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A dollar is a unit of reactivity for a nuclear reactor, calibrated to the interval between the conditions of criticality and prompt criticality. Prompt criticality will result in an extremely rapid power rise, with the resultant destruction of the reactor, unless it is specifically designed to tolerate the condition. A cent is 1 ⁄ 100 of a ...
In 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 depends on several factors, one of which is the ...
Nuclear reactor physics is the field of physics that studies and deals with the applied study and engineering applications of chain reaction to induce a controlled rate of fission in a nuclear reactor for the production of energy.
A fission fragment reactor is a nuclear reactor that generates electricity by decelerating an ion beam of fission byproducts instead of using nuclear reactions to generate heat. By doing so, it bypasses the Carnot cycle and can achieve efficiencies of up to 90% instead of 40–45% attainable by efficient turbine-driven thermal reactors.
A reactor can be unintentionally "shutdown" by having an excess of neutron poisons in the reactor vessel. Neutron poisons are chemical byproducts of the nuclear reaction which absorb neutrons, lowering reactivity in the reactor and potentially stalling the reaction if enough poisons are allowed to build up.
The Inhour equation used in nuclear reactor kinetics to relate reactivity and the reactor period. [1] Inhour is short for "inverse hour" and is defined as the reactivity which will make the stable reactor period equal to 1 hour (3,600 seconds). [2] Reactivity is more commonly expressed as per cent millie (pcm) of Δk/k or dollars. [3]
A reactor achieves criticality (and is said to be critical) when each fission releases a sufficient number of neutrons to sustain an ongoing series of nuclear reactions. [2] The International Atomic Energy Agency defines the first criticality date as the date when the reactor is made critical for the first time. [3] This is an important ...
Nuclear reactors can be susceptible to prompt-criticality accidents if a large increase in reactivity (or k-effective) occurs, e.g., following failure of their control and safety systems. The rapid uncontrollable increase in reactor power in prompt-critical conditions is likely to irreparably damage the reactor and in extreme cases, may breach ...