Lockheed Martin Energy Systems was fined by the Department of Energy for multiple violations of nuclear safety requirements at its site in Oak Ridge, TN. These violations included: (1) The December 8, 1999, explosion of sodium potassium liquid metal in the Alpha 5 Facility that resulted in injury to 11 workers. The contractor failed to identify and mitigate the explosive hazards associated with this material, despite a number of opportunities to do so.; (2) Violations of criticality safety requirements and work process controls which resulted in a DOE-ordered operational stand down on November 5, 1999, and curtailment of fissile material movements in Building 9212 on December 14, 1999; (3) Significant deficiencies in the design, procurement and fabrication of the Hydrogen Fluoride Supply System, a critical system required for resumption of enriched uranium operations. The investigation identified failures with virtually every phase of the project; and (4) Numerous examples of violations occurring during the period July 1998 to December 1999 involving failure to adhere to Operational Safety Requirements and other Authorization Basis requirements.