ACTINIDE BURNING IN A LEAD-BISMUTH-COOLED CRITICAL FAST REACTOR WITH ECONOMIC ELECTRICITY GENERATION *
A Lead Bismuth-cooled fast reactor concept for actinide burning and low-cost electricity production and excellent safety characteristics is proposed. The concept employs metallic thoriumbased fuel (Th-U-Pu-MA-Zr) in a 700 MWth core. The transuranics destruction rate per MWth-yr is 66% that of an accelerator-driven system using the same initial transuranics composition in fertile-free fuel. Coolant void reactivity mitigation is achieved through the use of streaming fuel assemblies and both the Doppler and fuel thermal expansion feedback are negative. The small negative fuel temperature and coolant temperature reactivity coefficients and negative core radial expansion coefficient provide self-regulating characteristics, so that the reactor is capable of inherent shutdown in major transients without scram, as in the Integral Fast Reactor (IFR). * This project is supported by an INEEL Laboratory Directed Research and Development Project.
Physics Studies of Weapons Plutonium Disposition in the Integral Fast Reactor Closed Fuel Cycle
The core performance impact of weapons plutonium introduction into the Integral Fast Reactor (IFR) closed fuel cycle is investigated by comparing three disposition scenarios: a power production mode, a moderate destruction mode, and a maximum destruction mode, all at a constant heat rating of 840 MW(thermal). For each scenario, two fuel cycle models are evaluated: cores using weapons material as the sole source of transuranics in a once-through mode and recycle cores using weapons material only as required for a makeup feed. In addition, the impact of alternative feeds (recycled light water reactor or liquid-metal reactor transuranics) on burner core performance is assessed. Calculated results include mass flows, detailed isotopic distributions, neutronic performance characteristics, and reactivity feedback coefficients. In general, it is shown that weapons plutonium does not have an adverse effect on IFR core performance characteristics; also, favorable performance can be maintained for a wide variety of feed materials and fuel cycle strategies.
U.S. spent-fuel disposal strategies and international safeguards
Domestic safeguards for fissile nuclear materials are universal, and a variety of international safeguards regimes are applicable, in most member states of the International Atomic Energy Agency (IAEA), to declared nuclear facilities dedicated to peaceful missions. The U.S. strategy to dispose of all spent nuclear fuels (SNFs) and high-level wastes (HLWs) in engineered geologic repositories has a sometimes-overlooked consequence, namely, the need to maintain domestic and international safeguards in perpetuity. The Office of Civilian Radioactive Waste Management of the U.S. Department of Energy (DOE), which has the responsibility to accept and store the spent fuels in the long term either in surface facilities or in engineered geologic repositories, has yet to include safeguards issues in their mission plan.'' There are several stages in the nuclear fuel cycle where materials usable in weapons are available for diversion. This discussion, however, is limited to the potential diversion of spent fuels for clandestine plutonium recovery. The concepts proposed here highlight safeguards elements necessary for a pragmatic safeguards system for SNF from nuclear power generation. The efforts required to initiate and maintain a verifiable international safeguards regime are examined in the context of a typical storage facility in the United States.