Nigeria shipped its highly enriched uranium (HEU) back to China, making it the 33rd country, plus Taiwan, to become HEU free. Nigeria’s one kilogram of HEU was used to fuel a Chinese-supplied miniature neutron source reactor used for a range of research activities. Although one kilogram of HEU is far less than what is necessary for a nuclear warhead, the fuel was enriched to more than 90 percent uranium-235, which is considered weapons grade.