Analytical results from an independent evaluation of the so-called “inherent reactor shutdown” mechanism in the proposed Power Reactor Inherently Safe Module (PRISM) advanced liquid-metal reactor design are discussed. Inherent reactor shutdown, in this context, refers to the tendency of the metal fuel reactor to inherently transition to a low power level when the reactor overheats significantly. Such behavior was demonstrated at the small Experimental Breeder Reactor II in 1986, but extrapolation to the proposed PRISM design concept requires extensive computer calculations. Analyses by Brookhaven National Laboratory (BNL) tend to confirm calculations submitted by General Electric (GE) and the Argonne National Laboratory staff providing technical expertise to GE on the metal fuel. The BNL calculations also indicate some problem areas, particularly with respect to very low probability events that could lead to sodium voiding.