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An improved zero-dimensional model for simulation of TRIGA Mark II dynamic response
Get PDFThe primary aim of this work is to improve the analysis of the dynamic behaviour of the TRIGA Mark II reactor at the University of Pavia through a zero-dimensional approach. Besides the coupling between neutronics (point-reactor kinetics with six delayed neutron precursors group) and thermal-hydraulics (two-region model, with fuel and coolant) implemented in earlier works, the new model considers also the time behaviour of the mass flow rate due to natural circulation, of the neutron poisons and of the primary and secondary pool temperature. The system of coupled first-order differential equations is non-linear, as some state variables, such as the mass flow rate and the coolant temperature, multiply each other. The SimulinkTM programming environment for dynamic analysis and control purposes is used to solve the system. A comparison with experimental data collected on-site for different reactor power transients and with measurements of the poison anti-reactivity during reactor shut-down and of the pool temperature allows the validation of the model. The model results and the experimental data reach a remarkable agreement. In addition, a linear stability analysis of the reactor is performed through the root locus and the stability map in terms of the thermal feedback coefficients. This analysis shows how the power level influences the dynamic of the system, and that, for certain values (always negative) of the fuel thermal feedback coefficient, positive values of the one for the moderator still ensures the system stability
A new diagnostic instrument to detect generalized roughness in rolling bearings for induction motors
No full textIn this paper the external stray flux around a motor has been investigated as a possible new diagnostic instrument to detect generalized roughness. This very common bearing fault has been slightly considered in the literature so far. Stray flux was measured by two probes, one commercially available and one realized in laboratory; the diagnostic content of both signals has been compared also with the measurement of the stator current. The experimental tests have been carried out on an induction motor by substituting one of its bearings with an artificially damaged one, according to three steps of progressive wear. The three measured variables have been analyzed in the frequency domain, by evaluating in particular the characteristic frequencies of the single-point bearing defects. The diagnostic content of the stray flux has been discovered as definitely higher with respect to the stator current and therefore its use to detect generalized roughness is promising
Nuclear Education & Training activity experience at the University of Pavia
No full textAt the University of Pavia, at the Laboratory for Applied Nuclear Energy (LENA) is installed a 250kW TRIGA MKII Type Research Reactor together with a radiochemistry laboratory dedicated to the manipulation, analysis and radiochemistry separations. As a University institution, one of the main purposes is to prepare new generations of students and graduates for their careers. The Laboratory, as a facility at the disposal of different University departments, provides practical exercises as part of university classes in particular for Physics, Chemistry and, within agreements with other Universities, also in nuclear engineering. The University of Pavia, in consideration of its facilities and expertise, hosts international courses and hands-on training to foreign Regulatory Body personnel, health physics staff, and radiation protection Advisors. The assets and key points of practical courses are discussed together with a list of the achievable expected outcomes
Utilization of the Triga Research Reactor of the University of Pavia.
Get PDFThe Laboratory of Applied Nuclear Energy (LENA), operates the TRIGA nuclear research reactor of the University of Pavia for more that 100 days per year, carrying out multidisciplinary activities in collaboration, or as a provider, with several institutions industries and research centres both at national and international level. This paper will present an overview of LENA’s reactor utilization
L.E.N.A. - Laboratory of Applied Nuclear Energy (University of Pavia) - Neutron Facilities & Main Activities
No full textThe TRIGA (Training Research and Isotopes-production General Atomics) Mark II nuclear research reactor installed at the Laboratory of Applied Nuclear Energy (L.E.N.A.) of the University of Pavia is licensed for operating at 250 kW power in steady state. Nowadays the Pavia TRIGA reactor is available for national and international collaboration in various research fields offering different in- and out-core neutron irradiation channels. A
subcritical assembly is also available at the University of Pavia (Chemistry Department Radiochemistry Area) for experimental activities. Current scientific and Educational &Training activities are also described
Characterization of the TRIGA Mark II reactor full-power steady state
No full textIn this paper, the characterization of the full-power steady state of the TRIGA Mark II nuclear reactor at the University of Pavia is achieved by coupling the Monte Carlo (MC) simulation for neutronics with the "Multiphysics" model for thermal-hydraulics. Neutronic analyses have been carried out with a MCNP5 based MC model of the entire reactor system, already validated in fresh fuel and zero-power configurations (in which thermal effects are negligible) and using all available experimental data as a benchmark. In order to describe the full-power reactor configuration, the temperature distribution in the core must be established. To evaluate this, a thermal-hydraulic model has been developed, using the power distribution results from the MC simulation as input. The thermal-hydraulic model is focused on the core active region and takes into account sub-cooled boiling effects present at full reactor power. The obtained temperature distribution is then entered into the MC model and a benchmark analysis is carried out to validate the model in fresh fuel and full-power configurations. An acceptable correspondence between experimental data and simulation results concerning full-power reactor criticality proves the reliability of the adopted methodology of analysis, both from the perspective of neutronics and thermal-hydraulics
Object-Oriented Modeling and simulation of a TRIGA reactor plant with Dymola
Get PDFThis work presents the modeling and simulation of a TRIGA-Mark II pool-type reactor with Zirchonium-Hydryde and Uranium fuel immersed in light water, with Modelica object-oriented language, in Dymola simulation environment. The model encompasses the integrated plant system including the reactor pool and cooling circuits. The reactor pool plays a fundamental role in the system dynamics, through a thermal feedback effect on the reactor core neutronics. The pool model is tested against three experimental transients: simulation results are in good accordance with experimental data and provide useful information about the inertial effect of the water inventory on the reactor cooling
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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