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Boiling water reactors generally have negative void coefficients, and in normal operation the negative void coefficient allows reactor power to be adjusted by changing the rate of water flow through the core. The negative void coefficient can cause an unplanned reactor power increase in events (such as sudden closure of a streamline valve ...
This is measured by the coolant void coefficient. Most modern nuclear power plants have a negative void coefficient, indicating that as water turns to steam, power instantly decreases. Two exceptions are the Soviet RBMK and the Canadian CANDU. Boiling water reactors, on the other hand, are designed to have steam voids inside the reactor vessel.
Parallel to the development of the ABWR, General Electric also developed a different concept, known as the simplified boiling water reactor (SBWR). This smaller 600 megawatt electrical reactor was notable for its incorporation—for the first time ever in a light water reactor [citation needed] —of "passive safety" design principles. The ...
Most reactor systems employ a cooling system that is physically separate from the water that will be boiled to produce pressurized steam for the turbines, like the pressurized-water reactor. But in some reactors the water for the steam turbines is boiled directly by the reactor core, for example the boiling-water reactor.
The prototype fast breeder reactor has a negative void coefficient, thus ensuring a high level of passive nuclear safety. This means that when the reactor overheats (below the boiling point of sodium) the speed of the fission chain reaction decreases, lowering the power level and the temperature. [ 25 ]
High-capacity pressurizers providing a large reactor coolant inventory; VVER-440 reactor hall at Mochovce Nuclear Power Plant. Reactor fuel rods are fully immersed in water kept at (12,5 / 15,7 / 16,2 ) MPa (1812/2277/2349 psi) pressure respectively so that it does not boil at the normal (220 to over 320 °C [428 to >608°F]) operating ...
Such a condition is called a "positive void coefficient", and the RBMK reactor series has the highest positive void coefficient of any commercial reactor ever designed. A high void coefficient does not necessarily make a reactor inherently unsafe, as some of the fission neutrons are emitted with a delay of seconds or even minutes (post-fission ...
The reactor had a dangerously large positive void coefficient of reactivity. The void coefficient is a measurement of how a reactor responds to increased steam formation in the water coolant. Most other reactor designs have a negative coefficient, i.e. the nuclear reaction rate slows when steam bubbles form in the coolant, since as the steam ...