Pressure increasing, emergency sirens ringing, water in the cooling tanks superheating. 9:27:40 AM UTC April 26, 1986: a planned safety test was conducted to assess the cooling circulation system in case of a power outage. Under normal operations, the reactors would emit a tremendous amount of heat, 6% of their total power output. With 1,600 individual fuel channels in each core, a coolant flow rate of 28 metric tons/hour was required to avoid meltdown. The examination began; the water system started to boil. The water flow rate for the reactors decreased, and the unstable reactor spiraled into a positive feedback loop. A catastrophic explosion sent a radioactive cloud as far as Canada.
The HBO mini-documentary Chernobyl provides an in-depth look at the events that led to the nuclear power plant meltdown, along with the devastation the meltdown caused in the surrounding areas. More importantly, we experience the tragedies and heroic acts of those who saved lives and those who saved humanity. As a biologist, I can’t help but wonder about the biological implications of the event both at that moment in history and also now, 30 years after.
Implications of Radiation Exposure to Humans
The most devastating implication of such an incident is of course the countless lives lost due to exposure to high levels of radioactive debris. However, for those who had survived or lived in the countries nearby, the exposure to the radioactive isotope iodine-131 was the greatest threat immediately following the meltdown. The threat is attributed to the short half-life of iodine-131 (8 days) and its potential to cause thyroid cancer. Iodine is normally used by the thyroid to produce hormones, however uptake of iodine-131 will mutate thyroid cells and cause cancer.
Four years after the incident, an increase in incidence of thyroid cancer was observed. Disproportionately, those affected the greatest at the time were adolescents in countries such as Belarus and Ukraine, closest to ground zero.
After the initial meltdown, the main crisis was due to radioactive fallout and iodine-131; however, three decades later, the concern shifted to caesium-137 and strontium-90. Both of these isotopes have a half-life of 30 years, leading to soil and water contamination with these radioactive isotopes which can persist for decades. Since caesium-137 can accumulate in biological organisms, livestock was tested in almost every European country. Due to the nature of these molecules and their inability to be readily excreted by the body, these compounds slowly aggregate into higher echelons of the food chain. The concern was that consumption of infected livestock could lead to chronic radiation exposure. The major consequences of such exposure is a much greater likelihood of developing lung, stomach, colon cancers and leukemias.
Implications for Wildlife
Beyond civilian exposure to acute radiation, the wildlife in the region were also devastated. The Red Forest died due to acute radiation exposure. DNA of animal and plant populations from regions affected by radioactive fallout tested positive for abnormalities attributed to radiation poisoning, all of which led to increased physical and behavioral abnormalities.
Three decades after the incident, wildlife is beginning to return the desolate region. Many species of animals including wolves, boars, bears, and eagles have taken up residence in regions devoid of humans. Furthermore, there is evidence to suggest plants have developed a tolerance to the high radiation levels allowing them to survive in radioactive environments. These mechanisms of survival are based around increased activity of the DNA repair machinery. The increased activity of the repair machinery means plants can to some extent reverse the damage caused from the radiation, thus becoming slightly more tolerant to harmful radiation exposure. That being said, life in the surrounding area still experiences the radiological effects of the disaster.
The Radioactive Climate
The disaster released 400 times more radioactive material than the atomic bombings of Hiroshima and Nagasaki. Almost 100,000 square kilometers were contaminated by radioactive fallout. The fallout mixing with cold fronts caused radioactive rainfall in much of northern Europe. Enhanced safety measures were undertaken by governments to reduce population exposure. As most of the radioactive isotopes could bioaccumulate through the food chain, guidelines and restrictions were advised for consuming fish and other animal products. Furthermore, stricter policies were enacted by countries on radiation management and radiation exposure to workers.
The Chernobyl Nuclear Exclusion Zone of Alienation was enacted and placed under strict military control to prevent further damage to society. This strict 30 km zone surrounds the remains of the reactors. Reactor four in particular is the highest radioactively contaminated region on Earth, sparking interest in science as well as the public. Even though Chernobyl has become a tourist attraction, access is only granted to people who apply.
Three decades have passed since the meltdown of reactor four, initially resulting in the release of a radioactive cloud that stretched halfway across the globe and immediately eradicated all life in the surrounding area. However, three decades later, Chernobyl is finally beginning to see the return of life.
By Syed Masood
Peer edited by Caitlyn Molloy and Justine Grabiec