36 years of Chernobyl: the BfS publishes the new radioactivity maps (2025)

First area-wide radiological mapping of the exclusion zone in over 30 years

Year of issue 2022
Date 2022.04.20

36 years of Chernobyl: the BfS publishes the new radioactivity maps (1) The BfS also took measurements of radioactivity in the exclusion zone around Chornobyl from Federal Police helicopters in 2021

On the occasion of the 36th anniversary of the Chernobyl disaster on 26 April, the Federal Office for Radiation Protection (BfS) has published the initial results of the radiological remapping of the exclusion zone. The underlying radioactivity measurements had already been carried out by BfS in September 2021 at the request of the State Agency of Ukraine on Exclusion Zone Management in cooperation with the Federal Police and Ukrainian partner organisations.

Two overview maps show the caesium-137 contamination of the soils and the local gamma dose rate within the exclusion zone. The local dose rate indicates how much radiation acts on a person from outside. The elevated local dose rate values measured in the exclusion zone today are almost exclusively due to caesium-137, which has a half-life of 30 years. Short-lived radioactive substances such as iodine-131 have not been detected for years.

The importance of international cooperation in radiation protection

36 years of Chernobyl: the BfS publishes the new radioactivity maps (3) Dr. Inge Paulini

"With the decision to publish the initial evaluations of measurement data from the Chernobyl exclusion zone despite the war in Ukraine, we want to underline the importance of close international cooperation in radiation protection", says BfS President Inge Paulini. "This is also a sign of respect for our Ukrainian colleagues who, despite the most adverse circumstances, continue their scientific and practical work in radiation protection."

"The measurements on which the maps are based were collected in 2021 in an unprecedented German–Ukrainian cooperation in the exclusion zone of Chernobyl", says Paulini. "In these difficult times, this joint scientific work is more important than ever. It shows perspectives for the time of reconstruction in Ukraine and can help answer practical questions dealing with radiation protection."

Current overview of the radiological situation

Spatial distribution of caesium-137 in the exclusion zone in kilobecquerels per square metre

36 years of Chernobyl: the BfS publishes the new radioactivity maps (5)

Local gamma dose rate in the exclusion zone of Chernobyl in microsieverts per hour

36 years of Chernobyl: the BfS publishes the new radioactivity maps (7) In the maps, 36 years after the reactor accident, the two main directions of dispersion (to the north and west) of the substances released from the reactor in 1986 are still clearly visible (click on the magnifying glass symbol to enlarge the maps).

The maps and the associated measurement data provide a comprehensive overview of the current radiological situation in the exclusion zone. With the help of these, it is possible to calculate how long personnel can be deployed in each location within the exclusion zone surveyed without being exposed to unacceptable levels of radiation.

This is important for the local fire brigade, which frequently has to fight forest fires in the exclusion zone. The programme previously used for deployment planning can now be updated with the new measurement data. In the same way, the current measurement data can be used to support war-related clean-up operations such as munitions clearance.

Because the BfS maps show the radiological situation in the exclusion zone before the war, they can be used as a comparison in the event of suspected major displacements of radioactive sub-stances and contaminated material. For example, as a result of tank movements or in the event of suspected new releases within the exclusion zone.

Review of the exclusion zone possible

In the long term, the Ukrainian radiation protection authorities can use the BfS measurement data as a planning basis for reassessing the size of the exclusion zone. The data can be used to assess which areas of the exclusion zone could be reopened for use.

Prerequisites for this would be additional detailed measurements on site to confirm a correspond-ing initial assessment.

Measurements from helicopters

For the first area-wide radiological mapping of the exclusion zone of Chernobyl in over 30 years, measurements were taken from helicopters.

36 years of Chernobyl: the BfS publishes the new radioactivity maps (9) BfS project manager Dr Christopher Strobl Source: BfS

"We keep this technology on hand so that we can quickly identify the affected areas in the event of an acute accident", says Christopher Strobl, the respective project manager at the BfS. The BfS works closely with the Federal Police, who provide the helicopters with crew and take care of the aeronautical preparation and coordination of the flights.

"During the measurements in Chernobyl, we were faced with a special challenge. If radioactive substances enter the environment during an accident, they are deposited directly into the soil", says Strobl. "However, 35 years after the Chernobyl disaster, the radioactive substances have migrated several centimetres deep into the soil."

Extensive measurements on the soil

In order to ensure that this circumstance did not falsify the measurement results, BfS measurement teams, together with Ukrainian experts, carried out additional measurements on the soil at almost two hundred points. They also took soil samples at these points in order to determine how deeply the radioactive substances have penetrated the soil in the meantime. Based on this, the shielding of the radiation by the soil was calculated from the measurement results.

The comparison of the soil-based measurements with the measurements from the helicopters showed good agreement and served to assure the quality of the measurement campaign.

36 years of Chernobyl: the BfS publishes the new radioactivity maps (11) Protective cover over the damaged Chornobyl reactor (New Safe Confinement) Source: SvedOliver/Stock.adobe.com

Maps confirm previous findings

The new maps provide an overview of the entire exclusion zone – with the exception of the direct perimeter of the damaged reactor: In order to protect the nuclear facilities in the exclusion zone, there is a no-fly zone; helicopter measurements were therefore not possible there.

The maps are more up-to-date and have a better spatial resolution than the previous overall representations from the 1990s. They confirm the findings from the years after the reactor incident. The two main directions of dispersion (i.e. to the north and west) of the substances released from the reactor in 1986 are clearly visible.

Wide range of gamma local dose rate

The local gamma dose rate determined in the exclusion zone of Chernobyl ranges from 0.06 to about 100 microsieverts per hour. In Germany, the natural local dose rate is usually between 0.06 and 0.2 microsieverts per hour. The lowest values measured in the exclusion zone thus do not differ from the situation in Germany.

36 years of Chernobyl: the BfS publishes the new radioactivity maps (13) Measurement of the local dose rate with a hand-held meter at the Chernobyl reactor in 2016 (ar-chive photo)

If, on the other hand, people in the Chernobyl exclusion zone were to stay outdoors permanently at the locations with the highest levels, a radiation dose of 20 millisieverts (20,000 microsieverts) would be reached after only about eight days. This is the maximum radiation dose that people in Germany who are occupationally exposed to radiation are allowed to receive per year.

Evidence of caesium-137

The caesium contamination of the soils in the exclusion zone varies between values below the detection limit of measurements from the air and a peak value of 50,000 kilobecquerels per square metre.

The highest value recorded in 2016 using the same measurement method in the Bavarian Forest – one of the areas in Germany most severely affected by the reactor accident in Chernobyl – was 24 kilobecquerels per square metre. This is just above the detection limit of measurements from the air.

Excellent international cooperation

"Almost 100 people were involved in the measurements at Chernobyl – both on site and in our data centre at the BfS", says BfS project manager Strobl as he expresses his thanks for the excellent international cooperation.

Federal police: important operational experience in contaminated areas

36 years of Chernobyl: the BfS publishes the new radioactivity maps (15)Klaus-Jürgen Jess, Einsatzleiter der Bundespolizei Source: Federal Police

The measurements in Ukraine were also an exceptional operation for the Federal Police. "The cooperation of the BfS and the Federal Police in radioactivity measurements from the air has a long tradition and is regularly exercised", says Klaus-Jürgen Jess, head of operations of the Federal Police. "In the Chernobyl exclusion zone, we were able to gain operational experience in a contaminated area for the first time and demonstrate our capabilities under these conditions."

Further scientific publications planned

The published overview maps are to be a prelude to the scientific evaluations and German–Ukrainian publications. "During the joint measurements, intensive personal and institutional contacts have grown", says Strobl. "It is important for us to show that these contacts have endured during and after the war and that further joint projects can grow out of them."

Cooperation between the Federal Office for Radiation Protection and the Federal Police

Radioactivity measurements taken from helicopters allow large areas to be examined for radioactive contamination within a short time. In addition to speed, the advantage of these measurements is that they also allow the investigation of areas that are inaccessible from the ground.

The BfS and the Federal Police have been working closely together for many years on the helicopter-supported detection of radioactive substances deposited in the soil. The air squadron of the Federal Police provided helicopters and crews. Experts from the BfS performed the measurements and ensured the radiation protection of all parties involved. Regular exercises are carried out in order to maintain operational readiness. In a radiological emergency, an area of around 100 square kilometres can be flown over and mapped within about three hours. The measurement results are available shortly after landing.

The Chernobyl accident and its consequences

  • The Chornobyl accident
  • Environmental contamination and other consequences of the Chornobyl reactor accident

Radiological measurement methods

  • Measurement systems
  • Helicopter-borne Measurements

Earlier BfS measurements in the vicinity of Chernobyl

  • 2018 Measurement exercise in Chornobyl (video diary)
  • 2016 Measurement exercise in Chornobyl

Press contact

  • Press office

State of 2022.04.20

36 years of Chernobyl: the BfS publishes the new radioactivity maps (2025)
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