Radiation situation in Ukraine

The war in Ukraine does not affect the radiation situation in Finland. Nor can any accident or damage related to radioactive materials or nuclear power plants in Ukraine cause a situation in which people in Finland need to be protected from radiation.

Ukraine has four active nuclear power plants (Hmelnytskyi, Rivne, Zaporizhzhia and Southern Ukraine) with a total of 15 reactors. Even if the nuclear power plants in use in Ukraine were badly damaged, the serious radiation effects would not reach Finland.

However, an accident or damage to a nuclear power plant in Ukraine could cause large local discharges if the containment building around the reactor was damaged at the same time. Radioactive substances could pollute the surroundings of the plant and people close to the plant could develop an illness from radiation and radioactive substances. However, there would be no significant dispersion of radioactive substances over a radius of more than 200 km from the accident.

Nuclear power plants are generally quite strong constructions, as they have to tolerate many extreme natural events. The multiple safety systems of nuclear power plants are capable of ensuring safety even if some part of the plant were damaged. However, nuclear power plants for civil use are not designed to withstand military attacks.

In addition to direct attacks on nuclear power plants, indirect impacts could occur. The operability of the electricity grid and plant maintenance, for example, as well as the ability and possibility of the personnel to look after the plant are vital in view of safety. For example, paralysing the Ukrainian electricity grid would affect the operation and production of nuclear power plants. Nuclear power plants would then have to operate with a standby supply system for significantly longer periods than in the case of normal disturbances.

STUK has no detailed information about the plants in Ukraine and their design criteria, or more detailed information about the preparedness and protection of nuclear power plants in Ukraine against intentional damage.

In any case, the Ukrainian nuclear power plants are water-cooled plants with the same basic structure as the Loviisa nuclear power plant in Finland. An accident such as the one in Chernobyl in 1986 is not possible in them. The Chernobyl reactor used graphite as the moderator, the combustion of which raised radioactive substances high into the air and subsequently spread them over a very large area through the air currents.

International conventions require that nuclear power plants are not attacked or damaged intentionally. An additional protocol to the Geneva conventions relating to the Protection of Victims of International Armed Conflicts in the Geneva outlaws military attacks on dams, dikes, nuclear power plants and other corresponding plants that would cause danger if damaged even if they were used for military purposes. This convention has been clearly violated several times during the war in Ukraine in the Chernobyl area and at the Zaporizhzhia nuclear power plant, for example.

Zaporizhzhia nuclear power plant

The six reactors of the Zaporizhzhia nuclear power plant have not been in full power operation since fall 2022. All reactors are currently generating much less decay heat than they would if the power plant was producing electricity at full capacity. According to the Ukrainian authority, SNRIU, five of the plant’s reactors are placed in cold shutdown and one reactor is placed in hot shutdown. The reactor in hot shutdown can be used to produce heat for the plant’s own use, even with the reactor shut down. An accident or damage to the Zaporizhzhia nuclear power plant could result in a release to the immediate surroundings of the plant if the containment building of one or several reactors were damaged at the same time. However, there would be no significant dispersion of radioactive substances over a radius of more than a few dozen kilometres from the accident.

In the case of a possible situation requiring protection of population, no iodine tablets would be needed in Ukraine or elsewhere in Europe, because the radioactive iodine produced in the fission reactions in the Zaporizhzhia nuclear power plant has already decayed almost completely during the cold shutdown (the half-life of iodine is eight days, and dozens of half-lives have already taken place).

Chernobyl

The Chernobyl nuclear power plant is located in the northern part of Ukraine. One of the four reactors of the plant was destroyed in 1986. A protective dome has been built on top of the destroyed reactor. The other three reactors have been permanently shut down and the fuel has been removed from their reactors. The Chernobyl area also has storages of spent nuclear fuel and other nuclear waste. The spent nuclear fuel stored in the Chernobyl area is still very radioactive. However, it has been cooled down for a long time and there is virtually no risk of radioactive substances spreading over a very large area.

The Chernobyl plant area is surrounded by a 30 km exclusion area, whose soil and vegetation still contain radioactive substances from the accident. The dose rate caused by external radiation there has remained high since the 1986 accident. Radioactive substances in the soil may be released into the air by movement in the area, for example, causing a momentary rise in radiation levels. Radioactive particles are heavy, as dust from the area is bound to the particles, and they do not travel long distances.

Radioactive substances elswhere in Ukraine

There are radioactive substances in research institutes and in storages for radioactive waste recovered from places other than nuclear power plants in different parts of Ukraine. The waste in the storages is mainly low-level waste from hospitals and industry.

Iodine tablets and how to take them

The authorities permanently recommend that people should have iodine tablets in their medicine cabinets at home for a possible radiation accident. Taking iodine tablets in the event of a radiation hazard situation due to a nuclear accident is recommended for people up to 40 years of age and pregnant women. When taken at the right time and in the correct doses, iodine protects the thyroid gland and reduces the risk of thyroid cancer. The situation in Ukraine has not affected this recommendation nor is there any special reason to purchase iodine tablets now.

Above all, iodine tablets must not be taken without instructions from the authorities. You should never take an iodine tablet ‘just in case’, as it is important to take the iodine tablet at the right time. The protective effect of the tablet is reduced if the tablet is taken too early or too late.

More information about iodine tablets

Additional information

Frequently asked questions

The Radiation and Nuclear Safety Authority has received a large number of questions related to the situation in Ukraine. We have compiled some of the most frequently asked questions and answers to them on this page.

No, it cannot. The Zaporizhzhya nuclear power plant can be cooled even if the water in the Kakhovka reservoir disappears beyond reach. The cooling water needed by the plant is normally taken directly from the reservoir, but the plant is prepared for the possibility that it will not be available. The cooling water required is then taken from a large pool built next to the nuclear power plant. The last of the plant's six reactors stopped generating electricity in autumn 2022, meaning that all reactors have been shut down. This means that considerably less water is needed for cooling than would be required if the reactors were normally generating electricity. The water in the water pool is sufficient.
The situation in Ukraine has no impact on the radiation situation in Finland. The authorities recommend that iodine tablets should be available at homes and workplaces as part of basic preparedness, but there is no need to purchase them separately due to the situation in Ukraine. Above all, iodine tablets must not be taken without instructions from the authorities. You should never take an iodine tablet ‘just in case’, as it is important to take the iodine tablet at the right time. The protective effect of the tablet is reduced if the tablet is taken too early or too late.
The distance impacts of the use of a nuclear weapon are very difficult to estimate as they depend on the size of the weapon and the height at which it is detonated. In order for the effects of the weapon to reach Finland, the nuclear weapon would need to be very large. Even this would not have an immediate effect: the direct heat and pressure effect of even a really big nuclear bomb extends over some dozens of kilometres at worst. Modern nuclear weapons designed to be used in combat are smaller so-called tactical nuclear weapons. The radiation effect is not the main destructive mechanism of a nuclear weapon, but the nuclear bomb also produces an extensive explosion. This means that damage is primarily caused by the effects of heat and pressure. At the moment, nuclear weapons do not represent a threat to Finland.
A meltdown of a nuclear reactor in Ukraine could cause large local discharges if the containment building around the reactor was damaged at the same time. However, there would be no significant dispersion of radioactive materials over a radius of more than 100 km from the accident. Therefore, immediate health effects could only occur near the plant. In practice, nothing related to possible radioactive materials or nuclear power plants in Ukraine can cause a situation that would require immediate radiation protection in Finland. Finland could be subject to restrictions on the use of certain foodstuffs if there was a nuclear accident or a nuclear attack in Ukraine. These kinds of actions would protect people from the long-term effects of radiation.
If radioactive substances were released from an operational nuclear power plant or Chernobyl in Ukraine, the effects would be mostly local and regional. People in Finland would not need to shield against radiation.
Finnish authorities use extremely precise and sensitive methods for detecting radioactivity in outdoor air and fallout, which is why trace activity concentrations might be detected in Finland as well. The concentration depends greatly on wind directions and the altitude of the release. A strong wind (more than 10 meters per second) blowing directly northwards from Ukraine toward Finland would carry the release to Finland in approximately two days. The release would of course become diluted on the way, as it would get mixed with air and a part of it would settle on the ground. Even in this case, people in Finland would not need to shield against radiation.
An accident such as the one in Chernobyl in 1986 is not possible. The reactor destroyed in Chernobyl was of a different type than the reactors in the current operating nuclear power plants in Ukraine. There was a design flaw in the Chernobyl reactor and the security systems had also been shut down before the explosion. The Chernobyl reactor used graphite as the moderator, the combustion of which raised radioactive substances high into the air and subsequently spread them over a very large area through the air currents.
STUK monitors the situation in Ukraine from the point of view of nuclear and radiation safety and reports, for example, on the situation of Ukraine's nuclear power plants and possible effects of the radiation situation on Finland on its website and social media channels. We do not take a position on energy, geopolitical or security policy issues. We also do not provide advice on medicines, illnesses or allergies. For example, for individual questions related to iodine tablets, please contact your physician or pharmacist.
The Finnish Ministry of Foreign Affairs (um.fi) is closely monitoring the situation in Ukraine and providing reliable information related to the crisis. STUK publishes information related to nuclear and radiation safety on its website and social media channels. It is especially important to be media and source critical during crises and serious events. Not all information shared online is reliable, and children, for example, must be protected from war material shared on social media.