Beginning in the 1950s, the Department of Energy (Department) and its predecessor agencies provided certain nuclear materials -- including plutonium and uranium -- to other government agencies, academic institutions, and commercial facilities. These materials, provided via loan or lease under authority granted by the Atomic Energy Act of 1954, were to be used for research, medical purposes, or projects consistent with the Department's mission. As of September 30, 2000, the Department had nuclear materials at over 300 non- Department domestic facilities. The Department and Nuclear Regulatory Commission (NRC) share responsibility for nuclear materials provided to licensees, including accounting for the material and tracking its location. The Nuclear Materials Management and Safeguards System (NMMSS) is an electronic database used by these organizations to assist them in carrying out their respective responsibilities. During our audit of the Department's Fiscal Year 2000 Financial Statements, the Office of Inspector General identified apparent inaccuracies in NMMSS.