On April 26, 1986, the worst nuclear accident in history took place. The explosion of one of the reactors of the nuclear power plant near the city of Chernobyl (Ukraine) covered the west of the Soviet Union and much of Europe with radiation, which was the largest environmental disaster caused by man. More than one hundred thousand people were evacuated and an exclusion zone of more than thirty kilometers was established that continues to exist today.
As a result of the explosion, many tons of fissile material from inside the reactor were scattered throughout the facility and the heat melted the walls of the reactor . A lava-like and intensely radioactive substance seeped down to the lower floors: some 170 tons of irradiated uranium flooded the basements of the reactor room, where they eventually cooled and hardened.
Now, scientists monitoring the ruins of the former Ukrainian nuclear power plant have detected an increase in fission reactions in an inaccessible chamber within the complex called the 305/2 subreactor room. Since the accident, no one has seen the inside of that chamber, not even with a reconnaissance robot, and many wonder what could happen there. There is danger?
According to scientists at the Institute for Nuclear Power Plant Safety Problems – based in the capital Kiev – the increase in neutron activity readings is revealing and, although the Chernobyl nuclear power plant is surrounded by a massive megastructure called Chernobyl New Safe Confinement (NSC) – in which there are hundreds of sensors active 24 hours a day to monitor factors such as air quality – in the aforementioned room scientists have noticed an increase in neutrons, which it may be a sign of fission .
At the moment, there is great uncertainty. Scientists may be required to intervene in the chamber to prevent another explosion . The positive side of this situation is that the sensors mark a gradual but slow increase in the number of neutrons in the chamber, suggesting that we would have a few years left to figure out how to quell the threat – levels have increased by around 40% since 2016–. With emissions increasing so slowly, the risk of hazards in the near future appears low. Worst-case scenarios would also fall far short of the 1986 catastrophe, but given the complex’s delicate situation and the fact that Room 305/2 is believed to contain about half of the original reactor fuel , even a small explosion would spew radioactive waste far away.
One of the plans is to use a robot to drill holes in the hardened radioactive zone and insert boron rods, which would act like the control rods of a reactor and reduce the amount of neutrons released. Thus, these would be less likely to hit and split the uranium cores.
