Fires are still blazing near the site of the world’s worst nuclear disaster. Ukraine’s President Volodymyr Zelenskiy has visited firefighters trying to extinguish the flames, marking the 34th anniversary of the accident.
How close to the Chernobyl nuclear plant did the recent forest fires come? Did the smoke that enveloped Kyiv contain dangerous levels of radioactivity? We look at these and other questions about the deadly legacy of the 1986 nuclear disaster.
The recent wildfires in Ukraine and Belarus came dangerously close to the Chernobyl nuclear power plant site. Some burn still; others are smoldering. So, too, are the lingering doubts about denials from the Ukraine government that the fires, which tore through areas of the already radioactive Chernobyl Exclusion Zone, posed no radiological risks to those breathing in their fumes.
These latest fires, in a region where brush and forest fires are a frequent occurrence at this time of year, began on April 4, 2020. At least two were allegedly deliberately set. The fires have burned around 40,000 hectares across Ukraine and Belarus.
The April 26, 1986 explosion and meltdown of Chernobyl nuclear reactor unit 4, showered long-lived man-made radionuclides across large swaths of the Former Soviet States and Europe. A 30-km area around the Chernobyl nuclear site, dubbed the Exclusion Zone, has since been off-limits to human habitation because of the high contamination levels within it.
Consequently, forest fires that occur in radiologically-contaminated areas such as the Exclusion Zone pose a particular danger, remobilizing and redistributing radionuclides by burning the vegetation and soils that had sequestered them.
Despite government denials, official monitoring shows that during the most recent fires, concentrations of radioactive cesium-137 in air increased several hundred times in Kyiv, Ukraine’s capital city. People in Kyiv have been told to shelter in place not only for protection from coronavirus, but also from smoke. But not from the radioactivity contained within it.
According to on-the-ground reporting, one fire came within 1 km of the shuttered Chernobyl reactor site and nuclear waste storage facility. Eagerly awaited rainstorms had helped firefighters put out open flames that had threatened to overtake the reactor site, but the rain ultimately contained the fires for only one day.
A highly contaminated region in Belarus, dubbed a State Radiation and Ecological Reserve, has also been ablaze.
Areas still contaminated by the radioactive fallout from the 1986 Chernobyl disaster are not restricted to inside the Zone. The most recent fires reached highly radioactively-contaminated areas outside the Zone, such as Volodymyrivka, located within the Kotovsky Forest, in the Polesskoye region.
Fires in this region in particular, are very serious, says the French laboratory, CRIIRAD, because the Polesskoye area is already highly contaminated (more than 1,480,000 Bz/m2 of cesium-137), increasing the chance of spreading the radioisotopes and making it more difficult for emergency personnel to respond.
Fires across Ukraine are often seasonal as people burn garbage and yard refuse at this time of year. Forbes reports that this year in particular was prone to fire because “Ukraine had an abnormally warm and snowless winter, which dried up the forest floor, followed by a dry and windy spring that aided the spread of flames.”
By April 6 there were more than 800 grass and brush fires burning in Ukraine, including 140 around Kyiv. A 27-year old man was arrested for setting the April 4 fires and Ukrainian police are still looking for additional suspects.
Zombie forests increase fire danger
Research indicates that fires are made more likely because forest matter in the contaminated areas around Chernobyl is taking years or even decades longer to decay than it should. In the areas with low radiation, 70 to 90 percent of the leaves were gone after a year. Where radiation levels were higher, “leaves retained around 60 percent of their original weight…” reported Smithsonian magazine in an article about research conducted there by Dr. Timothy Mousseau and colleagues. This indicates a fundamental disruption to the natural cycle of death feeding life, and calls into question the forest’s longer-term viability.
Creatures responsible for decay such as microbes, fungi and some types of insects, are essential components of any ecosystem because they recycle organic material back into the soil. Unfortunately, they do not function properly in the areas around Chernobyl, leaving a forest full of “‘petrified-looking pine trees’ that no longer seem capable of rotting,” reported Gizmodo of the Mousseau study.
Contamination danger hard to assess
Discerning which contamination is remobilized from fires, both inside and outside of the Exclusion Zone, is complicated even for experts and emergency personnel. Readings are often unreliable because both hotspots and permanent high readings already exist in certain areas and proper full testing has not been done.
Independent experts and activists are concerned that if levels of cesium-137 have increased in Kyiv from the recent fires, so have levels of plutonium and strontium-90; and that internal doses from these exposures, or from other radioactive micro- or nanoparticles, will not be properly accounted for. It is notoriously difficult to monitor for, and limit exposure to, this kind of pollution, as finding it requires sample collection and laboratory testing.
Not only does remobilization of radioactive contamination spread it further, it increases the availability for intake into the body through breathing, and from eating food contaminated by radioactive fallout from the smoke plumes. Radionuclides such as strontium-90 pose more of a threat inside the body, so risks from their exposure increase when they are remobilized.
Radionuclides are also redistributed in the environment so that what was not as contaminated one day can be highly contaminated the next through natural and unnatural processes that continually change contamination maps.
Some 200–300 people live in the Exclusion Zone, ignoring mandatory resettlement orders. Others live in populated areas nearby. Disaster tourism in the Exclusion Zone has increased since the hit HBO series Chernobyl, with tourist numbers reaching 124,000 last year. Without reliable, accurate, and publicly accessible measurements mapping out ever-shifting contamination, all of these demographics could unknowingly be exposing themselves to higher radiation levels. During past blazes, radiation levels in the burning forests around Chernobyl rose six to 12 times higher during the fires.
While the exposure risks due to fires are greatest for those combatting the blazes or who live and work in fire-affected areas, the impacts can also be felt by people living further away. Past fires have certainly moved radiation outside of the Exclusion Zone to other countries, including those in Scandinavia and Central and Southern Europe, resulting in small dose increases each time.
Researchers showed in 2015 that “wildfires that broke out in the Exclusion Zone in 2002, 2008 and 2010 have cumulatively redistributed an estimated 8 percent of the original amount of cesium-137 released in the 1986 disaster.”
While areas contaminated by the ruined Chernobyl reactor, have been ablaze a number of times: (1992, 2002, 2008, 2010, 2015 and 2018) Chernobyl’s environs are not the only place where wildfires threaten radiologically contaminated sites.
In late 2018, near Los Angles, the Woolsey wildfire endangered a former nuclear technology research site that had suffered a meltdown in 1959. This fire followed a 2005 fire that substantially damaged the facility.
The still open Los Alamos nuclear weapons site has been threatened by two fires: one in 2000 that resulted from a run-away controlled burn and “liberated” a number of radionuclides from the contaminated environment, blowing them across many states; and the most recent in 2011 started by nature, forcing mandatory evacuation of 12,000 residents.
Fires in radioactively contaminated ecosystems, whether natural or manmade, will continue to be of particular concern for the foreseeable future. Preventing the spread of radionuclides from these contaminated areas into town and cities — and properly accounting for any resulting health impacts — is extremely difficult. Governments might try to “move past” these contamination issues by denying public health risks. But the reality they refuse to face is that nuclear disasters are never-ending.
Cindy Folkers is the radiation and health specialist at Beyond Nuclear.