When attempting to run an RG 1.183 Rev. 1 compliant job, in the Source Scenario selection screen, Release Fractions and Timing tab, importing a .SRX file that contains the RG 1.183 Rev. 1 radionuclide groups will result in the Molybdenum group not being read in by SNAP/RADTRAD with no ability to add it in manually.
The Molybdenum group will show up if the user selects DBA AST on the Accident Parameters tab and checks the Use accident release fractions and timings box on the RFT tab, but in that case all gap and early in-vessel release fractions are uneditable.
There are scenarios where one might want to deviate from the built-in release fractions but maintain the RG 1.183 Rev. 1 radionuclide grouping. For example, in defining the release to the sump in an MHA LOCA, one might want to zero out the noble gas release, consistent with the Reg Guide. There does not appear to be a way to do this in the Scenario Selection tool if you're running a case with Rev. 1 radionuclide grouping. The import function should be updated to be able to read in .SRX files that contain all RG 1.183 Rev. 1 radionuclide groups, including Molybdenum.