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In September 2002 ABC News smuggled a 15-pound (6.8-kilogram) cylinder of depleted uranium metal, loaned by NRDC, into the United States, and televised the story on the first anniversary of the September 2001 terrorist attacks. In September 2003, the network did it again. It smuggled the same uranium cylinder into the country and aired another story on September 11, 2003.

Although the material is relatively harmless depleted uranium, weapon-grade uranium also would have passed through U.S. Customs without being detected. The lesson? Security procedures at U.S. borders cannot detect highly enriched uranium.

In 2002 the network shipped the depleted uranium cylinder, which is about the size of a soda can, by ocean freight from Istanbul to New York. In 2003, the network shipped it in a teak trunk from Jakarta to Long Beach, a port near Los Angeles.

In 2002 U.S. Customs inspected the shipping container at Staten Island in New York and failed to detect the uranium. In 2003, U.S. Customs inspected the container at Long Beach and again failed to detect it.

"The fact that ABC News was able to smuggle in what could have been weapon-grade uranium a second time speaks volumes about the failure of the Bush administration to secure nuclear weapon materials," said Tom Cochran, the physicist who heads NRDC's Nuclear Program. "We must eliminate the commercial use of weapon-usable uranium and reduce the inventories of highly enriched uranium used for weapons. U.S. Customs simply cannot stop it from being smuggled into the country."


What did ABC ship and how was it packaged?

Uranium (symbol U) is a slightly radioactive metallic element (atomic number 92; atomic weight 238.03). As found in nature, uranium is a mixture of three isotopes: U-234 (0.0054 weight percent), U-235 (0.711 weight percent) and U-238 (99.2836 weight percent). Most nuclear reactor fuel and nuclear weapon components are made with uranium in which the U-235 concentration has been increased by a process called enrichment. The output of an enrichment plant consists of enriched uranium product and the depleted uranium tails. By definition, depleted uranium contains less than the amount (0.711 percent) of U-235 found in nature, low-enriched uranium contains between 0.711 percent and 20 percent U-235, and high-enriched uranium contains 20 percent or more U-235.

In the late 1970s, NRDC purchased 15 pounds (6.8 kilograms) of depleted uranium (0.198 percent U-235) in the form of a metal cylinder.1 It had been cut from a rod of depleted uranium at a factory that made depleted uranium projectiles for the military.

Metallic uranium has a density of 18.95 grams per cubic centimeter (g/cm3) compared to 11.35 g/cm3 for lead and 1 g/cm3 for water. In other words, a given volume of depleted uranium is 18.95 times heavier than an equal volume of water. The 15-pound depleted uranium cylinder fits snugly in a 12-ounce soda can, a cylinder measuring roughly 4.7 inches (12 centimeters) in length and 1.2 inches (3 cm) in radius.

The specific activity (the radioactivity per unit mass) of the uranium isotopes in depleted uranium is about 15 million Becquerel per kilogram (15 x 106 Bq/kg).2 This is approximately 40 percent lower than that of naturally occurring uranium (25 x 106 Bq/kg) and about 150 times less than that of enriched uranium (approximately 2.3 x 109 Bq/kg).

A rad measures the absorbed dose: the amount of energy absorbed from any type of radiation per unit mass of the material absorbing the radiation. The dose rate from an unshielded slab of depleted uranium is about 0.2 rads per hour (rad/hr) at its surface. Some 80 percent of the dose is from alpha particles, which do not penetrate the skin, and 3 percent from beta particles, which can penetrate the skin but can be shielded with less than 1/8 of an inch (3 millimeters) of lead. The measured dose rate at the surface of the 15-pound depleted uranium cylinder using a RadAlert survey meter -- a hand-held radiation monitor using a Geiger-Mueller tube that does not detect alpha or low-energy beta radiation -- is 17 millirad per hour (mrad/hr), or 0.017 rad/hr.

For some kinds of radiation, such as the beta particles emitted by uranium, 1 rad equals 1 rem, which is a measure of the biological effect of a given radiation exposure. A person exposed to NRDC's depleted uranium would absorb 17 millirem per hour (mrem/hr), which is about 400 times higher than the 360 mrem per year average from various natural background and man-made radiation sources, such as medical X-rays.

For ABC to safely store and transport the 15-pound depleted uranium cylinder it was necessary to reduce the dose rate at the surface with shielding. NRDC packaged the depleted uranium cylinder in a lead-lined steel container, reducing the dose at the container surface from 17 mrem/hr to approximately 0.5 mrem/hr.3 NRDC constructed the steel container using off-the shelf (3-1/2 inch) plumbing pipe and end caps from a plumbing supply store. The overall length of the pipe and caps was 7.5 inches.

Had the 15-pound uranium cylinder been weapon-grade highly enriched uranium instead of depleted uranium (which is not suitable for nuclear weapons), the dose rate at the surface of the highly enriched uranium would have been more than 100 times higher. However, nearly all of this increase would be due to alpha radiation, which can be shielded with a sheet of paper. Meanwhile, the beta-ray dose rate would be about the same or lower and the gamma-ray dose would be ten or more times higher. At the surface of the shielded container the dose rate would be be about one to ten times higher. The dose rate of the highly enriched uranium cylinder could be easily reduced to that of the shielded depleted uranium container (i.e., 0.5 mrad/hr) by adding an additional 1/8 inch of lead (one-third of a centimeter) around the cylinder. This would add only about 6.6 pounds (3 kilograms) to the mass of the lead shielding.

In other words, it would be as easy to smuggle highly enriched uranium through U.S. Customs as NRDC's depleted uranium. Customs personnel used X-ray machines and simple radiation detector pagers to inspect the container holding NRDC's depleted uranium. Neither device was able to detect the depleted uranium, nor would they have been able to detect highly enriched uranium with slightly more shielding.

If NRDC's cylinder had been highly enriched uranium, 15 pounds are sufficient to construct a 1-kiloton (equal to 1,000 tons of TNT) nuclear device using the implosion technique.4 This bomb would be less powerful than weapons currently in U.S. and Russian arsenals, but it could still do a lot of damage. It would be about four times more powerful than the explosive energy of the two jets striking the World Trade Center and the collapse of the twin towers, which experts estimate to be equivalent to between a 0.20 kiloton to 0.25-kiloton explosion.

Hypothetically, terrorists could smuggle several 15-pound uranium slugs to build a bomb larger than 1 kiloton, making it closer to the size of various devices tested around the world. For example, an early Chinese nuclear weapons test used about 55 pounds (25 kg) of highly enriched uranium -- about 3.5 times the mass of NRDC's depleted uranium cylinder -- that had a yield of about 12 kilotons. China provided this nuclear bomb design to Pakistan. The design of Little Boy, the atomic bomb the United States dropped on Hiroshima, was based on a simpler, less efficient, technique. It used 141 pounds (64 kg) of highly enriched uranium (about 80 percent U-235) -- about 10 times the mass of NRDC's depleted uranium cylinder -- and produced a yield of 15 kilotons. The U.S. W33 artillery shell, which the Pentagon retired from the stockpile, had a yield of about 12 kilotons and an overall mass of about 243 pounds (110 kg). It probably contained about 110 to 132 pounds (50 to 60 kg) of highly enriched uranium -- about eight times the mass of NRDC's depleted uranium cylinder.


What should the United States do to prevent uranium smuggling?

The only effective means to significantly reduce the risk of smuggling weapon-grade uranium is to eliminate the material or maintain extremely tight security over it. For many areas of the world, particularly in Russia, it has been impossible to provide adequate security of weapon-usable highly enriched uranium and separated plutonium in the commercial sector.

Ultimately, the only effective way to prevent the unauthorized use of weapon-usable uranium is to blend existing stocks of highly enriched uranium into low-enriched uranium, which is not directly weapon-usable, and to prohibit the future commercial use of highly enriched uranium. The United States has in place programs to:

  • "blend down" excess military stocks of highly enriched uranium into low-enriched uranium for use as power reactor fuel;

  • improve the physical security of some Russian stocks of highly enriched uranium, and

  • convert research reactors that currently use highly enriched uranium fuel to low-enriched uranium fuel.

Unfortunately, the Department of Homeland Security is not responsible for these programs, and the Bush administration has not made them a high priority. Consequently, the administration is spending millions of dollars in a futile effort to detect weapon-usable material at U.S. borders, rather securing the material at its source or eliminating it altogether.



Notes

1. For educational or research purposes an individual can possess up to 15 pounds of depleted uranium under a Nuclear Regulatory Commission general license.

2. The international unit for measuring activity (the rate of radioactive decay) is the becquerel (Bq), where one Bq equals one disintegration per second. An older unit of activity is the curie (Ci), where one Ci equals 3.7 x 1010 disintegrations per second.

3. Under Department of Transportation regulations the dose rate at the container surface must be less than 0.5 mrem/hr in order to transport the depleted uranium without any external labeling indicating that it contains a radioactive source.

4. Thomas B. Cochran and Christopher E. Paine, The Amount of Plutonium and Highly Enriched Uranium Needed for Pure Fission Nuclear Weapons (Adobe Acrobat file, 307 k), Natural Resources Defense Council, Revised April 13, 1995.

last revised 9/11/2003

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