ucloar power is rc-emerging as a major part of the energy portfolios of a wide variety of nations. With over 50 reactors being built around the world today and over 100 more planned to come online in the next decade, many observers are proclaiming a "nuclear renaissance" (1). The success of a nuclear revival is dependent upon addressing a well-known set of challenges, for example, plant safety (even in the light of improved reactor designs), costs and liabilities, terrorism at plants and in transport, weapons proliferation, and the successful siting ofthe plants themselves (2, 3). Particularly challenging is the disposal of high-level nuclear wastes (HLW). More than a quarter-million tons of commercial HLW is in need of disposal worldwide (1). Wastes accumulate at all stages ofthe fuel and weapons development cycle: mining, enrichment, fabrication, and reactor operation. The most dangerous of these wastes accumulate at the...