When.com Web Search

Search results

  1. Results From The WOW.Com Content Network
  2. Fast-neutron reactor - Wikipedia

    en.wikipedia.org/wiki/Fast-neutron_reactor

    The BN-350 fast-neutron reactor at Aktau, Kazakhstan.It operated between 1973 and 1994. A fast-neutron reactor (FNR) or fast-spectrum reactor or simply a fast reactor is a category of nuclear reactor in which the fission chain reaction is sustained by fast neutrons (carrying energies above 1 MeV, on average), as opposed to slow thermal neutrons used in thermal-neutron reactors.

  3. Inhour equation - Wikipedia

    en.wikipedia.org/wiki/Inhour_equation

    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]

  4. Dollar (reactivity) - Wikipedia

    en.wikipedia.org/wiki/Dollar_(reactivity)

    If the excess reactivity of a reactor is 1 dollar (1$) or more, the reactor is prompt critical. Prompt neutrons are so numerous that the production of delayed neutrons is no longer needed to sustain the reaction. At or above 1$, the chain reaction proceeds without them, and reactor power increases so fast that no conventional controlling ...

  5. Neutron economy - Wikipedia

    en.wikipedia.org/wiki/Neutron_economy

    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 ...

  6. Fast fission - Wikipedia

    en.wikipedia.org/wiki/Fast_fission

    A fast neutron reactor uses fast neutrons, so it does not use a moderator. Moderators may absorb a lot of neutrons in a thermal reactor , and fast fission produces a higher average number of neutrons per fission, so fast reactors have better neutron economy making a plutonium breeder reactor possible.

  7. Neutron transport - Wikipedia

    en.wikipedia.org/wiki/Neutron_transport

    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.

  8. Delayed neutron - Wikipedia

    en.wikipedia.org/wiki/Delayed_neutron

    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 ...

  9. Nuclear reactor physics - Wikipedia

    en.wikipedia.org/wiki/Nuclear_reactor_physics

    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.