In a move that could add $1 billion to $2 billion to US Treasury coffers, the Maryland-based US Enrichment Corp. has received federal approval to proceed with its sale to the private sector. US Enrichment provides enriched natural uranium for nuclear reactor fuel. Free from government control, the company will have more say over the Atomic Vapor Laser Isotope Separation project -- a key technology in enriching natural uranium. Government funding for the company is anticipated to run out by May 1. More than 600 jobs could be lost when funding is cut.