plutonium on 2 percent, while contamination with Cs-137 covers an area of 3.01 million hectares, or 14.5 percent of the territory of Belarus.

Americium-241 was formed in the contaminated area as a result of the natural decay of plutonium-241. Due to the alpha decay of this highly radioactive element, the presence of americium will be 2.4 times higher in 2086 than during the initial post-accident period.

As of early 2013, a total of 2,393 settlements (28 cities and towns and 2,365 villages), or 10.1 percent of all settlements in Belarus, are within the area contaminated with radioactivity from the Chernobyl disaster. This territory has a population of 1,142,600, or 12 percent of the country’s total population. The contaminated area also includes 53 abandoned settlements.

The Chernobyl disaster had the greatest impact on the Brest, Gomel and Mogilev regions. Gomel and Mogilev were heavily contaminated with Cs-137. A contamination density of 40 or more curies per square kilometre was found over an area of 42,000 hectares, representing 1.4 percent of the total contaminated area. This density level covered 37,000 hectares in Gomel and another 5,000 hectares in Mogilev.

The territory of Belarus also accumulates radioactivity as a result of the global fallout of radionuclides following accidents at other nuclear power stations (e.g. the accident at the Fukushima nuclear power plant in Japan in March 2011) and other contamination.