bash@ihlpb.ATT.COM (Basham) (07/07/89)
From: bash@ihlpb.ATT.COM (Basham) This type of ammo seems to be pretty common with the Navy, but, what is it? Tom [mod.note: I'll give the quick answer, and leave it to others to elaborate. Depleted Uranium, or DU, is the byproduct of the production of enriched uranium (for reactors). It consists of the relatively stable uranium isotope, and so is only mildly radioactive. DU is extremely hard, and denser than tungsten (or lead); these two properties make it an excellent choice for kinetic energy armor penetrators. It is typically used as the penetrator of a discarding sabot (DS) round, and so achieves tremendous muzzle velocities (upwards of 4000 fps), which means it also has a very flat trajectory. This makes it a good round for the Phalanx missile defense system. In the US Army, DU is used for all tank guns (APFSDS); I'm uncertain if it's used by other nations. An added bonus of DU is that it is somewhat pyrophoric; that is, it is easy to ignite (say, by slamming it into a metal plate at a few thousand feet per second 8-); this gives it an added incendiary effect, which may or may not be useful against tanks. - Bill ] --------------------------------------------------------------------- -- Tom Basham AT&T Bell Laboratories (312) 979-6336 att!ihlpb!bash "If you can't beat 'em, infiltrate bash@ihlpb.ATT.COM and destroy them from within." bash@cbnewsd.ATT.COM
military@cbnews.ATT.COM (William B. Thacker) (07/08/89)
From: ulysses!smb > It consists of the relatively > stable uranium isotope, and so is only mildly radioactive. DU is > extremely hard, and denser than tungsten (or lead); these two properties > make it an excellent choice for kinetic energy armor penetrators. Anyway -- DU may or may not be ``mildly radioactive'' compared to the natural stuff. The issue is that U-235, the isotope separated out for use in bombs and reactors, fissions much more easily when bombarded by neutrons; U-238 has much more of a tendency to turn into plutonium (eventually, and via several indirect steps). The natural level of radioactivity of either -- that is, the spontaeous decay rate -- is of no particular interest militarily; the ability to fission, and to emit neutrons of the appropriate energy level during fission, thus causing a chain reaction, is what's interesting. I don't think uranium per se is that radioactive; it has quite a long half-life, which translates directly into ``not many atoms split per unit time''. Stuff with a short half life is much nastier, since you then get lots of radiation.
royf@cs.utexas.edu (Roy Forsstrom) (07/13/89)
From: pwcs.sbc.com!royf@cs.utexas.edu (Roy Forsstrom) In article <8076@cbnews.ATT.COM> military@cbnews.ATT.COM (William B. Thacker) writes: > > >From: ulysses!smb >> It consists of the relatively >> stable uranium isotope, and so is only mildly radioactive. DU is >> extremely hard, and denser than tungsten (or lead); these two properties >> make it an excellent choice for kinetic energy armor penetrators. > > >Anyway -- DU may or may not be ``mildly radioactive'' compared to the >natural stuff. The issue is that U-235, the isotope separated out for >use in bombs and reactors, fissions much more easily when bombarded >by neutrons; U-238 has much more of a tendency to turn into plutonium >(eventually, and via several indirect steps). The natural level of U-235 is just a few percent of natural uranium ore. It is separated out and used in military power reactors because it has a higher probability of fissioning with thermal "low kinetic energy" neutrons than U-238. A military power reactor may be enriched to over 90% U-235. The fission process produces more thermal neutrons, ~2.54, than fast neutrons giving a higher density within the reactor. It is also easier to moderate thermal neutrons--using plain water--than fast neutrons. Civilian reactors use slightly enriched U-238 for economic reasons. Late in life, a civilian reactor's power is mainly the result of plutonium fission. The unique requirements of a ship's power reactor, small, powerful, easy and accurate control, reliability and maintainability at sea, prompt the use of expensive and rare U-235. Formerly a nuclear reactor operator aboard the USS California, I'm now at- -----------------------------------+------------------------------------------- Roy Forsstrom 612-298-5569 | What are the Rights of Man and the Public Works Computer Services | Liberties of the World but Loose-Fish? pwcs!royf royf@pwcs.StPaul.GOV | - Moby Dick -----------------------------------+------------------------------------------- -- _______________________________________________________________________________ Roy Forsstrom What are the Rights of Man and the Public Works Computer Services Liberties of the World but Loose-Fish? pwcs!royf royf@pwcs.StPaul.GOV - Ishmael in Moby Dick