This is often the fuel of choice for reactor designs that NASA produces, one advantage is that uranium nitride has a better thermal conductivity than UO. Uranium nitride has a very high melting point. This fuel has the disadvantage that unless N was used (in place of the more common N), a large amount of C would be generated from the nitrogen by the (n,p) reaction. As the nitrogen needed for such a fuel would be so expensive it is likely that the fuel would require pyroprocessing to enable recovery of the N. It is likely that if the fuel was processed and dissolved in nitric acid that the nitrogen enriched with N would be diluted with the common N. Fluoride volatility is a method of reprocessing that does not rely on nitric acid, but it has only been demonstrated in relatively small scale installations whereas the established PUREX process is used commercially for about a third of all spent nuclear fuel (the rest being largely subject to a "once through fuel cycle"). All nitrogen-fluoride compounds are volatile or gaseous at room temperature and could be fractionally distilled from the other gaseous products (including recovered uranium hexafluoride) to recover the initially used nitrogen. If the fuel could be processed in such a way as to ensure low contamination with non-radioactive carbon (not a common fission product and absent in nuclear reactors that don't use it as a moderator) then fluoride volatility could be used to separate the  produced by producing carbon tetrafluoride.  is proposed for use in particularly long lived low power nuclear batteries called diamond batteries.