As a prerequisite to determining the combined effects of irradiation and Hydrogen content upon the mechanical properties of ASTM A542, A302B and HY 80 pressure vessel steels the cathodically induced hydrogen occlusion was studied. The rate of occlusion increased with increasing current density, poison concentration (sodium arsenate or carton disulfide) and irradiation. The induction period was reduced by increased current density and irradiation. Specimens were irradiated to 4 x 1017 n n/cm2 E > 1 MeV and the radioactivity measured 2-3 r/hr at contact prior to testing. Increasing the poison concentration and irradiation also resulted in an increase in the apparent "supersaturation" solubility. The increased occlusion rates found with the irradiated specimens were attributed to either changes in the specific rate constants for absorption and desorption or the number of surface active sites. The increased apparent solubility limit was attributed to increased hydrogen trapping.
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