The ruins of Chernobyl’s Reactor No. 4 are among the most hazardous locations on Earth. This site is not only treacherous but also heavily irradiated, enveloped in darkness, and encapsulated in a dilapidated concrete sarcophagus, which is being fortified with a new containment structure.

Scientists urgently need insights into the internal environment. One such scientist is Anatoly Doroshenko, a young researcher at the Institute for Safety Problems in Nuclear Power Plants (ISPNPP). His occupation is considered one of the world’s most perilous, requiring him to venture deep into the nuclear reactor remnants to gather readings and samples, often from as close as 8 meters from the core.

“I’m not scared,” Doroshenko stated, standing beside a model of Chernobyl within the ISPNPP lab located in the nuclear power plant’s exclusion zone. “Preparation has equipped me for this task, and embracing this moral responsibility is essential.”

“It’s a peculiar sensation, akin to summiting Mount Everest or exploring the ocean depths,” he adds, noting the continuous adrenaline rush he experiences.

Doroshenko is tasked with numerous responsibilities during each reactor investigation, but must maneuver between urgency and precision due to time constraints. “Understanding your environment is vital; self-control is crucial,” he emphasizes, repeating the last part earnestly.

“You must be aware that every surface is contaminated—knowing what you touch is essential to avoid personal contamination,” he explains. “It’s imperative to strategize since the time you can safely remain inside is limited. The desire to gain knowledge must be balanced with awareness of your surroundings.”

In low-risk areas of the reactor, Doroshenko dons a hat, protective gloves, and a respirator. In high-risk regions, he must wear a full-body suit, potentially layered with a polyethylene suit for dust protection. He also carries a lead apron, but its bulk can hinder movement in confined spaces.

As a young researcher, he has explored significant areas such as the main circulation pump, vital for cooling Reactor No. 4 and implicated in the safety tests leading to the 1986 disaster. “Visiting this pivotal site is crucial as we examine the destruction caused by the explosion,” he notes.

“Knowledge is our best protection,” asserts researcher Olena Paleniuk at ISPNPP. “Anatoly plays a crucial role here. Though we all often appear fatigued and somber, he excels in his responsibilities, and we lack a sufficient number of young experts skilled in dosimetry.”

Doroshenko’s supervisor, Victor Krasnov, noted that generations of scientists have ventured into the reactor post-1986 to collect measurements and install sensors. They navigate confined spaces filled with radioactive water and remnants of corium, a hazardous mix of molten fuel, concrete, and metal created during the disaster’s extreme heat.

“The initial explorers named various structures within informally—terms like elephant’s foot, cat house, and octopus beam,” recounts Krasnov. “Each route inside presents unique challenges due to utter devastation.”

Numerous risks abound, including the 2,200-ton upper bioshield, affectionately termed ‘Elena,’ dislodged during the explosion and now precariously tilted. Its potential collapse could unleash hazardous debris and a substantial cloud of radioactive dust.

Regular monitoring is crucial due to occasional surges in nuclear activity. The exact locations of all fuel material within the reactor remain uncertain, leading to periods of reactor activation.

As uranium or plutonium decays, it releases neutrons, which can trigger further fission reactions when absorbed by other unstable nuclei. High water levels can slow these neutrons and inhibit further reactions, a factor crucial to reactor safety management. Following the disaster, the sarcophagus created arid conditions, causing a peak in neutrons, while breaches allowed moisture and humidity to enter, diminishing neutron flux.

Undergoing the establishment of newer safety protocols, the low humidity currently decreases the likelihood of accidents, emphasizing the need for ongoing analysis by Doroshenko and his team to preemptively address any emerging issues.

Although stringent safety measures are enforced, it remains inherently perilous to traverse inside an exploded reactor. “We acknowledge the risks,” Doroshenko states. “My health concerns me, as neglect might lead to mistakes. While the long-term effects on my health remain unclear, adhering to radiation safety protocols allows me to mitigate those risks.”