We report the modeling and simulation of the soft-error rate (SER) in CMOS 130 nm SRAM induced by alpha-particle emission in silicon due to uranium contamination at ppb concentration levels. Monte-Carlo simulation results have been confronted to experimental data obtained from long-duration (>20 000 h) real-time measurements performed at the under-ground laboratory of Modane (LSM) and from experimental counting characterization using an ultra low background alpha-particle gas proportional counter. The calibration of simulations with the measured SER allowed us to determine a U-238 contamination level of 0.37 ppb (considered at secular equilibrium) in very good agreement with both corresponding alpha-particle emissivity levels measured and simulated at wafer-level in the range 1.1 to 2.3 x 10(-3) alpha/cm(2)/h.