I have a question about tritium breeding. How many free neutrons does D-T fusion produce? According to Wikipedia it is only one. Assuming less than 100% efficiency, this means we produce less than one tritium nucleus per reaction, meaning than we are losing tritium overall. How can we make up the shortfall?
Beryllium acts as a neutron multiplier: 9Be+n→24He+2n.
The consumable Be is supplied either as a solid metal layer, or as part of the molten salt (such as FLiBe) coolant, or both. The right amount of Be in the path of D-T neutrons theoretically allows the fusion reactor to have a Tritium Breeding Ratio (TBR) greater than one. That’s the good news!
Speaking practically, this hasn’t been shown to work yet, and my understanding is that it is a must-have for commercial D-T fusion. Recycling tritium within an operating D-T fusion plant (and beyond that, increasing global T inventory to bootstrap / enable the world to bring new fusion reactors online) is one of the key remaining engineering challenges to viable D-T fusion power, and is an active research area. The greater-than-unity breeding side of the problem is only the first challenge; separating, extracting, and capturing the freshly baked tritium is also an unknown. But we’ve known about this problem for a while, and there is room for optimism; ITER, for example is planning to test 6 different designs for tritium breeding blankets.
Does the Beryllium convert one fast neutron into two thermal neutrons? I assume we’re not getting money for nothing.
Tritium has a half life of twelve years, so perhaps we could wait to disassemble the blanket, no rush to extract the tritium.
There is a plasma physicist on YouTube who made a video explaining why, in his opinion, fusion power is far away. Tritium was one of the issues he raised.
You also get neutrons from D-D reactions (which produce 1 neutron about half the time). Even if the plasma isn’t hot enough to get a lot of D-D reactions, it will likely produce some to make up the shortfall.
Edit: and I completely forgot (lol) that when DD doesn’t produce a neutron it produces a tritium. So, that will also help.
I have a question about tritium breeding. How many free neutrons does D-T fusion produce? According to Wikipedia it is only one. Assuming less than 100% efficiency, this means we produce less than one tritium nucleus per reaction, meaning than we are losing tritium overall. How can we make up the shortfall?
Beryllium acts as a neutron multiplier: 9Be+n→2 4He +2 n.
The consumable Be is supplied either as a solid metal layer, or as part of the molten salt (such as FLiBe) coolant, or both. The right amount of Be in the path of D-T neutrons theoretically allows the fusion reactor to have a Tritium Breeding Ratio (TBR) greater than one. That’s the good news!
Speaking practically, this hasn’t been shown to work yet, and my understanding is that it is a must-have for commercial D-T fusion. Recycling tritium within an operating D-T fusion plant (and beyond that, increasing global T inventory to bootstrap / enable the world to bring new fusion reactors online) is one of the key remaining engineering challenges to viable D-T fusion power, and is an active research area. The greater-than-unity breeding side of the problem is only the first challenge; separating, extracting, and capturing the freshly baked tritium is also an unknown. But we’ve known about this problem for a while, and there is room for optimism; ITER, for example is planning to test 6 different designs for tritium breeding blankets.
Does the Beryllium convert one fast neutron into two thermal neutrons? I assume we’re not getting money for nothing.
Tritium has a half life of twelve years, so perhaps we could wait to disassemble the blanket, no rush to extract the tritium.
There is a plasma physicist on YouTube who made a video explaining why, in his opinion, fusion power is far away. Tritium was one of the issues he raised.
You also get neutrons from D-D reactions (which produce 1 neutron about half the time). Even if the plasma isn’t hot enough to get a lot of D-D reactions, it will likely produce some to make up the shortfall.
Edit: and I completely forgot (lol) that when DD doesn’t produce a neutron it produces a tritium. So, that will also help.