1,720,976 research outputs found
A Zero Dimensional Model for Simulation of TRIGA Mark II Dynamic Response
No full textIn this paper the development of a model for the nuclear research reactor TRIGA Mark II operating at University of Pavia is presented. Purpose of the modeling is to reproduce the dynamic behavior of the reactor on the entire operative power range, i.e. 0÷250 kW. A zero dimensional approach is accounted for and the coupling between neutronics and thermalhydraulics in natural circulation is considered. The model has been validated through
comparison with experimental data, concerning three different power transients. For neutronics, point reactor kinetics model with one energy group and six delayed neutron precursors groups has been adopted. The system reactivity can be modified moving the
control rods, which allow the reactor to operate at different power levels. As far as thermalhydraulics is concerned, two regions have been defined, i.e. the fuel and the coolant. Heat exchange (convective and conductive) has been modeled by proper adoption of a global heat transfer coefficient. This has been considered as a function of coolant mass flow rate through the core to introduce the effects of natural circulation, evaluated using Boussinesque
approximation for buoyancy effects. Neutronics and thermal-hydraulics are coupled together by means of fuel and moderator temperature feedback coefficients. The large thermal inertia
due to the mass of water in the tank containing the reactor core causes temperature variation during transients to be very small. Therefore, moderator temperature feedback coefficient can be neglected. On the contrary, the fuel temperature coefficient strongly influences the dynamic behavior of the system and has been estimated making a best-fit between the model response and the experimental data regarding positive reactivity insertion in the
system at three different power levels, i.e. 1 kW, 50 kW and 100 kW. The results obtained show that the fuel temperature coefficient is a monotonically increasing function of fuel
temperature and its magnitude is in agreement with the values found in literature. The nonlinear system of 9 coupled ODE has been solved by means of Simulink® (The MathWorks, Inc. 2008a), which represents a reliable tool for dynamic and control analysis.
The model reproduces the real behavior of the system in a very satisfying way: error on the power response simulation is less than 7% for the first transient and less than 1% for the other two transients
Home-made Refurbishment of the Instrumentation and Control System of the TRIGA Reactor of the University of Pavia
No full textThe Instrumentation and Control (I&C) System of the TRIGA reactor of the University of Pavia was dated (see Fig.1) and, in order to grant a safe and continuous reactor operation for the future, it became necessary to substitute or to upgrade the system. Since the substitution of the I&C system with a new-made one was very difficult to be performed due to long authorization procedures, an home-made refurbishment was planned. Using commercial components of high quality, almost a complete substitution, channel-by-channel, of the I&C system was realized without changing the operating and safety logics. The refurbished I&C system shows a very good operational behavior and reliability and will assure a continuous operation of the reactor for the future
Study of a new Automatic Reactor Power Control for the TRIGA Mark II Reactor at University of Pavia
No full textAbstract—The installation of a new Instrumentation and Control
(I&C) system for the TRIGA MARK II reactor at University of
Pavia has recently been completed in order to assure a safe and
continuous reactor operation for the future. The intervention
involved nearly the whole I&C system and required a channelby-
channel component substitution. One of the most sensitive
part of the intervention concerned the Automatic Reactor Power
Controller (ARPC) which permits to keep the reactor at an
operator-selected power level acting on the control rod devoted to
the fine regulation of system reactivity. This controller installed
can be set up using different control logics: currently the system
is working in relay mode. The main goal of the work presented in
this paper is to set up a Proportional-Integral-Derivative (PID)
configuration of the new controller installed on the TRIGA
reactor of Pavia so as to optimize the response to system
perturbations
A Zero Dimensional Model for Simulation of Triga Mark II Dynamic Response
No full textIn this paper the development of a model for the nuclear research reactor TRIGA Mark II operating at University of Pavia is presented. Purpose of the modeling is to reproduce the dynamic behavior of the reactor on the entire operative power range, i.e. 0÷250 kW. A zero dimensional approach is accounted for and the coupling between neutronics and thermal-hydraulics in natural circulation is considered
Study of a New Automatic Reactor Power Control for the TRIGA Mark II Reactor of the University of Pavia
No full textThe installation of a new Instrumentation and Control (I&C) system for the TRIGA MARK II reactor at University of Pavia has recently been completed in order to assure a safe and continuous reactor operation for the future. The intervention involved nearly the whole I&C system and required a channelby-
channel component substitution. One of the most sensitive part of the intervention concerned the Automatic Reactor Power
Controller (ARPC) which permits to keep the reactor at an operator-selected power level acting on the control rod devoted to the fine regulation of system reactivity. This controller installed can be set up using different control logics: currently the system is working in relay mode. The main goal of the work presented in this paper is to set up a Proportional-Integral-Derivative (PID) configuration of the new controller installed on the TRIGA reactor of Pavia so as to optimize the response to system perturbations
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Application of the Integrated Management System for Safety and Aging Management at TRIGA Research Reactor at LENA (Laboratory of Applied Nuclear Energy) – University of Pavia (Italy)
No full textThe Laboratory of Applied Nuclear Energy (“LENA”) is an Interdepartmental Research Centre of the University of Pavia, which operates a 250 kW TRIGA Mark II Research Nuclear Reactor. The Centre itself carries out research and training activities providing services both for private enterprises and public institutions. Aiming at continuous improvement of the reactor management and, in order to continuously grant reactor
safety operations and the satisfaction of all stakeholder’s (Regulators, Civil society, Population, Users & Customers) requirements, in 2008 LENA decided to implement an Integrated Management System (IMS). In 2010, this decision led to the ISO
9001:2008 certification of LENA for the operation of the reactor. In addition, through this systematic and graded approach, also the management aspects of safety (i.e. Nuclear Safety, Occupational Health and protection of the people, workers and environment), security, efficiency and effectiveness are satisfied. That means that trough the application of the IMS, LENA can monitor and manage also the aspect related to the reactor safety operations and maintenance, included those related to the ageing management. It is interesting to point out how the IMS encompasses a wide range of processes and tools for the management of safety aspects and how their utilization revealed an improvement in safety operations, during the last few years
Variations on the Author
Full text link“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
Education & Training with the TRIGA Research Reactor of the Laboratory of Applied Nuclear Energy (LENA) of the University of Pavia (Italy)
No full textThe Laboratory of Applied Nuclear Energy (“LENA”) is an Interdepartmental Research Centre of the
University of Pavia which operate, among other facilities, a 250 kW TRIGA Mark II Research Nuclear
Reactor. The reactor is at the disposal of researchers from Pavia University and of other users, for
research activities, training and education and other services.
Nowadays, training is one of the most important tools necessary to gain and maintain the required competence of the various categories of personnel operating in the nuclear field. Thanks to both the deep expertise gained in more than 45years of reactor operation and to the academic context in which reactor is operated, LENA developed a wide range of education and training programs covering most of the topics related to the nuclear field: from safety culture and radioprotection to quality assurance
and management system. The nature and scope of Education&Training programme are primarily oriented to students, researchers and professionals involved in nuclear safety-related activities, and are designed and developed both at theoretical and practical level, due to the possibility of operating the reactor and its facilities for specific training purpose. At the academic level, LENA provides courses for Nuclear Engineering and Physics Master Degrees and for post-graduated International Masters, where the typical recipients of the courses come both from national and international context. In addition, thanks to the expertise achieved in the operation and management of the reactor, LENA offers basic and advanced knowledge training courses for "nuclear technicians” to private Companies, Utilities and Governmental Institutions. Training programs, characterized by a significant experimental
component, can be arranged based on customer needs, providing training modules with different levels of detail. LENA basic training modules focus on subject related to Operation & Safety in Nuclear
Plants, Radiation Protection, Analytical Nuclear Techniques and their applications, Quality Assurance for safety in nuclear installations
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