SDL-2024-001#
Error in STDCOMP mixture processing with inputs using both default and user-specified isotopics.
Defect identifier |
|
Fix identifier |
N/A |
Fix deployed in production release |
v6.3.2 (projected) |
Fix deployed in beta release |
v7.0-beta09 (projected) |
Executive Summary#
A defect in StdComp mixture processing logic was identified where an
input that contains both a natural composition specification (no
user-provided isotopics), followed by a composition with user-specified
isotopics, produces the incorrect material density for the mixture with
the user-specified isotopics. This was related to a variable for the
isotopic breakdown that was incorrectly shared between two mixtures
defined with the same composition, e.g. uo2 with natural u, then
followed by a uc with 100% u-235.
Steps to Reproduce#
Execute the following input through the SCALE/bin/vulcan mixing utility:
=xsproc
test mixture densities
test-8grp
read comp
uc 1 den=8.29 1.0 end
b4c 2 den=8.29 1 293 6012 97.0 6013 3.0 end
end comp
end
What is the defective behavior?#
Mixture 2 does not have the specified density of 8.29 but is instead 8.2926:
------------------------------------------------------------------------------------
Mixture table for component comps at line:4, column:1
------------------------------------------------------------------------------------
Mixture = 1 with density(g/cc) = 8.2900 and temperature(K) = 293.00
Entry Mixture Nuclide Density (atoms/b-cm) Temperature (K)
------------------------------------------------------------------------------------
1 1 6012 1.975262e-02 293.00
2 1 6013 2.136389e-04 293.00
3 1 92234 1.078274e-06 293.00
4 1 92235 1.438369e-04 293.00
5 1 92238 1.982134e-02 293.00
------------------------------------------------------------------------------------
Mixture = 2 with density(g/cc) = 8.2926 and temperature(K) = 293.00
Entry Mixture Nuclide Density (atoms/b-cm) Temperature (K)
------------------------------------------------------------------------------------
6 2 5010 7.191972e-02 293.00
7 2 5011 2.894860e-01 293.00
8 2 6012 8.784422e-02 293.00
9 2 6013 2.507198e-03 293.00
------------------------------------------------------------------------------------
Entry Mixture Nuclide Density (atoms/b-cm) Temperature (K)
------------------------------------------------------------------------------------
End of mixture table for component comps at line:4, column:1
------------------------------------------------------------------------------------
What is the expected behavior?#
The user-specified density is produced in the mixture table.
Mitigation#
Is there a workaround?#
Specify isotopics for each mixture or use the default/natural. Use isotope-specific atomic number densities instead of basic composition entries.
Any additional notes on the scope of the defect?#
This defect can significantly affect results. Review of processed input (i.e., the mixture table) should always be performed. If the defect is active, it will be clear that the mixture density is incorrect.