Background Įconomic factors of scale mean that nuclear reactors tend to be large, to such an extent that size itself becomes a limiting factor. One concern with SMRs is preventing nuclear proliferation. US government studies to evaluate SMR-associated risks have slowed licensing. SMRs differ in terms of staffing, security and deployment time. The first unit of China’s pebble-bed modular high-temperature gas-cooled reactor HTR-PM was connected to the grid in 2021. The floating nuclear power plant Akademik Lomonosov (operating in Pevek in Russia's Far East) is, as of October 2022, the first operating prototype in the world. Īs of 2023, there are more than eighty modular reactor designs under development in 19 countries, and the first SMR units are in operation in Russia and China. SMRs should also reduce staffing versus conventional nuclear reactors, and are claimed to have the ability to bypass financial and safety barriers that inhibit the construction of conventional reactors. The greater safety should come via the use of passive safety features that operate without human intervention, a concept already implemented in some conventional nuclear reactor types. Ideally, modular reactors will reduce on-site construction, increase containment efficiency, and are claimed to enhance safety. Some SMR designs, typically those using Generation IV technologies, aim to secure additional economic advantage through improvements in electrical generating efficiency from much higher temperature steam generation. Many SMR proposals rely on a manufacturing-centric model, requiring many deployments to secure economies of unit production large enough to achieve economic viability. SMRs are typically anticipated to have an electrical power output of less than 300 MW e (electric) or less than 1000 MW th (thermal). Both thermal-neutron reactors and fast-neutron reactors have been proposed, along with molten salt and gas cooled reactor models. Designs range from scaled down versions of existing designs to generation IV designs. The term SMR refers to the size, capacity and modular construction only, not to the reactor type and the nuclear process which is applied. Small modular reactors ( SMRs) are a proposed class of nuclear fission reactors, smaller than conventional nuclear reactors, which can be built in one location (such as a factory), then shipped, commissioned, and operated at a separate site. High technology research required benefits other industries.Ĭosts of building and safely decommissioning are very high.Ĭannot react quickly to changes in electricity demand.Illustration of a light water small modular nuclear reactor (SMR) Public perception of nuclear power is negative. Low fuel quantity reduces mining and transportation effects on environment. Large-scale accidents can be catastrophic. Local thermal pollution from wastewater affects marine life. Waste is radioactive and safe disposal is very difficult and expensive. However, the financial costs of building and decommissioning a nuclear power station are very large, and the waste produced will remain radioactive - hazardous to humans and the environment - for thousands of years. In operation, a very small amount of nuclear fuel will consistently generate a very large amount of electricity and generate very little polluting material. Generating electricity using nuclear reactors carries high risk but offers large rewards. Advantages and disadvantages of nuclear power stations An uncontrolled fission reaction is the basis of an atomic bomb. Many of the features of the reactor are designed to control the speed of the reaction and the temperature inside the shielding. Concrete shield - the daughter products of the fission reaction are radioactive and can be a hazard. Coolant - this is heated up by the energy released from the fission reactions and is used to boil water to drive turbines in the power station.Control rods - these are raised and lowered to stop neutrons from travelling between fuel rods and therefore change the speed of the chain reaction.Moderator - graphite core - a graphite core, for example, slows the neutrons down so that they are more likely to be absorbed into a nearby fuel rod.The fuel is held in rods so that the neutrons released will fly out and cause nuclear fission in other rods. Nuclear fuel - the uranium or plutonium isotope that will split when triggered by an incoming neutron.A fission reactor contains a number of different parts:
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