[en] Under the current U.S. surveillance programs, the Charpy V-notch energy (CVE), yield strength, and tensile strength are measured (all as a function of test temperature) at various times during the operational life of the reactor vessel. Conventionally, the CVE vs. temperature data are fit using a hyperbolic tangent (tanh) function to determine the temperature at which the mean CVE is equal to 30 ft-lbs (41J). This index temperature, which is designated T30 or T41J, is used to track irradiation damage. Recently an alternative strategy for fitting the CVE vs. temperature data was proposed in which a single CVE vs. temperature relationship appears to well represent the behavior of a very wide variety of ferritic steels for temperatures at and below fracture mode transition. It was demonstrated that when upper shelf data are excluded from a fit of Charpy V-notch energy (CVE) vs. temperature a single exponential function is found that well represents the transition temperature behavior of ferritic steels. The findings suggest that a reanalysis of already tested Charpy surveillance specimens can provide the basis for development of an embrittlement trend curve that is less influenced by the biases that arise from the tanh curve fitting method. Recently, a program was initiated with a goal of using the Charpy MC transition data fit to define a reference temperature, to use instead of the traditionally defined tanh-based T30/T41J reference temperature, in development of an embrittlement trend curve. The existing USLWR database was mined for datasets with sufficient data points within the transition temperature region for use in defining a TCVE reference temperature. These values were then used to define ΔTCVE data with irradiation. This data, along with chemistry, temperature, flux and fluence information, was used to develop the embrittlement trend curve presented herein. Predictions of embrittlement behavior made using this ETC were then compared to predictions made using the more traditionally-derived tanh-based ΔT30/41J models

[en] The XRF Group of the PCI Laboratory provided the instrumentation for performing the measurements at the synchrotron beam line. The micro-beam X-ray scanning spectrometer was moved out from the Instrumentation Unit?s XRF laboratory and was installed at the synchrotron beam line. The spectrometer was equipped with three X-ray detectors, namely: a large area silicon drift detector (active area of 50 mm², positioned in the synchrotron orbital plane at 90 degrees in relation to the primary beam; the detector was provided by the Atominstitut, Vienna), for collecting the X-ray fluorescence spectra during elemental mapping and tomographic scanning; small area silicon drift detector (active area 2 mm², positioned in the beam behind the sample), for collecting X-rays transmitted through the sample; and a silicon drift detector (active area of 10 mm²) fitted with a polycapillary half-lens and aligned in confocal geometry. The analyzed samples were mounted on a motorized stage. The synchrotron beam was monitored with an ionization chamber and Si-PIN diode detectors. Four groups of samples were analyzed by performing 2D/3D tomographic scanning in absorption/fluorescence mode and in a 3D confocal mode: Freeze-dried human-bone sections prepared at the Atominstitut, Vienna, Austria in collaboration with the Instrumentation Unit. U/Pu-rich particles provided by the Institute for Transuranium Elements, Karlsruhe, Germany. Stained organs of malaria mosquitoes obtained from the Entomology Unit of the IAEA Laboratories and prepared using different methodologies by the Instrumentation Unit. Mineral grain sample prepared by the Agency?s fellow. Several additional measurements on standard samples were performed in order to establish the geometry of the synchrotron beam and other analytical parameters. The Instrumentation Unit is collaborating with the other groups on elaborating the acquired data. We would like to emphasize that the use of advanced analytical techniques in combination with synchrotron radiation source provided essential information about the investigated samples, which could not be obtained by other means. In particular, the use of the polarized and monochromatized synchrotron radiation dramatically improved the detection limits enabling X-ray fluorescence tomographic measurements of trace element distribution in bone tissue, mosquito samples and 3D mapping of element distributions in individual radioactive particles. The tasks were performed in cooperation with other research groups addressing the needs of the Member States laboratories. It should be a recommended way of bringing the Agency?s support and expertise in applications of advanced nuclear analytical techniques directly to its Member States