Stability of β-85 wt% Nb precipitates in pressure tubes

The analysis of bcc β-85 wt% Nb precipitate stability in pressure tubes of in-service nuclear reactors is performed here. The internal stresses generated by irradiation growth and creep processes and their influence on the anisotropy of the diffusion of vacancies and interstitials, are explicitly included in calculations. A slightly anisotropic shape of precipitates is predicted.