[AR] Re: MSR reactors.
- From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
- To: Arocket List <arocket@xxxxxxxxxxxxx>
- Date: Sat, 13 Jul 2019 00:17:13 -0400 (EDT)
On Fri, 12 Jul 2019, John Dom wrote:
Thorium reactors are still taken as a serious alternative to uranium
ones AFAIK. But no one ever experimented with Th much.
Thorium got a lot of attention early on, because uranium ore was scarce
(and there was very little of it in the US in particular) and thorium
quite a bit more abundant.
However, once people started seriously looking, it turned out that there
is *low-grade* uranium ore all over the place, including in the US.
Plus, of course, demand didn't rise to nearly the forecast levels. So the
feared uranium shortage evaporated, and thorium reactors and other breeder
reactors -- all basically ways of coping with uranium shortages -- went
very much on the back burner. There *is* substantially more thorium on
Earth than uranium, but for current demand it's not attractive enough.
This may change if people get serious enough about building tens of
terawatts of carbon-neutral power plants, which is what's probably needed
to cope with the industrialization of Asia and Africa without putting
truly excessive amounts of CO2 into the atmosphere. There are precious
few alternatives which will work on that scale. (Ground solar is not
among them, not without a major breakthrough in storage technology -- mere
refinement of lithium batteries won't suffice. Power satellites, on the
other hand, might do the job.) And even including low-grade ore, there
probably just isn't enough reasonably accessible U-235 on Earth to support
nuclear power on that scale.
As to Pu: the now miraculous stellar V'gers got the go-ahead to travel on
this week with their RTG's outputs rearranged. A 5 year mission extension?
Basically just a confirmation of plans made a long time ago. The Voyager
RTGs are now old enough that they can't support the full complement of
spacecraft subsystems and still-useful instruments, so it's time to start
shooting the weakest sled dogs :-) to keep the rest going a bit longer.
Henry
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