How to Calculate Atom/B-cm Values for Nuclear Fuel Composition?

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Discussion Overview

The discussion centers around the calculation of atom/b-cm values for a specific nuclear fuel composition, focusing on the methodology and formulas used to derive these values. Participants explore the theoretical and practical aspects of atomic density calculations in the context of nuclear materials.

Discussion Character

  • Technical explanation
  • Exploratory
  • Debate/contested

Main Points Raised

  • One participant presents a list of atom/b-cm values for various isotopes in a nuclear fuel composition and seeks clarification on the methodology used for these calculations.
  • Another participant outlines a step-by-step process for calculating atomic density, including adding atomic masses, knowing material density, calculating mass fractions, and applying a specific formula.
  • There is a question regarding whether each nuclide should be treated separately in terms of density or if a total density composition should be used.
  • Some participants express uncertainty about how to reverse engineer the calculations without knowing the density of the material.
  • A participant mentions obtaining the data from a serpent nuclear code input file, noting the absence of fuel density information and questioning how such fuel compositions are typically calculated.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the methodology for calculating atom/b-cm values, and multiple viewpoints regarding the treatment of nuclides and the necessity of density information remain unresolved.

Contextual Notes

Limitations include the lack of provided density values for the materials discussed, which affects the ability to fully understand the calculations. Additionally, there are unresolved questions about the separation of nuclide densities in the context of the overall composition.

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How to Calculate Atom/B-cm Values for Nuclear Fuel Composition?
Hello everyone,

I came across the following atom/b-cm values for a specific nuclear fuel composition:
U-234.81c 1.1369e-06
U-235.81c 3.0421e-05
U-236.81c 2.4896e-06
U-238.81c 0.019613
Np-237.81c 4.6686e-05
Pu-236.81c 4.97e-10
Pu-238.81c 0.00011695
Pu-239.81c 0.0022076
Pu-240.81c 0.0013244
Pu-241.81c 0.00019375
Pu-242.81c 0.00029277
Am-241.81c 0.00010791
Am-242m.81c 9.2989e-06
Am-243.81c 0.00010017
Cm-242.81c 5.625e-06
Cm-243.81c 5.4321e-07
Cm-244.81c 6.724e-05
Cm-245.81c 1.7397e-05
Cm-246.81c 9.2285e-06
Zr-90.81c 0.0037456629
Zr-91.81c 0.00081683844
Zr-92.81c 0.00124855430
Zr-94.81c 0.00126529876
Zr-96.81c 0.00020384560
Mo-100.81c 9.04954512e-05
Mo-92.81c 0.0001360496577
Mo-94.81c 8.53224251e-05
Mo-95.81c 0.0001474173129
Mo-96.81c 0.0001548471529
Mo-97.81c 8.89909086e-05
Mo-98.81c 0.0002256070916

I am curious about the methodology and formula used to calculate these atom/b-cm values. Could someone explain the process or point me to relevant resources or references?

Thank you!
 
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To calculate the atomic density of a material, follow these steps

1 - add up all the atomic masses
2 - know the density of the material
3 - calculate the mass fraction for each radionuclide
4 - calculate the atomic density with the formula
((density*mass fraction*avogadro number)/total atomic mass)*1e-24)

5 - result in atoms/barn-cm
 
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Alexander Camargo said:
To calculate the atomic density of a material, follow these steps

1 - add up all the atomic masses
2 - know the density of the material
3 - calculate the mass fraction for each radionuclide
4 - calculate the atomic density with the formula
((density*mass fraction*avogadro number)/total atomic mass)*1e-24)

5 - result in atoms/barn-cm
Will each nuclide be written here as density or total density composition?
 
emilmammadzada said:
Will each nuclide be written here as density or total density composition?
Atom Densities
 
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Alexander Camargo said:
Atom Densities
Isn't it separate for uranium and separate for neptunium in this composition?
 
emilmammadzada said:
Isn't it separate for uranium and separate for neptunium in this composition?
use the formula to reverse engineer this and get this answer, because just looking at the data like this, I can't tell. Do you have the density of this material?
 
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Alexander Camargo said:
use the formula to reverse engineer this and get this answer, because just looking at the data like this, I can't tell. Do you have the density of this material?
I got this data from the serpent nuclear code input file. There was no fuel density given there, I just wonder how the content of such fuels is calculated. There is no information about density here
% --- 2D SFR Assembly based on MET-1000

% --- Materials

mat fuel sum tmp 807.15 vol 89.15304673765142 rgb 255 0 0 burn 1
U-234.81c 1.1369e-06
U-235.81c 3.0421e-05
U-236.81c 2.4896e-06
U-238.81c 0.019613
Np-237.81c 4.6686e-05
Pu-236.81c 4.97e-10
Pu-238.81c 0.00011695
Pu-239.81c 0.0022076
Pu-240.81c 0.0013244
Pu-241.81c 0.00019375
Pu-242.81c 0.00029277
Am-241.81c 0.00010791
Am-242m.81c 9.2989e-06
Am-243.81c 0.00010017
Cm-242.81c 5.625e-06
Cm-243.81c 5.4321e-07
Cm-244.81c 6.724e-05
Cm-245.81c 1.7397e-05
Cm-246.81c 9.2285e-06
Zr-90.81c 0.0037456629
Zr-91.81c 0.00081683844
Zr-92.81c 0.00124855430
Zr-94.81c 0.00126529876
Zr-96.81c 0.00020384560
Mo-100.81c 9.04954512e-05
Mo-92.81c 0.0001360496577
Mo-94.81c 8.53224251e-05
Mo-95.81c 0.0001474173129
Mo-96.81c 0.0001548471529
Mo-97.81c 8.89909086e-05
Mo-98.81c 0.0002256070916