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– Amb. Thomas Hajnoczi
Chair, MTCR
May 19, 2021
IAEA: Seoul's Nuclear Sins in Past

Paul Kerr

International Atomic Energy Agency (IAEA) Director-General Mohamed ElBaradei issued a report Nov. 11 describing South Korea’s failure to notify the agency of past research that could have potentially aided a nuclear weapons program. The report, however, says there is no indication of recent activity.

The report provides more detail about the IAEA’s investigation—first disclosed in September—of Seoul’s unreported nuclear activities, which date back more than 20 years and include production of plutonium and enriched uranium. (See ACT, October 2004.) Both can be used as the explosive material in nuclear weapons.

ElBaradei said South Korea was required to report these activities as part of its safeguards agreement with the agency. Safeguards agreements require states-parties to the nuclear Nonproliferation Treaty (NPT) to allow the IAEA to monitor their declared civilian nuclear activities to ensure that they are not diverted to military use.

South Korea acceded to the NPT in 1975. It also signed a joint declaration with North Korea in 1991 stating that both countries will refrain from possessing nuclear fuel reprocessing and uranium-enrichment facilities. Such facilities can produce plutonium and highly enriched uranium, respectively.

The report calls South Korea’s failure to report these activities “a matter of serious concern,” but adds that “there is no indication that the undeclared experiments have continued.” South Korea had a nuclear weapons program during the 1970s, but discontinued it later that decade under U.S. pressure. (See ACT, October 2004.)

South Korea has maintained that scientists conducted the nuclear activities without the knowledge of high-level officials.

In a Nov. 26 statement, the IAEA Board of Governors expressed “serious concern” about Seoul’s unreported nuclear research, but also welcomed the government’s “cooperation” with the IAEA. The board did not refer South Korea to the UN Security Council, despite widespread speculation that it might do so. The IAEA is required to report findings of a country’s noncompliance with its safeguards agreement to the council.

South Korea disclosed its nuclear activities after ratifying an additional protocol to its IAEA safeguards agreement in February. Such protocols expand the IAEA’s authority to investigate NPT states-parties’ declared and undeclared nuclear facilities. They also require NPT members to declare significantly more of their nuclear-related activities than required by ordinary safeguards agreements.

South Korea submitted its initial declaration related to the protocol in August. IAEA inspectors have made three trips to the country since then to visit sites associated with Seoul’s nuclear activities.

Uranium Enrichment

According to ElBaradei’s report, South Korea told the IAEA in August that it used the atomic vapor laser isotope separation (AVLIS) method to conduct “laboratory scale” experiments involving “relatively small” amounts of uranium. This technology uses lasers to separate the fissionable uranium-235 isotope from vaporized uranium. “Enriched” uranium has a concentration of uranium-235 greater than the approximate 1 percent concentration that occurs naturally.

The report adds that, in 2000, South Korean scientists at the Korea Atomic Energy Research Institute (KAERI) produced 200 milligrams of enriched uranium. While the average enrichment level was about 10 percent uranium-235, some levels reached up to 77 percent—a level theoretically sufficient for a nuclear weapon. Most civilian power plants use fuel with a concentration of less than 20 percent uranium-235.

South Korea began laser research in the 1960s, the report says, and worked on developing AVLIS technology during the 1990s. South Korean scientists conducted several AVLIS-related experiments involving uranium between 1993 and 2000, as part of what government officials claim was a “broader experimental effort to apply AVLIS techniques to non-nuclear materials.” Seoul failed to report the uranium experiments to the IAEA as required by its safeguards agreement.

South Korea produced more than 150 kilograms of natural uranium metal from a less-processed form of uranium, the report says, adding that 3.5 kilograms of the metal were used in the enrichment experiments. Seoul both imported uranium ore and extracted uranium from a domestic mine, the report says.

South Korea also disclosed in October that it carried out an experiment from 1979 through 1981 using another method of uranium enrichment. Called the chemical exchange process, this method runs a solution containing uranium through a column of specially designed material to separate the uranium-235. According to the report, South Korea produced a “very small quantity” of uranium enriched to a degree just slightly greater than that of natural uranium. The government failed to report the use of 700 grams of uranium powder used in the experiment—a violation of its safeguards agreement.

Plutonium Separation

South Korea told the agency in March that in 1982, it had separated plutonium from depleted uranium in a hot cell associated with a research reactor. On Nov. 5, Seoul reported that that it had separated a total of 0.7 grams of the material.

According to the report, the IAEA assessed that only one plutonium separation experiment was conducted at the site and that the experiment could not have been conducted after 1982.

The IAEA began its investigation of the experiments after discovering particles of plutonium at the hot cell in 1997 and again in 2003.

Next Steps
The report states that the IAEA is continuing to assess Seoul’s nuclear declarations as well as investigate several other outstanding issues. The board requested that ElBaradei report on the investigation “as appropriate,” the chair’s statement says.

These include evaluating South Korea’s claim that the AVLIS experiments were only authorized by the president of KAERI. A diplomatic source in Vienna close to the IAEA told Arms Control Today Nov. 15 that higher-level officials were likely aware of the experiments, citing the involvement of 14 government scientists, the use of expensive equipment, and past efforts to deceive the agency.

The IAEA also is investigating the foreign assistance South Korea received for its laser program, although the report does not identify South Korea’s suppliers.

Additionally, the agency is attempting to resolve issues concerning Seoul’s plutonium and uranium-conversion experiments. The agency has asked the government to provide records or detailed explanations regarding its plutonium experiments, but South Korea has said the records do not exist.

According to the report, the IAEA also is trying to resolve a discrepancy concerning South Korea’s indigenous uranium ore. IAEA samples from the ore seem to contradict Seoul’s claim that the material was extracted from a South Korean mine.

The report states that South Korea has “provided active cooperation” since disclosing its undeclared nuclear activities to the IAEA, but Seoul has not always been so cooperative. South Korea originally denied that it had conducted either uranium-enrichment or plutonium-separation experiments. It also delayed giving IAEA inspectors access to its former laser-enrichment facilities until after ratification of its additional protocol. In addition, Seoul did not disclose all of its conversion activities in its August declaration.