Also residing near Chernobyl and within the exclusion zone is what is known as Chernobyl-2, Duga-3, or also referred to as the Russian Woodpecker and by NATO as the Steel Yard. This is an extremely large radar installation built by the Soviet Union and powered by the Chernobyl Nuclear Power Plant. Chernobyl-2 was used as part of the Soviet's early warning system during the Cold War in an attempt to detect missile launches. Unlike many of their radar systems at the time, Duga-3 was reportedly capable of detecting any missile launches from thousands of kilometers away. Duga-3 was eventually abandoned three years after the tragedy at Chernobyl. It was nicknamed as the Russian Woodpecker for a signal it produced that could be heard by shortwave radio systems around the world on very low frequencies. Chernobyl-2 was not visited during this trip to the Chernobyl Exclusion Zone.
A second nuclear explosion was possible as due to the internal heat rising within what was left of the reactor, the cement underneath the core began cracking. Heat was building up as the sand and other materials being dropped onto the nuclear fire were trapping the energy. The cement underneath cracking posed dangers due to a pool of water that formed when firefighters were originally working to address the fire. If this extremely hot nuclear lava mixed with the water and caused a steam explosion like what was feared by the Soviet government, Chernobyl would have been extremely devastating to much of Europe with much more nuclear material likely having been released. This risk was averted by dropping lead onto the fire, which lowered the burning temperature and when melted would plug the cracks. This strategy was not perfect due to the resulting lead that entered the atmosphere and still did not address the entire problem.
Miners had to be called in from Russia to build an underground tunnel from Chernobyl's Reactor #3 to Reactor #4 as a way to get closer to the blown RBMK reactor. This tunnel is still used today, but also underneath Reactor #4, these miners dug out a large room where a liquid nitrogen pump was to be setup. This was to freeze the ground to prevent nuclear material from leaving into the soil far underneath Chernobyl that would pollute the region's groundwater, but to also stabilize the reactor's foundation due to the frozen soil. However, according to some reports, the liquid nitrogen was not used but instead the room just filled in with cement to serve as a shield for nuclear material from getting deeper into the earth. Thousands of miners died because of this operation, but alas, these figures still are not found in the official Chernobyl death toll.
Touring Chernobyl was an unequivocally interesting experience from seeing the immediate effects of the world's worst nuclear disaster first hand in just the near vicinity of the accident to how the region is still very much impacted by this accident and will be for at least the next several hundred years. Cleaning up Chernobyl still will take decades more in constructing the delayed New Safe Confinement to then processing the nuclear waste from Chernobyl's reactors until they can be safely and permanently stowed. This work is expected to take until at least the year 2065.
For those interested in Chernobyl, touring the area is something worth doing in your lifetime. Ideally, it is also worth visiting before the New Safe Confinement covers it up and more of the buildings demolished or otherwise lost due to years of rotting and exposure to the natural elements in this radioactive wasteland. There may also be a return trip to Chernobyl's Exclusion Zone in the near future via the Phoronix "It Blew Up Real Good" Tour that's been proposed, so do voice in our forums if there is sufficient interest.