Two former Russian servicemen were detained here after authorities found 13 pounds of uranium-235 stashed in emptied 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 men arrested in Ukraine earlier this month told police that the cylindrical nuclear pellets in the glass 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 bomb-making--were also found in the pellets. Experts say 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% uranium-235, said physicist David Albright, president of the Institute for Science and International Security in Washington.
But even if the cache contains only moderate amounts of uranium-235, the seizure renews fears that significant quantities of nuclear materials may be slipping out of former Soviet republics undetected.
"First it was grams coming out, then kilograms, and the amounts are increasing," Albright said. "This problem just isn't going to go away, and it's not clear that Russian officials have turned the corner."
German intelligence services, in a report leaked to the press last month, said 124 attempts to smuggle nuclear materials were uncovered in 1994, compared with 56 such cases a year earlier, and noted a "quantum leap" in radioactive smuggling from the former Soviet Union.
FBI Director Louis J. Freeh has called the trend "the greatest long-term threat to the security of the United States" since the end of the Cold War.
There is no evidence to date that smugglers have laid hands on weapons-grade uranium--the stuff of Western intelligence nightmares--but there is ample reason to worry that they will.
"Russia has 2 million pounds of weapons-grade uranium," Albright said. "They really produced a lot of material, and their whole way of safeguarding it has more or less collapsed."
Intelligence agencies are especially worried that nuclear-threshold countries such as North Korea, Libya, Iran and Iraq may be willing to pay high prices for high-quality uranium and plutonium.
Russian officials have vowed to increase security at nuclear plants, believed to be the source of much of the nuclear material seized from smugglers. Nevertheless, the pace of the uranium seizures indicates that the leaks have yet to be plugged.
Last month, a Russian Cabinet minister revealed that 80% of the checkpoints at atomic power stations did not have equipment that could detect radioactive substances being taken out the door in an employee's pocket.
Harlamov, however, said he was unconvinced that the nuclear pellets seized in Kiev were smuggled from Russia.
Detailed chemical analysis can reveal where a batch of nuclear material was produced. But because Russia is the sole producer of all the nuclear material in Ukraine, simply demonstrating a Russian source would not prove that the nuclear pellets came to Ukraine illicitly.
With five nuclear power stations and more than 1,000 nuclear warheads inherited from the Soviet Union, Ukraine has its own potential for nuclear leaks.
For example, last year's disappearance of two nuclear fuel rods from the Chernobyl nuclear plant, site of a 1986 accident, remains to be solved.
According to Interior Ministry spokesman Ivan Levchenko, Ukrainian police thwarted two attempts at nuclear smuggling in 1993, but both involved less than three pounds of non-weapon material.
In January, authorities detained three traffickers with a vaguely described device made up of a uranium-235 core and a uranium-238 covering, Kievski Vedomosti reported without providing details.
It quoted Mikhailo Sadavy, deputy chief of the Interior Ministry's organized crime fighting unit, as saying: "It's early to say that Ukraine is a stable transit point for nuclear trade, but two incidents in a row put one on guard."
It was the hunt for the killers of the popular Russian journalist Vladislav Listyev that led to this month's seizure.
When Russian newspapers, read widely in Ukraine, published composite pictures of Listyev's suspected killers, callers to the Kiev police reported two men who resembled them.
Initially, investigators suspected the men were drug or weapons traffickers.
But when police detained one of them outside his apartment and checked the bag he was carrying, they found a cellophane-wrapped jar like the kind used for storing sour cream and preserves. The jar contained more than four pounds of the cylindrical pellets, which the suspect identified as uranium-235. Two similar jars were found in the apartment.
The suspected smugglers apparently took no precautions to protect themselves from the radioactive material.