Santa Barbara Research Center (SBRC) and Hughes Technology Center (HTC) have developed nuclear radiation testing methodology to measure performance of infrared (IR) focal plane arrays (FPAs) in simulated total ionizing dose, transient dose rate (and flux), and neutron fluence environments. Test methodology for FPAs requires that temperature, background, bias, and vacuum conditions be maintained and controlled during in-situ measurements of performance parameters, which are accomplished with specially fabricated dewars, configurable test sets, and a new FPA portable test set. Radiation sources, dewars and test-set configurations allow measurements of functionality, responsivity, noise, pulse-height distributions, and response/recovery time under operational conditions for the selected radiation environment. This paper summarizes test methodology for EPA testing that can be used for benign (clear) and radiation environments, and describes the use of custom dewars and integrated test equipment in an example environment. The test methodology, consistent with American Society for Testing Materials (ASTM) standards, is presented for the total accumulated gamma dose, transient dose rate, gamma flux, and neutron fluence environments. The merits and limitations of using Cobalt 60 for gamma environment simulations and of using various fast-neutron reactors and neutron sources for neutron simulations are presented. Test result examples are presented to demonstrate test data acquisition and FPA parameter performance under different measurement conditions and environmental simulations.