I generated hermal scattering data for h in h2o to use in MCNP code using openmc.data.njoy.make_ace_thermal module, and when I introduced the generated file in my model I got very small K effective. The expression I used is given bellow
openmc.data.njoy.make_ace_thermal(filename=‘n-006_C_012.endf’,
filename_thermal=‘tsl-crystalline-graphite.endf’,
xsdir=‘xsdir’,
ace=‘graph.th’,
stdout=True)
any help please !