​Current si​tuation

In a press release on 21 March 2022, the Ukrainian safety authority SNRIU indicated that forest fires had been burning in the Chernobyl exclusion zon​e since 11 March, mainly in the central and west areas of the exclusion zone created after the accident in 1986. The IAEA was also informed by SNRIU (cf. Update 30 – IAEA Director General Statement on Situation in Ukraine).

Experience feedback

Large-scale fires occur every year in Russia, Belarus and Ukraine. Some of these fires affect the areas contaminated by the Chernobyl accident. During such events, air masses can absorb radioactivity and move towards Western Europe and France, as was the case in 2002, 2010 and 2020, for example.

Since the Chernobyl accident, tree trunks/branches and litter (layer of leaves which fall year after year) in the contaminated areas of Belarus, Ukraine and Russia tend to store the radionuclides initially deposited on the ground and absorbed by roots. If such matter is burned, these radionuclides can be partially released in the smoke and hence contaminate the air. This is particularly true for caesium 137, the main radionuclide dispersed in Europe during the Chernobyl accident and still detectable today.

It is important to take note that these events have led, to date, to very low-level ambient activity, which cannot be measured in France other than using the air sampling stations of the IRSN OPERA-Air network. Measurements are taken for the filters in this network using high-performance laboratory techniques and detect very small amounts of radioactivity. During the episode in April 2020, only nine measurements taken at these samplers in France could be considered as in excess of usual background levels (approx. 0.1 µBq/m³ in France), with very low levels nonetheless, of between 0.51 ± 0.20 µBq/m³ of air (Fessenheim) and 1.31 ± 0.24 µBq/m³ of air (Cadarache). Other European countries and Ukraine also detected the impact of fires during this event. In the Chernobyl exclusion zone, activity levels occasionally reached several mBq/m³ of caesium 137.

​Available data on 24 March 2022

Equivalent Dose Rate (EDR) monitoring stations in the exclusion zone, managed by Ecocentre, a Ukrainian government-operated firm, and stations near to the Chernobyl reactors (including reactor n°4 damaged in 1986) managed by the site operator, ceased operation in late February 2022 due to the current conflict. On this basis, these stations are no longer providing data on radioactivity in the zone.

The Ukrainian national network station, located in the town of Chernobyl, is still transmitting data, but intermittently, due to power supply problems in the area. Up to 18 March, the last date on which this station transmitted the mean hourly EDR over a 24-hour period, radioactivity was not abnormally high.

The following map shows the stations of the Belarus and Ukrainian national networks, which transmit data to the European EURDEP system (mean EDR over 24h), in a 200 km radius around the Pripyat site. None of these stations have indicated a significant increase in EDR over the 11 - 18 March period, and local fluctuations were systematically less than 50 nSv/h.

SNRIU also informed the IAEA that very slight increases in airborne caesium-137 levels had been detected in Kiev and by radiological monitoring at the Rovno NPP and Khmelnitsky NPP in the west of the country, but that these detections did not pose a radiological problem.

In addition, aerosol filter measurements from other European countries currently available in the EURDEP system do not indicate any significant increase in caesium 137 ambient activity levels (see table below). Filters of IRSN's national OPERA-Air network for the period in question are analyzed as they are received.​

​IRSN publishes a new information report providing details of the arrangements planned in the event of a total loss of external supplies at the Zaporizhzhya nuclear power plant.

​The plant is currently connected to the Ukrainian electricity grid by two of the four 750 kV lines available. Two lines are currently unavailable due to the fighting; a third one was temporarily unavailable but was repaired on the evening of March 18, 2022. The power plant is also connected to the Ukrainian 330 kV grid, to which the Zaporizhzhya thermal power plant and the Dnipro and Kakhovka hydroelectric power plants are connected nearby. This 330 kV line is currently available.

The Zaporizhzhya NPP provides electricity to the Ukrainian power grid but when its reactors are shut down, the Ukrainian power grid provides power for its monitoring and backup systems. The availability of these external power supplies is therefore an important issue for ensuring the safety of the reactors.

On the basis of the information available to IRSN, the resources planned for the Zaporizhzhya power plant would enable the site teams, in the event of failure of the islanding transient, to cope with a situation of total loss of external power supplies for a period of at least 10 days. This conclusion is subject to the reliability of the equipment implemented, their initial fuel supply, the availability of crews and the absence of other factors that could aggravate the situation.

Download IRSN information report​​ from March 22​​, 2022: Arrangements in the event of a total loss of external power supplies of the Zaporizhzhya power plant in Ukraine

On 9 March at 11.22am, the Ukrainian nuclear safety authority SNRIU informed IAEA that the external power supplies of the Chernobyl plant facilities had been cut off. The site's emergency generators would be supplying power to the facilities, with enough fuel for 48 hours.

​IRSN presents below an assessment of the risks associated with the loss of external power supplies for the site’s various facilities, including the loss of emergency power supply, which is a potential situation that could come about rapidly if power is not restored to the site because the generator fuel reserves run out.

Reactors

​Reactors 1, 2 and 3 at the Chernobyl site have been shut down for over 20 years. All the fuel assemblies of these reactors have been transferred to the site's storage facility (see below). There is no risk of releases from these facilities, which are not backed up by diesel generators.​

Reactor 4, which was damaged in 1986, was initially covered by a temporary sarcophagus as an emergency measure. Uncertainties concerning the structural resistance of this sarcophagus led to the construction of a containment structure (NSC for New Safe Confinement), which was completed in 2017 (250 m wide, 160 m long, 100 m high). The temporary sarcophagus is being dismantled. The NSC ventilation system is backed up by two dedicated generators. In the event of total loss of electrical power, facility containment will be provided solely by the static containment of the structure. The dismantling of the sarcophagus of the damaged reactor has probably been suspended due to the conflict, so this containment should be sufficient to prevent releases into the environment.

Spent fuel storage facility

The facility consists of a storage pool (ISF-1) with approximately 20,000 assemblies and a dry storage facility (ISF2). Spent fuel elements are gradually transferred from the pool to ISF-2.

• Underwater storage pool ISF 1

The safety systems of this facility are backed up by two diesel generators with fuel reserves to last 48 hours.

The studies carried out after the accident at the Fukushima Daiichi plant on the consequences of total loss of the pool cooling systems indicate a slow rise in pool water temperature to a temperature of around 60°C but no dewatering of the assemblies and therefore no radioactive releases into the environment.

• ISF 2 dry storage facility

​To date, about 2,000 assemblies have been transferred from ISF-1 to ISF-2.

This facility does not present a risk in the event of total loss of electrical power, as the power removal from thefuel assemblies is completely passive.

Loss of the facility’s control systems

​Although the loss of power at the Chernobyl site does not have consequences that could lead to environmental releases, it does imply the loss of the facility's command-control systems. Thus, all the technical data used by the site’s real-time monitoring (water level, temperature, radioactivity, etc.) and alarm systems will cease to be available; this could delay the reactions of personnel if an incident occurs on the facility.

The loss of power would also mean the loss of lighting, heating and certain communication systems, resulting in deteriorated working conditions for personnel, who are already suffering from the stress of the current situation.

Download IRSN information note​​ from March 10​​, 2022​​ (PDF)

​Status on 7 March 2022

The invasion of Ukraine by Russian troops demands careful monitoring of its nuclear installations. Ukraine has 15 Russian-designed VVER reactors in service, research reactors, storage sites for sources and waste, as well as the reactors at the Chernobyl site, the last of which was shut down in December 2000, and the various facilities required to manage the accident site.

The major risk in terms of radioactive release concerns the power reactors in operation and the spent fuel pools [1]. The 1,000 MWe reactors [2] have concrete containment structures. In these facilities, the spent fuel pools are located inside the containment.

According to the information available to the Institute, the fire that occurred on the night of 3-4 March 2022 at the Zaporizhzhya nuclear power plant site did not cause any deterioration of reactor safety.

On the morning of 4 March, the Institute received confirmation from SNRIU that the electric power supply to the plant had not been damaged by the fire. This power supply is necessary to keep the facilities in a safe state, whether they are in operation or shut down. In this respect, the safety of Ukrainian power plants has been significantly improved since the accident at the Fukushima Daiichi plant. The plants are equipped with emergency electric power sources (4 generators per reactor, one of which is bunkered), and mobile equipment that can be connected to the reactor concerned. The fuel reserves for the diesel generators are sufficient to provide cooling for seven to ten days, after which refuelling will be necessary.

There have also been reports of damage to the containment structure of reactor 1, which had been shut down before the conflict began. This information has not been confirmed; it is more likely that the shots fired damaged a footbridge near the building. Regarding the operational status of the plant, the Ukrainian nuclear safety authority (SNRIU) reports that two of the plant’s six reactors are in service.

Concerning the environmental radioactivity monitoring networks, the Ukrainian national network is operational, with the exception of a few stations. Based on the information collected by IAEA from SNRIU and the data transmitted by the measurement network, there has been no increase in radioactivity since the fire that night. The absence of radioactive release is also confirmed by the monitoring networks of the countries bordering Ukraine, which do not indicate any abnormal increase.

Download IRSN information report from Ma​rch 7, 2022 (PDF)​

Notes:

1. The spent fuel pool contains fuel assemblies used in the reactor core. They are stored in this pool for a few years before being transported to other pools.
2. This means all Ukrainian reactors except Rovno 1 and 2, which have a capacity of 400 MWe.

​Note: This information report has been published in French on February 25, 2022.

In view of the situation in Ukraine, IRSN has produced an information note presenting the nuclear facilities in Ukraine and an overview on the radiological monitoring of the country.​

An increase of the radiological atmosphere around the Chernobyl site was reportedly observed on the stations near the installations. The Ukrainian safety authority mentions a resuspension of contamination by the passage of military tanks.

​IRSN does not have any information to confirm or refute this information. It is advisable to remain very cautious about these measurements at this stage. No increase in radioactivity has been detected in the European countries with which IRSN is in contact.

Download IRSN information report from Ma​rch 1, 2022: Situation of nuclear facilities in Ukraine

Since the publication of the IRSN information report of June 30, 2020, measurements available abroad have made it possible to model the transport of air masses in Western Europe and to determine a plausible geographic area of the release origin which is located on a territory covering part of the Baltic countries and Western Russia.

Measurements in France from the IRSN’s OPERA monitoring network do not reveal the presence of radionuclides linked to this release.

Regarding the cause of the release, new measurements confirm that the radionuclides identified and their proportions are characteristic of irradiated nuclear fuel.

The simulations make it possible to estimate the exposures that could result from the release. These are low in the immediate vicinity of the point of release and insignificant at longer distance. 

Download IRSN information report from July 22, 2020: Detection of an increase in airborne radioactivity levels in Northern Europe – Update of July 22, 2020

Modeling of the dispersio​n in Europe of the air masses slightly contaminated by artificial radionuclides - Version of July 22, 2020

The safety and radiation protection authorities of the Scandinavian countries have reported an increase in atmospheric radioactivity detected by their monitoring stations during June 2020. The levels recorded in these countries are very low and do not pose any risk to the public or to the environment.

To date, available measurements from the IRSN’s OPERA monitoring network show no abnormal increase in the level of atmospheric radioactivity in France.

The origin of the release is not identified at this stage. Based on the available measurements, IRSN is conducting investigations, including simulations, to better understand the source location and possible causes of this increase.

Download IRSN information report of June 30, 2020: Detection of an increase in airborne radioactivity levels in Northern Eur​ope

Since the publication of our information report of April 24, 2020, it seems that the fire outbreaks are now extinct. The new information report published today by IRSN contains the latest information available and updates the modeling of the trajectories of the fire-contaminated air masses.

It also offers a summary of events that have occurred and of their consequences, particularly in France. All the measurements, the modeling results and the dosimetric estimates confirm that these fires did not have any health consequences on the national territory.

Download the IRSN information note of May 05, 2020: Fires in Ukraine in the exclusion zone around the Chernobyl power plant: latest news and summary of consequences

Modeling of the dispersio​n in Europe of the air masses from the fires in the Chernobyl region: version of May 05, 2020