812 research outputs found
Neutron (n,xngamma) Cross-Section Measurements for 52Cr, 209Bi and 206,207,208Pb from Threshold up to 20MeV
No full textThe present report contains the thesis prepared by the author to obtain the degree of Doctor of Science from the University of Bucharest, Faculty of Physics. The work presented in this thesis was carried out at the GELINA facility and in the Neutron Physics Unit of the IRMM in Geel, Belgium. The work was performed while the author was employed as a JRC grant holder (contract number 20207) under the
supervision of A. Plompen. This work received financial support from the EUROTRANS Integrated Project under contract number 22390.JRC.D.5 - Neutron physic
ReciproCities: A dynamic equilibrium
No full textThis booklet is as an expansion of the ideas and concepts presented by Arjan van Timmeren in his inaugural speech to the Delft University of Technology on April 17th 2013. The speech in its original format (Dutch) can be found on the bottom margin of the page highlighted in blue. While the English text should be considered complimentary to the original speech, it contains significantly more data and figures and follows a markedly different pace.Architecture and The Built EnvironmentUrbanis
From Wastescapes Towards Regenerative Territories. A Structural Approach for Achieving Circularity
No full textIn this chapter, the understanding of circularity goes beyond material resource management, deepening the spatial implications of a more circular management and use of wastescapes, investigated at the urban and metropolitan scale. Besides the health (care) related challenges presented by the current outbreak of the COVID-19 pandemic, additional ones related to our living environment have been—and will continue to be—an urgent call for academic researchers, designers and policymakers to find (eco)innovative solutions and strategies for enhancing the quality of life of all and the availability of more and more safe public (open) spaces and facilities to sustain this. In this situation, the spaces most at risk of urban and peri-urban areas could be found in the unresolved places which are defined as wastescapes, since they are in general still poorly used and valued. Building on the European H2020 research project REPAiR, the definition of wastescapes, provided in this study, builds upon work for two main cases: the metropolitan areas of Amsterdam (The Netherlands) and Naples (Italy). Wastescapes are discarded territories, however, they can also be understood as opportunities to realize regenerative concepts and support strategies related to environmental, spatial and social challenges of the territories and their surroundings. Core is then to improve the socio-ecological values of such territories. Wastescapes are different case by case, being affected by site-specific challenges and characterized by high complexity. The research presented in this chapter shows that the route towards a Circular Economy requires the consideration of wastescapes as ‘spatial resources’ important to be included in strategies of transition. It represents a fundamental step to overcome problems related to both resource (and land) scarcity, land use in general and spatial fragmentation, while providing opportunities to include through eco-innovative services other values than just the monetary ones to society. The spatial regeneration of wastescapes in the built environment involves a re-thinking of the structure of these areas in a larger (metropolitan) context. Within such metropolitan settings, in particular peri-urban territories, also referred to as the areas in-between urban and rural landscapes, are most affected and characterized by this problem of wastescapes.Environmental Technology and Desig
Dimensions of Circularity for Healthy Metabolisms and Spaces
No full textIn this first chapter of the Book “Regenerative Territories. Dimensions of Circularity for Healthy Metabolisms”, the relation between circularity and space is explored. The main focus is the development over time, and in particular the way how spatial planning and strategies respond to new unpredictable urgencies and opportunities related with territorial metabolisms. In relation to space and time, 5 grand rules are explored as necessary to implement the transition towards Circularity: (1) The Circular Economy paradigm shift requires a socio-ecological perspective and looking beyond boundaries; (2) Circular Economy is based on systems thinking and territorial metabolism; (3) a Circular Economy calls for a renewed approach to the public domain and stakeholder involvement; (4) amplifying the definition of Circular Economy with the inclusion of wastescapes; and (5) Planning the Circular Economy as an open collaborative system. The paradigm shift of contemporary planning towards circularity is aimed to facilitate the capacity of cities to be adaptive and flexible to the speeding up of the biggest changes in the present-day society. Therefore, the relation between the various spatial scales is strictly interlinked to the time scales, as well as to the metabolic processes and Life Cycles of Territories. In this perspective, the “existing city” is a non-negotiable common heritage, the result of a “selective accumulation” of material and immaterial traces produced by the slow and progressive anthropic work in the territory. Contemporary spatial planning looks beyond boundaries. This concerns both the physical boundaries between areas or countries, both the boundaries of the various scale levels of solutions, of the interrelated networks, of the public space and, particularly, of their reciprocity. It induces the scrutinization of the underlying social needs and the finding of instruments that allow the spatial planning and renewed infrastructure to fit the changing social objectives such as sustainability and liveability. The territory of the Circular Economy is the city, as a complex and multidimensional organism. However, the most problematic field for experimenting with “circular planning” is the peri-urban territory consisting of urbanized areas, crossed by differentiated phenomena of settlement expansion beyond the limits of the countryside, which identifies rural and open space, traditionally coinciding with the limits of the city. A circular planning for the regeneration of the peri-urban identifies the waste spaces, the decay of the territory, the obsolescence and end of life of buildings, functions and urban parts now inadequate, namely wasted landscapes (wastescapes). The latter are both the result of metabolic transformations of the territory and generator of prospects and potential for rebalancing the material welfare of the city.Environmental Technology and Desig
Integral benchmark experiments on a large copper block using the GELINA accelerator to validate natCu neutron cross sections from different neutron cross-sectional databases
No full textA neutronics integral benchmark experiment on a pure copper block, aimed at testing and validating recent copper nuclear data libraries, has been performed at Geel Electron LINear Accelerator Facility (GELINA). GELINA is a powerful photoneutron source using a 75- μA , 110-MeV electron beam impinging on a depleted U rotating target, producing a white neutron spectrum ranging from the epithermal region up to about 20 MeV with a mean energy of about 1.4 MeV and intensity up to 3.2×1013 n/s. A large nat Cu block (dimensions 60×60×60 cm 3 ) has been positioned at 100 cm from the target. Thin activation foils were used as neutron flux probes and located inside the block in six positions at different depths with respect to the main neutron propagation direction. Materials whose activation cross section are sensitive to different neutron energy ranges were used, and the measured fluxes were compared with calculations performed using the MCNP6 neutron transport code coupled to different neutron cross-sectional databases (FENDL3.1, JEFF33_T2, and ENDF 7.1). The MCNP6 calculation also used the neutron spectrum produced by the GELINA accelerator. This is the first time that a neutronics integral experiment on copper is performed using such a white neutron spectrum and the results of our comparison could be used to validate the neutron copper cross sections in the neutron energy range covered by GELINA. The C/E results, taking into account the sources of uncertainties, are satisfactory: no large differences are observed among the result obtained using the three cross-sectional databases; however, the JEFF-3.3 seems, slightly, better predict the results.JRC.G.2 - Standards for Nuclear Safety, Security and Safeguard
Neutron Data Measurements for Energy Applications and Nuclear Waste Transmutation at JRC-IRMM
No full textStudies in nuclear energy and transmutation of radioactive waste require neutron data for conceptual and performance studies, to determine the viability of advanced ideas such as an Accelerator Driven System and to fix the safety margins of any new concepts. IRMM's neutron data-measurement program addresses data needs associated with Accelerator Driven Systems, management of radioactive waste, the thorium fuel cycle, safety issues of conventional reactors. Ongoing and recently completed activities include capture and total cross-section measurements for 127,129I, 206Pb, and 232Th; precision total cross-section measurements for 240,242Pu; inelastic-scattering measurements for 52Cr, 58Ni, 209Bi, and 207Pb; (n,2n) measurements for 207Pb, and (n,xp); and (n,x alpha) and (n,xn) cross-section measurements with the activation technique. Capture, total, and inelastic cross-section measurements make use of the pulsed white neutron source Gelina, whereas activation cross sections are determined at the Van de Graaff laboratory. An overview will be given of the above-mentioned activities and an outlook will be provided for the measurements in the near future.JRC.D.5 - Neutron physic
Gamma Production Cross Sections for Inelastic Scattering and (n,2n) Reactions
No full textIn recent years it was shown that precise measurements of gamma-production cross
sections for gammas associated with inelastics scattering and (n,xn) reactions can be
performed at a white spectrum time-of-flight facility. This first of all leads to
continuous energy excitation curves characteristic of the decay of excited states in
the residual nuclei. With enriched samples the different reaction channels leading to
the same residual nucleus are disentangled. At GELINA modern data-acquisition
techniques have allowed access to the range from threshold to 20 MeV with excellent
incident energy resolution (1 keV at 1 MeV, 36 keV at 10 MeV). Since typically for
inelastic scattering excitation curves are measured of the decay of the first 15-20
excited levels, these experiments provide detailed information for the validation and
optimisation of nuclear model calculations. The relevant aspects are the optical
model, direct and pre-equilibrium reactions, level densities, the discrete level and
decay scheme and gamma-ray strength functions. Examples will be shown for 209Bi,
207Pb and 208Pb.JRC.D.5 - Neutron physic
Neutron Data Measurements for Energy Applications and Nuclear Waste Transmutation at
No full textAbstract. Studies in nuclear energy and transmutation of radioactive waste require neutron data for conceptual and performance studies, to determine the viability of advanced ideas such as an Accelerator Driven System and to fix the safety margins of any new concepts. IRMM's neutron data-measurement program addresses data needs associated with Accelerator Driven Systems, management of radioactive waste, the thorium fuel cycle, safety issues of conventional reactors. Ongoing and recently completed activities include capture and total cross-section measurements for 127 129 I, 206 Pb, and 232 Th; precision total cross-section measurements for 240 242 Pu; inelastic-scattering measurements for 52 Cr, 58 Ni, 209 Bi, and 207 Pb; (n,2n) measurements for 207 Pb, and´n xpµ; and´n xαµ and´n xnµ cross-section measurements with the activation technique. Capture, total, and inelastic cross-section measurements make use of the pulsed white neutron source Gelina, whereas activation cross sections are determined at the Van de Graaff laboratory. An overview will be given of the above-mentioned activities and an outlook will be provided for the measurements in the near future
Neutron Activation Cross Sections for Safety of Nuclear Power Plants.
No full textAbstract not availableJRC.D - Institute for Reference Materials and Measurements (Geel
Cross-Section Measurements in the Fast Neutron Energy Range
No full textGeneration IV focuses research for advanced nuclear reactors on six concepts. Three of these concepts, the lead, gas and sodium fast reactors (LFR, GFR and SFR) have fast neutron spectra, whereas a fourth, the super-critical water reactor (SCWR), can be configured to have a fast spectrum. Such fast neutron spectra are essential to meet the sustainability objective of GenIV. Nuclear data requirements for GenIV concepts will therefore emphasize the energy region from about 1 keV to 10 MeV. Here, the potential is illustrated of the GELINA neutron time-of-flight facility and the Van de Graaff laboratory at IRMM to measure the relevant nuclear data in this energy range: the total, capture, fission and inelastic-scattering cross sections. In particular, measurement results will be shown for lead and bismuth inelastic scattering for which the need was recently expressed in a quantitative way by Aliberti et al. for Accelerator Driven Systems. Even without completion of the quantitative assessment of the data needs for GenIV concepts at ANL it is clear that this particular effort is of relevance to LFR system studies.JRC.D.5 - Neutron physic
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