Analysis and Characterization of Sequences in Atucha II PHWR

2009 ◽  
Author(s):  
Pablo Zanocco ◽  
Jose´ Gonzalez ◽  
Marcelo Gime´nez
Keyword(s):  
Heat Removal ◽  
Thermal Inertia ◽  
Primary System ◽  
Steam Generators ◽  
Plant Behavior ◽  
System Pressure ◽  
Lower Temperature ◽  
Safe Condition ◽  
Operational Modes

In this work, a case of loss of heat removal, caused by a loss of electrical supply, is analyzed for Atucha II PHWR. This reactor is similar to a PWR reactor in many aspects, but differs because it has, inside the pressure vessel, vertical coolant channels inside a moderator tank, which is at primary system pressure but a lower temperature. During the studied event, moderator temperature rises, heated by primary system (acting as a heat sink), until the temperatures are equalized. Given that primary and moderator systems are interconnected, the expansion of the moderator produces a rise in the level in pressurizer. The main aspects of the plant dynamic in the presented case are shown and analyzed. The normal strategy of the plant to cope with this initiating event is also discussed: the systems involved, operational modes and trigger signals are described. Then, three possible sequences are studied: heat removal by steam generators or moderator heat exchangers, and black out (no heat removal). The safety functions required to cope with this initiating event are also determined, as long as the associated safety and auxiliary systems. Representative variables of selected sequences are shown, in order to go further in understanding of the plant behavior. The different final stages are identified. The minimum capability of each system, necessary to achieve a plant safe condition, is also established. It was found that in this particular event, their requirements are less than the ones specified in the design basis. Also the influence of moderator system thermal inertia on transients is determined as a distinctive characteristics of this reactor.

scholarly journals Generation-IV Multi-Application Small Light Water Reactor (MASLWR)

2002 ◽  
Author(s):  
S. Michael Modro ◽  
James Fisher ◽  
Kevan Weaver ◽  
Pierre Babka ◽  
Jose Reyes ◽  
...  
Keyword(s):  
Natural Circulation ◽  
Thermal Power ◽  
Heat Removal ◽  
Steam Pressure ◽  
Light Water Reactor ◽  
Primary System ◽  
Light Water ◽  
Water Reactor ◽  
System Pressure ◽  
Environmental Laboratory

The Idaho National Engineering and Environmental Laboratory (INEEL), Nexant Inc. and the Oregon State University (OSU) have developed a Multi-Application Small Light Water Reactor (MASLWR) concept. The MASLWR is a small, safe and economic natural circulation pressurized light water reactor. MASLWR reactor module consists of an integral reactor/steam generator located in a steel cylindrical containment. The entire module is to be entirely shop fabricated and transported to site on most railways or roads. Two or more modules are located in a reactor building, each being submersed in a common, below grade cavity filled with water. For the most severe postulated accident, the volume of water in the cavity provides a passive ultimate heat sink for 3 or more days allowing the restoration of lost normal active heat removal systems. MASLWR thermal power of a single module is 150 MWt, primary system pressure 10.5 MPa, steam pressure 1.52 MPa and the net electrical output is 35–50 MWe.

scholarly journals Assessment of an Isolation Condenser of an Integral Reactor in View of Uncertainties in Engineering Parameters

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
G. Lorenzo ◽  
P. Zanocco ◽  
M. Giménez ◽  
M. Marquès ◽  
B. Iooss ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Monte Carlo ◽  
Target Point ◽  
Direct Monte Carlo Simulation ◽  
Identification System ◽  
Surface Model ◽  
Primary System ◽  
System Pressure ◽  
Safe Condition ◽  
Integral Reactor

RMPS methodology is used for estimating the uncertainties in the fulfillment of a target related with the design of the isolation condenser of a “CAREM-like” integral reactor. The passive-system assessment is made on a basis of a loss of heat sink transient. Given this scenario, the safety function is to remove the core decay heat after the actuation of the shutdown system, thus reducing the primary system pressure and leading the plant to a safe condition. The design target to evaluate is the avoidance of the RPV safety valves opening. In order to accomplish the evaluation, the following RMPS steps were followed:system identification, system modeling, characterization of TH phenomena, direct Monte Carlo simulation, sensitivity analysis, and quantitative reliability estimation.As main outcomes, a ranking of parameters' importance and an estimate of the failure probability, from a design target point of view, were achieved by sensitivity analysis and Monte Carlo simulations based on a response surface model.

The Synthesis and Characterization of Novel Cadmium Sulphide Nanocrystallites and their Thin Films

2014 ◽  
Vol 875-877 ◽  
pp. 228-231
Author(s):  
Shafique Ahmed Arain ◽  
Christopher Wilkins ◽  
Hafiz Badaruddin
Keyword(s):  
Thin Films ◽  
Vapour Deposition ◽  
Hexagonal Phase ◽  
Chemical Vapour ◽  
Cadmium Sulphide ◽  
Spherical Shape ◽  
Sem Analysis ◽  
Diethyl Dithiocarbamate ◽  
Lower Temperature

Diethyl dithiocarbamate [Cd (S2CN Et2)2] complex is used to deposit the cadmium sulphide thin film at much lower temperature by Aerosol Assisted Chemical Vapour deposition (AACVD) and same precursor is used to synthesize the nanocrystals in Oleylamine at elevated temperature. Thermogravimetric analysis shows that precursor [Cd (S2CN Et2)2] decomposes in the single stage, losing 62% of total weight. Deposition of thin films at 300°C and 400°C showed the growth of CdS clusters which were made of granular crystallites. These results are confirmed by SEM analysis. Thermolysis of the precursor in oleylamine at 240°C gave the nanoparticles most of them are monodispersed spherical shape, few having mono and dipod structures. TEM images confirm the structures. XRD results show the thin films and nanoparticles have hexagonal phase of CdS.

Physico-chemical characterization of Cu2+-exchanged sepiolite

Clay Minerals ◽  
1985 ◽  
Vol 20 (4) ◽  
pp. 467-475 ◽  
Author(s):  
A. Corma ◽  
J. Pérez-Pariente ◽  
J. Soria
Keyword(s):  
Chemical Characterization ◽  
Tetrahedral Symmetry ◽  
Pyramidal Geometry ◽  
Physico Chemical ◽  
One Step ◽  
Lower Temperature ◽  
Coordinated Water ◽  
Square Pyramidal Geometry ◽  
Different Levels

AbstractCopper-sepiolites exchanged at different levels have been studied by ESR, IR, and TG. The results indicate that in the unheated samples the Cu2+ ions are located in octahedral edge positions. After dehydration, the Cu2+ ions occur in two positions with different environments. Some of the Cu2+ ions lose the two molecules of coordinated water in one step, at low dehydration temperatures, and adopt a square pyramidal geometry. Other Cu2+ ions lose the coordination water in two steps, at lower temperature than the natural sepiolite, and adopt a tetrahedral symmetry.

The Design Features of Integrated Modular Water Reactor (IMR)

2004 ◽  
Author(s):  
Takashi Kanagawa ◽  
Masashi Goto ◽  
Shuji Usui ◽  
Tadahiko Suzuta ◽  
Akimi Serizawa ◽  
...  
Keyword(s):  
Control System ◽  
Water System ◽  
Heat Removal ◽  
Volume Control ◽  
Circulation System ◽  
Primary System ◽  
Main Theme ◽  
Two Phase ◽  
Water Reactor ◽  
Reactor Coolant

Small-to-medium-sized (300–600MWe) reactors are required for the electric power market in the near future (2010–2030). The main theme in the development of small-to-medium-sized reactor is how to realize competitive cost against other energy sources. As measures to this disadvantage, greatly simplified and downsized design is needed. From such point of view, Integrated Modular Water Reactor (IMR), which electric output power is 350 MWe, adopts integrated and high temperature two-phase natural circulation system for the primary system. In this design, main coolant pipes, a pressurizer, and reactor coolant pumps are not needed, and the sizes of a reactor vessel and steam generators are minimized. Additionally, to enhance the economy of the whole plant, fluid system, and Instrumentation & Control system of IMR have also been reviewed to make them simplest and smallest taking the advantage of the IMR concept and the state of the art technologies. For example, the integrated primary system and the stand-alone direct heat removal system make the safety system very simple, i.e., no injection, no containment spray, no emergency AC power, etc. The chemical and volume control system is also simplified by eliminating the boron control system and the seal water system of reactor coolant pumps. In this paper, the status of the IMR development and the outline of the IMR design efforts to achieve the simplest and smallest plant are presented.

scholarly journals Locusts use dynamic thermoregulatory behaviour to optimize nutritional outcomes

2011 ◽  
Vol 278 (1719) ◽  
pp. 2745-2752 ◽  
Author(s):  
Nicole Coggan ◽  
Fiona J. Clissold ◽  
Stephen J. Simpson
Keyword(s):  
Locusta Migratoria ◽  
Nutrient Use Efficiency ◽  
Assimilation Efficiency ◽  
Thermal Inertia ◽  
Temperature Selection ◽  
Nutrient Use ◽  
Wide Range ◽  
Lower Temperature ◽  
The Cost ◽  
Thermoregulatory Behaviour

Because key nutritional processes differ in their thermal optima, ectotherms may use temperature selection to optimize performance in changing nutritional environments. Such behaviour would be especially advantageous to small terrestrial animals, which have low thermal inertia and often have access to a wide range of environmental temperatures over small distances. Using the locust, Locusta migratoria , we have demonstrated a direct link between nutritional state and thermoregulatory behaviour. When faced with chronic restrictions to the supply of nutrients, locusts selected increasingly lower temperatures within a gradient, thereby maximizing nutrient use efficiency at the cost of slower growth. Over the shorter term, when locusts were unable to find a meal in the normal course of ad libitum feeding, they immediately adjusted their thermoregulatory behaviour, selecting a lower temperature at which assimilation efficiency was maximal. Thus, locusts use fine scale patterns of movement and temperature selection to adjust for reduced nutrient supply and thereby ameliorate associated life-history consequences.

scholarly journals Experimental Characterization of Traditional Mortars and Polyurethane Foams in Masonry Wall

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Dora Foti ◽  
Michela Lerna ◽  
Vitantonio Vacca
Keyword(s):  
Applied Load ◽  
Thermal Inertia ◽  
Masonry Wall ◽  
Polyurethane Foams ◽  
Masonry Walls ◽  
Masonry Buildings ◽  
Experimental Characterization ◽  
Shear Tests ◽  
The Poor

Masonry is a composite material largely used in construction. It exhibits several advantages, including significant compressive strength, thermal inertia, and aesthetic beauty. A disadvantage of masonry is mainly related to the inadequate shear strength due to the poor capacity and ductility of the adopted mortar. This aspect is crucial in seismic areas. In this paper, the behavior of polyurethane foams, used as adhesives for the construction of thin joints brick masonry walls, has been investigated. First, the characterization of components was carried out, followed by laboratory uniaxial tests on masonry walls and shear tests on triplets. Moreover, a comparison of the behavior of the foam-brick walls with respect to the traditional mortars masonry was carried out, as the type of joints varies and the arrangement of the holes of the bricks varies with respect to the direction of the applied load. Results provide indications on which adhesive has to be adopted for masonry buildings in reference to the site of construction (i.e., seismic hazard).

New Reactor Safety Measures for the European Sodium Fast Reactor - Part I: Conceptual Design

2021 ◽  
Author(s):  
Joel Guidez ◽  
Janos Bodi ◽  
Konstantin Mikityuk ◽  
Enrico Girardi ◽  
Bernard Carluec
Keyword(s):  
Fast Reactor ◽  
Heat Removal ◽  
Thermal Inertia ◽  
Lessons Learned ◽  
Reactor Safety ◽  
Fukushima Accident ◽  
Safety Level ◽  
Safety Measures ◽  
Sodium Fast Reactor ◽  
High Thermal Inertia

Abstract Following up the previous CP-ESFR project, the ESFR-SMART project considers the safety objectives envisaged for Generation-IV reactors, taking into account the lessons learned from the Fukushima accident, in order to increase the safety level of the European Sodium Fast Reactor (ESFR). In accordance with these objectives, guidelines have been defined to drive the ESFR-SMART developments, mainly simplifying the design and using all the positive features of Sodium Fast Reactors (SFR), such as low coolant pressure, efficiency of natural convection, possibility of decay heat removal (DHR) by atmospheric air, high thermal inertia and long grace period before a human intervention is needed. In this paper, a set of new ambitious safety measures is introduced for further evaluation within the project. The proposed set aims at consistency with the main lines of safety evolutions since the Fukushima accident, but it does not yet constitute the final comprehensive safety analysis. The paper gives a first review of the new propositions to enhance the ESFR safety, leading to a simplified reactor, forgiving and including a lot of passivity. This first version is supported by the various project tasks in order to assess the relevance of the whole design in comparison to the final safety objectives.

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