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Small modular reactors (SMRs) are part of a new generation of nuclear power plant designs being developed in several countries. The objective of these SMRs is to provide a flexible, cost-effective energy alternative. Small reactors are defined by the International Atomic Energy Agency as those with an electricity output of less than 300 MWe, although general opinion is that anything with an output of less than 500 MWe counts as a small reactor.〔Radiation & Transport Safety Section, ("Status of Small Reactor Designs Without On-Site Fueling" ), (''International Atomic Energy Agency (IAEA)'' )〕〔Carlson, J. ("Fast Neutron Reactors" ), (''World Nuclear Association'' )〕 Modular reactors are manufactured at a plant and brought to the site fully constructed. They allow for less on-site construction, increased containment efficiency, and heightened nuclear materials security. ==History== Electricity was first generated from nuclear energy on December 20, 1951 in the high desert of south-eastern Idaho. The original electrical output was estimated at 45 kW.〔Stacy, S. ("The Reactor Zoo Goes Critical" ), (''Proving the Principle'' )〕 Since then, reactors have grown much larger, with electrical outputs of over 1,400 MW.〔Atteberry, J. ("Five Biggest Nuclear Reactors" ), (''How Stuff Works'' )〕 Almost 50 years after the first nuclear energy was generated, applications for reactors with low electrical outputs are being introduced again. According to a report prepared by Oak Ridge National Laboratory, the long-term goal of nuclear power is to "develop an economic, safe, environmentally acceptable, unlimited supply of energy for society." Remote locations often have difficulty finding economically efficient, reliable energy sources. Small nuclear reactors have been considered as solutions to many energy problems in these hard-to-reach places. Many of these smaller reactor designs are being made "modular" – in other words, they will be manufactured and assembled at a central factory location. They are then sent to their new location where they can be installed with very little difficulty. These SMRs are particularly useful in remote locations where there is usually a deficiency of trained workers and a higher cost of shipping. Containment is more efficient, and proliferation concerns are lessened.〔("Small Modular Reactors" ), (''Department of Energy – Office of Nuclear Energy'' )〕 SMRs are also more flexible in that they do not necessarily need to be hooked into a large power grid, and can generally be attached to other modules to provide increased power supplies if necessary. There may be some economic benefits to SMRs as well. While the small power output of an SMR means that electricity will cost more per MW than it would from a larger reactor, the initial cost of building the plant is much less than that of constructing a much more complex, non-modular, large nuclear plant. It makes an SMR a smaller-risk venture for power companies than other nuclear power plants.〔Black, R. ("Bringing Small Modular Reactors (SMRs) to Domestic Markets: DOE Presentation to Foundation for Nuclear Studies" ), (''Nuclear Foundation'' )〕 SMRs produce anywhere from ten to 300 megawatts, rather than the 1,000 megawatts produced by a typical reactor. Safety features include a natural cooling feature that can continue to function in the absence of external power; which was precisely the problem that was faced in Japan when the 2011 tsunami hit. The SMR also has the advantage of having underground placement of the reactors and spent-fuel storage pools, which provides more security. Smaller reactors would be easier to upgrade quickly, require a permanent workforce, and have better quality controls, just to name a few more advantages.〔(Ernest. "Why We Still Need Nuclear Power: Making Clean Energy Safe and Affordable." Foreign Affairs 90, no. 6 (November 2011): 83-94. )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Small modular reactor」の詳細全文を読む スポンサード リンク
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