Nuclear Reactions at Chernobyl Are Spiking in an Inaccessible Chamber
mardi 18 mai 2021, 00:00 , par Slashdot
Now, researchers have seen a spike in neutron emissions from the room, with levels increasing around 40 per cent since the start of 2016. This points to a growing nuclear fission reaction, so researchers are trying to determine if this surge will fizzle out, as previous spikes in other parts of the ruins have done, or whether they will need to find a way to access the room and intervene. Neil Hyatt at the University of Sheffield, UK, who studies nuclear waste disposal, likens the situation to 'embers in a barbecue pit' and says 'it's a reminder to us that it's not a problem solved, it's a problem stabilised.'
One suggestion for why this is happening is that a new structure placed over the ruined reactor in 2016 is causing the plant to dry out. When uranium or plutonium fuel decay radioactively, they emit neutrons, which can promote a fission reaction if the neutrons are captured by another radioactive nuclei. However, large amounts of water slow these neutrons down, preventing them from being captured. The original shelter, which was hurriedly constructed over the reactor in the months following the accident, was riddled with holes that allowed rainwater and birds inside. If the rainwater was helping to suppress reactions in room 305/2, its absence due to the new structure could mean there is no longer enough water in the room to sufficiently slow neutrons down.
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