Units on buGroups setting

[drewj-usnctech]

From docs: https://terrapower.github.io/armi/user/inputs/settings_report.html?highlight=bugroups

What are the anticipated units on this? Looking at some other examples that only include e.g.,

buGroups: [100]

my first reaction is %FIMA.

[john-science]

Yeah, those are just percentages:

armi/armi/physics/neutronics/crossSectionGroupManager.py

Lines 652 to 659 in 75f65b2

	def _setBuGroupBounds(self, upperBuGroupBounds):
	"""
	Set the burnup group structure
	Parameters
	---------
	upperBuGroupBounds : list
	List of upper burnup values in percent.

And the list of percentages has to be monotonic (it can only ever increase).

[jakehader]

Yes you're right that it is %FIMA. This has pretty much been the standard use case at TerraPower, but given that there is a burnup parameter for MWdkg on the blocks (maybe composites too?) then this could be an easy enough extension. I think that there is some interplay with the cross section / lattice physics interface with which parameter is being compared to so maybe we could need to configure an application for which "burnup" is the standard to use.

Consider opening another issue / feature request on this if it is important for your work. Burnup in MWd/kg is clearly a standard in the industry though. Also, if you have time to help with this type of PR it would be appreciated of course! 🙂

[john-science]

Yes, it is %FIMA.

Perhaps that needs to be in the docstrings somewhere.

[ntouran]

yeah we should clarify in the setting definition itself so it shows up on https://terrapower.github.io/armi/user/inputs/settings_report.html?highlight=bugroups

[john-science]

@ntouran I will add that to the docs, sure.

[drewj-usnctech]

@john-science @jakehader @ntouran thank you for the fast response! I'll make an issue for specifying burnup groups in MWd/kg X. Probably initial heavy metal?