As noted throughout this report, USEC will be going through a period of transition during 2013 as we cease enrichment at the Paducah plant, complete the Megatons to Megawatts program, complete the American Centrifuge RD&D program and appropriately reduce the size of our corporate organization. Given the uncertainties of that transition and the incremental nature of federal funding for the RD&D program, our guidance for USEC financial results and metrics for 2013 will be limited.
In line with our previous guidance, we expect SWU volume for the LEU segment in 2013 to decline by about one-third compared to 2012. The average SWU price billed to customers is expected to increase by about 5 percent. We anticipate full-year revenue for the LEU segment of $1.4 billion, with about $50 million attributable to natural uranium sales. For the six-month period ending June 30, 2013, we expect LEU segment revenue of approximately $625 million.
NAC International was the largest source of revenue for the contract services segment in 2012 and we sold NAC on March 15, 2013. Results of operations for NAC in 2013 and the gain on sale, expected to total approximately $30-$40 million, will be recorded below the gross profit line in the first quarter of 2013.We are in the midst of an RD&D program that has an 80 percent DOE and 20 percent USEC cost share. We have adjusted our program spending to accommodate changes to the timing and amount of federal funding. Federal funding for the program has been incremental and subject to Congressional action. We have no assurance that the remaining federal funds for the program will be appropriated; therefore we are not providing guidance for spending on advanced technology. Also below the gross profit line, we expect selling, general and administrative expenses of $29 million during the six-month period ending June 30, 2013.