NNSA converts domestic and international civilian research reactors and isotope production facilities from the use of weapons of mass destruction (WMD)-usable highly enriched uranium (HEU) fuel to low enriched uranium (LEU) fuel.  These efforts result in permanent threat reduction because the use of WMD-usable HEU in the civilian fuel cycle is minimized or eliminated.  NNSA also assists reactor operators to perform feasibility studies and safety analyses required for regulatory approval to convert the reactors and to procure LEU replacement fuels.