Cycle Scenarios Research Articles

Quantification of the differences introduced by nuclear fuel cycle simulators in advanced scenario studies

Uncertainty propagation and quantification, when applied to the field of nuclear fuel cycle scenario studies, usually only considers a set of easily quantifiable input parameters, leaving out the effects of the modelling approaches. In order to extend the validity of these analyses, two different codes, ANICCA and TR_EVOL (developed respectively by SCK·CEN and CIEMAT), have been benchmarked through a study of an advanced and realistic nuclear fuel cycle scenario with the aim of assessing the impact of the use of different tools in the fuel cycle scenario uncertainty quantification. Additionally, a classical uncertainty propagation analysis was done following the total Monte Carlo and sensitivity approaches in order to compare the system uncertainties with the dissimilarities due the simulators. Results shows that the impact of the fuel cycle simulators cannot be neglected for certain observables, and that their effects become relevant as the scenarios extends over time due their cumulative effect.

The use of recycled semiconductor material in crystalline silicon photovoltaic modules production - A life cycle assessment of environmental impacts

To offset the negative impact of photovoltaic modules on the environment, it is necessary to introduce a long-term strategy that includes a complete lifecycle assessment of all system components from the production phase through installation and operation to disposal. Recycling of waste products and worn-out systems is an important element of this strategy.As the conclusions from the previous studies have shown, thermal treatment provides an efficient first step in the recycling process, while chemical treatment was more advantageous in the second step.This study aims to assess the environmental impact of recovering and recycling the valuable semiconductor silicon wafer material from photovoltaic solar cells. A comparison was made between producing new solar cells with or without recycled silicon material.The analysis of the photovoltaic cell life cycle scenario including material recycling presented in this article was performed using SimaPro software and data combined and extended from different LCI databases. The idea is that the use of recycled materials, which were energy-consuming in the primary production stage, allows to meaningly reduce the energy input in the secondary life cycle.All stages of the silicon cell life cycle contribute to the Global Warming Potential (GWP) and greenhouse gas emissions reductions through the use of recycled silicon material represented 42%. The total environmental impact of photovoltaic production can be reduced by as much as 58%, mainly through reduced energy consumption in the production process of high purity crystalline silicon.

ИССЛЕДОВАНИЯ ПОТЕНЦИАЛА ДВУХКОМПОНЕНТНОЙ СИСТЕМЫ ЯЭ В РАЗНЫХ УСЛОВИЯХ ЕЁ РАЗВИТИЯ

The aim of the work is to study the possibility of long-term management of a developing or non-developing nuclear power system. The concept of fuel supply control is introduced. Nuclear power systems with different structural organization of generating capacities and a closed nuclear fuel cycle are considered. A comparison is made of these systems in terms of their development potential, ratio between the number of thermal and fast reactors and the possibilities of fuel supply. It is noted that the ratio is determined by the breeding characteristics, the balance of plutonium and natural uranium in the system, as well as the needs for NP development. A feature of the two-component systems of nuclear reactors considered in the work, consisting of thermal reactors of different types and fast reactors BN-1200, is that the SNF stocks of all types of reactors are completely processed during the considered time interval and all the excess separated plutonium is used to manufacture MOX fuel. The requirements to the characteristics of fast reactor breading are put forward. The important role of mastered and promising technologies with the possibility of their flexible adaptation to changes in the nuclear power development scale and rate is emphasized. It is shown that the system including advanced fast neutron sodium reactors having flexible breading can offer increased tolerance to possible changes in the nuclear power development rate. The results of simulation of fuel cycle scenarios for the considered two-component nuclear energy system are presented.

Battery Loss and Stress Mitigation in a Cascaded H-Bridge Multilevel Inverter for Vehicle Traction Applications by Filter Capacitors

In this paper, two types of filter capacitors of varying capacity were connected to the battery packs of a cascaded H-Bridge single-star multilevel vehicle traction inverter, and their influence on the battery losses has been analyzed. The battery and capacitor simulation models used are experimentally verified in a downscaled system. Different capacitor configurations were simulated for four-drive cycle scenarios to determine the potentials for the mitigation of current pulse stresses and battery loss reduction with respect to the added weight. By adding capacitors corresponding to a weight of 4% of the initial battery storage, the peak current is reduced by 5%-20%, depending on the operating point from dc to a few kilohertz, and the battery losses are reduced by 10%. In comparison, it is demonstrated that adding supercapacitors is more beneficial for lower output frequencies, while adding electrolytic capacitors is better for higher output frequencies. Furthermore, the low-order voltage harmonics of the dc-rails between the converter and battery were reduced by 10%-30% for frequencies above 9 kHz, which decreases the potential of electromagnetic disturbances. In addition, during cold battery temperatures, when it is very important to avoid heavy cyclings, the loss reduction using the capacitors was 2.5 times larger than for nominal temperature.

Studying the dynamics of nonlinear interaction between enterprise populations

The article highlights the results of a study of the dynamic evolutionary processes of trophic relations between populations of enterprises. A model based on differential equations is constructed, which describes the economic system and takes into account the dynamics of the specific income of competing populations of enterprises in relations of protocooperation, nonlinearity of growth and competition. This model can be used to analyze the dynamics of transient processes in various life cycle scenarios and predict the synergistic effect of mergers and acquisitions. A bifurcation analysis of possible scenarios of dynamic modes of merger and acquisition processes using the neural network system of pattern recognition was carried out. To this end, a Kohonen self-organizing map has been constructed, which recognizes phase portraits of bifurcation diagrams of enterprises life cycle into five separate classes in accordance with the scenarios of their development. As a result of the experimental study, characteristic modes of the evolution of economic systems were revealed, and also conclusions were made on the mechanisms of influence of the external environment and internal structure on the regime of evolution of populations of enterprises.

A life cycle scenario analysis of different pavement technologies for urban roads

In the past, lowest price was the award criterion, given that structural capacity and safety were assured.In the last years, environmental, energy, and long-term impacts have been introduced (climate change, resource depletion, energy consumption, generated solid waste, discharged water, and emissions).Unfortunately, the introduction of new pavement technologies and materials (i.e., waste plastics) affects maintenance and rehabilitation processes and call for accurate and timeliness studies and criteria.Consequently, this paper presents an energy and environmental assessment of an Italian urban road and considers different material-related scenarios that fully comply with emerging technologies.A life-cycle approach is applied to assess energy and environmental impacts of a typical Italian urban road, according to the ISO 14040 series. In more detail, the authors assess the energy and environmental profile of different scenarios of bituminous mixtures. The aim of scenario analysis is to identify the less impacting scenario from an energy and environmental point of view. For each analyzed scenario, the contribution of each life-cycle step to the total impacts and the energy and environmental hotspots are identified in order to define suitable options for improvement.The results of the analysis show that step of material production, including raw material extraction and resource supply, is relevant to almost all the assessed impact categories (average contribution higher than 50%). This is mainly due to the production of bitumen, which is a petroleum-based product. Moreover, the scenario analysis highlights that the pavement scenarios that are characterized by the use of recycled materials involve lower energy and environmental impacts, due to the saving of virgin raw materials and avoided impacts for disposal.

Probabilistic Analysis of Major Construction Materials in the Life Cycle Embodied Environmental Cost of Korean Apartment Buildings

This study employs probabilistic analysis to evaluate the life cycle embodied environmental cost of Korean apartment buildings, with a focus on six major construction materials. To this end, the bill of materials was analyzed for 443 Korean apartment buildings according to the type and plan form, and probability density functions (PDFs) were established for the input quantities of the six materials under consideration. Life cycle scenarios were then examined for each material, and their respective life cycle embodied environmental cost factors were established, using a monetary valuation-based damage cost life cycle analysis model. The estimated environmental costs were evaluated by apartment structural type and plan form, based on probability distributions using the Monte Carlo simulation (MCS). Building life cycle embodied environmental cost was estimated between 16.87 USD/m2 and 23.03 USD/m2 (90% confidence interval). Among the structure types analyzed, the highest costs were associated with the wall structure, followed by rigid frame and flat plate structures; at the plan form level, costs followed the sequence plate-type > mixed-type > tower type for a given type of structure.

Life cycle simulation system as an evaluation platform for multitiered circular manufacturing systems

A life cycle simulation (LCS) is a powerful tool for evaluating the life cycle scenarios of circular manufacturing. Although many LCSs have been developed so far, they were specific to particular scenarios and products. Therefore, we developed a general-purpose LCS system that can be used to evaluate various life cycle scenarios including multiple circulation paths such as closed-loop and cascade reuse and recycling. This system is useful for developing effective circular manufacturing systems with proper life cycle options. We applied it to a closed-loop and cascade reuse of lithium-ion batteries of electric vehicles in order to demonstrate its effectiveness.

Comparing life cycle assessment modelling of linear vs. circular building components

As the construction industry consumes vast amounts of natural resources and in return produces large waste quantities, interest in circular economy has emerged as the means to reduce sector specific environmental impacts meanwhile ensuring continued economic growth. Life cycle assessment is a scientifically based and ISO standardized method for assessing resource consumptions and environmental impacts of products, systems or services over its entire life cycle and has been increasingly used in the construction industry and in some recently published circular economy studies. However, circular economy brings about ‘rethinking’ present well established building systems as well as the future life cycle scenario of these. Hence, this also means rethinking how life cycle assessments are performed on these building systems as it is suggested by some that life cycle assessment is a linear environmental impact assessment approach that misfits the circular economy idea of multiple product life cycles. The paper at hand aims at visually demonstrating variations in life cycle environmental impacts and material flows when supplying buildings with linear components compared to prospective circular designed building components for reuse and recycling and how they are modelled in life cycle assessments.

Effect of the number of water alternating CO2 injection cycles on CO2 trapping capacity

The CO2 storage capacity is greatly affected by CO2 injection scenario – i.e. water alternating CO2 (WACO2) injection, intermittent injection, and continuous CO2 injection – and WACO2 injection strongly improves the CO2 trapping capacity. However, the impact of the number of WACO2 injection cycles on CO2 trapping capacity is not clearly understood. Thus, we developed a 3D reservoir model to simulate WACO2 injection in deep reservoirs testing different numbers of WACO2 injection cycles (i.e. one, two, and three), and the associated CO2 trapping capacity and CO2 plume migration were predicted. For all different WACO2 injection cycle scenarios, 5000 kton of CO2 and 5000 kton of water were injected at a depth of 2275m and 2125m respectively, during a 10-year injection period. Then, a 100-year CO2 storage period was simulated. Our simulation results clearly showed, after 100 years of storage, that the number of WACO2 cycles affected the vertical CO2 leakage and the capacity of trapped CO2. The results showed that increasing the number of WACO2 cycles decreased the vertical CO2 leakage. Furthermore, a higher number of WACO2 cycles increased residual trapping, and reduced solubility trapping. Thus, the number of WACO2 cycles significantly affected CO2 storage efficiency, and higher numbers of WACO2 cycles improved CO2 storage capacity.

Dilatancy and tensile criteria for salt cavern design in the context of cyclic loading for energy storage

In the current energy transition context, salt caverns are promising for massive energy storage but their design methodology needs to be updated to face the challenge of new operating scenarios. This work proposes a new methodology based on the development of a new rheological model that includes dilatancy and tensile criteria, consistent with the long and short term conditions.To illustrate the difference between the classical and the new methodologies, fully coupled thermo-mechanical numerical simulations of a spherical cavern, filled with either methane or hydrogen, and the surrounding rock salt are performed under various cycling scenarios. Although the two studied gases show distinctive thermodynamic behaviors, the storage of hydrogen does not raise new issues in terms of the cavern design. Concerning the operation history, in addition to the fact that lowering the cycling amplitude limits the development of dilatancy and tension, it is observed that employing a high cycling rate leaves the dilatancy unchanged but intensifies the tension, both in extent and magnitude, even for a small cycling amplitude.

Uncertainty quantification on advanced fuel cycle scenario simulations applying local and global methods

A European fuel cycle scenario based on PATEROS where the minimization and the posterior stabilization of the TRU inventory is the main goal, has been studied in terms of uncertainty propagation of the input parameters with the fuel cycle transition scenario TR_EVOL code. Local and global sensitivity methods (namely sensitivity coefficients and Sobol decomposition of variance) were used in a complementary way in order to overcome the limitations of each technique. Those parameters with the largest impact in terms of uncertainty quantification are presented for the most relevant outputs in this kind of scenarios. It was found that the UOX thermal efficiency is the variable with the highest impact in the Pu stocks, while for the MA stocks the isotopic composition of the ADS fuel plays the relevant role. Neither significant interactions nor high order effects were found over the selected input parameters, indicating that for this scenario, the response model can be approximated by a multivariable linear function.

Mapping Frictions Inhibiting Bicycle Commuting

Urban cycling is a sustainable transport mode that many cities are promoting. However, few cities are taking advantage of geospatial technologies to represent and analyse cycling mobility based on the behavioural patterns and difficulties faced by cyclists. This study analyses a geospatial dataset crowdsourced by urban cyclists using an experimental, mobile geo-game. Fifty-seven participants recorded bicycle trips during one week periods in three cities. By aggregating them, we extracted not only the cyclists’ preferred streets but also the frictions faced during cycling. We successfully identified 284 places potentially having frictions: 71 in Münster, Germany; 70 in Castelló, Spain; and 143 in Valletta, Malta. At such places, participants recorded bicycle segments at lower speeds indicating a deviation from an ideal cycling scenario. We describe the potential frictions inhibiting bicycle commuting with regard to the distance to bicycle paths, surrounding infrastructure, and location in the urban area.

Optimizing Nuclear Material Accounting and Measurement Systems

The ability to create nuclear weapons from 235U and 239Pu makes it imperative to closely account for these materials as they progress through a nuclear fuel cycle. Improved measurement systems provide more accurate estimates of material quantities and material unaccounted for (MUF). This paper provides examples of how two safeguards computational toolboxes can optimize and analyze hypothetical nuclear fuel cycle scenarios. The NUclear Measurement System Optimization (NUMSO) toolbox uses operations research techniques to find optimal solutions to safeguards measurement problems based on minimizing the variance of the estimated MUF. The SafeGuards Analysis (SGA) toolbox employs Monte Carlo techniques to analyze a given configuration of measurement methods and material flows to determine the probabilities of Type I (false detection) and Type II (missed detection) errors. Applying these toolboxes to a realistic fuel cycle scenario demonstrates the capability of NUMSO and SGA to address nuclear safeguards problems. Working in tandem, both toolboxes are able to determine how to quickly improve upon an existing safeguards measurement system and to calculate the resulting improvement in the error probabilities of the system. This information shows engineers not only how to develop new measurement systems but also how to improve existing systems in the most efficient manner.

The effects of radiation chemistry on radiochemistry: when unpaired electrons defy great expectations

In liquid/liquid extraction fuel cycle scenarios, successful metal partitioning depends upon maintaining predictable ligand concentrations and metal valence states in a non-equilibrium system perturbed by the constant input of energy. Energetic particles from nuclide decay interact with solution to yield ions and radicals that react with solutes. These reactions have the potential to interfere with the expected separations chemistry. This paper describes example reactions of the main transient products of aqueous and organic diluents with ligands or metal ions. These reactions tend to decrease ligand concentrations, generate unwanted products, and change metal valence states. It discusses the effects of these reactions on the desired separations, using examples mainly from work conducted at the Idaho National Laboratory Center for Radiation Chemistry Research (CR2).

Modeling of gas exchange dynamics using cycle-ergometer tests

This paper presents a novel discrete-time linear parameter-varying model for gas exchange dynamics during cycling. This model is intended to be used for enhancing the control design process of electrical assistance in bicycles. The mathematical model relates the oxygen consumption and carbon dioxide production to the developed power at the pedal level. The proposed model is also able to predict the excess of CO2 while high intensity workout is performed. This has been possible by using a time-varying parameter which is scheduled according to the difference between the masses per unit time of O2 and CO2. An illustration of the proposed methodology for identification and validation of the model is also presented in this paper. The model parameters for a given individual, were obtained by using measured data of cycle-ergometer tests from two different cycling scenarios.

Evaluation of ideal double-tank hybrid pneumatic engine system under different compression cycle scenarios

A double-tank hybrid pneumatic engine system, with one low pressure tank and one high pressure tank has been proposed to improve the energy conversion efficiency and auxiliary braking power output of regenerative braking of vehicles. The performance of three ideal compression cycle scenarios for the double-tank system has been investigated and the results are compared with that of ideal one-tank scenario in order to identify the optimal compression cycle under different primary performance requirements. Results indicate the maximum brake mean effective pressure can be improved to not over 0.2 MPa less than the HP tank pressure and the highest improvement of total air mass recovered can reach over 40% utilising the double-tank scenarios. Scenario 3 performs the best at the braking power output ability, while scenario 4 shows the greatest high pressure compressed air recovery potential. Considering about the LP tank air sources, scenario 2 is the only one that can operate independently without other air complements, which also performs the best at the energy conversion efficiency among the three double-tank scenarios.

Clark’s Crow: A design plugin to support emergy analysis decision making towards sustainable urban ecologies

Architects working with city planners and developers in the shaping of urban environments typically consider multiple factors in isolation, from urban design and socio-economic relationships to data analyses. Analyses regarding urban life cycle scenarios are exemplar of this trend, with considerations made in isolation at the later stages of the design-development process when the scope for decisions which could ultimately affect the sustainability of an urban environment is much more limited. This paper defines our effort to introduce a new tool, named “Clark’s Crow”, which aims to address this shortcoming by promoting awareness of the impact of different design options through a biophysically based ecological accounting method in the early stages of urban design-development. The tool is used within existing architectural design environments with an aim to offer a socio-ecological analysis during the design decision-making process. Clark’s Crow is underpinned by the emergy analysis method, which aims to consider both the energy, material, and information flows of a system, such as an urban ecology, and to understand both the work of the techno-sphere in constructing our urban environments and that of the geo-biosphere in sustaining such development. Clark’s Crow facilitates emergy analysis in the early stages of urban design, thereby allowing queries regarding material and energy flows to be addressed in conjunction with design choices at this initial stage. In this paper, we demonstrate the effectiveness and features of Clark’s Crow through a case study of development using next generation systems in Manhattan, New York, depicting how an emergy analysis approach can lead to an understanding of the value and impact of speculative buildings towards sustainable design-development.

Freeze start drive cycle simulation of a fuel cell powertrain with a two-phase stack model and exergy analysis for thermal management improvement

This paper integrates a two-phase fuel cell stack model, previously published and validated in Tang et al. (2017) for the specific purpose of investigating freeze start behavior, into a full-hybrid fuel cell powertrain model to simulate cold start. The aim of the simulation is to provide an overview of exergy loss distribution during a cold start drive cycle scenario. Another intention is to propose a methodology for suggesting the directions in thermal management development. The powertrain model simulates an Artemis-like transient drive cycle starting from −20 °C. The heater-core bypass and fuel cell stack power threshold are selected as representative thermal/energy management options. To evaluate the impact of the selected options on the warm up, the accumulated energy consumption and exergy flow rates are analyzed. The statistics from our simulation show that the inefficient energy consumption occurs mainly in the city stage shortly after the successful freeze start. The tank-to-wheel efficiency merely achieves 10.3% in the city stage, while the fuel cell stack can reach nearly 73% exergy efficiency throughout the entire drive cycle and tank-to-wheel efficiency reaches 29.3% at the end of the whole drive cycle. The improvement is suggested to be focused in the low power demand stages by cutting down to the actual power ratio needed and simultaneously minimize the relevant thermal-hydraulic inertia. Several optimization directions such as cascaded fuel cell stack alignment, split cooling and power demand threshold for active rapid warm up are drawn. The established fuel cell powertrain model combined with exergy analysis is a suitable methodology for further detailed thermal and energy management investigations.

Preliminary sustainable and economic analysis of nuclear fuel cycle with subcritical system

Summary Nuclear power is attractive for helping carbon reduction and energy restructuring, but the low utilization of nuclear resource and technical problems on reprocessing are key issues for further nuclear development. Subcritical system might be a potential way to solve these problems, which include fusion-driven subcritical system and accelerator-driven subcritical system. Especially the new subcritical system conception spent fuel burner could be used for waste transmutation, nuclear fuel breeding, and energy production. In this contribution, 2 nuclear fuel cycle scenarios with subcritical system for spent fuel burning and pressurized water reactor were assessed with the performances of sustainability of resources, environmental impacts, and economy. The results showed that the advanced fuel cycle based on subcritical system is an attractive option for the long-term development of nuclear power in China.