Two former Russian servicemen were detained here after authorities found 13 pounds of uranium-235 stashed in emptied glass sour cream jars in their apartment, officials confirmed Tuesday.
The size of the seizure - the second in Ukraine this year - raises fresh concerns about the potential danger of nuclear materials hemorrhaging from the former Soviet Union into the hands of outlaw regimes and international terrorists.
The traffickers arrested in Ukraine earlier this month told police that the cylindrical nuclear pellets in the jars were bomb-grade uranium-235 from Russia, Kievski Vedomosti newspaper reported Tuesday.
Ukrainian Interior Ministry spokesman Olexandr Harlamov, who co-wrote the newspaper article, confirmed that preliminary laboratory tests have shown that the radioactive cache contains uranium-235 but said more testing is needed to determine how pure it is.
Uranium-238, radium and palladium - materials not used in bombmaking - were also found in the pellets. Experts say that 30 pounds to 40 pounds of nearly pure uranium-235 is enough to build a simple atomic weapon.
The Ukrainian seizure will be deemed significant if the material is found to be highly enriched, meaning that it contains more than 20 percent uranium-235, said physicist David Albright, president of the Institute for Science and International Security in Washington.