Tungsten is an essential element in all conceptual designs for thermionic nuclear space reactors because of its highly desirable physical properties including a favorable work function at high temperatures. However, a serious disadvantage is the high cross section for thermal neutron absorption exhibited by four of the five naturally occurring isotopes of tungsten. Tungsten-184 is the only isotope with a small cross section (2.4 millibarns); the other four isotopes have a combined cross section of about 80 barns, I.E., Roughly 35,000 times that of tungsten-184. If enriched tungsten-184 were used in reactor fabrication, reactor efficiency could be improved by orders of magnitude since the tungsten component located in the neutron flux required to sustain the chain reaction has a vastly lowered neutron capture cross section compared to natural abundance tungsten. In this study, optimal operating conditions are being investigated to enrich tungsten-184 in multi-kilogram amounts using gas centrifuge technology. Development of an enrichment process for tungsten-184 would make high efficiency, thermionic nuclear space reactors possible. The principal benefit is the deployment of reactors in the 10-30 kilowatt range that would be used for tracking devices, communications systems, .G., For submarines and global air traffic control, and many other possibilities in military and civilian applications. The use of quiet, in-core, thermionic reactors for submarine power systems has particularly significant potential for the near future.
