The VVR-S nuclear research reactor owned by Horia Hubulei National Institute of Physics and Nuclear Engineering was designed for research and radioisotope production being permanently shut-down in 2002 after 40 years of operation. The decommissioning of the reactor started in 2010 and is planned to be finalized in 2020, being the first nuclear research reactor that has started the decommissioning project from the South-East of Europe. This paper presents the lessons learned from the decommissioning of systems, structures, equipment and components from pumps room. The experiences gained cover a diverse range of topics from planning, approval, radiological characterization process made, dismantling, equipment used, resources, etc. Radiation protection and economics are the key factors for the selection of technology for decommissioning. The evaluation of the available technology has been made and areas for improving the technology have been identified. Dedicated and advanced technologies were chosen to perform specific tasks. The project was planned well in advance. Safety aspects have been taken into consideration. Resource constraints have also been an important issue considered in defining the decommissioning strategy. Experiences and knowledge were presented and shared with the community.
Using recycled concrete aggregates (RCA) is a matter of high priority in the construction industry worldwide. In countries like the Netherlands, Denmark, Germany, USA, Japan, France recycled concrete aggregates obtained from demolition are valorized up to 90%, mainly for road construction and less in the manufacture of new concrete.
Recycled concrete aggregates (RCA) generally result from a two-stage crushing of the concrete obtained from demolition followed by the screening and removal of contaminants (wood, plastic, metal, ceramics etc.). The literature review showed that the recycled aggregates concrete (RAC) are less resistant, with 15 to 40% versus concrete obtained using natural aggregates. The factors that play a role in the reducing of mechanical resistance are presented and analyzed in this study.
This paper presents a study on the use of recycled aggregates, from a concrete of specified class, to acquire new cement concrete with different percentages of recycled aggregates. In order to evaluate the influence upon the properties of the new concrete obtained, recycled aggregates have been characterized in terms of the granulosity, the granule shape, the absorption of water, behavior to the Los Angeles test, the content of attached mortar etc.
Modeling of the powder compaction process in dies requires the determination of characteristics for use as input to the model or for con®rmation of the output from the assumed model. The distributions of normal stress on work punches were determined during one-sided die compaction of a ceramic powder using an experimental device comprised of split punches and equipped with strain gauges. The effect of presence or absence of lubrication and its in¯uence on powder conditioning were studied. The experimental data obtained were mathematically processed using spline functions that con®rmed the previous theoretical observations. The distributions of normal stress on the punches presented in this study are much more detailed than those reported in the literature. For all test cases studied, stress distribution on the upper punch shows the same shape with close numerical values. On the lower punch, the largest decrease of the normal stress is noticed when the``as received'' powder is compacted without lubrication. The bene®cial effect of lubrication and powder conditioning for homogeneity was demonstrated with respect to the distribution of normal stress on the lower punch. Results showed that the spline functions better represent the experimental data.
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