The walk-away safe, SLIMM and VSLLIM small and micro reactor designs have recently been developed at the University of New Mexico’s Institute for Space and Nuclear Power studies. These passive operation reactors concepts could generate 10–100 MWth and 1.0–10 MWth without refueling for 6.3–68 full power years (FPYs) and 5.8–92 FPY, respectively. These factory constructed, assembled and sealed reactors would be transported to designated sites by truck, rail or barge, and installed below ground, to protect against impact by an airplane or a missile, and mounted on seismic insolation bearings, to resist earthquakes.
This paper describes the design, operation and passive safety features of the SLIMM and VSLLIM reactors and presents estimates of operation lives and post-operational biological dose rates. Results of passive removal of decay heat by natural circulation of ambient air along the outer surface of the guard vessel wall will also presented and discussed.