What is neutron flux

The amount of fissile U per the volume of the reactor core. The atomic number density of U in the volume of the reactor core:. N Moreover, it will be assumed. The recycled plutonium contains only the fissile Pu. The presence of these amounts will be neglected in this example. A typical thermal reactor contains about tons of fuel HM — heavy metal.

If the reactor power is MWth, determine the reaction rate and the average core thermal flux. N Pu The amount of fissile Pu per the volume of the reactor core. The atomic number density of Pu in the volume of the reactor core:. Note that there is a difference between neutron fluxes in the uranium fueled core and the MOX fueled core. The average neutron flux in the first example, in which the neutron flux in a uranium-loaded reactor core was calculated, was 3.

This fact is of importance in the reactor core design and the design of reactivity control. It is primarily caused by:. The relatively lower average neutron flux in MOX cores has the following consequences on reactor core design:.

In a power reactor over a relatively short period days or weeks , the atomic number density of the fuel atoms remains relatively constant. Therefore, the average neutron flux remains constant in this short period when a reactor is operated at a constant power level. On the other hand, the atomic number densities of fissile isotopes over months decrease due to the fuel burnup, and the macroscopic cross-sections decrease. This result is slow to increase in the neutron flux to keep the desired power level.

Neutron Nuclear Reactions. Search Search. It is a scalar quantity, and it can be calculated as the neutron density n multiplied by neutron velocity v.

Neutron Flux and Intensity — Examples We have to distinguish between the neutron flux and the neutron intensity. Example - Neutron flux in a typical thermal reactor core.

If the reactor power is MW th , determine the reaction rate and the average core thermal flux. V where: P — reactor power MeV.

Example - Neutron flux in a MOX fueled thermal reactor core. Mixed oxide fuel , commonly referred to as MOX fuel , is nuclear fuel that contains more than one oxide of fissile material.

MOX fuels usually consist of plutonium blended with natural uranium. Nuclear and Reactor Physics: J. Lamarsh, Introduction to Nuclear Reactor Theory, 2nd ed. Lamarsh, A. Skip to content. Neutron flux density. This website uses cookies to improve your experience.

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