A nuclear reactor is a device used to initiate and control a fission nuclear chain reaction. Nuclear reactors are used at nuclear power plants for electricity generation and in nuclear marine propulsion. When a fissile nucleus like 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. The process is carefully controlled using control rods and neutron moderators to regulate the number of neutrons that continue the reaction, ensuring the reactor operates safely, although inherent control by means of delayed neutrons also plays an important role in reactor output control. The efficiency of nuclear fuel is much higher than fossil fuels; the 5% enriched uranium used in the newest reactors has an energy density 120,000 times higher than coal.
A nuclear electric rocket is a type of spacecraft propulsion system where thermal energy from a nuclear reactor is converted to electrical energy, which is used to drive an ion thruster or other electrical spacecraft propulsion technology. The nuclear electric rocket terminology is slightly inconsistent, as technically the "rocket" part of the propulsion system is non-nuclear and could also be driven by solar panels. This is in contrast with a nuclear thermal rocket, which directly uses reactor heat to add energy to a working fluid, which is then expelled out of a rocket nozzle.
A radioisotope thermoelectric generator, sometimes referred to as a radioisotope power system (RPS), is a type of nuclear battery that uses an array of thermocouples to convert the heat released by the decay of a suitable radioactive material into electricity by the Seebeck effect. This type of generator has no moving parts and is ideal for deployment in remote and harsh environments for extended periods with no risk of parts wearing out or malfunctioning.
A natural nuclear fission reactor is a uranium deposit where self-sustaining nuclear chain reactions occur. The idea of a nuclear reactor existing in situ within an ore body moderated by groundwater was briefly explored by Paul Kuroda in 1956. The existence of an extinct or fossil nuclear fission reactor, where self-sustaining nuclear reactions have occurred in the past, are established by analysis of isotope ratios of uranium and of the fission products. The first such fossil reactor was first discovered in 1972 in Oklo, Gabon by researchers from the French Alternative Energies and Atomic Energy Commission (CEA) when chemists performing quality control for the French nuclear industry noticed sharp depletions of fissionable 235
U
in gaseous uranium made from Gabonese ore.
Chalk River Laboratories is a Canadian nuclear research facility in Deep River, about 180 km (110 mi) north-west of Ottawa.
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:
A molten-salt reactor (MSR) is a class of nuclear fission reactor in which the primary nuclear reactor coolant and/or the fuel is a mixture of molten salt with a fissile material.
Nuclear fuel refers to any substance, typically fissile material, which is used by nuclear power stations or other nuclear devices to generate energy.
The Bhabha Atomic Research Centre (BARC) is India's premier nuclear research facility, headquartered in Trombay, Mumbai, Maharashtra, India. It was founded by Homi Jehangir Bhabha as the Atomic Energy Establishment, Trombay (AEET) in January 1954 as a multidisciplinary research program essential for India's nuclear program. It operates under the Department of Atomic Energy (DAE), which is directly overseen by the Prime Minister of India.
Research reactors are nuclear fission-based nuclear reactors that serve primarily as a neutron source. They are also called non-power reactors, in contrast to power reactors that are used for electricity production, heat generation, or maritime propulsion.
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 Susquehanna Steam Electric Station is a nuclear power station on the Susquehanna River in Salem Township, Luzerne County, Pennsylvania.
Carolinas–Virginia Tube Reactor (CVTR), also known as Parr Nuclear Station, was an experimental pressurized tube heavy water nuclear power reactor at Parr, South Carolina in Fairfield County. It was built and operated by the Carolinas Virginia Nuclear Power Associates. CVTR was a small test reactor, capable of generating 17 megawatts of electricity. It was officially commissioned in December 1963 and left service in January 1967.
Reactor-grade plutonium (RGPu) is the isotopic grade of plutonium that is found in spent nuclear fuel after the uranium-235 primary fuel that a nuclear power reactor uses has burnt up. The uranium-238 from which most of the plutonium isotopes derive by neutron capture is found along with the U-235 in the low enriched uranium fuel of civilian reactors.
The hydrogen-moderated self-regulating nuclear power module (HPM), also referred to as the compact self-regulating transportable reactor (ComStar), is a type of nuclear power reactor using hydride as a neutron moderator. The design is inherently safe, as the fuel and the neutron moderator is uranium hydride UH3, which is reduced at high temperatures (500–800 °C) to uranium and hydrogen. The gaseous hydrogen exits the core, being absorbed by hydrogen absorbing material such as depleted uranium, thus making it less critical. This means that with rising temperature the neutron moderation drops and the nuclear fission reaction in the core is dampened, leading to a lower core temperature. This means as more energy is taken out of the core the moderation rises and the fission process is stoked to produce more heat.
NuScale Power Corporation is a publicly traded American company that designs and markets small modular reactors (SMRs). It is headquartered in Portland, Oregon. A 50 MWe version of the design was certified by the US Nuclear Regulatory Commission (NRC) in January 2023. The current scalable 77 MWe SMR VOYGR design was submitted for NRC review on January 1, 2023, and as of December 2023 was about a third complete.
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.
Nuclear power in space is the use of nuclear power in outer space, typically either small fission systems or radioactive decay for electricity or heat. Another use is for scientific observation, as in a Mössbauer spectrometer. The most common type is a radioisotope thermoelectric generator, which has been used on many space probes and on crewed lunar missions. Small fission reactors for Earth observation satellites, such as the TOPAZ nuclear reactor, have also been flown. A radioisotope heater unit is powered by radioactive decay and can keep components from becoming too cold to function, potentially over a span of decades.
Shine Technologies is a private corporation based in Janesville, Wisconsin. The company applies nuclear fusion and advanced separation technologies across fields of critical need, including nondestructive testing, radiation hardening services for industrial and defense applications, and the production of radioisotopes, including n.c.a. lutetium-177 for cancer treatment.
The Aurora powerhouse is an advanced fission plant concept design that received a site use permit for testing in 2020 from the United States Department of Energy (DOE). The site use permit, issued in December 2019 is not a Nuclear Regulatory Commission permit. It will use "recycled" high-assay, low-enriched uranium (HALEU) fuel originally fabricated for the Experimental Breeder Reactor II (EBR-II), and if fully operational, would become "the first fuel-recycling commercial reactor in the United States". The DOE's Idaho National Laboratory (INL) said it would provide 10 tons of HALEU for the test reactor which corresponds to most of the available supply. Reprocessing would occur at INL's Materials and Fuels Complex (MFC) and possibly also the Idaho Nuclear Technology and Engineering Center (INTEC), neither of which are operational facilities as of early 2020.
