This week Rostekhnadzor issued a license to build the world’s first experimental demonstration power unit with a lead-cooled BREST-OD-300 fast neutron reactor. The project is being implemented at the site of the Siberian Chemical Combine of Rosatom near Tomsk
What does it mean? This means that the creation of the most modern, efficient and safe nuclear reactor in the world has officially begun in Russia . It’s just so pretentious? In this case, it is not a cliché. Let’s explain and start from afar. That is why nuclear energy has not yet conquered absolutely the whole world? After all, the problem of emissions from hydrocarbon power plants is now so acute. It would seem that nothing better than nuclear power could be invented. There are two reasons.
First: depleted uranium
Accumulated during uranium enrichment for reactor fuel and already spent fuel . What to do with them? In fact, the problem of their storage is not so terrible, because there are not so many of them and they are not so radioactive, and the methods are quite reliable. But still.
The second reason: fear of a repeat of Chernobyl.
The first problem with “waste” is solved with the help of fast reactors. In such, recycled fuel elements of conventional nuclear power plants are used as fuel elements. And in the process, they also enrich depleted uranium. Bingo! How? Here is brief explanation:
“Conventional” thermal (much less fast) neutron reactors use enriched radioactive uranium-235. Fast reactors can use both thorium-232 and weapons-grade plutonium, which in conventional reactors cannot participate in a controlled reaction. This solves the problem of spent nuclear fuel and weapons-grade plutonium stockpiles. But how is the problem of depleted uranium-238 solved?
It is placed in the reactor core. Neutrons are fast, so they have enough energy to turn depleted uranium into plutonium. Which can be used right there (well, not quite right there, but after processing into special assemblies) as fuel.
Experiments with such reactors were carried out at the dawn of nuclear power, but then there was simply not enough technology and materials to create such complex systems. It is a little paradoxical that neutrons are initially fast during the reaction. In the classical scheme, they have to be slowed down with the help of fuel compaction and special moderators and reflectors. But now in Russia there are such technologies, materials and specialists to cope with fast particles.
Solving problem with nuclear waste
There are now only two such commercial reactors in the world, both in Russia. Therefore, sometimes you can see panic news that “nuclear waste” is being brought from Europe to Russia . This is not waste, but raw material for the fuel of our nuclear power plants. And we are also paid extra for this. Moreover, in fast neutron reactors most of the radioactive superheavy elements are “burned out”, which in a conventional reactor go to waste. Combustion is not a very good term. Because smoke and soot remain from the fire, but not here. They, these elements, are simply not available at the output.
The second reason, security, is also being addressed. A second Chernobyl will not happen at the current level of technology. A lot of special and active and passive (like several thick reinforced concrete sealed capsules) have been invented since then.
But it is possible to make a peaceful atom even safer. In the abbreviation BREST, “BR” stands for “fast reactor”, and “EST” stands for “natural safety .
In ordinary fast reactors, sometimes mercury is used as a coolant, but more often it is liquid sodium (and in “ordinary”, thermal reactors , it is most often water). It boils at 883.15 ° C. And upon contact with air, it actively reacts chemically. So an explosion is purely potential.
In BREST, liquid lead is used. It does not react with air, it boils well over a thousand degrees, and in the event of a depressurization (and so unlikely) it will simply solidify and cool the reactor core by itself.
So in Russia two futures began at once : the future of a closed nuclear cycle and the future of naturally safe reactors.
This material was prepared with the support of Postnews.