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Fire prevention
in radiation
contaminated
forests

G. Allard

Gillian Allard is Forest Protection
Officer in the Forestry Department, FAO,
Rome.

In forests contaminated by radiation from the Chernobyl nuclear accident in 1986, fire poses a continual risk: forest fires could send clouds of smoke carrying radioactive material into the atmosphere (OCHA, 2000). The fuels burnt in forest fires contain radioactive cesium, strontium and often plutonium. In the products of fuel combustion (ash and partially burnt fuels), the concentration of radionuclides sharply increases. A part of the radioactive ash remains on the fire site, and the other part is released in smoke aerosols and transported over various distances (Dusha-Gudym, 1996).

The contaminated forests of the Ukraine (over 1 million hectares), the Russian Federation (about 1 million hectares) and Belarus (over 2 million hectares, one-fourth of the country's forests [UN, 2001]) are predominantly young and middle-aged pine and pine-hardwood stands in high fire danger classes. Large areas of forest are on drained peatland. Surface fires in contaminated litter and humus and ground fires in contaminated peat pose a serious danger. The fire danger is expected to increase in the future as debris, litter and standing dead trees accumulate because these forests are not thinned (UNECE/FAO, 1992). In Belarus the large areas of coniferous forests with understorey vegetation provide conditions favourable for the transformation of surface fires to crowning fires, and 29 percent of forest land now falls in the highest fire risk category (UNECE/FAO, 2001).

Efforts have continually been made to confront the risk. Shortly after the accident, in 1987, trees in the "Red Forest", a pine forest close to the Chernobyl site, were cut down and buried to reduce the land contamination and prevent the dispersion of radionuclides through forest fires. These trees, on about 375 ha, were all killed by the heavy radiation doses; about 100 000 m3 of dead trees were buried (together with the top 10 to 15 cm of soil, which was removed to reduce the soil contamination). This measure, combined with other fire prevention strategies, has much reduced the probability of dispersion of radionuclides by forest fires (NEA, 1995).

In Belarus, fire prevention in the forest is under the jurisdiction of the Ministry of Forestry, implemented by the State Forestry Departments, nine aerial fire protection groups and three air bases of the State enterprise Bellesavia. Belarus has 188 fire-chemical stations in forest districts and in areas of high fire hazard to allow timely response to wildfires. As of 1996 there were 636 caches of fire suppression equipment in those forest districts lacking fire-chemical stations. Fire brigades consisting of forest workers are set up during the fire season. Local people and personnel, as well as the engineering capabilities of local enterprises and organizations, are also mobilized (UNECE/FAO, 2001). Fire detection is carried out through ground patrol, tower observation and aerial patrol. A total of 26 lookout towers are equipped with television/video and remote infrared fire detection and environmental monitoring systems. The local population has an important role in early forest fire detection. The Department of Science of the Ministry of Forestry coordinates the work of scientific institutions in the field of fire control through government programmes and contracts (UNECE/FAO, 2001).

The use of prescribed fire is banned by law in Belarus. Sustainable land-use practices employed in the country to reduce wildfire hazards include:

Despite all efforts, forest wildfires continue to occur. In May 1992, the most critical fire year since the accident, severe wildfires in the Gomel Region of Belarus spread into the Ukraine and penetrated into the 30-km exclusion zone around the Chernobyl Power Plant. The fire was reported to have affected 500 ha, including 270 ha of forests. Within the exclusion zone the level of radioactive caesium in aerosols increased ten times (UNECE/FAO, 1992). In May 2000 fires broke out in the area of Chernobyl, but not in the 30-km exclusion zone. About 1 000 firefighters battled flames on about 1 400 ha of peat bog. Belarus officials reported, however, that levels of radiation were not increased in the sparsely populated area (WISE/NIRS, 2000). 

Bibliography

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