Normalization Factor in Section 8.3

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Hi All,

I have questions regarding the normalization factor that is shown in Section 8.3 of the User’s Guide.

Let’s suppose that we have a hexagonal fuel assembly (see image), and a 3D regular mesh is created to tally the flux. This mesh will later be used to create an image of the flux distribution in the assembly, similar to the one shown in the example “Pandas DataFrame” for the fission rate (Out [22]). The power of the assembly is known, and we want to report and plot the flux in typical units “neutrons/cm2-s”.

Figure_FA

As shown in that section, the system power is divided by the observed heating rate to obtain the normalization factor. My questions are:

  1. To transform the flux units in each cell of the mesh and then plot the result, do we use the power of the assembly and divide by the heating rate tallied in each cell, or an average power for each cell of the mesh should be determined and then divide by the heating rate tallied in each cell?

  2. In this case, what is the volume used to get the flux in typical units, the volume of the hexagon, or the volume of each cell of the mesh?

Thank you in advance,
Javier

1 Like
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Hi @Javier_Gonzalez. Generally when doing a power normalization, the normalization factor is calculated globally and applied the same everywhere. So you would find the total heating in your system and calculate the ratio as the total expected power divided by the total observed heating. That ratio gets you from a quantity that is “per source neutron” to “per second”. To get the “per centimeter²” part, you divide by each cell by its volume. In your case, this means that you’d use the volume of the red part of each of the mesh cells. Think about it this way — if you have two cells, one of which is very small and the other of which is very large, and both have the same tallied flux “per source neutron”, the smaller one actually has a much higher flux accounting for the fact that the volume is small.

Hope this helps!

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Thank you @paulromano.