Complex sentence: The Megatons to Megawatts Program, successfully completed in December 2013, is the popular name given to the program which is also called the United States-Russia Highly Enriched Uranium Purchase Agreement.
Split into simpler sentences: The Megatons to Megawatts Program, successfully completed in December 2013, is the popular name given to the program. Also called the United States-Russia Highly Enriched Uranium Purchase Agreement.