GROUPR producing zeroes above fission break in IWT=4

[nathangibson14]

Certain choices of parameters on Card 8c (options for IWT=4) in GROUPR cause erroneous results. In the simple example given here, using 1.0 eV for the thermal break eb (as in input) leads to appropriate results. Instead, choosing 3.0 eV (as in bad_input) results zeroes for fluxes and cross sections above the fission break (ec).

iwt4.zip