Conversion from atoms/b-cm to grams

User Support
1

Hello,

I am currently working on a VVER pin burnup. For my project, I have to find out the mass of certain nuclides (e.g. U-238) at each step of the burnup. Right now, I can use the following code to get the atom density of U-238 at the end of burnup.

import openmc.deplete
chain = openmc.deplete.Chain.from_xml(“/home/chain_endfb80_pwr.xml”)
model = openmc.Model(geometry=geometry, settings=settings)
operator = openmc.deplete.CoupledOperator(model, “/home/DepletionChain/chain_endfb80_pwr.xml”)
depletion=[0.1,1,3,4.9,5,10,10,20]
integrator = openmc.deplete.CELIIntegrator(operator, depletion, power_density=36.8, timestep_units=‘MWd/Kg’)
integrator.integrate()
results = openmc.deplete.Results(“depletion_results.h5”)
_depletion, u238 = results.get_atoms(“1”, “U238”, nuc_units=‘atom/b-cm’)
u238

This gives me the following result,

array([0.02120867, 0.02120763, 0.0211971 , 0.02116481, 0.0211101 ,
0.02105137, 0.02092497, 0.02078413, 0.02045383])

Now, I wish to convert each of these above values (which is in atom/b-cm) to grams. How can I do that?

2

atom/(barn cm) is simply 1e24 times atoms/cm3 both need a volume to convert to g
if you really only want mass (g) then I suppose atoms is easier, just multiply number of atoms by molar mass