The Atomic Vapor Laser Isotope Separation program at Lawrence Livermore National Laboratory in Livermore, Calif., has been suspended, according to USEC Inc., an energy company based in Bethesda, Md., that sells enriched uranium and manages the program under contract with the US Department of Energy. After completing a review of the program's technology, the company concluded that nagging technological problems would require too much money and would drive up the cost of plant construction. As a result, the 26-year research effort, which received about $100 million in funding in the last year, will be wound down, leaving about 550 employees scrambling. Livermore is looking to reassign many of the 200 who work directly for the labs; most of the remaining 350 work for contractors and will face layoffs.