Abstract: A recycle loop method and recuperative heating system is provided for thermally recombining hydrogen and oxygen, such as may be desired in connection with a dissociated gas stream from a containment vessel for a nuclear reactor under loss of coolant accident conditions. The dissociated charge stream is preferably heated by indirect heat exchange with a resulting water vapor containing combined stream to effect heat conservation and, also preferably, the recuperative heat exchange operation and the high temperature recombining reaction are carried out in a unitary zone incorporating electrical, non-flame, heat input means.