Scientists have found that the wreckage of the Chernobyl nuclear accident in Ukraine has recently shown signs of a “resurgence”: nuclear reaction activity in one room at the accident site has spiked by about 40 percent compared to 2016. Monitors are keeping a close eye on the situation there.
After the 1986 accident, collapsed walls blocked access to the building, and many rooms and aisles were blocked. Tons of nuclear fission reaction material flew out from inside the reactor and was scattered around the building’s interior. The high temperatures melted the mud and concrete and steel of the reactor walls and mixed them together to form a highly radioactive, lava-like material that flowed to the floors below.
Room 305/2, a sub-reactor believed to be filled with large amounts of this nuclear material, was buried tightly. No one has been near it since the accident, and not even the robots have been able to detect what’s going on inside.
And now, monitors have found a sudden spike in neutron radiation levels in this chamber, an increase of about 40 percent from early 2016. This indicator means that the nuclear reaction inside is intensifying.
Neil Hyatt, an expert on nuclear waste disposal at The University of Sheffield, told NewScientist that the situation at the Chernobyl ruins is akin to “ashes in a barbecue”. “It’s not a problem that’s been solved, it’s just been stabilized for the time being.”
Investigators speculate that the reignition of the nuclear reaction may be linked to a new protective shield built in 2016.
In 2016, the European governing body spent $2 billion to build a giant hood, and it took two weeks to push it a little bit over the accident site to cover it. The thinking was that the hood would protect the ruins from leaking more nuclear waste for at least the next 100 years. According to The Globe and Mail, “The Chernobyl station is encased in a giant new grave.
This protective shield is an upgrade to the first one at the ruin site. A few months after the accident, emergency crews added a cover to it. That cover had so many holes that rainwater and birds could enter the ruins. Researchers estimate that neutrons emitted during the decay of uranium and plutonium, if captured by other radioactive nuclei, would have contributed to the reignition of the nuclear reaction. Because there was enough water inside the ruins, that water prevented the neutrons from being captured to produce the reaction.
But the situation changed in 2016 when a new hood was added. The new hood may have resulted in insufficient water in the 305/2 chamber to inhibit the reignition of the nuclear reaction inside. However, this indicates that there is still some water inside the ruins, because if the chamber were completely dry, neutrons would travel too fast to be captured by radioactive nuclei to produce a reaction.
Therefore, investigators estimate that the current amount of water is at a bad level, which just contributed to the deterioration of the situation.
There have been several similar events in the ruins since the accident, and each time they have reignited and then subsided on their own. The researchers hope that this time it will also quell itself, but in the meantime they are prepared to intervene with measures in case the nuclear reaction intensifies to dangerous levels, such as pouring in a liquid containing gadolinium nitrate to absorb the excess neutrons and curb the nuclear fission reaction.