Small modular reactors (SMRs) are nuclear fission reactors that are a fraction of the size of conventional reactors. They can be manufactured at a plant and transported to a site to be installed. Modular reactors reduce on-site construction, increase containment efficiency, and enhance safety. The greater safety comes via the use of passive safety features that operate without human intervention. SMRs also reduce staffing versus conventional nuclear reactors.[1][2] SMRs are claimed to cross financial and safety barriers that inhibit the construction of conventional reactors.[2][3]
SMR designs range from scaled down versions of existing designs to generation IV designs. Both thermal-neutron reactorsand fast-neutron reactors have been proposed, along with molten salt and gas cooled reactor models.[4]
The main hindrance to commercial use is licensing, since current regulatory regimes are adapted to conventional designs. SMRs differ in terms of staffing, security and deployment time. One concern with SMRs is preventing nuclear proliferation.[5][6][7][8] Licensing time, cost and risk are critical success factors. US government studies that evaluated SMR-associated risks have slowed licensing.[9][10][11]
Technologies[edit]
Cooling[edit]
Conventional reactors use water as a coolant. SMRs may use water, liquid metal, gas and molten salt as coolants.[22][23]
Thermal/electrical generation[edit]
Some gas-cooled reactor designs drive a gas-powered turbine, rather than boil water. Thermal energy can be used directly, without conversion. Heat can be used in hydrogen production and other commercial operations,[22] such as desalination and the production of petroleum products (extracting oil from tar sands, creating synthetic oil from coal, etc.).[24]
Staffing[edit]
Reactors such as the Toshiba 4S are designed to run with little supervision.[1]
Load following[edit]
Nuclear plants typically cover the base load of electricity demand.[25] SMR designs can provide base load power or can adjust their output based on demand. Another approach is to adopt cogeneration, maintaining consistent output, while diverting otherwise unneeded power to an auxiliary use.
District heating, desalination and hydrogen production have been proposed as cogeneration options.[25] Overnight desalination requires sufficient freshwater storage to enable water to be delivered at times other than when it is produced.[26]
https://en.wikipedia.org/wiki/Small_modular_reactor
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