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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]
Suppose also that the reactor is highly supercritical and ΔK/K is 0.00700. Reactivity in dollars = ρ / β eff = 0.007 / 0.007 = 1$ If the excess reactivity of a reactor is 1 dollar (1$) or more, the reactor is prompt critical. Prompt neutrons are so numerous that the production of delayed neutrons is no longer needed to ...
In order to maintain a chain reaction in a nuclear reactor, a neutron moderator is used to slow the neutrons down. This moderator is often used as the coolant that is used for energy extraction as well, and the most common moderator is water. The neutrons also slow due to elastic and inelastic collisions with fuel and other materials in the ...
k eff > 1, supercritical: the neutron density is increasing with time. In the case of a nuclear reactor, neutron flux and power density are proportional, hence during reactor start-up k eff > 1, during reactor operation k eff = 1 and k eff < 1 at reactor shutdown.
The mere fact that an assembly is supercritical does not guarantee that it contains any free neutrons at all. At least one neutron is required to "strike" a chain reaction, and if the spontaneous fission rate is sufficiently low it may take a long time (in 235 U reactors, as long as many minutes) before a chance neutron encounter starts a chain reaction even if the reactor is supercritical.
Hanford’s B Reactor supplied the plutonium for the Nagasaki bomb and launched the Atomic Age. How a small reactor in Eastern WA became the world’s first nuclear plant 80 years ago Skip to main ...
Thus, by widening the margins of non-operation and supercriticality and allowing more time to regulate the reactor, the delayed neutrons are essential to inherent reactor safety, even in reactors requiring active control. The lower percentage [3] of delayed neutrons makes the use of large percentages of plutonium in nuclear reactors more ...
We have a giant fusion reactor in the sky,” he said. "If you can generate energy from solar panels and store it with batteries, you can have energy 24 hours a day."