Abstract : The embrittlement condition of the Army SM-1A reactor pressure vessel, as modified by the recently completed in-place anneal, was assessed and an analysis was made of the reembrittlement behavior of the vessel steel with subsequent radiation service. Experimental results from the reactor surveillance program developed through one complete irradiation and annealing cycle are presented, together with a summary of experimental information on the annealing response of the vessel steel (A350-LF1, Mod.) from accelerated irradiation programs. These data indicate a 0 deg F maximum pressure vessel wall Charpy-V 30 ft-lb transition temperature after the in-place anneal versus a -80 deg F preservice transition temperature (based on the notch-ductility properties of a duplicate ring forging). The maximum Charpy-V 30 ft-lb transition temperature of the pressure vessel before the annealing operation was estimated at 190 deg F. A projection of postanneal pressure vessel lifetime in terms of neutron fluence >0.5 Mev was derived from spectra calculations and the experimentally predicted reirradiation response of the pressure vessel steel. The maximum permissible vessel wall fluence is estimated at 5.5x10 to the 19th power n/sq cm > 0.5 Mev. This is comparable to 124.7 Megawatt years of reactor operation. (Author)