 | This article needs to be updated.(October 2017) |
The Toshiba 4S (Ultra super safe, Small and Simple) is a micro sodium-cooled nuclear fission reactor design.
| This article needs to be updated.(October 2017) |
The Toshiba 4S (Ultra super safe, Small and Simple) is a micro sodium-cooled nuclear fission reactor design.
The plant design is developed by a partnership that includes Toshiba and the Central Research Institute of Electric Power Industry (CRIEPI) of Japan. [1]
The technical specifications of the 4S reactor are unique in the nuclear industry. [2] The actual reactor would be located in a sealed, cylindrical vault 30 m (98 ft) underground, while the building above ground would be 22×16×11 m (72×52.5×36 ft) in size. This power plant is designed to provide 10 megawatts of electrical power with a 50 MW version available in the future. [3]
The 4S is a fast neutron sodium reactor. It uses neutron reflector panels around the perimeter to maintain neutron density. These reflector panels replace complicated control rods, yet keep the ability to shut down the nuclear reaction in case of an emergency. Additionally, the Toshiba 4S utilizes liquid sodium as a coolant, allowing the reactor to operate 200 degrees hotter than if it used water. [ clarification needed ] Although water would readily boil at these temperatures, sodium remains a liquid; the sodium coolant therefore exerts very low pressure on the reactor vessel even at extremely high temperatures. [ citation needed ]
The Toshiba 4S Nuclear Battery was proposed as the power source for the Galena Nuclear Power Plant in Alaska, but the project was abandoned in 2011 and Toshiba did not proceed with an application for certification of the design. [4]
A research team including Allison Macfarlane and Rodney C. Ewing evaluated waste production of a number of small nuclear reactors, including the 4s, and published their findings in Proceedings of the National Academy of Sciences of the United States of America . They found that small modular reactors produce more radioactive waste than conventional reactors. These claims were contested by NuScale Power. [5]
A nuclear reactor is a device used to initiate and control a fission nuclear chain reaction. They are used for commercial electricity, marine propulsion, weapons production and research. When a fissile nucleus, usually uranium-235 or plutonium-239, absorbs a neutron, it splits into lighter nuclei, releasing energy, gamma radiation, and free neutrons, which can induce further fission in a self-sustaining chain reaction. Reactors stabilize this with systems of active and passive control, varying the presence of neutron absorbers and moderators in the core, maintaining criticality with delayed neutrons. Fuel efficiency is exceptionally high;low-enriched uranium has an energy density 120,000 times higher than coal.
A pressurized water reactor (PWR) is a type of light-water nuclear reactor. PWRs constitute the large majority of the world's nuclear power plants.
A boiling water reactor (BWR) is a type of nuclear reactor used for the generation of electrical power. It is the second most common type of electricity-generating nuclear reactor after the pressurized water reactor (PWR).
A breeder reactor is a nuclear reactor that generates more fissile material than it consumes. These reactors can be fueled with more-commonly available isotopes of uranium and thorium, such as uranium-238 and thorium-232, as opposed to the rare uranium-235 which is used in conventional reactors. These materials are called fertile materials since they can be bred into fuel by these breeder reactors.
A fast-neutron reactor (FNR) or fast-spectrum reactor or simply a fast reactor is a category of nuclear reactor in which the fission chain reaction is sustained by fast neutrons, as opposed to slow thermal neutrons used in thermal-neutron reactors. Such a fast reactor needs no neutron moderator, but requires fuel that is relatively rich in fissile material when compared to that required for a thermal-neutron reactor. Around 20 land based fast reactors have been built, accumulating over 400 reactor years of operation globally. The largest was the Superphénix sodium cooled fast reactor in France that was designed to deliver 1,242 MWe. Fast reactors have been studied since the 1950s, as they provide certain advantages over the existing fleet of water-cooled and water-moderated reactors. These are:
Passive nuclear safety is a design approach for safety features, implemented in a nuclear reactor, that does not require any active intervention on the part of the operator or electrical/electronic feedback in order to bring the reactor to a safe shutdown state, in the event of a particular type of emergency. Such design features tend to rely on the engineering of components such that their predicted behaviour would slow down, rather than accelerate the deterioration of the reactor state; they typically take advantage of natural forces or phenomena such as gravity, buoyancy, pressure differences, conduction or natural heat convection to accomplish safety functions without requiring an active power source. Many older common reactor designs use passive safety systems to a limited extent, rather, relying on active safety systems such as diesel-powered motors. Some newer reactor designs feature more passive systems; the motivation being that they are highly reliable and reduce the cost associated with the installation and maintenance of systems that would otherwise require multiple trains of equipment and redundant safety class power supplies in order to achieve the same level of reliability. However, weak driving forces that power many passive safety features can pose significant challenges to effectiveness of a passive system, particularly in the short term following an accident.
The integral fast reactor (IFR), originally the advancedliquid-metal reactor (ALMR), is a design for a nuclear reactor using fast neutrons and no neutron moderator. IFRs can breed more fuel and are distinguished by a nuclear fuel cycle that uses reprocessing via electrorefining at the reactor site.
DEMO, or a demonstration power plant, refers to a proposed class of nuclear fusion experimental reactors that are intended to demonstrate the net production of electric power from nuclear fusion. Most of the ITER partners have plans for their own DEMO-class reactors. With the possible exception of the EU and Japan, there are no plans for international collaboration as there was with ITER.
Generation IVreactors are nuclear reactor design technologies that are envisioned as successors of generation III reactors. The Generation IV International Forum (GIF) – an international organization that coordinates the development of generation IV reactors – specifically selected six reactor technologies as candidates for generation IV reactors. The designs target improved safety, sustainability, efficiency, and cost. The World Nuclear Association in 2015 suggested that some might enter commercial operation before 2030.
The lead-cooled fast reactor is a nuclear reactor design that uses molten lead or lead-bismuth eutectic coolant. These materials can be used as the primary coolant because they have low neutron absorption and relatively low melting points. Neutrons are slowed less by interaction with these heavy nuclei so these reactors operate with fast neutrons.
The Gas Turbine Modular Helium Reactor (GT-MHR) is a class of nuclear fission power reactor designed that was under development by a group of Russian enterprises, an American group headed by General Atomics, French Framatome and Japanese Fuji Electric. It is a helium cooled, graphite moderated reactor and uses TRISO fuel compacts in a prismatic core design. The power is generated via a gas turbine rather than via the more common steam turbine.
A sodium-cooled fast reactor is a fast neutron reactor cooled by liquid sodium.
The BN-600 reactor is a sodium-cooled fast breeder reactor, built at the Beloyarsk Nuclear Power Station, in Zarechny, Sverdlovsk Oblast, Russia. It has a 600 MWe gross capacity and a 560 MWe net capacity, provided to the Middle Urals power grid. It has been in operation since 1980 and represents an improvement to the preceding BN-350 reactor. In 2014, its larger sister reactor, the BN-800 reactor, began operation.
A liquid metal cooled nuclear reactor, or LMR is a type of nuclear reactor where the primary coolant is a liquid metal. Liquid metal cooled reactors were first adapted for breeder reactor power generation. They have also been used to power nuclear submarines.
Lead-Bismuth Eutectic or LBE is a eutectic alloy of lead and bismuth used as a coolant in some nuclear reactors, and is a proposed coolant for the lead-cooled fast reactor, part of the Generation IV reactor initiative. It has a melting point of 123.5 °C/254.3 °F and a boiling point of 1,670 °C/3,038 °F.
Gen4 Energy, Inc was a privately held corporation formed to construct and sell several designs of relatively small nuclear reactors, which they claimed would be modular, inexpensive, inherently safe, and proliferation-resistant. According to news coverage, these reactors could be used for heat generation, production of electricity, and other purposes, including desalination.
TerraPower is an American nuclear reactor design and development engineering company headquartered in Bellevue, Washington. TerraPower is developing a class of nuclear fast reactors termed traveling wave reactors (TWR).
The small modular reactor (SMR) is a class of small nuclear fission reactor, designed to be built in a factory, shipped to operational sites for installation and then used to power buildings or other commercial operations. The term SMR refers to the size, capacity and modular construction. Reactor type and the nuclear processes may vary. Of the many SMR designs, the pressurized water reactor (PWR) is the most common. However, recently proposed SMR designs include: generation IV, thermal-neutron reactors, fast-neutron reactors, molten salt, and gas-cooled reactor models.
The RAPID-L, RAPID-LAT is a micro nuclear reactor concept conceived as a powerhouse for colonies on the Moon and Mars. It is based on the RAPID-series fast breeder reactor using a liquid lithium-6 design. The study was funded by the Japan Atomic Energy Research Institute (JAERI) in FY 1999–2001. The research was carried out by Japan's Central Research Institute of Electric Power Industry (CRIEPI), Komae Research Laboratory.