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Alessandro Lo Bue, an industrial engineer with 20 years of experience in measurements of large volume components for nuclear fusion, moved from the private sector to work with EUROfusion’s Italian Research Unit. He is now working with Fusion for Energy. His story "Fusion Sarcophagi" in Fusion In Europe is a fiction set in the future. "This story is set in 70 years in the future: the existing sarcophagus made to contain Reactor 4’s radioactivity is close to the end of its working life. A team of fusion engineers customizes the Breeding Blanket technology to replace the sarcophagus," explains Alessandro. "Hope this story inspires you to dig further to better understand this key fusion technology," he adds.
“Ladies and gentlemen, quiet please. Quiet!!”
Italo Delivero’s voice booms over the hum of conversations between attendees. Having regained control, he continues. “As you all know, in 30 years the core of Chornobyl’s sarcophagus shelter will require major maintenance. This will require long design and construction phases to complete properly, which is why we are meeting to talk about this today. My proposal is to completely change the sarcophagus idea to take advantage of the uranium core activity by using new shielding capable of producing fusion fuel.”
“But why would we want to replace its simple design with something so complex and expensive?” asks someone in the auditorium.
Italo’s reply is immediate. “Because we can take advantage of the nuclear activity at this site. We can use the neutrons it generates to make tritium and in so doing make a very efficient shield for the outside world.”
“Ok. But why should we care about tritium?”
A worldwide expert in tritium breeding blanket technology, Italo continues, “As you know, a tokamak fusion reactor uses two hydrogen isotopes as fuel: deuterium and tritium. It also uses helium as a refrigerant for its superconductive magnets. Helium reserves are low due to the numerous superconductive magnets being produced and used by the growing number of fusion power plants. And while each tokamak generates tritium, the quantity produced is only enough to cover the reactor’s own needs. To start up a new fusion reactor we therefore need an external tritium source. And nowadays the only source is a particular type of fission reactors, the CANDU reactors, which are being progressively shut down…”
“To be absolutely clear: despite being an isotope of hydrogen, tritium has a half-life of 12.3 years, meaning it is not found in our topsoil.”
“In fusion reactors, tritium and deuterium are fused together producing helium and a spare neutron which has a lot of energy. This neutron is so powerful that if it encounters a lithium atom it will divide it into two lighter atoms: tritium and helium. This encounter is the purpose of the Tritium Breeding Module which surrounds the plasma of a fusion reactor. Afterwards, the two new atoms that are produced in different proportions are filtered and extracted from the lithium-based substance (possibly a lithium-based alloy in liquid form) of the breeding blanket and reused by the fusion reactor itself... It may sound easy but is extremely difficult in practice.”
“The Breeding Blanket technology is already present today in fusion reactors. It works similarly to the lungs in the human body. Just like the blood cycles through the lungs, exiting them enriched with oxygen, the liquid lithium-based alloy enters the blanket and comes out enriched with tritium and helium, all thanks to the energetic neutrons created by a fusion reaction.”
After Italo completed his explanation, someone from the audience asked, “But isn’t the technology to do so not yet on the market and won’t it cost a fortune to develop and install?”
In response, Italo offered attendees a simpler explanation. “The Breeding Blanket technology is already present today in fusion reactors. It works similarly to the lungs in the human body. Just like the blood cycles through the lungs, exiting them enriched with oxygen, the liquid lithium-based alloy enters the blanket and comes out enriched with tritium and helium, all thanks to the energetic neutrons created by a fusion reaction.”
Noticing people’s excitement and wanting to fuel their fever, Italo added, “In fact right now a drone with special scanning equipment is flying above Chornobyl’s Reactor 4 and Alex the Beef, one of the best metrologists on the market, is going to make a digital reconstruction of the site.”
The conference continued with lots of discussions and brainstorming. In the days that followed, Italo’s idea gained a lot of support. Two years later, it went on to receive support at the international level in the form of funding.
Today the Tritium Breeding Sarcophagus (TBS) will be installed. All operations are directed by Mr. Alfred Bigdoor, an experienced and well-known nuclear engineer. The huge half sphere, a jungle of pipes, is ready to be fit onto the site. It resembles a giant ice cream spoon, but instead of scooping up ice cream it will be collecting neutrons.
From a nearby building, hot lead-lithium alloy will be pumped through the TBS like blood through veins. Geiger counters are ready to measure the tritium inside the returning lead-lithium line at the processing station. Additional counters outside the TBS but still within the shield will check if the sarcophagus’ shield activity provided is effective.
The radioactive counters located around the site are buzzing like crazy when Alfred gives the sign to start the flow of liquid lithium inside the TBS. Minutes later these external counters stop their buzzing pitch and begin giving off single beeps, a sign that the radiation level is now at normal levels. The shielding function of the TBS is a success!!
Meanwhile, the Geiger counters inside the filtration area start to buzz without pause. It’s a clear sign that tritium storage has begun.
“It works! It works!” screams Alfred. Emotions are running high. “Has the helium and tritium filtration begun?” he asks his main collaborator.
“Yes, we have started accumulating helium and tritium,” comes the answer.
“Bravo, well done!!”
Alfred calls Italo to share the results. What once was a threat to both the environment and mankind has now become a source of fuel for fusion power plants. After a month of irradiation and filtration, enough tritium is collected to meet the needs for a brand new fusion reactor in the UK.
It’s a happy turn of events. In the end, even the devil is an angel!