Chernobyl Nuclear Power Plant Catastrophe: FAQ

The Shelter Structure that covers the nuclear reactor number 4 building of the Chernobyl NPP

1.    What exactly happened and when?

On April 26, 1986, at 1:23 a.m., two explosions took place at the fourth power unit of the Chernobyl nuclear power plant, which destroyed and melted the reactor. This accident, as well as other accidents at other nuclear power plants that have occurred in the world, was a combination of miscalculations by the NPP developers and errors of the personnel.

During the explosion, the nuclear reactor collapsed, part of the building of the 4th power unit collapsed, and a large amount of radioactive substances spilled into the environment with nuclear fuel: strontium, caesium, uranium, plutonium, americium, radioactive iodine and others. The radioactive dust cloud covered not only Ukraine, Belarus and Russia, but also most of the European countries. On April 27, the authorities started evacuating the population from the 30-kilometer (18-mile) zone around the reactor. The evacuation went on until May 6. Over 90,000 people were removed from the contaminated territories.

2.     What is the Exclusion Zone? Is there a specific radius of the zone?

The Exclusion Zone is a territory closed for visitors which suffered most after the accident due to contamination with long-lived radionuclides (radioactive particles), with an area of about 2,600 square kilometres (1003 sq. miles), which is three times as big as the area of Kyiv.

The zone does not have a clear radius around the reactor but is conventionally called a 30-kilometer zone and is divided into two zones: the industrial zone, which is the most polluted one and closest to the nuclear power plant; and the zone of the biosphere reserve around it. The reserve serves as a sort of buffer zone and is used primarily for scientific observations and research.

3.    Is it safe to go to the Exclusion Zone? Can I visit?

Due to weather conditions and the wind direction following the accident, the radioactive contamination spread through the Zone unevenly (spottily). Because of that, there are areas with low contamination in the Zone, which are relatively safe to visit. However, unprotected stay in the majority of the Zone still threatens a dangerous dose of radiation.

This means that the Exclusion Zone is only open for personnel (see item 5) as part of official and business delegations. Adult citizens of Ukraine can visit the Exclusion Zone as part of an organized tour, as the official route has been created in a way that would minimize visitors' exposure to radiation.

4.    Are there people who live in the Zone? Is it legal? Who are stalkers?

In 1986, all residents of the surrounding localities were removed from the Zone. Yet, some of them came back, even though it is prohibited by the Law of Ukraine "On the Legal Regime of the Territory Exposed to Radioactive Contamination due to the Chernobyl Disaster."

As of April 2019, there were 130 such "independent settlers" in the Zone, with most of them living in the city of Chernobyl, 18 km (ca. 11 mi) away from the Chernobyl NPP. Other illegal visitors of the Chernobyl zone are the so-called "stalkers," people who illegally enter the territory of the Exclusion Zone for the purpose of extreme tourism. According to law enforcement data, there are about 300 cases of illegal entry into the Exclusion Zone recorded every year.

5.    Is there anyone working in the Zone now?

There are about 10,000 people working in the Exclusion Zone now. They include the personnel of the State Agency for Exclusion Zone Management, of the Chernobyl NPP, of the Shelter Structure, of the waste disposal sites and research institutions, including the Specialized Public Enterprise Econcentre, which accounts for monitoring of the radiation background in the Exclusion Zone.

6.    When will the Exclusion Zone become suitable for life again?

For the Zone to become suitable for people's life again, most radionuclides which entered the environment as the result of the explosion at the 4th reactor of the NPP need to disintegrate and form simpler (non-radioactive) elements. Since the half-life (the time needed for the intensity of radiation to reduce by half) of some radionuclides (americium, plutonium, uranium) constitutes up to 24,000 years, the Exclusion Zone will remain dangerous to people for the foreseeable future unless the complicated and costly procedure of deactivation is carried out — collection of contaminated earth, matter, plants, etc.

7.    What is the Shelter Structure?

The Shelter Structure, also known as the Chernobyl NPP sarcophagus, is an object covering the nuclear reactor number 4 building of the Chernobyl NPP to limit the spread of radiation, which was built in 1986. Its designed lifetime was 20 to 40 years, which is why the construction of the "New Safe Confinement" (see item 8) started in 2012.

8.    What is Safe Confinement? Is the reactor going to need another shelter structure in the future?

The New Safe Confinement, or the Arch, is a new structure build to cover the ruined energy reactor and the sarcophagus, which is designed to serve for 100 years after being commissioned. During this time, the old sarcophagus and the remnants of the 4th reactor are meant to be disassembled and reburied. It is expected that by the time when the Arch needs to be dismantled, there will be no need for a new shelter structure.

9.    Are the three other power units of the Chernobyl NPP still working?

After the accident, the first two power units remained in regular working condition and were shut down on April 27, 1986. The third power unit, which was technically connected to the fourth, was shut down an hour and a half after the accident. After a number of decontamination measures for facilities and reduction of the radiation level, including construction of protective screens and elimination of technical shortcomings in the construction of the radiator (which led to the explosion in the first place, see item 1), Chernobyl NPP resumed work with the first two reactors as early as in autumn 1986 and worked until 1996 (the first power unit) and 1999 (the second power unit). In December 1987, unit 3 returned to operation. It worked until December 2000. After the power units were shut down, the process of decommissioning Chernobyl NPP completely started. It will continue until about 2064.

10. Is there radioactive waste buried in the Exclusion Zone? Is such waste still being buried?

Over 95% of radioactive waste in Ukraine formed during the disaster at the Chernobyl NPP and in the course of its containment. This waste is located under the Sarcophagus and in over 600 temporary shelter facilities. The biggest facilities for radioactive waste are Buriakivka, Pidlisnyi and CNPP Stage III.

There is also the storage system called Vector which is being built in the Exclusion Zone for long-term storage of radioactive waste both from within the Zone and from beyond. There should be facilities built there for storage of high-level radioactive waste coming back from Russia after processing spent fuel from Ukrainian NPPs.

There is a storage facility for spent nuclear fuel working on the site of Chernobyl. It contains fuel from three CNPP reactors. Since this facility is old, another one has been built to replace it. The new one can be used for 100 years.

In addition, there is a central storage facility for spent nuclear waste being built there. It will store spent fuel from Khmelnytskyi, Rivne and Yuzhnoukrainsk NPPs for 100 years.

11. What about the nature and animals? 

Nature began to recover in the Zone with the absence of people. There, you can find Przewalski's horses, who were brought in back in the '90s to keep them from extinction, moose, foxes, wolves, lynxes, black storks and many other animals, including those listed in the Red Data Book of Ukraine. Plants have been recovering as well, many forests going back to their original state in the absence of preventive logging.

However, it would be wrong to assume that the radioactive contamination does not impact the flora and the fauna. Scientists point out that under the influence of radiation, insects and plants are mutating. The harmful effects of radiation can easily be observed on insect populations, since it is easy to find areas for comparison in the Zone that differ from each other only in the intensity of radiation.

12. The 2020 fires in the Exclusion Zone: How close did the fire get to the station, the Shelter Structure or the waste disposal site?  Has the radiation been released again?

Fires of various sizes occur in the Exclusion Zone every year in the spring and summer, one of the reasons being brush burning. In 2020, the dry winter led to the biggest fire yet, which raged on for almost a month, destroying about 11,500 ha of forest area, about 5% being in the reserve area. The fire caused damage to the fauna and flora. The fire destroyed part of the abandoned villages, the Smarahdovyi sanatorium, the Kazkovyi children’s camp, the territory of the military city Chernobyl 2 and part of the Chernobyl city. These objects were all part of the tourist route. The power plant did not suffer any damage. As reported by journalists, the flames came close to the disposal of radioactive waste Pidlisnyi, but the fire was extinguished in time.

According to the State Emergency Service, the radiation levels in Kyiv and the oblast were normal during the fire, with an increased level observed only in the Exclusion Zone itself. The danger of the Chernobyl fires is that radionuclides that remained in the soil and accumulated in plants are released and enter the environment. The hot air picks up chunks of dust and the formed ash, after which they are carried by the wind. The number of radionuclides in the smoke is not sufficient to significantly affect the pollution of large areas. However, this air pollution is dangerous for firefighters and other people caught in the smoke near the fire. A person can inhale a radioactive particle that, once in the lungs, will irradiate the human body for a long time, causing diseases of internal organs.

13. Solar station in Chernobyl — what is it? Is it safe? At what stage is it now?

In the early 2017, then-Minister of Ecology Ostap Semerak said he intended to organize the construction of a solar power station with a capacity of over 1 GW (about the same as the capacity of one NPP reactor) in the Exclusion Zone. As early as October 2018, a 1-MW solar power station opened there. The solar station is located near the ruined 4th power unit of Chernobyl NPP. In November 2019, the Ukrainian Association of Renewable Energy announced the tender for construction of the next 7 MW in the Exclusion Zone and plans to increase the capacity of the station to 100 MW.

The project Solar Chernobyl was created to make use of the territory which cannot be used otherwise. Any economic activity increases the number of people and vehicles in the Zone and increases the risk of unauthorized transportation of radioactive materials out of the Zone. In addition, the construction of such an object in the Zone requires special attention to safety guidelines, as employees may end up in contaminated areas and be exposed to increased amounts of radiation.

Written by:

Oleksandra Zaiika, Energy Policy Expert, Centre for Environmental Initiatives EcoAction;

Oksana Alieva, coordinator of the Climate Change and Energy Policy programme, Heinrich Boell Foundation, Kyiv Office — Ukraine.