EFFECT OF PREINJECTED HELIUM ON THE RESPONSE OF V-20TI PRESSURIZED TUBES TO NEUTRON-IRRADIATION

Vanadium-20% titanium tubes pressurized to stresses of 34 and 39 MPa were irradiated at 700 degree C to a fluence of 3. 9 multiplied by 10**2**6 n/m**2, corresponding to a displacement damage level of 22 dpa. The tubes were injected with 15 appm He prior to irradiation to determine the effect of helium on the microstructural and creep response. Helium promoted cavity formation, primarily within existing precipitates, but total swelling remained low. Under some conditions, an apparent enhanced creep deformation due to helium was found. The results suggest that the increase in creep deformation in the presence of helium may be sensitive to stress.