Re: Nuclear heater for Expeditions

Dan Clemmensen (
Thu, 08 Jan 1998 22:52:42 -0500

Eugene Leitl wrote:
> On Wed, 7 Jan 1998, Dan Clemmensen wrote:
> > True. but the original question was (more or less) "can we build 'mister
> > fusion'?" I responded "Yes, given nanotech."
> 'Mr. Fusion' as in 'Back to the Future'? Not with hot fusion (while the
> cold one being still mythical). Reactor volume way too small (even JET is
> too small). Perfect diamondoids (which are as susceptible to rad ageing
> as everything else) are no Unobtainium.
I'm presuposing a new ICF fusion reactor based on starting at extreme
pressure in a diamondoid container.
[SNIP argument about a "traditional" plasma fusion]

> The smaller the reactor, the more critical the operation regime. The
> enrichened uranium high-flux research reactor currently being erected in
> Munich, Garching has a core the size of a wastebasket. Its energy density,
> and large surface of the cooling vents at a record neutron flux do not
> seem to make for a passively safe system.
That a fission system. While I feel that traditional fission systems are
safer for the environment than any current alternative, I'm not willing
to argue the point. It's irrelevant to "mister fusion."

> > recovery of the dangerous isotopes generated by neutron activation, then
> > all that remains is deactivation of those same isotopes. This is also
> > perfectly feasible, because these isotopes can be exposed to still more
> > fast neutrons by recycling them back into the fusion reactor. Most of
> This is a feature I also do not like about planned fusion tritium
> breeders. Though power density of a hypothetical production tokamak will
> be relatively low, the wall radiation load will be quite demanding. We
> have already miles and miles of tritium-contaminated liquid lithium pipes,
> now we must also intertwine them with hot waste ducts. I do not see how
> this will limit the total waste curie output.
I concur. So do most nuclear engineers, but they don't talk about it
much. the public still believes fusion is clean, and the engineers
know that fusion (and fission) are a whole lot cleaner than fossil
fuels, so the engineers try to avoid tainting fusion with the
associated with radioactivity.

> > atoms will eventually transform to stable isotopes under additional
> > exposure to fast neutrons. The tiny percentage that do not can be
> > separated (again by nanotech) and deactivated in a tiny particle
> Not by nanotech. It just makes conventional isotope separation cheaper,
> and increases the yield. It is difficult to see how dirt cheap but precise
> macroscopic structures could make such a big difference.
But "cheaper" and "yield" are the two main points. "Cheaper" makes a
concept econimically feasible. "high yield" means you can eliminate
essentially all the waste.

> > accellerator. These processes are on balence highly exothermic, so the
> Why tiny? I do not see how nanotech can decrease the accelerator size
> significantly. Novel acceleration principles do not rely on nanotech for
> implementation.
No, but nanotech should permit extreme precision. This generally permits
extreme efficiency, which may permit significant size reduction.