The U.N. nuclear watchdog agency said Thursday that South Korea four years ago produced a small amount of uranium enriched to close to the level that could be used in weapons.
A confidential study prepared by the International Atomic Energy Agency in Vienna confirmed previous news reports that the South Koreans had failed to disclose several experiments involving uranium enrichment and conversion and plutonium separation between 1982 and 2000.
The report called the concealment “a matter of serious concern,” but said agency inspectors had discovered no evidence that South Korea was pursuing a nuclear weapons program.
A copy of the eight-page report was made available to The Times on Thursday. IAEA officials declined to comment on the findings. The agency’s board of governors will take up the matter at a Nov. 25 meeting.
A Western diplomat in Vienna said the United States might push for South Korea’s hidden experiments to be referred to the United Nations Security Council as a violation of the Nuclear Nonproliferation Treaty.
This may serve as a precedent for taking similar action against Iran, which the United States has accused of secretly operating a nuclear weapons program. Iran has maintained that its nuclear program is strictly to generate electricity.
The IAEA is expected to issue a new report soon on Iran’s disputed program in preparation for the upcoming board meeting. Iran concealed key aspects of its nuclear program for 20 years, and the United States is demanding that it be referred to the Security Council for possible sanctions.
Tehran failed to give a definitive response Thursday to a European deal to freeze Iran’s nuclear program. In a Paris meeting last weekend, Britain, France and Germany had offered lucrative trade incentives and a way to avoid sanctions if Iran agreed to suspend sensitive nuclear enrichment activities.
If Iran refuses to halt its nuclear enrichment work, the European Union would back U.S. efforts to refer the issue to the Security Council, which could impose sanctions. Iran had promised a reply by Thursday so it could be included in a report the IAEA may distribute to its board members as early as today.
Although Iranian officials said they had delivered an answer to European ambassadors in Tehran on Thursday night, EU diplomats said it was not the clear answer they had hoped for. Some suspected it was a gambit to keep negotiations open, and perhaps attract a better offer from the European countries. The three nations had offered Iran a light water nuclear reactor in the future, which would be more difficult to use for weapons production than a heavy water reactor. They also promised diplomatic and economic rewards for total suspension, but Iran wanted tangible benefits up front, officials said.
A similar deal with Britain, France and Germany signed in October 2003 fell apart within six months because of a lack of agreement on the terms.
South Korea had rebuffed IAEA inspectors several times in recent years, according to the report. The government disclosed some of the experiments earlier this year, blaming them on scientists operating without government approval or knowledge.
South Korean officials denied that any bomb-grade uranium had been produced. But the new report said that experiments using a technique called laser isotope separation had enriched uranium from 10% to 77% of the isotope U-235. The research took place at the government-affiliated Korea Atomic Energy Research Institute.
The enrichment process is central to producing material for nuclear weapons, which usually have fuel cores enriched to between 80% and 90%.
The IAEA praised South Korea’s cooperation since its disclosure of the experiments.
The report said that the investigation was continuing and that inspectors were examining the level of foreign assistance provided to South Korea.
The disclosure forced South Korea to insist that it had no ambitions for nuclear weapons, in an attempt to head off complications in on-again, off-again talks between North Korea and five other nations about the North’s nuclear program.