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A positron annihilation spectroscopy (PAS) investigation of radiation-induced damage in RPV welds was conducted. Eight different materials with composition variation of Mn, Ni, Si and Cr were manufactured based on typical WWER-1000 materials. This variation was chosen to observe the potential of synergistic role of these elements on the reactor pressure vessel (RPV) degradation. Materials were irradiated at the High Flux Reactor (HFR) in Petten as a part of LYRA-10 experiment, to displacement damage of ∼ 0.1 dpa. Subsequently, the as-received and irradiated materials were studied by the means of positron annihilation spectroscopy in the laboratory of the Institute of Nuclear and Physical Engineering of the Slovak University of Technology in Bratislava. Positron Annihilation Lifetime Spectroscopy (PALS) and Coincidence Doppler Broadening Spectroscopy (CDBS) were used to analyze the microstructure of samples. The obtained analysis from both techniques showed an increased rate of positron trapping at radiation-induced vacancy clusters with increasing content of Ni, Mn and Si in the materials. [ABSTRACT FROM AUTHOR]

In this study, a comparison is made between two Atomic Force Microscopy (AFM) vibration-isolation measures: a passive anti-vibration table and an acoustic isolation cover. The focus was on determining the standard deviation from height measurements taken at a single point on a surface. Based on its magnitude, the effectiveness of specific vibration-suppression measures can be determined. Deactivating the air table on which the microscope is placed resulted in an increase in height standard deviation by a factor of 3.1. The impact of the cover, under our typical measurement conditions, was found to be negligible, falling below the detectable threshold of our measurements. [ABSTRACT FROM AUTHOR]

Irradiation, heat and mechanical stresses are factors which influence structural materials of nuclear power plants (NPP), e.g. reactor pressure vessel steels and may reduce lifetime of NPP operation [1-3]. High radiation and thermal loads are expected in the newest generation of nuclear power plants, such as Generation IV (GEN IV) and fusion reactors, which will be operated at temperatures between 550 - 1 000 °C and will be exposed to irradiation over 100 DPA during planned lifetime (more than 60 years) [4]. Consequently, the demands on the structural materials are very high and so the research and development needs to be focus on their improved characteristics. The advanced structural materials, as oxide-dispersion-strengthened (ODS) steels, are developed for application in cooling systems, reactor pressure vessel or fuel cladding of the GEN IV nuclear power plants. The ODS steels fulfill demands on radiation, thermal and mechanical resistance during operation of nuclear reactor. ODS steels have high thermal corrosion resistance based on alloying by chromium, aluminum, silicon and on formation of dispersive stable oxides (Y2O3) in the microstructure. The experiments in this paper are focused on the laboratory produced model ODS alloys. The experimental analysis of materials at microstructural level was performed by Pulsed Low Energy Positron System and the nanoindentation techniques. [ABSTRACT FROM AUTHOR]