Quotes of the Day

In the 1970s, South Korea ran a program to develop technology to reprocess spent nuclear fuel. By 1976, it was in the final stages of buying a reprocessing plant from France when the U.S. pressured Seoul to end the program. Washington suspected Korea wouldn't merely reprocess the fuel for power generation, but was planning to use the technology to make plutonium for atomic weapons. For Kim Chul, the nuclear expert who headed the project, the reprocessing dream never died. Kim keeps the only known copy of the project blueprints on a shelf in his study. "We should own that technology," says Kim. "We were stopped by international society."

Apparently, not completely, as revelations pouring out of Seoul this month have revealed. One centers around an idle TRIGA Mark III research reactor located in a dilapidated building in a residential suburb of Seoul. In the 1970s and '80s, the TRIGA Mark III was used by Korean nuclear scientists to test nuclear fuel and study isotopes. In April or May 1982, scientists took an irradiated test fuel rod from the reactor and placed it in one of the research installation's "hot cells," a room clad with lead to block radioactivity. Using robotic arms and peering through a leaded window, the scientists sliced open the rod and dissolved it. That process separated a small quantity of the plutonium that had been produced when the fuel was burned inside the reactor.

South Korea is not allowed to make plutonium or enriched uranium, the two fuels for nuclear bombs, under its nonproliferation commitments, and the procedure carried out in 1982 would have had few other purposes. "It is something which is pretty exclusively reserved for finding out about plutonium," says a Geneva-based diplomat. It's also a procedure that's hard to cover up—although South Korea appears to have tried. The Ministry of Science and Technology says it reported the experiment to the International Atomic Energy Agency (IAEA) in 1983, but its report had a significant error. South Korea told the IAEA its scientists had dissolved fuel from a fresh rod, not a spent one. Plutonium cannot be extracted from a fresh uranium fuel rod. The IAEA had no reason to be alarmed until 1997, when an inspection of the facility by the IAEA turned up traces of plutonium.

Last week, South Korea confessed to the 1982 plutonium experiment just a week after admitting its scientists had enriched a small amount of uranium in 2000 at a different facility in the city of Taejon, 120 km south of Seoul. The government went into strenuous spin mode, especially when accused of covering up the nuclear fiddling, a charge that was "groundless and unsubstantiated," according to the Foreign Ministry. But official explanations for how the nuclear materials got produced became more threadbare through the week. The uranium experiment in 2000 was supposedly carried out by a small group of very junior scientists in Taejon. But last week, a Geneva-based diplomatic source disclosed that senior scientists were also involved. The government maintains that the small amount of uranium produced was extremely weak; diplomats close to the investigation tell TIME South Korea has admitted to the IAEA it was of near weapons-grade potency. With regard to the plutonium production in 1982, the government said the misreporting to the IAEA in 1983 was a "mistake," that the final report on the experiment was lost and the leader of the group had died. Therefore, the government said, it had no record of how much plutonium was produced—or, ominously, where the material ended up.

South Korea relies on atomic energy for 40% of its electricity, which translates into a vast industry of power plants, government-run research labs—and a whole lot of hot fuel rods. But it is also a major player in the six-nation talks that are trying to arm-twist North Korea into shuttering its own uranium- and plutonium-based nuclear-weapon programs. After hearing the South's explanations, Pyongyang quickly trumpeted a "double standard." Then came news that the South had noticed an enormous explosion in North Korea last week, though the source was unclear.

But one thing is clear: this story isn't over. Earlier this month, an IAEA team left Seoul after taking more samples at the TRIGA Mark III reactor. According to the Geneva-based diplomat, "There is more to come."

• Donald Macintyre and Anthony Spaeth
• More details come to light concerning South Korea's nuclear research