We consider a theoretical calculation of a proposed atomic iodine laser system excited by a nuclear‐powered photon source. Overall system efficiency of 1.6% is calculated for the KrF fluorescent system and 2.3% for the Ar2F system. Laser power output of about 30 kW is estimated for a laser tube 1.8 cm in diameter and 60 cm long when used with a fast burst reactor. Such systems should easily scale to very high power.