Run PyNE R2S step 2

[gonuke]

Using the ALARA output from #21 and the same R2S config file from #20, run step 2 to generate:

• mesh-based photon source

Risk: OpenMC meshSpatial source only supports 1 group source
MITIGATION:

• complete workflow with only one group defined in photon source by ALARA, and then try
• defining multiple meshSpatial sources, on for each group