Recent progress in understanding reactor pressure vessel steel embrittlement

Understanding the Role of Defect Production in Radiation Embrittlement of Reactor Pressure Vessels

“…2 is, for the same damage level, the ternary alloy experienced substantially more embrittlement than uanlloyed Fe regardless of the irradiating species. The pronounced effect on embrittlement of alloying species has been well-documented in previous neutron irradiation experiments [1]. Similar behavior has also been reported in recent work examining electron irradiation-induced hardening.…”

“…Small-angle neutron scattering (SANS) experiments [1] and recent electron microscopy work are consistent with this CRP interpretation. High resolution electron microscopy (HREM) in higher Cu-content (21.3 wt.% Cu) binary alloys shows evidence for pure Cu precipitates forming subsequent to electron-or neutron-irradiation [19,20].…”

“…In the interim however, damage rate effect differences are discounted by considering model predictions and additional existing data from the neutron irradiation test matrix. Although rate theory modeling has not been applied to analyze the specific results of our experiment, the cluster-recombination rate theory model of Odette [1] suggests that there should be only a minimal to modest effect on hardening for this difference, at the damage rate levels studied. This prediction appears supported by neutron irradiated data for an Fe-Cu alloy (taken from the same IVAR and "piggy-back" experiments) as shown in Fig.…”

“…With the goal of better modeling radiation effects of interest to embrittlement a hybrid approach has evolved in which the nascent defect production results of MD simulations have been used as input to rate theory models [1][2][3][4]11]. MD simulations in pure Fe, over the time scale of many of picosecond, show that primary defect production varies with the energy of the initiating recoil atom.…”

“…copper-rich precipitates (CRPS)] and defect clusters [1][2][3][4] with fluence. Embrittlement is caused by yield stress increases introduced by these hardening centers (hence the terms "embrittlement" and "hardening" are used interchangeably in the remainder of the paper).…”