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0 pointspfdietz5y ago0 comments

80% of the energy from DT fusion comes out as neutrons, which enter a blanket and deposit energy there by collisions and nuclear interactions.

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6 comments · 2 top-level

Baeocystin5y ago· 3 in thread

Thank you!

Do you know how far along are we in understanding how to build an effective blanket that can withstand the neutron flux while maintaining its physical integrity?

pfdietzOP5y ago

It's not a solved problem (since really testing a wall design requires a working high power source of fusion neutrons), and it's not clear it can be solved in a sufficiently practical way. Indeed, the ability of the first wall to withstand the energy flowing through it will likely cause DT fusion reactors to have low volumetric power density, with sad effects on their economics.

Baeocystin5y ago

Thanks again for the reply.

DennisP5y ago

SPARC's approach is for the blanket to be a molten salt, and also function as a coolant. That will surround an inner wall which gets replaced annually. They tested joints in the REBCO superconductors, so the reactor can be opened up on hinges.

jnxx5y ago· 1 in thread

> which enter a blanket

So, what is that blanket made of?

It needs to be a material which:

- can withstand high temperatures and radiation

- does not becomes radioactive itself

- facilitates production of Tritium by breeding

- operates in very high magnetic fields, which means high forces

No such material is known so far.

It is a bit like some engineer from 1700 said: "Well, you could just build a more efficient and compact and light steam engine, and connect it to a machine which has flapping wings, and then you have a transport vehicle which can carry people across the Atlantic ocean at supersonic speed, and at little cost."

tuatoru5y ago

Not such a bad analogy, as the blanket will get hot, and the heat will be used to turn water into steam, which will power generating plant. Just like in the 18th and 19th centuries.

It would have had to have been an unusually well informed and far-sighted engineer though, as Savery's engines first worked in 1698 and the first for-sale commercial engine, Newcomen's, wouldn't happen until 1712. And they were incredibly inefficient: 0.01% to 0.1%.

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