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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
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.
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 ...
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.
Containment systems for nuclear power reactors are distinguished by size, shape, materials used, and suppression systems. The kind of containment used is determined by the type of reactor, generation of the reactor, and the specific plant needs. Suppression systems are critical to safety analysis and greatly affect the size of containment.
Units 1 through 4 at the plant. At the time of the earthquake, Unit 4 had been shut down for shroud replacement and refueling since 29 November 2010. [1] [2] All 548 fuel assemblies had been transferred in December 2010 from the reactor to the spent fuel pool on an upper floor of the reactor building [3] where they were held in racks containing boron to damp down any nuclear reaction. [4]
Radiation monitors in general have a number of process-control applications in nuclear power plants; [9] a major CPAM application in this area is the monitoring of the air intake for the plant control room. In the event of an accident, high levels of airborne radioactivity could be brought into the control room by its HVAC system; the CPAM ...