▁difficult ▁to ▁work ▁with ▁because ▁of ▁g amma ▁radiation ▁but ▁are ▁f ission able ▁in ▁a ▁fast ▁re actor . ▁ ▁Re processing ▁methods ▁ ▁U ran ium ▁ox ides ▁react ▁with ▁flu or ine ▁to ▁form ▁g ase ous ▁u ran ium ▁hex a flu or ide , ▁most ▁of ▁the ▁plut on ium ▁react s ▁to ▁form ▁g ase ous ▁plut on ium ▁hex a flu or ide , ▁a ▁majority ▁of ▁f ission ▁products ▁( es pecially ▁electro pos itive ▁elements : ▁l anth an ides , ▁str ont ium , ▁b arium , ▁y tt rium , ▁ca es ium ) ▁form ▁non vol atile ▁flu or ides . ▁F ew ▁met als ▁in ▁the ▁f ission ▁products ▁( the ▁transition ▁met als ▁n io b ium , ▁r uth enium , ▁te ch net ium , ▁mol y b den um , ▁and ▁the ▁hal ogen ▁i od ine ) ▁form ▁vol atile ▁( bo iling ▁point ▁< 2 0 0   ° C ) ▁flu or ides ▁that ▁accomp any ▁the ▁u ran ium ▁and ▁plut on ium ▁hex a flu or ides , ▁together ▁with ▁in ert ▁g ases . ▁Dist ill ation ▁is ▁then ▁used ▁to ▁separate ▁the ▁u ran ium ▁hex a flu or ide ▁from ▁the ▁mixture . ▁ ▁The ▁non vol atile ▁al kal ine ▁f ission ▁products ▁and ▁minor ▁act in ides ▁is ▁most ▁suitable ▁for ▁further ▁processing ▁with ▁' d ry ' ▁electro chem ical ▁processing ▁( py ro chem