Passive nuclear safetyPassive 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 (usually overheating resulting from a loss of coolant or loss of coolant flow).
Light-water reactorThe light-water reactor (LWR) is a type of thermal-neutron reactor that uses normal water, as opposed to heavy water, as both its coolant and neutron moderator; furthermore a solid form of fissile elements is used as fuel. Thermal-neutron reactors are the most common type of nuclear reactor, and light-water reactors are the most common type of thermal-neutron reactor. There are three varieties of light-water reactors: the pressurized water reactor (PWR), the boiling water reactor (BWR), and (most designs of) the supercritical water reactor (SCWR).
Void coefficientIn nuclear engineering, the void coefficient (more properly called void coefficient of reactivity) is a number that can be used to estimate how much the reactivity of a nuclear reactor changes as voids (typically steam bubbles) form in the reactor moderator or coolant. Net reactivity in a reactor is the sum total of multiple contributions, of which the void coefficient is but one. Reactors in which either the moderator or the coolant is a liquid typically will have a void coefficient value that is either negative (if the reactor is under-moderated) or positive (if the reactor is over-moderated).
Neutron temperatureThe neutron detection temperature, also called the neutron energy, indicates a free neutron's kinetic energy, usually given in electron volts. The term temperature is used, since hot, thermal and cold neutrons are moderated in a medium with a certain temperature. The neutron energy distribution is then adapted to the Maxwell distribution known for thermal motion. Qualitatively, the higher the temperature, the higher the kinetic energy of the free neutrons. The momentum and wavelength of the neutron are related through the de Broglie relation.
Boiling water reactorA boiling water reactor (BWR) is a type of light water 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), which is also a type of light water nuclear reactor. The main difference between a BWR and PWR is that in a BWR, the reactor core heats water, which turns to steam and then drives a steam turbine. In a PWR, the reactor core heats water, which does not boil.
Lucens reactorThe Lucens reactor was a 6 MW experimental nuclear power reactor built next to Lucens, Vaud, Switzerland. After its connection to the electrical grid on 29 January 1968, the reactor only operated for a few months before it suffered an accident on 21 January 1969. The cause was a corrosion-induced loss of heat dispersal leading to the destruction of a pressure tube which caused an adjacent pressure tube to fail, and partial meltdown of the core, resulting in radioactive contamination of the cavern.
Supercritical water reactorThe supercritical water reactor (SCWR) is a concept Generation IV reactor, designed as a light water reactor (LWR) that operates at supercritical pressure (i.e. greater than 22.1 MPa). The term critical in this context refers to the critical point of water, and must not be confused with the concept of criticality of the nuclear reactor. The water heated in the reactor core becomes a supercritical fluid above the critical temperature of 374 °C, transitioning from a fluid more resembling liquid water to a fluid more resembling saturated steam (which can be used in a steam turbine), without going through the distinct phase transition of boiling.
Reservoir engineeringReservoir engineering is a branch of petroleum engineering that applies scientific principles to the fluid flow through a porous medium during the development and production of oil and gas reservoirs so as to obtain a high economic recovery. The working tools of the reservoir engineer are subsurface geology, applied mathematics, and the basic laws of physics and chemistry governing the behavior of liquid and vapor phases of crude oil, natural gas, and water in reservoir rock.
Unconventional (oil & gas) reservoirUnconventional (oil & gas) reservoirs, or unconventional resources (resource plays) are accumulations where oil & gas phases are tightly bound to the rock fabric by strong capillary forces, requiring specialised measures for evaluation and extraction. Petroleum reservoir Oil and gas are generated naturally at depths of around 4 or 5 kms below Earth’s surface. Being lighter than the water, which saturates rocks below the water table, the oil and gas percolate up through aquifer pathways towards Earth's surface (through time) by buoyancy.
Decay heatDecay heat is the heat released as a result of radioactive decay. This heat is produced as an effect of radiation on materials: the energy of the alpha, beta or gamma radiation is converted into the thermal movement of atoms. Decay heat occurs naturally from decay of long-lived radioisotopes that are primordially present from the Earth's formation. In nuclear reactor engineering, decay heat continues to be generated after the reactor has been shut down (see SCRAM and nuclear chain reactions) and power generation has been suspended.
