RADIATION IN CHERNOBYL NOW AND THEN
Radiation is a common way of emitting energy and it is common everywhere in the world, including within our bodies. For decades the word “radiation” has been connected or localised with a place that changed the history of mankind. Chernobyl is a symbol of the largest nuclear energy disaster in the history of mankind with some fatal consequences caused by the radiation spread from the explosion of the 4th unit of the Chernobyl power plant. The levels of radiation in the power plant and in the nearby areas (including the city of Pripyat) ranged from 0.1 to 300 Sieverts per hour (almost billion – 1,000,000,000 times more than the usual natural background radiation measured in microSieverts - μSv). Mostly radioactive isotopes of iodine 131, caesium 137 and strontium 90 were thrown into the air. Spending even 10 minutes around the burning reactor would result in Acute Radiation Sickness (ARS) and cause hazard to life.
Weeks after the accident with the continuing liquidation works (the fire at the reactor core was fully extinguished two weeks after the explosion) in addition to the fact that the most dangerous particles (e.g. Iodine 131) had a very short half-life* and turned into less dangerous or stable isotopes, the radiation level was slowly dropping. Building the safe confinement, the sarcophagus (completed by November 30, 1986, in the astonishing time of only 7 months) over the destroyed reactor helped the radiation to further decrease and allowed people to conduct further liquidation works. The radioactive isotopes are typically rather heavy and hence naturally go deeper into the soil; every year they decrease by around one centimetre, sinking down into the soil.
Nowadays the evacuated areas remain wasteland, however, it is very hard to find radioactivity that exceeds the natural background radiation. Also, that is one of the reasons that the 30-kilometre exclusion zone has now been turned into a nature reserve. Within the 10-kilometre zone you can still find radioactive hotspots, i.e. spots on the ground with condensed radiation that still exceed the natural level by a hundred and even a thousand times. During your Chernobyl trip, you will be shown such places, however, you will not stay there very long. Even the Red Forest area (the pine forest behind the power plant that dried up, due to radiation a few days after the accident) is only a drive through visit.
In 2016 when the New Safe Confinement (LINK TO BLOG) was slid over the old sarcophagus, radiation levels around Chernobyl power plant dropped by 3-4 times and are now 1.2 μSv (microSieverts) per hour. In the nearby city of Pripyat, the radiation level can reach 0.9 μSv/hour at some places, but typically does not exceed the natural radiation levels of 0.3 μSv /hour. The radiation levels vary, based on, for example, the weather (lower in the winter, higher in the summer).
Is it dangerous to visit Chernobyl?
After all these years it is safer than ever to travel to Chernobyl. Operating for over 10 years CHERNOBYLwel.come have developed the safest routes avoiding radioactive places during the Chernobyl tours, or the group is near to these places for only a brief amount of time. Still we manage to see all the most important and interesting places and buildings, and on some tours, even inside the power plant. During one day spent in the Chernobyl exclusion zone the body receives a dose of radiation comparable to the natural background radiation found all around us. To put this in perspective, this dose is typically 300 times less than a whole body X-ray scan and is comparable to several hours spent on an aeroplane, where we are more exposed to cosmic radiation coming from the outer space. In figures, you will receive 3-4 μSv of gamma radiation in one day (see the types of radiation below), a dose of radiation that is absolutely not harmful. In comparison, most of the nuclear power plants around the world have a safety limit for their employees set at 50-100 μSv per day. Most probably you will get more radiation during your flight to Kiev than from one day in Chernobyl.
Visitors to the Chernobyl exclusion zone should avoid radioactive dust, which might occur at some places and get stuck in small (not dangerous) amounts on their clothes or shoes. Due to this, CHERNOBYLwel.come suggests that all visitors wash all their clothes and shoes thoroughly as soon as they return home. Every adventurer travelling with CHERNOBYLwel.come gets a free fabric respirator. And, as the only tour company in Ukraine, we also offer you the use of Geiger Muller counters free of charge, in order to improve your comfort and safety. Despite the low risk, and there has been no more than 10 cases in 10 years when our tourists had to wash their shoes before passing the dosimetric control, we ask you to stay close to your guide and obey his or her instructions. This way, we can ensure a 100% safe Chernobyl tour for you.
MORE ON RADIATION
All the objects around us, including our bodies, are made from atoms, which are composed of protons and neutrons found in the nucleus, and the electrons orbiting them. Atoms of the same chemical element have the same number of protons but can differ in the number of neutrons. We call these different variants of the same element isotopes. For example, two of the most well known isotopes of carbon are the so called carbon-12 and and carbon-14, where the number indicates the total number of protons and neutrons.
We can then divide all isotopes, based on whether they are stable or change in a process that we call radioactive decay, or simply just radioactivity. The speed with which some radioactive isotope decay is characterised by the half-life, which varies from tiny fractions of a second to billions of years. If the half-life is short, the decay is fast, and we say that such an isotope is more radioactive, and vice versa.
It is important to understand that certain levels of radioactivity are very common, because every element has some radioactive isotopes and many of them can be found naturally around us. This makes all objects around us radioactive to some extent, even including our bodies that contain small amounts of radioactive carbon-14 and potassium-40, and typically around 8000 atoms of it decay every second. Our bodies are of course accustomed to these low levels of radioactivity, which are harmless.
Radiation is the transportation of energy and can be divided into either ionizing or non-ionizing based on its ability to ionize atoms and molecules and disrupt the chemical bonds among them. For example, the visible light or radio waves are both types of safe non-ionizing electromagnetic radiation, while radiation emitted in radioactive decay is usually the dangerous ionizing radiation. The danger of ionizing radiation lies in the fact that it can disrupt chemical bonds inside the cells of living organisms, which can damage them and therefore lead to adverse health effects.
The amount of absorbed radiation is called a dose and for us the most important is the so-called effective dose, which takes into account the amount of, the type of radiation and its biological effect. This is exactly what our dosimeters during your visit of Chernobyl will measure. The units of effective dose are Sieverts or more practically microSieverts (1/1 000 000 of Sievert). Our dosimeters measure both the actual level of radiation in microSieverts per hour and also automatically calculate the total dose during the time the dosimeter is switched on. As we have already mentioned during the typical excursion day in the Exclusion Zone your dosimeter will measure about 3-4 microSieverts of gamma radiation.
Talking about receiving a dose of radiation may sound threatening, but it is important to put this into perspective. We have to understand that some levels of radiation i.e. background radiation are completely natural and occur everywhere in the world. Background radiation consists of multiple sources including radiation coming from all the radioactive isotopes that naturally occur in everything around us, and cosmic radiation coming from outer space. The most significant source of background radiation is the radioactive gas called radon released naturally from the ground that we inhale with air. Particularly, inside buildings with bad ventilation this gas can concentrate and the radiation levels can easily become greater than most places in the Exclusion Zone.
In figures, the world average for all sources of background radiation is around 8 microSieverts per day. So you can see that the 3-4 microSieverts measured by your dosimeter during the 10-12 hours of our excursion are completely safe and are comparable to what you would receive normally everyday at home. Moreover, there are many places that now have naturally much higher levels of radiation than Chernobyl today. Guarapari Beach in Brazil holds the record, where, at some spots, levels of radiation can exceed the current Chernobyl levels hundreds of times.
Beside natural sources of background radiation, there are also many artificial sources that we are exposed to routinely. This includes various medical procedures, but also smoking, since cigarette smoke contains significant amounts of radioactive polonium-210 that can cause cancer. Another radioactive activity is plane travel since at high altitudes we are more exposed to cosmic radiation that is usually shielded by the atmosphere. We list the most common artificial sources in table 1 below. As you can see smoking is one of the most radioactive activities that a human can experience and by smoking one pack a day, in one year you will receive a dose 10 000 times larger than during an excursion to the Zone.
Looking for more radiation in your life?
Bananas are the most radioactive fruit out there. They contain a radioactive isotope Potassium-40. Eating one banana is equal to a 0.1 microSieverts dose of radiation, however the instance of this radiation received by your body cannot be compared to smoking nor to visiting Chernobyl.