VASIMR

>
> Why should we ignore nuclear?
>

I don't think we should ignore nuclear, but I don't think that nuclear
will mean a plutonium reactor running a generator. I think it will be
nuclear powered thermonic generators that are low efficiency and low
maintenance systems.

The main problems I see with nuclear are the following:

cost - the simplest reactors still need enriched uranium unless you
want to build a CANDU reactor (very!! big). Enriched uranium is not
cheap. Plutonium is even more expensive.

containment - you need enough shielding between people and the
reactor. I confess this might be a mute point because you need
shielding for cosmic rays, but the question is how much extra
sheilding do you need?

maintenance - nuclear reactors just don't sit and produce power. They
need skilled people (lets call him Homer) to actually run the reactor,
monitor it, etc...

heat - the best rankine cycle is 40% efficient. This means you need
radiators to remove the other 60%. The mass of the radiators will
easily be as much as the reactor itself if not more. The radiators
make the ship as big as any with a solar power systems and just as
hard to move.

Bill