Chernobyl: effects of forest fires in areas with radioactive contamination via Green Cross

A new report issued by Green Cross Switzerland has found that Russia’s devastating 2010 forest fires had the potential of spreading radionuclides released by the 1986 Chernobyl nuclear disaster in neighbouring Ukraine across vast areas.

n the northern hemisphere summer of 2010, devastating forest fires raged in many areas of Russia, including areas that were seriously affected by radioactive contamination in the Chernobyl catastrophe. Green Cross Switzerland has been helping the affected population to help themselves in these areas for many years with the Social and Medical Care Programme.

Due to the combustion of contaminated forests, radionuclides could easily spread across large areas via wind and ashes, a hazard expert report on the effects of forest fires in the areas of Chernobyl contaminated by radioactivity was compiled in collaboration with Prof. Dr. Vladimir M. Kusnetsow.

From 2010 to 2011, 1,876 radiation measurements were carried out in four of the villages evacuated in the 1980s and the surrounding forests in the Bryansk Oblast. Furthermore, 248 soil and wood samples were analysed. In an area contaminated with 1 curie per km² (1 Ci/km2), the average annual dose through external radiation is 1 millisievert per year, and in the zones of the Bryansk Oblast affected with 15-40 Ci/km2, accordingly up to 40 millisievert per year (international limit value is 1.0 mSv/year). The town of Nowosybkow is located here, with around 40,000 inhabitants and several villages.

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Radioactive forest contamination after the Chernobyl catastrophe has risen

As the investigation of the forests near Bryansk showed, after the reactor accident in the nuclear power station at Chernobyl, 171,300 hectares of forest were contaminated with radionuclides (contamination level: 1-5 Ci/km² – 102,600 ha, 5-15 Ci/km² – 39,700 ha, 15-40 Ci/km² – 26,800 ha, more than 40 Ci/km² – 2,200 hectares).

The forests are, therefore, particularly badly contaminated, because after the reactor catastrophe it acted as a physical barrier for air masses, which prevented the radioactive particles in the air from moving further.

We only know the volume of the most highly contaminated part (29,000 hectares): 6.3 million m3. The radionuclides are increasingly integrated into the wood of the trees, and today can be found in the uppermost layers of wood (5 – 8 cm), and Caesium137 quickly accumulates in the leaves and needles. Due to the ongoing incorporation, every year more than ten thousand m3 of wood is unusable for commercial use.

Due to the radiation risk, the forests in Bryansk have not been cultivated for 27 years now and are impassable today. In certain places, the radiation is so strong that any work must be monitored by a radiation protection service. This makes both fire prevention and fire fighting almost impossible.

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Forest fires increase annual dose uptake

In the densely populated areas, almost all the forests are contaminated by radionuclides, which has wide reaching ecological, social and economic consequences. The most urgent task in the decontamination of the forest contaminated by radionuclides is to restore the significant socio-economic infrastructure in the affected areas and promote marketing.

In the government programme to deal with the consequences of radioactive accidents for the period up to 2010, no budget was provided for forestry work. Even in the laboratories for radiation control, the service life has expired on practically all of the equipment, and the spectrometers used since 1990 are hardly fit for the job anymore. In addition, there is a lack of concepts for secure storage of radioactive wood waste.

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Contact:

• Dr. Stephan Robinson, Unit Manager (Water, Legacy), Green Cross Switzerland on tel. 061 382 91 97.