Wednesday, September 06, 2006

Problems with Problems With The Orion Spacecraft #10: Fission Free Bombs

based on fission free bombs - POS

A common misconception, based on poorly sourced Usenet articles.

The most detailed official document available, from NASA and General Atomic explains in detail how to reduce fallout from fission triggered devices.

GA-5009 pg 82/94 - "products could be reduced by factors of 100 to 1,000. Such
improvements would be obtained by reducing the fraction of total yield due
to fission by two to three orders of magnitude, the remaining yield being
contributed by fusion. A further advantage from this approach is the
improvement in fuel economics.
It is also possible to consider the focusing of fission products
upward from the point of explosion, at some sacrifice in ISP . This could
reduce those fission products likely to be trapped in the atmosphere to
approximately 1percent or less of that estimated in the hemispherical expansion

It is believed that some combination of these suggested techniques
could conceivably result in a reduction of the trappage to only 1/1,000,000th of
current estimates. Considering the longer-term possibilities, if and when
pure fusion devices become a reality, fission products, by definition, will
not be present."

GA-5009 pg 29/41 "With pulse-unit redesign, orders-of-magnitude improvements
in fission-product release (near-fusion or total-fusion energy source)"

GA-5009 pg 81/93 "characteristic of the current pulse-unit design is that most
of the fission products and the unburned fuel tend to leave the point of
explosion within a 2 Pi r solid angle and hemispherically away from the
vehicle. Assuming that all of the fission products are ejected in this
manner provides an upper limit to the trapped fission yield per explosion
for any particular vehicle."

- An early example of the error-

From: Henry Spencer
Subject: Re: Revive Orion?
Date: Sun, 17 Aug 1997 00:00:38 GMT

In article <>,
John Bicketts wrote:
>The Orion project of the 50's and 60's designed a workable spacecraft
>powered by small atom bomb explosions. The ships could be big...
> Anyway, does anyone think they could be revived today?

There are a number of problems, and overall it is not a good idea.

For one thing, it is illegal. The treaty is still in effect. Admittedly,
it would be easier to negotiate changes to it now, with the Cold War gone.

For another, Orion always had a problem that was never satisfactorily
solved: its fuel was horribly expensive. Fission bombs are costly. Most
of the enthusiasm for Orion (and most of the optimistic commentary about
how little environmental impact ground-launched Orions would have) was
based on the assumption that "fission-free" nuclear bombs -- pure-fusion
bombs triggered by some non-fission means -- would soon be available.


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