How to find the conversion ratio?

basically, i have loads of atoms in fuel and i was wondering how would I find the conversion ratio?

This would involve running a depletion calculation and tracking the fissile atom inventory over time to see how many fissile atoms are produced for each fissile atom that is consumed. If you have a depletion results file, you can get the number of atoms of particular nuclides using the openmc.deplete.ResultsList.get_atoms method.

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when i print the pu in atom/b-cm i get these. Would i just compare the 1 item in the list with the last or do i need to do it for every isotope that i put int?

0.001534026
0.001539292
0.001574878
0.001615969
0.001687505
0.001747488
0.001796663
0.001837391
0.001870907
0.001918016
0.001944628

I think you should write a python function which identifies whether an isotope is considered fissile, since not all plutonium isotopes are fissile. Paul’s method would be the time-integrated conversion ratio. I think another meaningful definition would be the rate of fissile atom production divided by the rate of fissile atom consumption, which would be more convenient since you’d not need to track the fissile atom consumption rate over time.

IIRC, the latter is what Serpent outputs.

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Could i not look at the conversion ratio of lets say Pu239 by simply dividing the end of cycle pu239 atom density by beginning of cycle?

No, because you could have the situation where there’s zero plutonium initially. Then you’d have division by zero.

Yes, on second thought, I think you’re better off calculating conversion rate using a a ratio of reaction rates as suggested by @gridley. Namely, the numerator (fissile material produced) can be calculated by summing the tallied (n,gamma) reaction rates for each fissionable nuclide, and the denominator (fissile material destroyed) can be calculated by summing the tallied absorption reaction rates for each fissionable nuclide.

Hye Paul

I have a question regarding calculating conversion ratio. As you mentioned earlier, should this be fissionable nuclide or fertile nuclide?

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Yes, you’re right – the numerator represents production of fissile nuclides, so you would want the (n,gamma) reaction rates for fertile nuclides.

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Hello,
I want ask about how to obtain the absorption value of the depletion results. As we know that to get the reaction (n,gamma) we can write ‘(n,gamma)’ in openmc.deplete.ResultList.get_reaction_rate?

I have tried writing ‘absorption’ but it doesn’t work.

thank you,
Anas

Hi Anas,
Total absorption is not stored in the depletion ResultList, but only the reactions defined in your depletion_chain XML file. So if, for example, you have defined (n,gamma), (n,p) and (n,a) for a specific nuclide in your depletion chain, you can only retrieve those.

Lorenzo

@anas If you want to get a reaction rate during depletion that is not calculated by default (such as the absorption rate), you can create a normal tally using the Tally object, export it to XML, and then it will be accumulated during transport and written to the OpenMC statepoint files (openmc_simulation_#.h5).

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Hallo everyone…
I want find the conversion ratio for SFR but I found an error in my program:


please help me!

Hello;

I think that the problem is originated from the type of used variables in the indicated equation by the debugger. You should verify that they are from same type and you are not summing a string with integer.
probably you need to share a part of your python code to see how the error did occur.

N.B: it will be better if you start your own post and do not use ongoing or solved ones to post your problem :wink:
Best regards

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Okee Thank You for your advice Sir, I will try :slightly_smiling_face::pray:

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