talley question in OPENMC

User Support
1

Hi, All:

In OPENMC, (n,2n) and (n,3n) tally is write like n2n and n3n in tallies.xml file
Is there any feasibility to tally (n,gamma) and (n,p) reaction ration in tallies.xml file

Yours NiuOBA

2

In the developmental branch, there is now a capability to explicitly name reactions, so for example you could give:

(n,2n) (n,3n) (n,gamma) (n,p)

In the currently released version, the same can be achieved, but MT numbers must be used for the (n,gamma) and (n,p), so it would be:

n2n n3n 102 103

Best,
Paul

3

Dear Paul Romano

Thank you for your quickly reply
It really helps me a lot

Another question is:
How can I find the TM token number real physical meaning, do you have a table?

The tally result for n2n n3n 102 and 103 is Reaction Ratio, which means Macro-Cross section times flux.
Is there and feasibility for me to get micro-cross section times flux, directly from OPENMC.
I mean not manually change the result into micro-.

Thank you for your help in advance.

Yours
NiuOBA

4

The physical meaning of MT numbers can be found in Appendix B of ENDF-102:
https://www.oecd-nea.org/dbdata/data/manual-endf/endf102.pdf

Currently no, there is no automatic way to obtain microscopic cross sections; you’d have to do it manually using the known number densities. I would suggest taking a look at the new Python API as that might aid your post-processing. An example can be found here:
http://mit-crpg.github.io/openmc/pythonapi/examples/pandas-dataframes.html

Best,
Paul