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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 ...
InHour is a unit of reactivity of a nuclear reactor.It stands for the inverse of an hour.It is equal to the inverse of the period in hours. One InHour is the amount of reactivity needed to increase the reaction from critical to where the power will increase by a factor of e in one hour.
Neutron transport (also known as neutronics) is the study of the motions and interactions of neutrons with materials. Nuclear scientists and engineers often need to know where neutrons are in an apparatus, in what direction they are going, and how quickly they are moving.
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.
1. A uranium-235 atom absorbs a neutron and fissions into two new atoms (fission fragments), releasing three new neutrons and some binding energy. 2. One of those neutrons is absorbed by an atom of uranium-238 and does not continue the reaction. Another neutron is simply lost and does not collide with anything, also not continuing the reaction.
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 ...