Drilled concrete cores from the centralpart of the containment structure of reactor 2 in Oskarshamn weretested in the present study. Optical microscopy and scanning electron microscopy wereapplied.The microscopy analyses performed have not documented any changes in the properties of the concrete that can be interpreted as beingdue to the specific environment to which the samples havebeen exposed. The parameters that havebeen studied includecrack patterns that could indicate volume changes inthe aggregate or cement pasteand indications of alkali silica reaction. The observed differences in the concrete surface compared to the inner part of the concrete are such that they couldoccur in concrete exposed to a normal indoor environment. There are no crack patterns to indicatethat the radiation has caused a volume increase inthe aggregate or drying shrinkage in the cement paste. Thereareno changesin the crack patterns, porosity or polarization properties that may indicate reduced mechanical strength. The damage seen in the surface of sample 5 is likely to have beencaused by a local mechanical impact and thisdamage is superficial andlocal. The mechanical properties of the concrete were evaluated by uniaxial compression tests on cylinders machined from drilled cores. Full-field strain measurement was performed on the surface of the cylinders during the compression test. Optical full-field deformation measurement was conducted usinga measurement technique based on Digital Image Correlation (DIC) with a stereoscopic camera set-up, consisting of two CCDcameras. The basic idea behind DIC is to measure the deformation of the specimen duringtesting by tracking the deformation of a surface speckle pattern in a series of digital images acquired during loading. That there is some variation in strain between the various segments is natural, since the local stiffness depends on aggregate sizeand location. The general picture is that the strain distribution is relatively uniform along the length of the cylinder,which indicates that the tested cylinders do not exhibit any degradation of mechanical properties. There is also no significant difference between the cylinders taken towards the insideof the structure, compared with thosetaken towards the outside.The overall conclusion is that the tests carried out do not indicate any degradation of the mechanical properties, and that the properties in general are equivalent for the cores taken towards the inside and the outside of the structure.