Recently, you might have read articles that the fission reaction at Chernobyl is starting again and there is a risk of a new explosion. But all these articles use a single source as information. And the information in it is quite exaggerated. Let’s make things straight.
Image by Артём Апухтин from Pixabay
@kralizec and subscribe to my Youtube channel at Kralizec Gaming Youtube ChannelFour years ago, a new sarcophagus was put over the destroyed reactor at Chernobyl and more precise borders to the closed areas were arranged this year. And thanks to the popularity of the HBO tv-series Chernobyl is becoming a tourist attraction and after the COVID-19 pandemic ends, this could become an easy source of income to revitalize the area. Even some parts of the industrial park near the power plant itself are starting to be used again.
So, none of this sounds really scary. And that really not sensational. That’s probably part of the reason why many journalists around the world decided to talk about an article from Sciencemag.org and presented the world with scary headlines that sound like Chernobyl will explode again.
Let’s instead be rational and look at the reality behind the scary headlines. The insides of the destroyed reactor are mostly investigated at this point. Yes, there are some points that include parts of the melted active zone and solidified corium – a mixture of molten materials that include nuclear fuel. The picture of the so-called Elephant’s Foot is the best example of corium. But there are others but mostly hidden under a layer of concrete.
This solidified material does include uranium and transuranium elements that can undergo fission reactions. Either neutron inducted fission but also spontaneous fission. But the fission itself doesn’t mean a fission chain reaction will take place. It is obviously important to watch over Chernobyl and add materials that can effectively absorb neutrons such as boron, gadolinium, or cadmium. And many of the places with corium are already being monitor with neutron detectors.
In the past, we have observed increased amounts of neutrons in certain places. You might have heard about the incident from 1990. That’s why we apply liquids that include materials that can absorb the neutrons and in 1990 we used gadolinium. Back then, the suspect behind the increase in neutrons was regular water that might have entered the old sarcophagus and moderate the neutrons.
Currently, we are working on improving the monitoring system. And it's because of these improvements that we got the information about higher amounts of neutrons from one of the places with corium that is at this time inaccessible that caused the scary headlines in the press. But we need to remember that these changes took place over four years and are thus relatively slow. The original article doesn’t provide this information nor any other details. And from the data we have, it doesn’t even have to be an increase in fission but just a change of the neutron spectrum caused by moderation intensity.
Luckily, I can give at least some credit to the authors of the original article, they did mention the new sarcophagus can have an effect. This is because the new sarcophagus is hermetic and thus prevents rainfall from entering. Thus, the inner parts of the destroyed reactor are now drying up. In general, less water should lead to less fission but certain material combinations can lead to the opposite at the beginning of the process.
All this new information only showcases the importance of monitoring Chernobyl. But what needs to be stressed is the fact that there is no real danger of Chernobyl exploding. Any possible local increase in fission could at worst increase the temperature of the molten corium. This could lead to more radioactive material being released but this could also happen just because of the change of properties of corium itself. But that is the reason the new hermetic sarcophagus was built.
