(phil hunt) wrote in message ...

snip

What's an LWR?

LWR = Light Water Reactor; usually commercial reactor, used for
producing electrical power.

MTR = Material Test Reactor; high-power reactor, usually used for
intense irradiation of target materials (such like U235).

I thought gas centrifuges are for separating U235 from U238, not
for producing Pu239.

The centrifuges are used to whirl UF6 gas ("Uranium Hexaflouride")
into highly enriched uranium, needed for building the weapon: i.e. for
getting HEU. Usual uranium has something like 20% of the U-235
isotope: you need 85-90% U-235 in Uranium in order to get weapon grade
material. Using the "gas centrifuge" for this is the simpliest and
cheapest (of three or four) mean of producing nuclear weapons. The
South Africans used this technique to produce their, just for example.
See also:
http://www.fas.org/nuke/intro/nuke/uranium.htm

Tom Cooper
Co-Author:
Iran-Iraq; War in the Air, 1980-1988
http://www.schifferbooks.com/militar...764316699.html

Iranian F-4 Phantom II Units in Combat
http://www.osprey-publishing.co.uk/t...hp/title=S6585