Temperature Reactivity - how to test

User Support
1

Below please see the material specification for a molten salt reactor fuel. I am using the
materials.temperature = 1200.0
line to change the analyzed temperature, but no change occurs in the calculated keff. As you can see from the below snippet, I am using the 80x library.
What am I doing incorrectly?

Thank you, and I apologize if this is a duplicate question.
Brian

From Experience with the Molten-Salt Reactor Experiment - Haubenreich and Engel

LiF-BeF2-ZrF4-UF4 (65 29.1 5.0 0.9 mole %, U235 33% enrichment

FuelSalt = openmc.Material(1,“FuelSalt”)
FuelSalt.add_nuclide(‘U235’,0.003,‘ao’)
FuelSalt.add_nuclide(‘U238’,0.006,‘ao’)
FuelSalt.add_nuclide(‘Li7’, 0.69,‘ao’)
FuelSalt.add_nuclide(‘F19’, (.691 + .2912 + .054 + .014),‘ao’)
FuelSalt.add_nuclide(‘Be9’, .291,‘ao’)
FuelSalt.add_nuclide(‘Zr91’,.05,‘ao’)
FuelSalt.set_density(‘g/cm3’, 2.3)

#Graphite Moderator
Graphite = openmc.Material(2,“Graphite”)
Graphite.add_nuclide(‘C12’,1.0,‘ao’)
Graphite.set_density(‘g/cm3’, 2.1)

#Hastelloy N alloy - specified as weight percent in Haynes documentation
Hastelloy = openmc.Material(3,‘Hastelloy’)
Hastelloy.add_nuclide(‘Ni59’,0.71,‘wo’)
Hastelloy.add_nuclide(‘Mo96’,0.16,‘wo’)
Hastelloy.add_nuclide(‘Cr52’,0.07,‘wo’)
Hastelloy.add_nuclide(‘Fe56’,0.04,‘wo’)
Hastelloy.add_nuclide(‘C12’ ,0.0006,‘wo’)
Hastelloy.add_nuclide(‘Si28’,0.01,‘wo’)
Hastelloy.add_nuclide(‘Mn55’,0.008,‘wo’)
Hastelloy.add_nuclide(‘V51’, 0.0014,‘wo’)
Hastelloy.set_density(‘g/cm3’, 8.86)

materials=openmc.Materials([FuelSalt,Graphite,Hastelloy])
##Changing this temperature specification does not change the keff???
materials.temperature = 1200.0
materials.cross_sections="/home/brian/OpenMC_data/NuclearData/lib80x_hdf5/cross_sections.xml"
materials.export_to_xml()

2

You have two options for changing the temperature in the problem: either specify the temperature for each Cell or Material instance,

# material
FuelSalt = openmc.Material(1, "FuelSalt", temperature=1200)

# or, cell
fuel = openmc.Cell()
fuel.temperature = 1200

or use Settings to set a default temperature.

settings = openmc.Settings()
settings.temperature = {
'default': 1200.0,
'method' : 'interpolation'
}
3

That worked, thank you so much!