A nanostructured ferritic alloy (NFA), 14YWT, was produced in the form of thin walled tubing. The stability of the nano-oxides (NOs) was determined under 3.5 MeV Fe+2 irradiations up to a dose of similar to 585 dpa at 450 C-circle. Transmission electron microscopy (TEM) and atom probe tomography (APT) show that severe ion irradiation results in a similar to 25% reduction in size between the unirradiated and irradiated case at 270 dpa while no further reduction within the experimental error was seen at higher doses. Conversely, number density increased by similar to 30% after irradiation. This 'inverse coarsening' can be rationalized by the competition between radiation driven ballistic dissolution and diffusional NO reformation. No significant changes in the composition of the matrix or NOs were observed after irradiation. Modeling the experimental results also indicated a dissolution of the particles. Published by Elsevier B.V.