Abstract: The reliability of SRAMs that exposed to radiation has been studied with the aims of driving predictive model based on suffering multiple bit upsets.A method based on simple birthday statistics used to predict the cumulative probability of SRAMs suffering soft errors.An improved non-cumulative probability function was proposed to evaluate the periodic memory scrubbing technology which used to improve the effective BER over physical BERs.The predictive model is in good agreement with test results for SRAM processed using 90 nm bulk process technology under proton test.