The quasistatie method was compared with a direct finite-difference method of solving two-dimensional, thermal reaeto~ t~ansient problems with thermal-hydraulicfeedback. Calculations using both metbds Mere perfomed for a eylind~ieal (P-z), D20-mode~ated and-cooled, uranium-fueled reactor. This study shous that the quasistatie method is capable of producing highlg accurate ~esults, relative to the direct finite-differenee method, for two-dimensional thermal reactor transients with feedback. The quasistatic method also offe~s the :flexibilit~{ of using larger time steps between flux shape calculations uithout encountering numerical problems than the direct method. The quasistatic and direct method codes used in this uork aye eompwable with respect to accuracy and computing costs except for transients uith ueak spatial effects. For such t~ansients, much larger time steps can be used in the quasistatic code than in the direct method code to achieve a specified accuracy which, in turn, provides a considerable savings iz computing costs.
Nuclear fission energy is as inexhaustible as those energies usually termed "renewable"' such as hydro, wind, solar, and biomass. But, unlike the sum of these energies, nuclear fission energy has sufficient capacity to replace fossil fuels as they become scarce. Replacement of the current thermal variety of nuclear fission reactors with nuclear fission fast reactors, which are 100 times more fuel efficient, can dramatically extend nuclear fuel reserves. The contribution of uranium price to the cost of electricity generated by fast reactors, even if its price were the same as that of gold at US$14,000/kg, would be US$0.003/kWh of electricity generated. At that price, economically viable uranium reserves would be, for all practical purposes, inexhaustible. Uranium could power the world as far into the future as we are today from the dawn of civilization-more than 10,000 years ago. Fast reactors have distinct advantages in siting of plants, product transport and management of waste. BackgroundIn 1983, Bernard L. Cohen [Cohen, 1983] showed quantitatively that uranium as nuclear fission fuel is, for all practical purposes, inexhaustible, given the use of fuel efficient breeder reactors. This idea had also been suggested earlier by others [Lewis, 1968]. The aim of this paper is to support this claim and show that technology is close at hand to take full advantage of this endless resource.When energy sources such as hydro, wind, solar, biomass and geothermal are termed "renewable", what is really meant is that they are inexhaustible. If, for all practical purposes, nuclear fission fuel is inexhaustible, then it too is one of the "renewables". Moreover, nuclear fission has much greater capacity to provide energy than all of the other "renewable" energies put together. The paper in Track 1 of this conference, "A Strategy for Adequate Future World Energy Supply and Carbon Emission Control" [Lightfoot, 2006], makes the case that nuclear fission is the only source of energy large enough to replace fossil fuels on the scale required that is available now.Currently, primary energy supplied by nuclear fission is about 29 EJ/yr (EJ = 1 exajoule = 1018 joules = 0.95 quads) and is growing slowly at about 0.3 EJ/yr [Schneider, 2005]. However, as fossil fuels become scarce the use of nuclear fission energy will have to grow considerably faster than the current rate if it is to replace even the 2005 fossil fuel consumption of 388 EJ.The uncertainty of long term fossil fuel supply is a good reason to proceed expeditiously with development and commissioning of nuclear fast reactors. We must be ready with a source of fuel that is large enough to displace fossil fuels because they comprise 85% of the world's fuel supply and are directly related to people's well-being [Hoffert, 1997].Replacing the current thermal reactors which use about 0.7% of the uranium fuel with fast breeder reactors that consume virtually all of the uranium will assure long term energy 1-4244-0218-2/06/$20.00 C)2006 IEEE.
Demonstrating a credible and acceptable way to safely recycle 'used' nuclear fuel will clear a socially acceptable pathway for nuclear fission to be a major low-carbon energy source for this century. Here we advocate for an accelerated timetable for commercial demonstration of Generation IV nuclear technology, via construction of a prototype metal-fueled fast neutron reactor and associated 100 t/year pyroprocessing facility to convert and recycle spent fuel (routinely mischaracterized as "nuclear waste") that has accumulated from decades of lightwater reactor use. Based on the pioneering research and development done during the 'Integral Fast Reactor' (IFR) program at Argonne National Laboratory, 1 a number of synergistic design choices are recommended: (a) a pool-type sodium-cooled reactor; (b) metal fuel based on a uranium-plutonium-zirconium alloy, and (c) recycling using electrorefining and pyroprocessing, thereby enabling the transmutation and repeated reuse of the actinides in the reactor system. We argue that alternative technology options for the coolant, fuel type and recycling system, while sometimes possessing individually attractive features, are challenging to combine into a sufficiently competitive overall system. A reactor blueprint that embodies these key design features, the General Electric-Hitachi 380 MWe PRISM, 2 based on the IFR, is ready for a commercial-prototype demonstration. A two-pronged approach for completion by 2020 could progress by a detailed design and demonstration of a 100 t/year pyroprocessing facility for conversion of spent oxide fuel from light-water reactors 3 into metal fuel for fast reactors, followed by construction of a prototype PRISM as a commercial-scale demonstration plant, with an initial focus on secure disposition of separated plutonium stocks. Ideally, this could be achieved via an international collaboration. Several countries have expressed great interest in such collaboration. Once demonstrated, this prototype would provide an international test facility for any concept improvements. It is expected to achieve significant advances in reactor safety, reliability, fuel resource sustainability, management of long-term waste, improved proliferation resistance, and economics.
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