Fix two SCORE_DECAY_RATE bugs
Fix two SCORE_DECAY_RATE bugs

Bug 1: the wrong nuclide index was used resulting in a segfault
Bug 2: two branches in the tally logic did not use the correct nu value

smharper/openmc,amandalund/openmc,shikhar413/openmc,shikhar413/openmc,smharper/openmc,liangjg/openmc,mit-crpg/openmc,walshjon/openmc,walshjon/openmc,wbinventor/openmc,paulromano/openmc,mit-crpg/openmc,liangjg/openmc,mit-crpg/openmc,smharper/openmc,amandalund/openmc,paulromano/openmc,paulromano/openmc,amandalund/openmc,wbinventor/openmc,shikhar413/openmc,mit-crpg/openmc,walshjon/openmc,liangjg/openmc,liangjg/openmc,smharper/openmc,amandalund/openmc,wbinventor/openmc,wbinventor/openmc,shikhar413/openmc,paulromano/openmc,walshjon/openmc