Irradiation induced shifts in the nil ductility temperature can lead to significant loss of toughness and brittle failure for nuclear reactor components at relatively low exposure levels. In addition to embrittlement concerns in pressure vessel steels for existing reactors, this may complicate the use of similar materials such as ferritic steels in future reactor concepts. In this study, we investigate the deformation behavior of iron using an advanced, 3d dislocation dynamics model leveraging realistic dislocation networks comprised of edge, screw, mixed character, and junction segments. The model includes a temperature dependent, anisotropic Peierls barrier for screw dislocations paired with thermally activated mechanisms including both cross-slip and climb. Dislocation microstructures are loaded in uniaxial tension and compared to systems which include varying densities of radiation induced precipitates. Application across many loading conditions provides direct quantification of shifts in the yield point as a function of temperature, strain rate, and precipitate content.