The results of the concrete shield of the EWA nuclear reactor

This paper is presenting the study of the concrete shielding of EWA research nuclear reactor which was after the ageing process and also under radiation during the reactor exploitation from 1958 year. According to the assessment the reactor was in exploitation till 24 February 1995 during 107400 h under the load of 10 MW, after taking into account the technological breaks and that in the begging years the reactor power was lower. For sampling of the concrete shielding the 7 cores were drilled in, wherein except rollers of different length and of diameters of 100 and 80 mm, the irregular pieces and concrete rubble were obtained. The specimens drilled out over the horizontal channel had the density of 2.4 g/cm(3) and under this channel, where in concrete were more steel pieces, the density was 3.1 g/cm(3). The compressive strength of concrete samples drilled out over and under the channel was 30.6 MPa and 28.2 MPa respectively. The coarse aggregate was iron ore: crushed goethite with the grains up to 29 mm; the content of this aggregate was from 25% to 35%. The goethite and quartz sand grains under 2 mm was fine aggregate. The concrete samples had high open porosity in the range from 24.5% to 30.7%. Despite of numerous found cracks of aggregate grains the research results did not give the possibility to establish the radiation influence in the examined layer of concrete shielding.