Reactor kinetics investigations have been performed for cold-start-up, hot-start-up, hot-standby, and operating-power reactivity accidents using the UO2-fueled, pressurized-water type SPERT-III reactor. Power excursion behavior was predicted for every SPERT-III experiment by digital computer calculations using the SPERT-developed PARET code. Extrapolations for severe cold-start-up excursion consequences were obtained from severe transient tests on SPERT-III fuel samples in the SPERT-IV capsule driver core. Analyses of the SPERT-III data show that prompt moderator heating was as significant as the Doppler effect in limiting the magnitude of power excursions in the SPERT-III core at operating temperatures. Comparisons of calculations and experimental data demonstrate that PARET is capable of predicting power excursion behavior in SPERT-III within experimental uncertainty for the range of conditions investigated. The SPERT-III integral-core tests also provide a broad base of experimental data for demonstrations of the capabilities of other existing models in predicting non-damaging power excursion behavior in UO2-fueled reactors.