The United States of America ratified the Joint Convention on the Safety of Spent Fuel Management and on the Safety of Radioactive Waste Management (Joint Convention) in April 2003. The Joint Convention establishes an international peer review process among Contracting Parties and provides incentives for nations to take appropriate steps to bring their nuclear activities into compliance with general safety standards and practices. The U.S. participated in Review Meetings of the Contracting Parties to the Joint Convention in November 2003, May, 2006, and May 2009, in Vienna, Austria. This Fourth Report, an update of the U.S. National Report prepared under the Joint Convention in September 2011, documents spent fuel and radioactive waste management safety in the U.S. under the terms of the Joint Convention. It was prepared by the U. S. Government for review by the Contracting Parties.