vapors and liquid of lower temperature and pressure and suitable for final energy extraction with a heat exchanger not shown or for inputting to a separator not shown that isolates the components of the effluent for disposal or other use such as fuel for reactor 116 or elsewhere fig2 illustrates an alternative embodiment of a latter compression and expansion stage 200 generally a stage located directly upstream or closest to a reactor 218 of the present disclosure generally latter compression and expansion stage 200 e g third compression and expansion stage 128 in the illustrative embodiment of fig1 may include a latter stage compressor 202 and an additional compressor 204 mounted on e g a common shaft 206 that may also be shared with a respective latter stage expansion turbine 208 additional compressor 204 may provide additional compression of an input 272 from a previous stage to stage 200 e g cooled third stage input 172 of fig1 when required by process requirements latter stage expansion turbine 208 may receive a bootstrap bypass drive stream 210 from latter stage compressor 202 a valve 212 may be provided for controlling the flow of bypass drive stream 210 into latter stage expansion turbine 208 a heat exchanger 214 may be included to reduce the temperature.