Threats can only be successfully avoided if we understand their nature and act accordingly. There are many myths associated with nuclear energy and radioactivity, which create ignorant panic and misguided behaviour, and thus pose an even greater threat than originally feared.

When talking about the dangers of nuclear power plants, it is important to bear in mind that not every radiation source is dangerous to humans or the environment (as long as we consider the natural background radiation that surrounds us every day to be safe anyway). To put it very simply, only radioactive radiation is dangerous to humans if they are very close to the source, or a little further away but for a longer period of time. For this reason, accidents at nuclear power plants also vary greatly in their degree of danger - a reactor failure may not always be dangerous if the radiation does not penetrate the containment or if a small amount of a short-lived radioactive isotope mixes and disperses in seawater. However, there is a serious problem if long-lived radioactive elements are transported over a large area or if radiation levels rise above limits where they should not.

Indirect risks must also be taken into account - for example, in the case of the Fukushima accident, the main risk to human life was not the radiation dose but the problems and stress caused by evacuation.

Yes, but it is important to understand that anything can be dangerous if used incorrectly or if safety rules are not followed. The safety rules for nuclear power plants are very thorough and, for example, in Europe, where the general safety culture is very high, there has never been a single fatal accident in the entire history of nuclear power, unlike all other forms of electricity generation. Estonia must base its regulatory development on the standards of the International Nuclear Energy Agency and the EU directives. It is also sensible to build only a type of reactor in Estonia that has already been successfully licensed elsewhere and is producing electricity. These factors provide the assurance that Estonian nuclear power plants will be built and operated safely, as has been the case for over forty years with nuclear power plants in Finland, Sweden, Belgium, the Netherlands and elsewhere in Europe. Nuclear energy is proven safest energy source.

The effect of radiation on an organism is best described by the equivalent dose, which is measured in Sv. When measuring the effective dose received by the whole human body, the time spent exposed to radiation must also be taken into account. 

For example, the normal range for natural background radiation is considered to be 2.4 millisieverts per year (mSv/y) on average. About half of this dose (1.26 mSv/y) is from inhaled air, 0.29 mSv/y from food, 0.48 mSv/y from the ground and 0.39 mSv/y from cosmic radiation. If we add to this the calculated average dose from X-rays, CT scans (the main source of anthropogenic radiation is medicine, with an average of 0.6 mSv/a), nuclear accidents and nuclear testing, the total average dose to the average person is 3.01 mSv/a. Converted into hours, this is 0.00034 mSv/h or 0.34 micro-sievert per hour (μSv/h).

The radiation levels around us vary greatly from region to region - for example, in Brazil, the popular Guarapar beach has 90 μSv/h (micro-sievert per hour), while next to the Chernobyl nuclear reactor sarcophagus it is 90 μSv/h (micro-sievert per hour). more than 100 times lower - 0.81 μSv/h. In comparison, the average natural radiation flux in Finland is 0.09 μSv/h, in Estonia 0.08 μSv/h. In an aeroplane flying at an altitude of 10 km, the radiation background is about 5 μSv/hour.

Thus, a background radiation dose of about 0.1-1 μSv/h at ground level, plus radiation doses from air travel, medical research and other human activities, up to 10 μSv/h in the short term, can be considered normal.

Certain medical devices can deliver higher doses of radiation in a short time - for example, a single CT scan can give a person a dose of 10-30 mSv, or an accumulated dose of 80 mSv over 6 months in an international space station.

However, the doses that pose a health risk are significantly higher and depend largely on the duration of exposure. For example, the minimum dose that has been shown to increase the likelihood of cancer is 100 mSv/y, or 100 000 μSv/y, but in radiotherapy, for example, very localised doses exceeding 2000 mSv, or 2 000 000 μSv/y, are used to treat cancer. If a person were to spend hours exposed to such radiation, death would be very likely.

Thus, nuclear materials pose a health risk, especially when they are in close proximity for long periods of time. 

Ei. Tuumarelvas peab olema U-235 rikastusaste üle 80%, et tuumade lõhustumise ahelreaktsioon saaks olla plahvatuseks piisava kiirusega. Elektrijaama tuumkütuses on rikastusaste about 4-5% or 20 times lower.

No. The Chernobyl RBMK reactor was dangerous because of a design flaw and blatant violations of operating rules. In addition, the RBMK (in its configuration at the time) was also uniquely capable of such a sequence of steam and hydrogen explosions, such a graphite burn-up, and such a very large release of radioactive material. All reactors developed in the West have an explosion-proof pressure vessel, a containment and do not have a positive reactivity coefficient or detonating shutdown rods as was the case with the RBMK reactor type. Also, no Western reactor contains such a large quantity of fuel or graphite with water, which at extremely high temperatures would turn into hydrogen and explode in the reactor core.

The worst possible accident involving a water reactor occurred in the wake of the Tokuhu earthquake and tsunami at Fukushima Daichi (the first), where no one received a life-threatening dose of radiation. To date, residents have been allowed to return to live in all settlements in the evacuation zone of the Fukushima plant (local radiation information is available from the from here). It is worth noting that the shutdown of the second (Daini) multi-reactor plant in Fukushima and the closest (Onagawa) plant to the earthquake went smoothly.

The Fukushima accident is unfortunate, but it is rather a good example of the safety of nuclear power, because 15 000 to 20 000 people died in the earthquake and tsunami, but none died from radioactivity.

In a nuclear power plant, the nuclear fuel (the only truly dangerous material) is contained inside the reactor, usually in a water vessel, because water is relatively effective at blocking not only alpha and beta radiation but also gamma radiation (gamma radiation loses 50% of its energy after passing through 15 cm of water). (The water itself does not become radioactive, but heats up and flows through a heat exchanger, giving off a large amount of heat.) The water itself does not become radioactive, but heats up and flows through a heat exchanger, giving off a large amount of heat. This heat, in turn, heats the water in the other tank, which evaporates and drives the steam to power the turbine.) In addition to the thick layer of water, the thick reactor shell also prevents the radiation from spreading. Outside this, the radiation level is safe enough for humans. The design of the reactor building and the atmospheric air further reduce the energy of the radiation, and the radiation level outside the plant fence is comparable to the natural background.

Choosing the right location for a nuclear plant is the most important factor in protecting the environment. Estonia's northern coast is ideal for this, as it has a thick layer of waterproof blue clay, several tens of metres thick, close to the surface and therefore geologically avoids the risk of groundwater pollution.