312 research outputs found
I2S-LWR Top-Down Differential Economics Evaluation Approach
The Integral Inherently Safe Light Water Reactor (I2SāLWR) is a design concept of a large
(~1000 MWe) light water reactor with integral primary circuit configuration. One of the key design
features promoting inherent safety is implementation of an integral primary circuit configuration,
which in turn requires a compact design of the core and primary circuit components.
Assessments of the cost of I2S-LWR is an important aspect of the overall evaluation of the new
reactor concept. There are several approaches to cost estimation and economics evaluation of the new
nuclear power technologies. Frequently used guidelines rely on the Code of Accounts, originally
developed in the U.S. Department of Energy (DOE) Energy Economics Data Base (EEDB) Program
Code of Accounts, proposed as evaluation tool by C.R. Hudson, and further popularized in the
guidelines for economic evaluation of bids, by The International Atomic Energy Agency (IAEA).
The code of accounts allows to break down main costs (Total Capital Investment Cost, Fuel Cycle
Cost, Operation and Maintenance) to individual systems and items.
This work aims to implement and apply a top-down differential economics evaluation approach
to the Code of Accounts based guidelines, to assess the costs of the I2S -LWR relative to a
representative āstandardā PWR. In this methodology, a representative PWR design was taken as a
reference and the differential cost was estimated for each individual account based on the design
difference (or similarity). Cost estimating techniques were applied to the accounts representing
systems that differ from the ones of the reference PWR. In this manner, the cost of the common
components cancels out, and the uncertainty in the estimate is reduced.
While this preliminary evaluation yet needs to be completed, the indications so far are that the
I2S-LWR LCOE will be economically competitive with a standard PWR
Cost optimization in agribusiness based on life cycle costing
In efforts to achieve and sustain competitiveness and contribute to the goal of sustainable development of society, entity management requires information that will enable the adoption of adequate decisions. The changed business environment and the growing importance of the issues that emerge from the domain of traditional business, both spatial and temporal, have necessitated the monitoring of costs not only during the production phase, but throughout the entire grain cycle of the product. Since conventional cost accounting systems do not have the capacity to generate the above information, in theory and practice, a life cycle costing system (LCC) has been developed. The aim of the paper is to point out the specificity and importance of perceiving and capturing the impacts and consequential costs that arise during the life cycle of the product, with particular reference to agribusiness, precisely because of the complexity of optimizing costs in that sector
Mineralni trioksidni agregat u terapiji eksterne resorpcije korena izbijenog zuba sa nezavrŔenim rastom korena - ishod posle deset godina
Introduction Root resorption may occur as a consequence of avulsion injury and may lead to the progressive loss of tooth structure. The aim was to report the outcome of root resorption treated with mineral trioxide aggregate in a replanted immature permanent incisor after 10 years of follow-up. Case outline This case presents external root resorption that was detected 18 months after the avulsion injury in a nine-year-old child. Apical portion of the canal was filled with mineral trioxide aggregate and the rest of the canal was filled with a canal sealer and gutta-percha. Control examinations were performed six months after the completion of the endodontic treatment and afterwards yearly. The tooth was asymptomatic clinically and radiographs did not show progression of root resorption up to four years of follow-up. Infraposition of the injured tooth was detected five years after the replantation, but without significant radiographic changes, until the eight-year follow-up, when root resorption was detected again. However, the tooth was still hard and symptomless at the 10-year follow-up. Conclusion Mineral trioxide aggregate may have an important role in the preservation of replanted immature teeth for a prolonged period.Uvod Resorpcija korena zuba se može javiti kao posledica povrede i može voditi progresivnom gubitku zubnih struktura. Cilj rada je bio da se prikaže kliniÄki ishod replantacije izbijenog stalnog zuba sa nezavrÅ”enim rastom korena posle deset godina. Prikaz bolesnika Predstavljen je sluÄaj eksterne resorpcije korena zuba detektovane 18 meseci posle avulzione povrede kod devetogodiÅ”njeg deteta. Apikalni deo kanala korena zuba je napunjen mineralnim trioksidnim agregatom, dok je ostatak kanala opturiran pastom i gutaperka poenima. Kontrolni pregledi su obavljani Å”est meseci posle zavrÅ”etka endodontskog leÄenja i, posle toga, jednom godiÅ”nje. Do Äetvrte godine praÄenja zub je bio bez kliniÄkih i radiografskih znakova progresije resorpcije korena. Infrapozicija povreÄenog zuba uoÄena je pet godina posle replantacije, ali bez znaÄajnih radiografskih promena sve do osme godine praÄenja, kada je uoÄeno napredovanje resorpcije korena. Ipak, posle deset godina zub je i dalje bio kliniÄki bez simptoma. ZakljuÄak Mineralni trioksidni agregat može imati znaÄajnu ulogu u dugotrajnom oÄuvanju replantiranih zuba sa nezavrÅ”enim rastom korena
Integration of process planning, scheduling, and mobile robot navigation based on triz and multi-agent methodology
U radu je predstavljena metodologija za razvoj softverske aplikacije za integraciju projektovanja tehnoloÅ”kog procesa, terminiranja proizvodnje i navigacije mobilnog robota u tehnoloÅ”kom okruženju. Predložena metodologija je bazirana na primeni teorije inventivnog reÅ”avanja problema i multiagentske metodologije. Matrica kontradikcije i inventivni principi su se pokazali kao efektivan alat za otklanjanje kontradiktornosti u koncepcijskoj fazi razvoja softvera. Predložena multiagentska arhitektura sadrži Å”est agenata: agent za delove, agent za maÅ”ine, agent za optimizaciju, agent za planiranje putanje, agent za maÅ”insko uÄenje i agent mobilni robot. Svi agenti zajedno uÄestvuju u optimizaciji tehnoloÅ”kog procesa, optimizaciji planova terminiranja, generisanju optimalnih putanja koje mobilni robot prati i klasifikaciji objekata u tehnoloÅ”kom okruženju. Eksperimentalni rezultati pokazuju da se razvijeni softver može koristiti za predloženu integraciju, a sve u cilju poboljÅ”anja performansi inteligentnih tehnoloÅ”kih sistema.This paper presents methodology for development of software application for integration of process planning, scheduling, and the mobile robot navigation in manufacturing environment. Proposed methodology is based on the Russian Theory of Inventive Problem Solving (TRIZ) and multiagent system (MAS). Contradiction matrix and inventive principles are proved as effective TRIZ tool to solve contradictions during conceptual phase of software development. The proposed MAS architecture consists of six intelligent agents: job agent, machine agent, optimization agent, path planning agent, machine learning agent and mobile robot agent. All agents work together to perform process plans optimization, schedule plans optimization, optimal path that mobile robot follows and classification of objects in a manufacturing environment. Experimental results show that developed software can be used for proposed integration in order to improve performance of intelligent manufacturing systems
Liquid-salt-cooled Reactor Start-up with Natural Circulation
The Liquid-Salt-Cooled Very High-Temperature Reactor (LS-VHTR) was modeled using
the neutronics analysis code SCALE6.0 and the thermal-hydraulics and kinetics modeling code
RELAP5-3D with objective to devise, analyze, and evaluate the feasibility and stability of a start-up
procedure for this reactor using natural circulation of the coolant and under the Loss Of Offsite
Power (LOOP) conditions.
This Generation IV reactor design has been initially developed by Oak Ridge National
Laboratory and studied by researchers worldwide for almost a decade. While neutronics and
thermal-hydraulics analyses have been previously performed to show the performance of the reactor
during normal operation and for shutdown scenarios, no study has heretofore been published to
examine the active or passive start-up of the reactor.
The fuel temperature (Doppler) and coolant density coefficient of reactivity of the LSVHTR
were examined using the CSAS6 module of the SCALE6.0 code. Negative Doppler and
coolant density feedback coefficients were calculated.
Two initial RELAP5 simulations were performed to obtain the steady-state conditions of the
model and to predict the changes of the thermal-hydraulic parameters during the shutdown of the
reactor. Next, a series of step reactivity additions to the core were simulated to determine how much
reactivity can be inserted without jeopardizing the safety and stability of the core. Finally, a start-up
procedure was developed, and the restart of the reactor with natural convection of the coolant was
simulated. The results of the simulations demonstrated the potential for natural circulation start-up
of the LS-VHTR
Metodologija pregleda i ocena stanja konstrukcije izložbenih hala Beogradskog sajma
Beogradski sajam predstavlja jedno od najuspelijih ostva-renja domaÄe arhitekture i graÄevinskog konstrukterstva. SagraÄen je izmeÄu 1954. i 1957. godine, prema arhitek-tonsko-urbanistiÄkom reÅ”enju Milorada PantoviÄa i kon-struktivnim reÅ”enjima Branka Žeželja i Milana KrstiÄa, kao moderno oblikovani kompleks sa tri izložbene hale prepoz-natljivih kupola. Hala 1 je najveÄi objekat kompleksa i zaÅ”ti-Äena je kao spomenik kulture. Svojim specifiÄnim reÅ”enjem predstavlja izuzetno konstruktivno ostvarenje, a njena kupola i danas drži Ginisov rekord za ovu vrstu konstrukcije. Insti-tut IMS redovno prati stanje objekata Beogradskog sajma i kroz struÄnu podrÅ”ku obezbeÄuje sigurnu i funkcionalnu eks-ploataciju izložbenih hala. U radu su prikazani metodolo-gija i rezultati pregleda i ocene stanja konstrukcije Hale 1 nakon skoro 70 godina upotrebe, ukljuÄujuÄi sprovedeno ispitivanje sile prednaprezanja u žicama kablova prstenas-tog nosaÄa kupole Hale 1
Nuclear and thermal hydraulic calculation of a representative I2S-LWR first core
The Integral Inherently Safe Light Water Reactor (I2S-LWR) concept developed by Georgia
Tech is a novel PWR reactor delivering electric power of 1000 MWe while implementing inherent
safety features typical for Generation III+ small modular reactors. The main safety feature is based
on integral primary circuit configuration, bringing together compact design of the reactor core (121
fuel assembly), control rod drive mechanism (CRDM), 8 primary heat exchangers (PHE), 4 passive
decay heat removal systems (DHRS), 8 pumps, and other integral components. A high power
density core based on silicide fuel and APMT (FeCrAl) stainless steel cladding is selected to
achieve a high thermal power. Initial representative first core nuclear design is proposed by
Westinghouse. Full core 3D depletion calculation was performed using PARCS code. The cross
section library is prepared using FA2D code and verified using Polaris sequence from SCALE 6.2
beta5. The axial and radial reflectors are assumed to be homogeneous water-APMT mixtures. The
axial reflectors are both assumed to be 12 inch (30.48 cm) sections composed of 30% APMT steel
by volume. The radial reflector is assumed to be 90% APMT steel by volume. The reflector
constants were calculated using SCALE TRITON sequence. The thermal hydraulic part of the
model is based on COBRA subchannel code coupled to PARCS code. Initial depletion calculation
is based on one thermal hydraulics channel per fuel assembly approach. The hot fuel assembly is
determined using separate pin-by-pin COBRA subchannel model and pin power reconstruction data
from PARCS. The objective of the paper is demonstration of LWR design methodology
applicability to silicide fuel and identification of possible improvements in the first core design
PCA Benchmark Analysis with ADVANTG3.0.1. and MCNP6.1.1b Codes
The Pool Critical Assembly Pressure Vessel (PCA) benchmark is a well known benchmark in
the reactor shielding community which is described in the Shielding Integral Benchmark Archive
and Database (SINBAD). It is based on the experiments performed at the PCA facility in the Oak
Ridge National Laboratory (ORNL) and it can be used for the qualification of the pressure vessel
fluence calculational methodology. The measured quantities to be compared against the calculated
values are the equivalent fission fluxes at several experimental access tubes (A1 to A8) in front,
behind, and inside the pressure-vessel wall simulator. This benchmark is particularly suitable to test
the capabilities of the shielding calculational methodology and cross-section libraries to predict invessel
flux gradients because only a few approximations are necessary in the overall analysis. This
benchmark was analyzed using a modern hybrid stochastic-deterministic shielding methodology
with ADVANTG3.0.1 and MCNP6.1.1b codes. ADVANTG3.0.1 is an automated tool for
generating variance reduction (VR) parameters for Monte Carlo (MC) calculations with
MCNP5v1.60 code (and higher versions). It is based on the multigroup, discrete ordinates solver
Denovo, used for approximating the forward-adjoint transport fluxes to construct VR parameters for
the final MC simulation. The VR parameters in form of the weight windows and the source biasing
cards can be directly used with unmodified MCNP input. The underlining CADIS methodology in
Denovo code was initially developed for biasing local MC results, such as point detector or a
limited region detector. The FW-CADIS extension was developed for biasing MC results globally
over a mesh tallies or multiple point/region detectors. Both CADIS and FW-CADIS are based on
the concept of the neutron importance function, which is a solution of the adjoint Boltzmann
transport equation. The equivalent fission fluxes calculated with MCNP are based on several highenergy
threshold reactions from international dosimetry libraries IRDF-2002 and IRDFF-2014,
distributed by the IAEA Nuclear Data Section. The obtained results show a good agreement with
referenced PCA measurements. Visualization of the deterministic solution in 3D was done using the
VisIt code from the Lawrence Livermore National Laboratory (LLNL)
Challenges in experimental evaluation of morphological, chemo-mechanical and adhesive properties of glass-ionomer based dental materials
Changes in composition and new material characteristics require verification in clinical and experimental studies. Investigating glass-ionomer cements under laboratory conditions encounters problems in interpreting the results and in comparing them with other types of materials tested in the same way. As the connection between the glass-ionomer cements and the dental tissues is delicate, it is often the case that the impact of fractures and other artifacts is either underestimated or over-dimensioned when interpreting the results. A critical review was performed, with defining the main problems regarding the usage of SEM, EDX and nanoindentation techniques in glass-ionomer based materials evaluation
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