Radioactivity warning sign on a hill at the east end of Red ForestThe “red forest” in Chernobyl’s exclusion zone is on fire again. When one reactor core of the 4-reactor Chernobyl complex melted down and exploded in 1986, it showered large swaths of land across the Former Soviet States with long-lived man-made radionuclides, fallout which also extended to Europe. Areas contaminated by the ruined reactor, including the red forest, have been ablaze a number of times: 1992, 2002, 2008, 2010, 2015 and 2018.
While a 27-year old man has been arrested for setting the two most recent fires on April 4 near the village of Volodymyrivka, (reportedly “for fun”), by April 6 there were more than 800 grass and brush fires burning in Ukraine, including 140 around Kyiv, as people often burn garbage and yard refuse at this time of year.
Forest fires in radiologically-contaminated areas anywhere pose a particular danger, remobilizing and redistributing radionuclides by burning the vegetation that had sequestered them. The 30-km exclusion zone has a lot of dead, dried, forest matter because some forests around Chernobyl are having difficulty decomposing, making fires more likely.
Some of these blazes are in highly radioactively-contaminated areas such as Volodymyrivka, located within the Kotovsky Forest, in the Polesskoye region. Fires in this region 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.
Because the radiation levels in the area of the current fires are already very high, it is unclear whether the reports of elevated radiation levels are in fact due to the recent fires, or whether they reflect the ongoing highly radioactive conditions there.
Reports differ as to how much radioactivity might be remobilized from the April 4 fires. 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. As a result, Ukraine’s state ecological inspection service and Ukraine’s emergency service have been releasing what appears to be contradictory information on new contamination levels potentially caused by the recent fires. Reports also reflect the increased challenges of working in a radioactively-contaminated environment while maintaining emergency personnel safety.
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.
Reports have also differed on how many, or what portion of the April 4 fires, which the suspect said he set in three places, and which divided into at least two separate blazes, has been contained. The fires have burned at least 250 acres. According to Ukraine’s emergency services, as of April 9, firefighters were still engaged in containing a fire in the Kotovsky forest. It is unclear whether this fire is the one set deliberately on April 4.
Ukraine’s emergency services claim that Kyiv, 100 km from the site, has not measured an increase in radioactivity – a claim that is so far supported by international monitoring stations there.
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. For example, a 2010 blaze remobilized radioisotopes, sending them thousands of kilometers from the fire.
Research indicates that fires in the already contaminated areas could result in releases of cesium-137 considered “high” on the INES (International Nuclear Events Scale) used to measure nuclear disasters. During past blazes, radiation levels had risen six to 12 times higher during the fires.
Researchers in 2015 showed 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.”
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. 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. Past fires have certainly moved radiation outside of the exclusion zone to other countries, resulting in small dose increases each time. photo credit: Timm Suess / CC BY-SA