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Criticality accidents are divided into one of two categories: Process accidents, where controls in place to prevent any criticality are breached;; Reactor accidents, which occur due to operator errors or other unintended events (e.g., during maintenance or fuel loading) in locations intended to achieve or approach criticality, such as nuclear power plants, nuclear reactors, and nuclear ...
More than 30 people were over-exposed to radiation when the starboard reactor cooling system failed and the reactor temp rose uncontrollably. Emergency repairs ordered by the captain successfully cooled the reactor and avoided meltdown, but exposed the workers to high levels of radiation. [17] 8 Radiation accident in Morocco: 1984 March
Neutron irradiation embrittlement limits the service life of reactor-pressure vessels (RPV) in nuclear power plants due to the degradation of reactor materials. In order to perform at high efficiency and safely contain coolant water at temperatures around 290°C and pressures of ~7 MPa (for boiling water reactors) to 14 MPa (for pressurized water reactors), the RPV must be heavy-section steel.
Failure to remove decay heat may cause the reactor core temperature to rise to dangerous levels and has caused nuclear accidents. The heat removal is usually achieved through several redundant and diverse systems, and the heat is often dissipated to an 'ultimate heat sink' which has a large capacity and requires no active power, though this ...
Radiation hardening is the process of making electronic components and circuits resistant to damage or malfunction caused by high levels of ionizing radiation (particle radiation and high-energy electromagnetic radiation), [1] especially for environments in outer space (especially beyond low Earth orbit), around nuclear reactors and particle accelerators, or during nuclear accidents or nuclear ...
In most reactors it takes the form of a sealed metallic or ceramic layer. It also serves to trap fission products, especially those that are gaseous at the reactor's operating temperature, such as krypton, xenon and iodine. Cladding does not constitute shielding, and must be developed such that it absorbs as little radiation as possible.
The Fukushima Daiichi nuclear disaster in 2011 occurred due to a loss-of-coolant accident. The circuits that provided electrical power to the coolant pumps failed causing a loss-of-core-cooling that was critical for the removal of residual decay heat which is produced even after active reactors are shut down and nuclear fission has ceased.