Combine orange juice and sugar in a large nonaluminum skillet. Bring to a boil over medium heat, stirring constantly until sugar dissolves. Cook 17 minutes or until mixture is reduced to 1 cup. Remove from heat; add butter, stirring until butter melts. Gently stir in orange sections. Serve warm, or cover and chill. Stir gently just before serving. Store in an airtight container in refrigerator.