Re Fusion

Robert Neil uarn at MCK-UAII.MCK.NCSU.EDU
Thu Jun 5 08:13:13 MDT 1997


> >I believe you are referring to a breeder reactor. The reason this
> >died is because the reprocessed material is high grade fissionable
> >material. This was considered too high a security risk since, with
> >that stuff, even Sadam could build a thermonuclear device.

This was the rationale behind Jimmy Carter's extremely inept decision
to kill the US breeder reactor program. Natural Uranium is
approximately 99% U238 and .3% U235. U235 is the fissionable product,
U238 is not.  In order have enough high-speed neutrons to maintain a
self-sufficient chain reaction in a nuclear power plant, the fuel
must be 7% fissionable material - hence the need to "enrich" natural
Uranium with U235. Extracting enough U235 from natural Uranium for
enrichment is difficult because they share many physical and chemical
products.

In order to create a fission reaction capable of exploding (or
igniting a fusion reaction) you need something on the order of 97%
fissionable material - i.e., "bomb-grade" material. In a breeder
reactor, some of the remaining 93% non-fissionable U238 is allowed to
capture a neutron and transmutate to Plutonium. Plutonium is
fissionable and is much easier to extract from U238 than is U235
because it is chemically different and has different properties.

In short, the fuel for conventional light-water reactors in the US is
natural Uranium enriched to 7% U235. You can't make a bomb from this.
Breeder reactor produce P239 which is easily extractable and can be
made into a bomb.


===============================================================
Robert Neil
Computing Consultant II
Urban Affairs - NC State University, Box 7401
Raleigh NC 27695   fax: (919) 515-3642
---------------------------------------------------------------
"A candle may light the way in the darkness, but NUCLEAR POWER
 means we can have cold beer while we watch the Superbowl." CS
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