Keyword:EXTRACTXS

EXTRACTXS trgt MT prdt

---

This keyword extracts the energy dependant reaction cross sections read from the read in nuclear data, providing the same functionality as the stand alone extract_xs_endf tool, see Reaction extract. Unlike the stand alone tool the EXTRACTXS keyword allows for the extraction of cross sections from EAF-style nuclear data libraries. The keyword takes three agruments:

1. trgt: the target nuclide e.g. C14
2. MT: the MT number of the reaction to be extracted
3. prdt: the product of the reaction

EXTRACTXS can be used multiple times in a single input file and for each entry, if a corresponding cross section is found in the nuclear data, an output file will be produced in the same directory as the input file. These files are named:

<trgt>_<MT>_<prdt>.xs

and the 8 columns produced contain

1. En-low = lower energy of the group
2. En-high = higher energy of the group
3. flux = group flux(i), as in the flux file
4. flux-unc = 0.000000E+00
5. gxs = group cross section
6. gxs_unc = mapped variance one sigma of the group cross section, in percent
7. greac-rate= flux(i)*gxs(i)/flux(1:groups)
8. cum-rate = incremental sum of the greaction-rates, in percent

For uncertainties to be printed when using EAF libraries the data must be read in via the crossuc key in the FILES file. If the reaction MT is not found a warning is printed to the .log file and no output is produced for that MT. If the MT in question does not produce a single daughter (e.g. a fission cross section) the prdt argument still needs to be included as it is used for output naming. For example, including

< -- Control phase -- >
...
EXTRACTXS U235 18 FISS
FISPACT
* Title of the simulation
< -- Initial phase -- > 
...
< -- Inventory phase -- > 
...

Would produce an file called U235_ 18_FISS.xs. Cross sections for gas production, kerma and DPA can be extracted with this method.