The influence of neutron irradiation on the microstructure and related mechanical properties of Ti Grade 2 in coarse- and ultrafine-grained conditions was investigated. It was found that mechanical ...properties of the coarse-grained (CG) state were significantly affected by neutron irradiation. At room temperature (RT), the yield stress increased by more than 30%, whereas the ductility decreased by more than 50%. An even bigger difference in the mechanical properties between irradiated and non-irradiated states was observed at a temperature of 300 °C. Changes in the mechanical properties can be attributed to the high density of defect clusters/dislocation loops induced by neutron irradiation. On the other hand, the ultrafine-grained (UFG) state is more resistant to radiation damage. The mechanical properties at RT did not change upon neutron radiation, while at a temperature of 300 °C, the yield stress increased only by about 10%. Enhanced radiation resistance of the UFG state can be attributed to the presence of a high density of dislocations and dense network of high-angle grain boundaries, which act as traps for radiation-induced defects and, thus, prevent the accumulation of these defects in the microstructure.
The radiation-induced volumetric expansion (RIVE) of concrete aggregates is the driving mechanism behind the degradation of the concrete biological shield (CBS) in nuclear power plants (NPPs). The ...RIVE of concrete aggregates, which are commonly used in NPP CBS, is investigated in this study. The cylindrical samples with the height of 1 and 2 cm and the diameter of 1 cm were manufactured from rocks (concrete aggregates). Prior to irradiation, the mineral composition of the aggregates was determined using X-ray diffraction analysis with Rietveld refinement. Also, the volume of the aggregates was measured before and after irradiation using water pycnometry and Vertex 251HM MicroVu with touch sensors and optical profilometry. The irradiation of the aggregates was performed in the LVR-15 research reactor. The temperature of irradiation was controlled and did not exceed 60 °C. The concrete aggregates were irradiated up to two different dose levels. Simultaneously, the Rigid-Body Spring Model was used in order to develop in-house software for prediction of RIVE of aggregates. The results of experimental investigation and numerical predictions in terms of RIVE showed good correlation. The obtained experimental and numerical data will be used for further development of the software for prediction of radiation-induced concrete deterioration.
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