A delegation from the United Nation's nuclearwatchdogarrived in Seoul on Sunday for a follow-up inspection after South Korea admitted toclandestinenuclear programs.

The four inspectors from the International Atomic Energy Agency immediately went to the Korean Atomic Energy Research Institute, about 150 kilometers south of Seoul, after they arrived Sunday. The team's eight-day itinerary is being kept secret.

The team did not speak to reporters at Incheon International Airport in Seoul.

The delegation will carry out more checks of government-run nuclear research facilities where unauthorized experiments were conducted, some more than 20 years ago. They will also question the scientists involved.

IAEA inspections in late August and early this month showed that South Korean government facilities had made unauthorized nuclear experiments.

South Korea admitted experimenting with traces ofplutoniumin 1982 and uranium enrichment in 2000.

Myongji University professor Lee Dong-bok, in Seoul, says he thinks the IAEA will find that South Korea does not have a weapons program. Professor Lee says the amount of nuclear material involved in the experiments was too small and not of weapons-grade quality.

"This enrichment was part of the scientific experiment, in the framework of the nuclear fuel cycle, rather than enrichment for any military purpose," he said.

The team, headed by Finland's Saukkonen Heikki Antero, will refer its findings to the U.N. Security Council, which could impose sanctions if South Korea is found in violation of its international nuclear agreements.

Therevelationsabout the South Korean programs have complicated international efforts to get communist North Korea to abandon its nuclear weapons development.

Pyongyang's news agency on Saturday said South Korea's clandestine nuclear experiments prove that the United States has a double standard when it comes to nuclear proliferation on the Korean peninsula. The report also said the communist state will never dismantle its nuclear deterrent force until Washington changes its hostile policy.

watchdog: a guardian or defender against theft or illegal practices or wasteclandestine（监察人员）

clandestine: conducted with secrecy; withdrawn from public notice, usually for an evil purpose; kept secret; hidden; private; underhand（秘密的）

plutonium: solid silvery gray radioactive transuranic element whose atoms can be split when bombarded with neutrons; found in minute quantities in uranium ores but is usually synthesized in nuclear reactors; 13 isotopes are known with the most important being plutonium 239（钚元素）

revelation: the act of revealing, disclosing, or discovering to others what was before unknown to them（显露；泄露）