FLUX AND COMPOSITION DEPENDENCE OF IRRADIATION CREEP OF AUSTENITIC ALLOYS IRRADIATED IN PFR AT SIMILAR-TO-420-DEGREES-C

Swelling and irradiation creep of five austenitic stainless steel allo ys irradiated at similar to 420 degrees C in the Prototypic Fast React or (PFR) were examined. The specimens were in the form of pressurized creep tubes, constructed in the USA and irradiated in PFR in a joint U SA/UK experiment. The alloy compositions varied greatly, with the grea test elemental variation in the nickel content, which ranged from 15% to 40% over the five alloys. For each alloy, at least two identical se ts of tubes were constructed. Each tube-set was irradiated at a differ ent neutron flux level. Swelling was observed to vary with both alloy composition and flux. Irradiation creep was examined from the perspect ive of the (B) over bar = (<(epsilon)over bar>) over dot/<(sigma)over bar> = B-0 + D(S) over dot creep model. The values of both creep coeff icients, B-0 and D, were typical for austenitic stainless steels and w ere found to be insensitive to flux over the range of fluxes in this e xperiment. However, the creep coefficients may be mildly sensitive to alloy composition. (C) 1998 Elsevier Science B.V. All rights reserved.