CANDU

Very similar concepts were done with Uranium solutions in the 50s. The
uranium silicide was suppose to be a liquid core reactor at one point
pretty much exactly what you described. Liquid cores do have some
advantages (being liquids you can chemically process waste while the
reactor is running.)

The problem at the time was the metallurgy and material science to
contain a reacting liquid core was thought to be beyond the technology
at the time and after several successful experiments the Canadian
government shut down the labs (also a lot of US politics probably had
a lot to do with it).

I stumbled onto this research work when doing my course work. I don't
think anyone had moved the books in decades when I saw them, and they
disappeared entirely about two years later in a book reshuffle in the
engineering library.

Canada was the only major source of uranium in the free world in the
fifties so had a vested interest in moving the research along. Today
if you are truly interested you can go up to any one of the thousands
of uranium mines up in northern Ontario and set up shop mining your
share. There is still a lot of uranium but the cost is too high.

The books I found were research notes on different types of reactor
geometries. They included natural,and enriched uranium, plutonium and
thorium reactors.

Bill

--- In spacesettlers@y..., Ryan Healey wrote:
> --- Bill wrote:
> > >
> > > Silicon moderator probably wouldn't be very good as the best
> > moderators are
> > > elements with a low atomic mass. Silicon would probably be just
too
> > heavy to
> > > work well. Even if it does work the reactor is going to be very
> > large.
> >
> > Actually silicon is surprisingly a very good moderator. The
problem is
> > that uranium silicide is a liquid at about 600 C. Most reactors a
> > running at about a 1000C.
>
> That is interesting. I wonder why it would be like that. As for
liquid
> reactors, I've been thinking about having Uranium metal in liquid
form with a
> graphite moderator. The uranium would pass through pipes made of
Boron or
> Hafnium when they are going to the heat exchangers. The Uranium
would of
> cousre stay liquid. I wonder if such a setup would work (would
probably use W
> walls).
>
> > > I have heard that it may be possible to use Magnesium Flouride
as a
> > moderator
> >
> > I was actually testing MgF2 as a moderator at University a
lifetime
> > ago. It was a project that we had. It didn't do very well. Alpha
rays
> > made it brittle.
>
> In which case we shouldn't be using it.
>
> > could use
> > > Zirconium Deutride instead to allow Natural U to be used.
> > >
> > Interesting idea but the main problem in CANDUs at the moment is
> > zircomium-hydride cracking of the tubes. The uranium is contained
in
> > Zr tubes. The heavy water at high pressure and temperature
produces
> > zircomium hydride that crack the tubes.
>
> I've never heard of the ZrH2 problem with CANDUs and would also
expect it to
> appear in LWR reactors (most of them use Zr as the cladding
material). Anyway
> I'm thinking about using the ZrD2 as a solid lump of moderator (they
> investigated ZrH2 for use as an NTR moderator).
>
> > > I have also been thinking about using a *gasp* plastic moderator
> > (would still
> > > require the enrichment), but the low melting point and radiation
> > damage
> > > problems plastics have would make that a bad idea.
> >
> > I think the key hear is to use it as a moderator not as a support
> > structure. Imagine plastic pellets packed with uranium pellets.
Maybe
> > it would work.
>
> It might work, although there is likely to be quite a bit of
outgassing and
> decomposition while the reactor is operating.
>
> > Bill
>
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