U.S. National Nuclear Security Administration announced successful removal of "the last known HEU from Nigeria." The material, "more than 1 kg" of HEU, was supplied to the NIRR-1 research reactor by China. It was returned to the country of origin. A miniature neutron source reactor (MNSR), NIRR-1 is operated by the Center for Energy Research and Training (CERT) at the Ahmadu Bello University, Zaria. It was converted to LEU fuel in October 2018.
The NIRR-1 reactor conversion and removal of HEU from Nigeria is part of the effort to convert MNSR reactors to LEU. In 2016 China converted one of its MNSR reactors, MNSR IAE in Beijing. In 2017, it helped convert the GHARR-1 reactor in Ghana. HEU was removed from Ghana in August 2017. Chinese-origin MNSR reactors that use HEU fuel are located in Pakistan and Syria. China operates an HEU MNSR reactor in Shenzhen University.
Nigeria became the 34 country plus Taiwan that had all their HEU removed. (NNSA counts 33 countries plus Taiwan, but its count does not include Iraq. UPDATE: NNSA used to exclude Iraq from its list of cleaned out countries, but recently counts it in. The current difference in numbers is due to the fact that NNSA does not count Jamaica as a cleaned out country since it has never had more than 1 kg of HEU. In any event, that material was removed in September 2015http://fissilematerials.org/blog/2015/09/allheuremovedfromjama.html.)