Fission reaction has started again inside the Chornobyl Nuclear Power Plant in a mass of nuclear fuel. The task of the scientists is to determine the level of danger and understand whether or not there is a necessity to interfere to prevent one more emergency as Science reported.
The scientists noticed that the nuclear reactions have started just recently.
“It’s like the embers in a barbecue pit,” nuclear materials chemist at the University of Sheffield Neil Hyatt says.
The worst part is not the fact that the fission reactions have started in the mass of nuclear fuel but that it takes place in the area inaccessible due to the debris and flooding.
Junior staff scientist of the Institute for Safety Problems of Nuclear Power Plants (ISPNPP) in Kyiv, Ukraine Anatolii Doroshenko told about the growth of a number of neutrons – the signal of fission. The scientists cannot determine the level of danger now – it is not excluded that the emergency is possible. The colleague of Doroshenko – Maksym Saveliev supposes that we have a few years to observe the situation and determine further actions.
Graphite control rods and sand dumped on the core to try to extinguish the fire melted together into lava and flowed into the reactor hall’s basement rooms and hardened. However, the water started to seep in and possibly, it became the accelerator that launched the reactions – it slows neutrons increasing the chances to split a nucleus of uranium and washing down nuclear fuel-containing materials.
One of the factors for the appearance of water under the reactor is groundwaters. Deputy Head of Institute for Safety Problems of Nuclear Power Plants Serhiy Paskevych explained that the water rise was provoked by a wall in the ground – 2km building that is 40-60 deep under the ground and it almost rings the Chornobyl Nuclear Power Plant. It was built to prevent the leak of radioactive water to Prypiat River and prevent the pollution of the surrounding groundwaters. The water had nowhere to flow and it started to grow, flooding the basement of the Shelter gradually.
The water was rising not only down but also up. The second important factor is rain. The Shelter had a leak and water constantly seeped in. It also constantly interacted with fuel-containing materials under the reactor, and a few rooms full of water with radionuclide appeared in the basements of the Chornobyl Nuclear Power Plant.
In 2019, the New Safe Confinement was installed and the rainwater stopped seeping into the Shelter. Consequently, the mass part of the water dried out – currently, it is observed in a few rooms. The number of neutrons has started to reduce and it shows the gradual decrease of fission.
However, the scientist found out that another situation is observed in some rooms with fuel-containing materials. The researchers are sure that the drying out of radioactive water somehow enhances neutrons during the fission of the uranium nucleus. However, they cannot explain it now.
Currently, the water comes more active. According to Paskevych, there are about 70 cubes of water at the lower levels in the two or three rooms of the Chornobyl Nuclear Power Plant. Scientists are afraid that this process will speed up exponentially – the warms of fission evaporate water and it can lead to “uncontrolled release of nuclear energy”. There is no need to worry about the second Chornobyl disaster; however, any explosive reaction can partially destroy the Shelter and the New Safe Confinement will be full of radioactive dust that currently stays in basements.
One of the problem areas is the 305/2 room. The levels of radiation coming from it do not allow to install controllers. Gadolinium nitrate used by scientists for absorption of neutrons and suppression of fission is also cannot be sprayed there as the room is debris-ridden.
One of the ideas is the creation of the robot resistant to radiation to make it drilling a hole in the concrete and put there rods with boron that can absorb the neutrons.
Ukraine is planning for a long time to put fuel-containing materials to storage, where they pose no danger for the surrounding world. The scientists plan to present a plan until September. However, fission significantly complicates this process.
As we reported, Ukrainian scientists found extremely rare plants in the Chornobyl biosphere recreation zone, as they were on a botanic expedition.