According to the World Nuclear News, Nigeria is officially HEU-free. The IAEA monitored the transfer of HEU from Nigeria to China. “More than 1 kilogram of Chinese-origin HEU from the Nigerian Research Reactor-1 (NIRR-1) was returned to China in an operation involving the two countries, the International Atomic Energy Agency and the US Department of Energy’s National Nuclear Security Administration (NNSA).”