The report, Commercial Spent Nuclear Fuel and High-Level Radioactive Waste Inventory Report(FCRDNFST- 2013-000263, Rev.4), provides information on the inventory of commercial spent fuel, referred to in this report as used nuclear fuel (UNF), as well as Government-owned UNF and High Level Waste (HLW) in the U.S. Department of Energy (DOE) complex. Inventory forecasts for commercial UNF were made for a few selected scenarios of future commercial nuclear power generation involving the existing reactor fleet including one scenario involving reactors under construction.