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Advanced Fission Technologies and Systems
Published in William J. Nuttall, Nuclear Renaissance, 2022
Nuclear reactors based upon fast neutron fission were regarded by many in the 1960s and the 1970s as the vital technological step to ensure the long-term sustainability of nuclear power. During those years energy policymakers were troubled by the anticipated depletion of crude oil reserves. Their forward predictions showed a continued expansion of conventional thermal nuclear power plants with uranium-based fuel cycles. This led to a second fuel resource insecurity reminiscent of their petroleum fears. In the long term, the worry was that uranium ores would be depleted as a source of uranium-235 nuclear fuel. The fast reactor concept held out the prospect of near indefinite sustainability for nuclear energy. Fast reactors would open up a much wider range of possibilities, as at fast neutron energies, a wider range of nuclear processes are possible including, for example, the enhanced conversion of fertile uranium-238 into fissile plutonium-239. While the term ‘fast’ applies to the neutron energies involved, it is the aspect of the conversion of abundant uranium-238 into plutonium-239 that, in those years, led to the insertion of the word ‘breeder’ into the title ‘fast breeder reactor’. The ability of such reactors to produce (or ‘breed’) their own fuel (e.g. plutonium-239) from otherwise useless materials (e.g. uranium-238) seemed to many to be the long-term sustainable solution to the anticipated depletion of the world’s uranium-235.
Fast Reactors, Gas Reactors, and Military Reactors
Published in Robert E. Masterson, Nuclear Engineering Fundamentals, 2017
Technically speaking, a fast reactor is defined as one where the fission chain reaction can be sustained by fast neutrons alone. In other words, a fast reactor does not require a moderator to slow the neutrons down. However, it does require fuel that is relatively rich in fissile content compared to the fuel that is used in thermal water reactors. Most of the neutrons in a fast reactor have energies between 10 keV and 10 MeV. Fast reactors rarely have neutrons with kinetic energies below 10 keV. These neutrons can be used to produce extra nuclear fuel or to transmute long-lived radioactive wastes into less troublesome ones. Because the cross sections of most nuclear materials are much lower at high neutron energies than they are at thermal energies (see Chapter 4), the critical mass in a fast reactor is much greater than it is in a thermal one. In practice, this means that the fuel in a fast reactor must have a fissile content of at least 20%, while in a thermal reactor, the fissile content is generally less than 5%. (In a BWR, it can be as low as 3.5%, and in a CANDU reactor, it can approach 0.71%.)
Nuclear and Hydropower
Published in Roy L. Nersesian, Energy Economics, 2016
Fast neutron and fast breeder reactors depend only on prompt or fast neutrons, not delayed or slow neutrons, to maintain a chain reaction, requiring a greater degree of technological sophistication. A fast breeder reactor is designed to create more plutonium 239 from irradiating uranium 238 than fissionable material consumed. Thus, fast breeder reactors can extend uranium reserves forever, at least from the perspective of human existence. A fast neutron reactor does not create more plutonium 239 than fissionable material consumed and thus has an extended core life compared to conventional reactors. Over 400 hours of operating history are associated with 22 fast neutron reactors, most built for experiment or as prototypes. Those still in operation include one experimental fast reactor in China, an experimental and a demonstration (400 mW) fast reactor in India, an experimental and a demonstration (714 mW) fast reactor in Japan, and two experimental fast reactors, a demonstration (1,470 mW) and a commercial (2,100 mW), in Russia.27
An Experimental Investigation of Two-Phase Frictional Pressure Drop in Straight-Tube Steam Generator Used in SFR
Published in Nuclear Science and Engineering, 2023
S. P. Pathak, K. Velusamy, K. Devan, V. A Suresh Kumar
The sodium-cooled fast reactor (SFR) uses sodium as the primary coolant, and the fission energy produced in the reactor core is transported through sodium to a steam generator (SG). Various designs of sodium-heated SGs are in use in SFRs worldwide. SFR SGs are capable of producing steam at higher pressures and temperatures. The present study considers the once-through, straight-tube shell-and-tube-type SG. In these SGs, the feedwater enters the SG inlet water channel and flows upward through the tubes, picking up the heat from secondary sodium flowing downward through the shell side. The feedwater experiences various flow regimes along the tube length, and finally, it is converted to superheated steam while leaving the SG.
Tensile properties of modified 316 stainless steel (PNC316) after neutron irradiation over 100 dpa
Published in Journal of Nuclear Science and Technology, 2023
Yasuhide Yano, Tomoyuki Uwaba, Takashi Tanno, Tsunemitsu Yoshitake, Satoshi Ohtsuka, Takeji Kaito
One of modern society’s most pressing environmental problems is the need to reduce carbon dioxide and greenhouse gas emissions. In this regard, nuclear energy is increasingly recognized not only as a climate-friendly energy option but also as a facilitator of transformation in the energy sector [1]. As a nuclear energy strategy, fast reactor (FR) cycle systems have been developed as a major source of energy for the future from the viewpoint of their competitive economic and safety benefits relative to light water reactor cycle systems.