101,861 research outputs found
Calculation tool for heat exchanger tube rupture in pool-type reactors
No full textIn the framework of MYRRHA Project, a pool-type experimental and material testing irradiation facility operated with Lead Bismuth Eutectic (LBE) coolant and able to operate in both sub-critical and critical mode is designed to be built in Mol, Belgium, in SCK•CEN domain.
SCK•CEN entered the pre-licensing phase for the MYRRHA reactor. A complete safety analysis must be performed to provide the necessary data to the safety authority.
An event with potential serious consequences is the Primary Heat Exchanger Tube Rupture (PHXTR), involving the release of water from a failed tube in a hot liquid metal pool.
In the first phase of a PHXTR accident, the water in the Secondary Cooling System is released in the Primary System pool in choked flow regime. Afterwards, the water bubble formation and characterization is important for the definition of the water specific volume increase and for the estimation of the water mass fraction redirected in the reactor Lower Plenum, with the risk of void insertion in the core and consequent reactivity excursion.
An analytical calculation model to evaluate the evolution of any bubble distribution has been set up. The main purpose is to describe the evolution of the main system variables during the accidental event, by checking the potential insurgency of any reactor safety issue due to pressure peaks or core void insertion
Myrrha primary heat exchanger tube rupture: Phenomenology and evolution
No full textIn the framework of MYRRHA Project, a pool-type experimental and material testing irradiation facility operated with Lead Bismuth Eutectic (LBE) coolant and able to operate in both sub-critical and critical mode is designed to be built in Mol, Belgium, in SCK•CEN domain. In addition to the material testing function, targets of the MYRRHA reactor are to prove the feasibility of the ADS technology as Minor Actinides (MAs) burner and to act as a demonstrative plant for future Gen-IV heavy metal cooled reactors. SCK•CEN entered the pre-licensing phase for the MYRRHA reactor. In order to provide the safety authority all the required data, a complete safety analysis must be performed, studying the transients defined by the list of postulating initiating events. In particular, an accident with potential serious consequences is the Primary Heat Exchanger Tube Rupture (PHXTR), involving the sudden release of single phase or two-phase water from a tube break in a hot liquid metal pool. This accident evolution is strongly characterized by the design of the MYRRHA Primary Heat eXchanger (PHX) and its direct surroundings in the reactor vessel and by the thermal-hydraulical conditions of the MYRRHA primary and secondary cooling system. In the first phase of a PHXTR accident, the water in the Secondary Cooling System (SCS) is released in the Primary System (PS) pool in regime of choked flow due to the pressure difference. Being the water released in an overheated, low-pressure environment, a flashing with potential sudden specific volume increase is expected. The heat transfer phenomena leading to the phase change velocity depend by the actual number of bubbles released in the hot liquid metal pool, function of the actual break size and shape. Its characterization is important for the definition of the overall specific volume increase and for the estimation of the water mass fraction redirected through the Primary Pump in the reactor Lower Plenum, with the risk of void insertion in the core and consequent reactivity excursion. A simplified calculation model to evaluate the history of any given bubble distribution generated by any water flow rate through any break has been set up. The main purpose is to describe the evolution of the main system state variables during the accidental event, by checking the potential insurgency of any reactor safety issue due to pressure peaks or core void insertions
GCFR Coupled Neutronic and Thermal-Fluid-Dynamics Analyses for a Core Containing Minor Actinides
No full textProblems about future energy availability, climate changes, and air quality seem to play an important role in energy production. While current reactor generations provide a guaranteed and economical energy production, new nuclear power plant generation would increase the ways and purposes in which nuclear energy can be used. To explore these new technological applications, several governments, industries, and research communities decided to contribute to the next reactor generation, called “Generation IV.” Among the six Gen-IV reactor designs, the Gas Cooled Fast Reactor (GCFR) uses a direct-cycle helium turbine for electricity generation and for a CO2-free thermochemical production of hydrogen. Additionally, the use of a fast spectrum allows actinides transmutation, minimizing the production of long-lived radioactive waste in an integrated fuel cycle. This paper presents an analysis of GCFR fuel cycle optimization and of a thermal-hydraulic of a GCFR-prototype under steady-state and transient conditions. The fuel cycle optimization was performed to assess the capability of the GCFR to transmute MAs, while the thermal-hydraulic analysis was performed to investigate the reactor and the safety systems behavior during a LOFA. Preliminary results show that limited quantities of MA are not affecting significantly the thermal-fluid-dynamics behavior of a GCFR core
Bibliographie Hilarion G. Petzold 1958 – 2009 mit Anhang als Einführung
No full textDieses Archiv enthält die Gesamtbibliographie der Werke des Autors nebst einiger Texte „Über H. G. Petzold“ im Schlussteil der Bibliographie sowie einen Anhang mit einer Einführung in die Architektur des Werkes in seinem wissenslogischen Aufbau als Ausarbeitung seines „Tree of Science Modells“ (2007).This archive contains the complete bibliography of the author and some texts about H. G. Petzold, moreover an epilogue with an introduction to the architecture of the works in its epistemological structure and composition and as an elaborations of Petzold’s „Tree of Science Modell (2007).https://www.fpi-publikation.de/polyloge/01-2009-petzold-h-g-gesamtbibliographie-h-g-petzold-1958-2009-updating-november2009/peerReviewedpublishedVersio
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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3346: Samuel G. Freedman, author, 2013
No full textPhotograph of author Samuel G. Freedman, at NT Daily Slash meeting in the Mayborn School of Journalism at UNT
The Right to Strike under the United States Constitution: Theory, Practice, and Possible Implications for Canada
No full textAnswering critics of the Canadian Supreme Court's judgment in B.C. Health, the author argues that the Court laid the foundation for a principled and durable doctrine protecting constitutional labour rights, one that goes directly to the heart of the matter — the inequality of workers’ power in the employment relation. In the author’s view, two paths could lead from B.C. Health to the recognition of Charter protec- tion for a right to strike: one that treats the right as an accessory to col- lective bargaining, and one that upholds the right directly on the basis of the Charter values of equality and participation. The author supports the latter approach, contending that constitutional rights should be defined in relation to fundamental values, in a way that is not contingent on time-bound or fact-sensitive assessments about the role of strikes within a particular collective bargaining regime. Although a Charter right to strike may involve the courts in difficult choices about when to defer to legislative policy decisions, and courts may lack the institutional capac- ity to deal effectively with labour law issues, the author points out that judges can look to ILO standards for expert guidance. Noting that the U.S. experience in this area might be of considerable use to Canadians, the author concludes by providing an overview of American case law concerning a constitutional right to strike.Peer reviewe
G-Rank: Unsupervised Continuous Learn-to-Rank for Edge Devices in a P2P Network
No full textRanking algorithms in traditional search engines are powered by enormous training data sets that are meticulously engineered and curated by a centralized entity. Decentralized peer-to-peer (p2p) networks such as torrenting applications and Web3 protocols deliberately eschew centralized databases and computational architectures when designing services and features. As such, robust search-and-rank algorithms designed for such domains must be engineered specifically for decentralized networks, and must be lightweight enough to operate on consumer-grade personal devices such as a smartphone or laptop computer. We introduce G-Rank, an unsupervised ranking algorithm designed exclusively for decentralized networks. We demonstrate that accurate, relevant ranking results can be achieved in fully decentralized networks without any centralized data aggregation, feature engineering, or model training. Furthermore, we show that such results are obtainable with minimal data preprocessing and computational overhead, and can still return highly relevant results even when a user’s device is disconnected from the network. G-Rank is highly modular in design, is not limited to categorical data, and can be implemented in a variety of domains with minimal modification. The results herein show that unsupervised ranking models designed for decentralized p2p networks are not only viable, but worthy of further research.https://github.com/awrgold/G-RankComputer Scienc
Author inscription in The Chinese slave-girl: a story of woman's life in China
No full textThis edition includes a gift inscription by author Rev. J.A. Davis, "To Rev. A. G. Russell with the warmest regards of the author J.A. Davis."Davis, John Agnell, 1839-1897
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