Nature 211, pp.291–292. The accessible abstract discusses reduced high-temperature ductility, thin-foil observations of bubbles and a helium embrittlement mechanism involving grain boundaries. The abstract was inspected; the subscription-only full article was not required for the stated claim.
Nature 216, 575–576. The opening description identifies Dounreay-irradiated type316 specimens and thin-foil electron microscopy.