A second team of U.N. nuclear experts arrived in North Korea on Saturday to monitor the shutdown and sealing of the country's sole plutonium-producing reactor. The six-member International Atomic Energy Agency team will replace an initial team that went to North Korea on July 12 to supervise the shutdown of the Yongbyon reactor, the key component of the North's nuclear program. «I am leading the verification mission to continue activities, monitoring and verification activities,» Ryszard Zarucki, told broadcaster APTN on his arrival at the Pyongyang airport. He said he expects to stay about two weeks in North Korea.