The changes in resistivity for niobium and tantalum wires, which had been loaded with 5.37% (atom ratio) and 6.24% tritium respectively, was measured over a 1‐year period. After an initial rapid increase corresponding to roughly 5 &mgr;&OHgr; m for He interstitials, the resistivity reached a local maximum. It then continued to increase at a rate expected for the development of insulating He bubbles and material swelling. The local maximum corresponds to the point at which active acoustic emission is taking place and is indicative of dislocation loop punching at the bubbles. The stabilization of the resistivity after this local maximum is thought to be due to the general lattice relaxation and the formation of a complex and well‐developed dislocation network.