Within 6 months, the daughter elements of any sample of originally 100% pure U-238 will be emitting substantial quantities of Beta radiaton along with some gamma radiation as well, due to the radioactive decay process. See below.
Contamination of Persian Gulf War Veterans andOthers by Depleted Uraniumby Leonard A. Dietz
July 19, 1996 (last updated Feb. 21, 1999)
<snip>
Only the first three isotopes in the uranium decay series or chain headed by U-238 are important in determining the radioactivity of DU (Ref. 12). Uranium-238 decays into thorium-234 (Th-234), which decays into protactinium-234 (Pa-234), which decays into U-234, etc. down the decay chain. The 246,000 year half life of U-234 is too long for it to decay much during our lifetimes and produce significant numbers of decay progeny.
The U-238 decay chain is broken during the chemical reduction of uranium hexafluoride into DU metal and is broken again during the melting and processing of the metal into a penetrator. To determine the maximum time it takes to regain equilibrium in the partial decay chain, we assume a solid sample of uranium that initially contains only the U-238 isotope, i.e. no decay progeny. Using Bateman's equations, (Ref. 13), we calculate the growth of Th-234 and Pa-234 activities as a function of elapsed time in weeks. The results are given in Table II.
Table II. Radioactivity (disintegrations/second) in 1 gram of
U-238 with no decay progeny initially present.
Half lives used:
U-238 = 4.47e9 years
Th-234 = 24.10 days
Pa-234 = 1.17 minutes, 6.69 hours (two decay states)
U-234 = 2.46e5 years (Ref. 14).
Scientific notation is used, i.e. 2.46e5 = 246000.
Weeks U-238 ---> Th-234 ---> Pa-234 ---> U-234
------------------------------------------------------------
0 12,430 0 0 0.000
1 12,430 2,270 2,150 0.000
5 12,430 7,890 7,840 0.001
10 12,430 10,770 10,750 0.004
15 12,430 11,830 11,820 0.007
20 12,430 12,210 12,210 0.010
25 12,430 12,350 12,350 0.013
30 12,430 12,400 12,400 0.017
(Sorry, the table formatting doesn't carry over in the cut and paste. Click on the link below to read the article and you'll see the table formatted properly /JC)After 25 weeks, Th-234 and Pa-234 have reached 99.4% of the decay rate of U-238 and for practical purposes have reached secular equilibrium with U-238, their parent isotope. Secular equilibrium means that the decay progeny of U-238 are being replaced at the same rate they are decaying; after 25 weeks all three isotopes are decaying at approximately the same rate. This is a maximum time; in reality, equilibrium will be reached much faster, since these two isotopes can never be separated totally from U-238. The isotope U-238 emits alpha particles and also emits some gamma rays. Its decay progeny Th-234 and Pa-234 each emit beta particles and gamma rays. An alpha particle is a fast helium atom with its two electrons removed, a beta particle is a high-speed electron and a gamma ray is like an X-ray.
From this analysis
we conclude that in a solid sample of DU, six months at most after manufacture of a DU penetrator, or DU armor for a tank, or DU particles in a person's body, substantial additional radiation in the form of beta particles and gamma rays always will be present. In fact, most of the penetrating gamma radiation and all of the penetrating beta radiation from DU comes, not from uranium, but from the decay progeny of U-238 (Ref. 15). In a year, only one-thousandth of a gram (1 milligram or mg) of DU generates more than a billion alpha particles, beta particles and gamma rays. The U.S. Army has investigated the generation of DU aerosols in armored vehicles hit by DU cannon rounds. Their investigators report "...that personnel inside DU struck vehicles could receive a dose in the `tens of milligrams' range due to inhalation" (Ref. 16). This exposure results in an acute dose of uranium.
http://www.wise-uranium.org/dgvd.html And here is Leonard Deitz's academic and work background just in case you want to question his knowledge of the topic. It's taken from his obituary as he recently passed away.
Leonard A. Dietz, age 82, of Niskayuna, died October 24, 2005. Dr. Dietz was born in Manistee, Mich. and grew up there. In February 1943, he joined the U.S. Army Air Corps and after graduating from flying training, served as a pilot in the 506th Fighter Group, 462nd Fighter Squadron and was based on Iwo Jima. He flew the P51D Mustang fighter on very long range missions during the closing months of World War II. He was awarded three Air Medals and a Distinguished Unit Citation, and was discharged from the Air Corps in August 1946 as a 1st Lt.
After the war, he graduated from the University of Michigan in 1949 with a BS in physics, and received an MS in physics in 1950. He then joined GE and worked in the general engineering laboratory in Schenectady until 1955, when he transferred to Knolls Atomic Power Laboratory where he worked for 28 years. He was an experimental research physicist in mass spectrometry and was responsible for developing advanced mass spectrometer instrumentation and new analytical techniques for isotope ratio analysis of uranium and plutonium. His extensive published research in ion detection resulted in ion pulse-counting detectors for mass spectrometry.
He was manager of a technical group that included the mass spectrometer component. Dr. Dietz was active in a local Boy Scout troop while his sons were growing up and was a volunteer fireman for 14 years. He was treasurer of Jones Boarding Home, a local non-profit corporation that took care of mentally disadvantaged adults, and was active in the First Unitarian Society of Schenectady and the Unitarian Universalist Society of Albany, and was president of the Albany Memorial Society.
After the 1991 Persian Gulf War, he provided physics support on airborne uranium particles from depleted uranium munitions to TV, radio and print journalists, to Congress, and to environmentalists and researchers who were investigating the spread and health risks of these radioactive particles. A generous and loving husband and father, Dr. Dietz is survived by his wife of 55 years, Betty; his children, Thomas, Kristin and Allen; two grandchildren, Max and Iris.
http://www.umrc.net/news.aspxWikipedia entry on U238 (Depleted Uranium)
While uranium-238 is minimally radioactive, its decay products - Thorium 234 and Protactinium 234 - are beta particle emitters with half-lives about 20 days and one minute respectively (Pa 234 decays to Uranium 234, which has a half-life of hundreds of millennia, and this isotope does not build to equilibrium concentration for a very long time). When the two first isotopes in the decay chain reach their (tiny) equilibrium concentrations, a sample of initially pure uranium-238 will emit three times the radiation due to uranium-238 itself, and most of this will be beta radiation. After all the beta radiation is almost over, the by-product of uranium-238 would be (Pb) lead.
http://en.wikipedia.org/wiki/U238While it's true external alpha particles can be stopped from penetrating the skin by the layers of dead cells on the outside of the skin, in combat situations when the depleted burns or explodes extremely small microscopic pieces of DU are created which will get blown around by the wind, mixed with dust particles etc and will get inhaled into the lungs and from there they can pass through the lung/blood barrier into the blood stream and be stored in internal organs and bone. Medical authorities like Dr. Asaf Durakovic, former Professor of Nuclear Medicine at Georgetown University, and Dr. Rosalie Bertell among others believe believe there is plenty of evidence to show that once inside the body even the alpha radiation is much more harmful to the cells than when it is external to the body (not to mention the beta and gamma that will also be present as well)as noted above.
AMERICA'S RADIOACTIVE MUNITIONS THREAT TO OUR OWN TROOPS AS WELL AS ENEMY
By John Hanchette
<snip>
A fellow of the American College of Physicians, a medical consultant for Hadassah University in treating the children of Chernobyl, a U.S. medical team leader for the Nuclear Treaty Joint Verification component in the former Soviet Union, chief of nuclear medicine at the VA Medical Center in Wilmington, Del., Durakovic held the highest radiology credentials an official in Washington could hold.
Durakovic was the guy the Federal Emergency Management Agency (FEMA) designated to assess the White House for radiation -- and hopefully pronounce an all-clear -- in case some terrorist detonated a low-level nuclear suitcase bomb or similar device in Washington. A colonel in the U.S. Army Reserves, Durakovic served in Desert Shield, the five-month preparatory run-up in combat theater to Gulf War One, as chief of a medical detachment. No one told him about DU weaponry either.
After the war, as a VA doctor, he assessed 24 soldiers from a New Jersey transportation and supply company who had briefly inspected and cleaned some tanks destroyed by DU. He sent his readings to two other VA doctors in Boston, who confirmed 14 of the two dozen troops had been contaminated. The VA asked Durakovic to refrain from publicly describing the effects of DU on the human body. He refused. He said that was akin to "lying." The VA fired him. Durakovic soon testified before the House Government Reform Committee. When investigators for that panel -- about the only federal group that showed real concern over Gulf War Illness -- met, the records of the 24 New Jersey troop examinations had somehow disappeared.
http://www.niagarafallsreporter.com/hanchette54.html
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