By John C. Zink, Ph.D., P.E.,
Those of us who have been intimately involved with nuclear power for a number of years have learned that the public has trouble separating nuclear energy issues from other nuclear topics. Because of this, any nuclear related controversy seems to stir up otherwise latent nuclear power phobias. Recent publicity over the use of depleted uranium bullets in the Balkans is such an issue.
Depleted uranium is readily available as a byproduct from the production of the highly enriched uranium used for nuclear weapons, or from the production of the slightly enriched uranium used in nuclear power reactors. Because of its high density and its availability, designers sometimes specify it as a lead substitute – commonly for ship ballast and, in this case, for armor-piercing shells. Depleted uranium has a theoretical density 1.7 times that of lead and is only 60 percent as radioactive as natural uranium. Normally, any health concerns would focus on its chemical properties as a heavy metal poison, not on its radioactivity.
The current controversy arose over alleged health effects from NATO use of depleted uranium armor-piercing shells during the Balkans conflict. In May 1999, the United Nations Environment Programme (UNEP) established a Balkan Task Force to perform an environmental assessment in the aftermath of the Balkan conflict. During August 1999, a team of scientists took samples at six sites prominently involved in the conflict. In October 1999, UNEP issued its preliminary finding that there was no uranium contamination above the normal background levels at any of the sampled sites. Also in the summer of 1999, the Hungarian government undertook a special examination of air sampling data it gathered during and after the conflict. While the Hungarian samples did contain traces of uranium, careful analysis showed it to be natural uranium, not depleted uranium. There are uranium mines in the sampled area, and the Hungarians concluded that weapons explosions during the war stirred up the soil, suspending detectable amounts of natural uranium in the air. They did not detect any depleted uranium from the weapons themselves.
These findings did not end the controversy. UNEP led another fact-finding mission to Kosovo in November 2000. The data from this mission are still being evaluated, and a January UNEP press release says still more field work and laboratory analyses will be required before scientists can reach a firm conclusion regarding potential health hazards and their origins.
While it is always important to do a thorough analysis, the bad news is that this issue will continue to fester in the public consciousness as information slowly dribbles out from the continuing studies. The first such information came in the form of a press release UNEP issued February 16, 2001. According to UNEP, “Traces of plutonium have been detected in the DU (depleted uranium) penetrators found at sites in Kosovo … The presence of these transuranic elements in the DU indicates that at least some of the material has been in nuclear reactors. However, the amount of plutonium found in the DU penetrators is very low and does not have any significant impact on their overall radioactivity.”
The Associated Press added fuel to the controversy by reporting that, “Rounds of depleted uranium fired by NATO warplanes in Kosovo two years ago contained deadly plutonium …” Aha! deadly plutonium, reactors, weapons – they are all connected. Over the years, the anti-nukes have tried to make this connection while demonizing plutonium as “the most dangerous substance known to man.” This must have made an impression on the Associated Press writer who inserted “deadly,” which did not appear in the UNEP press release.
The UNEP speculation that some of the depleted uranium material may have come from a nuclear reactor also didn’t help. It could be true, but it isn’t necessarily so. Depleted uranium is about 99.8 percent U-238, vs. 99.3 percent U-238 in natural uranium. There is an occasional spontaneous fission in U-238, which releases neutrons. Some of these, subsequently, may be absorbed in other U-238 nuclei to form U-239, which eventually turns into plutonium-239. This sequence of events occurs in nature, but its effects would be slightly more pronounced in depleted uranium than in natural uranium. It can yield trace amounts of plutonium without any help from nuclear reactors.
Just when nuclear power plants are setting new records for safety and reliability, just when they have attained operating costs lower than coal plants, and just when the public is beginning to acknowledge their important contribution to the nation’s energy mix, here comes new “ammunition” for the anti-nukes. There shouldn’t be any connection between nuclear power and heavy metal ammunition used in war, but you can count on the anti-nukes to make such a connection and to use it to attack nuclear power. Unfortunately, the public will probably not understand that this is just a shell game.