Under the ruins of Reactor No. 4 at Chernobyl, there is a hidden but very dangerous nuclear block called the Elephant’s Foot. The mass is composed of curium, a mixture of molten lava, including uranium, zirconium and concrete, created by the 1986 disaster.
Radiation levels were so high that even five minutes of exposure could have been fatal.Now that much of the radiation has decayed, it is an impenetrable relic of the nuclear age. The density of such a mass (which previously required it to be detonated with an AK-47), combined with the risk of inhaling radioactive dust, makes moving the mass nearly impossible with available technology. The block now sits inside a billion-dollar steel dome, a terrifying, silent reminder that it will remain there for the next 300 years.
Chernobyl’s 2,000-kilogram elephant foot remains untouchable
The only thing keeping this mass intact is its composition, known as corium – the material that forms when a nuclear plant’s reactor core melts and cools to a temperature exceeding 2,000 degrees Celsius. This mass consists of not only the uranium in the fuel rods, but also the metal of the control rods and the concrete foundation of the reactor building, all fused together into a ceramic-like glass mass.
According to research published by the VG Khlopin Radium Institute, when the corium mass was originally formed, it was too dense to be penetrated by remotely operated machines, and the only way to verify the presence of the corium mass was to fire armor-piercing rounds from a Kalashnikov rifle into the mass and use basic sampling methods permitted by Soviet authorities. Attempts to attempt to break up a corium mass today would create millions of tiny, hot, highly radioactive particles that would become airborne, and would pose an almost certain and fatal inhalation hazard to any worker near the corium mass.
From 10,000 to 100 Roentgens: How Time Neutralizes the Elephant’s Foot
In 1986, the radiation level emitted by an elephant’s foot was about 10,000 roentgens per hour, providing a 50% chance of death within 3 minutes. Data from the OECD’s Nuclear Energy Agency show that isotopes such as ruthenium-106 have reached negligible levels due to their short half-lives; The mass itself would still provide exposure to gamma rays due to cesium-137. By 2016, on-site measurements indicated radiation levels at around 100 roentgens per hour; Sufficient exposure to radiation may result in severe radiation sickness within an hour.
Radioactivity is not only present on the surface of the corium, but it is also part of the 2000 kilogram mass; Therefore, there is no chemical treatment technology for curium; Only the natural time and half-life of radioactive components can reduce their lethality.
Why do modern robots still fail inside Reactor 4?
Even in 2026, due to the intense ionizing radiation present in the lower levels of the reactor, semiconductor structures suffer from catastrophic ionizing interference when exposed to the intense radiation levels inside the reactor. As World Nuclear News reports, the new secure confinement arc (NSC) is designed to bury the corium for at least 100 years until a mechanical system can be found to safely move or manipulate the mass without posing a risk to the structural integrity of the building or the environment. The goal of the project is to provide “burial” until the technology for safe separation or neutralization of 2,000 kilograms of radioactive silicate glass is established.
