Experimental tests of irradiation-anneal-reirradiation effects on mechanical properties of RPV plate and weld materials

摘要

The Charpy-V (C(sub V)) notch ductility and tension test properties of three reactor pressure vessel (RPV) steel materials were determined for the 288(degree)C (550(degree)F) irradiated (I), 288(degree)C (550(degree)F) irradiated + 454(degree)C (850(degree)F)-168 h postirradiation annealed (IA), and 288(degree)C (550(degree)F) reirradiated (IAR) conditions. Total fluences of the I condition and the IAR condition were, respectively, 3.33 (times) 10(sup 19) n/cm(sup 2) and 4.18 (times) 10(sup 19) n/cm(sup 2), E > 1 MeV. The irradiation portion of the IAR condition represents an incremental fluence increase of 1. 05 (times) 10(sup 19) n/cm(sup 2), E > 1 MeV, over the I-condition fluence. The materials (specimens) were supplied by the Yankee Atomic Electric Company and represented high and low nickel content plates and a high nickel, high copper content weld deposit prototypical of the Yankee-Rowe reactor vessel. The promise of the IAR method for extending the fluence tolerance of radiation-sensitive steels and welds is clearly shown by the results. The annealing treatment produced full C(sub V) upper shelf recovery and full or nearly full recovery in the C(sub V) 41 J (30 ft-lb) transition temperature. The C(sub V) transition temperature increases produced by the reirradiation exposure were 22% to 43% of the increase produced by the first cycle irradiation exposure. A somewhat greater radiation embrittlement sensitivity and a somewhat greater reirradiation embrittlement sensitivity was exhibited by the low nickel content plate than the high nickel content plate. Its high phosphorus content is believed to be responsible. The IAR-condition properties of the surface vs. interior regions of the low nickel content plate are also compared.