X-Message-Number: 20253
Date: Sat,  5 Oct 2002 14:54:35 -0700
Subject: Re: CryoNet #20208 Nuclear energy
From:  (Tim Freeman)

> From: Thomas Donaldson
> There seems to be a unified view that the pollution of nuclear
> power will stay with us for a long time. That is, thousands of
> years.  At least 2 ways to deal with that problem in far less
> than 1000 years can be suggested:
> 
> 1. Throw the waste into the Sun.

Probably would need nuclear rockets to get you there, so there may not
be a net cleanup.

> 2. Process it into useful elements
>    The problem that many get hung up on here is that such 
>      processing can also produce material useful for weapons.

I hear that this is not so.  The Integral Fast Reactor project claims
to do the reprocessing without having any intermiediate products that
are nonradioactive enough to easily steal without killing off the
thieves or pure enough to make into weapons.  The reprocessed elements
are used as recycled fuel, so it doesn't have to go anywhere.  Check
out:

http://www.nuc.berkeley.edu/designs/ifr/

From: 
>The real problem is not here, it is in the Avogadro number: If the mass of a 
>typical radio-active atom is 60 atomic mass, then there are near 10 000 
>billions of billions atoms in one g. Assume you are losing one part per 
>million of that material in the processing, that is 10 millions billions 
>atoms. If the half-life is 1000 year (31 billions seconds) There will be 150 
>000 disintegrations per second in the environment. 

The important thing is how much damage the disintegrations do, not how
many there are.  Your 150,000 number is meaningless without this information.

You have to look at the ratio between pollution produced and useful
produced energy.  Nuclear power has a high power density and highly
toxic waste; the key question is how the ratio between these two high
numbers compares to the corresponding ratio for, say, energy produced
from coal.  It's misleading to talk about the pollution without saying
how much power was produced and how much pollution would result from
producing that much power by other means.

The outputs from the IFR are either stable or have a short (~30 year)
half-life, so the 1000 year half-life is avoidable.  The highly
radioactive isotopes get sorted out and put back into the reactor
until they transmute again.

There's an article in there somewhere where the chief IFR guy admits
that nuclear power is not economically necessary yet, since
conventional means of producing power are presently somewhat cheaper.
I'm more afraid of global warming than nuclear power, so I hope
economics forces the shift soon.

-- 
Tim Freeman       

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