Strong discrepancy between update 31 and 32 while depleting with burnup steps and employing edepmode 3

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augusto_vib
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Strong discrepancy between update 31 and 32 while depleting with burnup steps and employing edepmode 3

Post by augusto_vib » Thu Jun 24, 2021 3:50 pm

Hello,

So I realized that if I do a depletion calculation with the neutron-photon coupling activated (by means of the edepmode 3) with update 31 and with update 32, then I get very different results (this is if I deplete with burnup steps instead of days steps). What I want to say is that I think that this type of execution with update 31 is wrong (I think that the one from version 32 is correct). Now, if you deplete with days instead of burnup, then the executable created with update 31 gives similar results than the one related to the newest update 32. So I find a bit odd this behavior. Could you help me verify that actually the code of update 32 is correct while depleting with different edepmodes ? I tried to attach the results but they are too large. Instead, I attached the input that I use in case if it is of interest (I could also share results if required). Now, my main goal is to compare how de edepmode affects the spent fuel inventory at some discharge burnup point so just need to be sure that the code is correct.

Thank you.
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Riku Tuominen
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Re: Strong discrepancy between update 31 and 32 while depleting with burnup steps and employing edepmode 3

Post by Riku Tuominen » Thu Jun 24, 2021 4:43 pm

Hi,

you are correct that the code gives different results with versions 31 and 32. In version 31 the burnup step length was converted from MWd/kgHM to seconds based on energy deposition to only burnable materials which is not the same as the total power in energy deposition modes 2 and 3. In version 32 this was changed so that energy deposition to all materials is used with energy deposition mode 2 and 3. I think this is the better way but in general the definition of burnup using units such as MWd/kgHM in enegy deposition modes 2 and 3 is a bit problematic since energy is deposited to materials other than fuel. As an example, how should the burnup of a single fuel pin be calculated? What energy divided with the initial heavy metal mass of the pin?

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