Energy Systems Engineering

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Computing reliability indices of a wind power system via Markov chain modelling of wind speed
(Proceedings of the Institution of Mechanical Engineers, Part O: Journal of Risk and Reliability, 2024-02) Eryılmaz, Serkan; Bulanık, İrem; Devrim, Yılser
Statistical modelling of wind speed is of great importance in the evaluation of wind farm performance and power production. Various models have been proposed in the literature depending on the corresponding time scale. For hourly observed wind speed data, the dependence among successive wind speed values is inevitable. Such a dependence has been well modelled by Markov chains. In this paper, the use of Markov chains for modelling wind speed data is discussed in the context of the previously proposed likelihood ratio test. The main steps for Markov chain based modelling methodology of wind speed are presented and the limiting distribution of the Markov chain is utilized to compute wind speed probabilities. The computational formulas for reliability indices of a wind farm consisting of a specified number of wind turbines are presented through the limiting distribution of a Markov chain. A case study that is based on real data set is also presented.
Experimental and modeling studies of a high-temperature electrochemical hydrogen compressor
(International Journal of Hydrogen Energy, 2024-01) Bulanık Durmuş, Gizem Nur; Kuzu, Cemil; Devrim, Yılser; Çolpan, C. Özgür
Some non-technical factors such as economics and logistics prevent hydrogen (H2) technologies from becoming more widespread in daily life. Today, the prevalence of H2 technologies requires new technological developments. Electrochemical hydrogen compressors (ECHC) are of great interest due to their ability to pressurize and purify in one step. In this study, the electrochemical H2 compression performance of high phosphoric acid (PA) doped poly 2,2-m-phenylene-5,5-benzimidazole (PBI) membrane-based HT-ECHC under high temperature and non-humid conditions was investigated through both an experimental and a numerical approach. The H2 compression capacity of HT-ECHC at different operating voltages was examined by performance tests at 160 °C, and it was determined that the electrochemical compression performance increased with increasing operating voltage. It was observed that the current density values also increased with increasing voltage, and it was determined that a current density of 61.2 A was obtained at 1 V. As a result of the tests, H2 was successfully compressed from atmospheric pressure to 60 bar by HT-ECHC without any gas leakage. The results of the developed model were compared with the experimental performance test data, and the variation of molar flow, cell voltage, and cell efficiency over time was examined. It has been determined that the back diffusion from the cathode to the anode in the cell increases with the increasing operating voltage of HT-ECHC and therefore the cell efficiency decreases. It has been evaluated that the developed model and experimental results are in good agreement.
Green hydrogen based off-grid and on-grid hybrid energy systems
(International Journal of Hydrogen Energy, 2023-12-25) Ceylan, Ceren; Devrim, Yılser
This study aims to evaluate a green hydrogen (H2) based hybrid energy system (HES) from solar and wind renewable energy sources. The proposed HES contains PV panels, wind turbines and a proton exchange membrane water electrolyzer. Meteorology data such as solar radiation, temperature and wind speed were obtained from Atilim University Incek Campus Meteorology Station (Ankara, Turkey). The designed HES has been examined as both grid-connected and off-grid. In the grid-connected system, the electricity requirement of the load is supplied by the sun and wind, and the surplus energy produced is stored by producing H2 using an electrolyzer. In the off-grid HES, the electricity requirement of the load is completely provided by the proton exchange membrane fuel cell (PEMFC). In this system, the electrolyzer produces the H2 needed by the PEMFC with the energy provided by solar and wind energy. According to the results, 20,186 kWh of energy is produced annually in the on-grid and 3273 sm3 of H2 is stored. The off-grid system is investigated for Design-1 and Design-2 using two different wind turbine (WT) rated power. In Design-1 and Design-2, annually 95,145 kWh and 83,511 kWh of energy are produced annually 17,942 sm3 and 14,370 sm3 H2 are stored, respectively. When the on-grid and off-grid systems are examined; levelized cost of energy (LCOE) was calculated as 0.223 $/kWh for the on-grid system and 0.416 $/kWh and 0.410 $/kWh for Design-1 and Design-2 for off-grid systems, respectively.
Performance analysis of a gas-to-power system based on protonic-ceramic electrochemical compressor
(International Journal of Hydrogen Energy, 2023-12-05) Baniasadi, Ehsan; Ghojavand, Fateme; Çolpan, Can Özgür; Devrim, Yılser
In this study, two scenarios are considered to evaluate the performance of a protonic ceramic electrochemical hydrogen compressor (EHC) and reformer integrated with a proton exchange membrane fuel cell (PEMFC). First scenario includes integration of an EHC with PEMFC and in the second scenario, steam methane reforming (SMR) is replaced by an EHC. Results show that the highest energy and exergy efficiencies of the system in the first scenario is achieved when the area-specific resistance (ASR) in EHC is 1.5 Ωcm2. An increase in the working temperature of EHC causes a considerable rise in the exergy destruction and an increase of energy efficiency by 7% in the first scenario, while the temperature of the reformer affects the exergy destruction, negligibly. The parametric study indicates that the best value of the current density of PEMFC is 0.8481 A/cm2 and 0.8324 A/cm2 and the best current density of PEM-EHC value is 0.4468 A/cm2 and 0.11 A/cm2 in the 1st and 2nd scenarios, respectively. Under the same conditions, energy and exergy efficiencies for the first scenario are 61.63% and 54.9% and for the second scenario are 42.48% and 14.61%, respectively.
An Integrated Decision-Making Framework for Mitigating the Impact of Urban Heat Islands on Energy Consumption and Thermal Comfort of Residential Buildings
(Sustainability, 2023-06-16) Turhan, Cihan; Atalay, Ali Serdar; Akkurt, Gülden Gökçen
Urban heat island (UHI) is a zone that is significantly warmer than its surrounding rural zones as a result of human activities and rapid and dense urbanization. Excessive air temperature due to the UHI phenomenon affects the energy performance of buildings and human health and contributes to global warming. Knowing that most of the building energy is consumed by residential buildings, therefore, developing a framework to mitigate the impact of the UHI on residential building energy performance is vital. This study develops an integrated framework that combines hybrid micro-climate and building energy performance simulations and multi-criteria decision-making techniques. As a case study, an urban area is analyzed under the Urban GreenUP project funded by the European Union’s Horizon 2020 Programme. Four different strategies to mitigate the UHI effect, including the current situation, changing the low-albedo materials with high-albedo ones, nature-based solutions, and changing building façade materials, are investigated with a micro-climatic simulation tool. Then, the output of the strategies, which is potential air temperature, is used in a dynamic building energy simulation software to obtain energy consumption and thermal comfort data of the residential buildings in the case area. Finally, a multi-criteria decision-making model, using real-life criteria, such as total energy consumption, thermal comfort, capital cost, lifetime and installation flexibility, is used to make a decision for decreasing the UHI effect on residential energy performance of buildings. The results showed that applying NBSs, such as green roofs and changing existing trees with high leaf area density ones, have the highest ranking among all mitigation strategies. The output of this study may help urban planners, architects, and engineers in the decision-making processes during the design phase of urban planning.
A Novel Data-Driven Model for the Effect of Mood State on Thermal Sensation
(Buildings, 2023-06-29) Turhan, Cihan; Özbey, Mehmet Furkan; Çeter, Aydın Ege; Akkurt, Gülden Gökçen
Thermal comfort has an important role in human life, considering that people spend most of their lives in indoor environments. However, the necessity of ensuring the thermal comfort of these people presents an important problem, calculating the thermal comfort accurately. The assessment of thermal comfort has always been problematic, from past to present, and the studies conducted in this field have indicated that there is a gap between thermal comfort and thermal sensation. Although recent studies have shown an effort to take human psychology into account more extensively, these studies just focused on the physiological responses of the human body under psychological disturbances. On the other hand, the mood state of people is one of the most significant parameters of human psychology. Thus, this paper investigated the effect of occupants’ mood states on thermal sensation; furthermore, it introduced a novel “Mood State Correction Factor” (MSCF) to the existing thermal comfort model. To this aim, experiments were conducted at a mixed-mode building in a university between 15 August 2021 and 15 August 2022. Actual Mean Vote (AMV) and Profile of Mood States (POMS) were used to examine the effect of mood state on thermal sensation. The outcomes of this study showed that in the mood states of very pessimistic and very optimistic, the occupants felt warmer than the calculated one and the MSCFs are calculated as −0.125 and −0.114 for the very pessimistic and very optimistic mood states, respectively. It is worth our time to note that the experiments in this study were conducted during the COVID-19 Global Pandemic and the results of this study could differ in different cultural backgrounds.
Integration of psychological parameters into a thermal sensation prediction model for intelligent control of the HVAC systems
(Energy and Buildings, 2023-10-01) Turhan, Cihan; Özbey, Mehmet Furkan; Lotfi, Bahram; Akkurt, Gülden Gökçen
Conventional thermal comfort models take physiological parameters into account on thermal comfort models. On the other hand, psychological behaviors are also proven as a vital parameter which affects the thermal sensation. In the literature, limited studies which combine both physiological and psychological parameters on the thermal sensation models are exist. To this aim, this study develops a novel Thermal Sensation Prediction Model (TSPM) in order to control the HVAC system by considering both parameters. A data-driven TSPM, which includes Fuzzy Logic (FL) model, is developed and coded using Phyton language by the authors. Two physiological parameters (Mean Radiant Temperature and External Temperature) and one psychological parameter (Emotional Intensity Score (EIS) including Vigour, Depression, Tension with total of 32 subscales) are selected as inputs of the model. Besides the physiological parameters which are decided intentionally considering a manual ventilated building property, the most influencing three sub- psychological parameters on thermal sensation are also selected in the study. While the physiological parameters are measured via environmental data loggers, the psychological parameters are collected simultaneously by the Profile of Mood States questionnaire. A total of 1159 students are participated to the questionnaire at a university study hall between 15th of August 2021 and 15th of September 2022. The results showed that the novel model predicted Thermal Sensation Vote (TSV) with an accuracy of 0.92 of R2. The output of this study may help to develop an integrated Heating Ventilating and Air Conditioning (HVAC) system with Artificial Intelligence – enabled Emulators that also includes psychological parameters.
Gender inequity in thermal sensation based on emotional intensity for participants in a warm mediterranean climate zone
(International Journal of Thermal Sciences, 2023-03-01) Çeter, Aydın Ege; Özbey, Mehmet Furkan; Turhan, Cihan
The deficiencies of the one of the most preferred conventional thermal comfort models, the Predicted Mean Vote/Percentage of Predicted Dissatisfied (PMV/PPD) method have emerged over time since the model does not take psychological parameters such as personal traits, mood states and adaptation into account. Therefore, researchers have focused on Adaptive Thermal Comfort models that integrate human behaviours into the model for better prediction of thermal comfort. In addition to the influence of the behaviours of occupants, thermal comfort may be evaluated as a subjective term, thus, the effect of one of the psychological parameters, current mood state, on thermal sensation cannot be ignored for predictions. Although, the effect of current mood state on thermal sensation is a vital concept, the findings of the studies are not effective and comprehensive in the literature. For this reason, the aim of this study is to examine the relationship between current mood state and thermal sensation in gender difference aspect. Therefore, a series of experiments were conducted in a university study hall between August 16th, 2021 and August 1st, 2022. The current mood states of the participants were evaluated with the Profile of Mood States (POMS) questionnaire and the results were represented by a novel approach called Emotional Intensity Score (EIS). One tailed t-test was applied for investigating the relationship between the EIS and the thermal sensation. Findings of the research showed that a significant association exists between the EIS and thermal sensation for male participants while no relationship was found for female.
A novel comfort temperature determination model based on psychology of the participants for educational buildings in a temperate climate zone
(Journal of Building Engineering, 2023-10-01) Özbey, Mehmet Furkan; Turhan, Cihan
Maintaining thermal comfort in the educational buildings is vital due to the impacts on learning effectiveness of students. Therefore, development of a proper comfort temperature in educational buildings is a must. In naturally ventilated and mixed-mode buildings, the adaptive thermal comfort model, which considers additively psychological, and behavioural factors to the Fanger's PMV/PPD model, is commonly applied based on regression analyses. However, the psychological adjustments based on current mood state are very limited in these adaptive thermal comfort models. Therefore, this study focuses on the psychological adjustments in terms of Profile of Mood States in order to predict comfort temperature of students in a case building. The experiments are conducted in a university on a temperate climate zone for a long period-data including both heating and cooling seasons. In this study, the comfort temperatures for each student are determined via Griffith method for the case building. Moreover, the current mood states of students are assessed utilizing the Profile of Mood States survey, which are collected via a developed mobile application. As a conclusion, the relation between the current mood state of the students and comfort temperature are statistically investigated. The results show that a Griffith constant are found as 0.332/K and mean annual comfort temperature is found as 21.32 °C in the case building. Additionally, a significant difference is found in the comfort temperatures among the students who have more, or fewer concerns than typically reported. The novelty of the study is to present a comfort temperature determination model which considers human psychology as a starter study in the literature.
The Influence of Meteorological Parameters on PM10: A Statistical Analysis of an Urban and Rural Environment in Izmir/Türkiye
(Atmosphere, 2023-02-23) Birim, Necmiye Gülin; Turhan, Cihan; Atalay, Ali Serdar; Akkurt, Gülden Gökçen
Air pollution is a substantial menace, especially in industrialized urban zones, which affects the balance of the environment, life of vital organisms and human health. Besides the main causes of air pollution such as dense urbanization, poor quality fuels and vehicle emissions, physical environment characteristics play an important role on air quality. Therefore, it is vital to understand the relationship between the characteristics of the natural environment and air quality. This study examines the correlations between the PM10 pollutant data and meteorological parameters such as temperature (Tair), relative humidity (RH), and wind speed (WS) and direction (WD) under the European Union’s Horizon 2020 project. Two different zones (Vilayetler Evi as an urban zone and Sasalı Natural Life Park as a rural zone) of Izmir Province in Türkiye are used as a case study and the PM10 data is evaluated between 1 January 2017 and 31 December 2021. A one-tailed t-test is used in order to statistically determine the relationships between the PM10 pollutant data and meteorological parameters. As a further study, practical significance of the parameters is investigated via the effect size method and the results show that the RH is found to be the most influencing parameter on the PM10 for both zones, while Tair is found to be statistically non-significant.
High-temperature electrochemical hydrogen separation from reformate gases using PBI/MOF composite membrane
(International Journal of Hydrogen Energy, 2023-06-15) Durmuş, Gizem Nur Bulanık; Eren, Enis Oğuzhan; Devrim, Yılser; Çölpan, C. Özgür; Özkan, Necati
In this paper, the high-temperature electrochemical Hydrogen (H2) purification performance of a polybenzimidazole/UIO-66 metal-organic framework (PBI/UIO-66) membrane is investigated and analyzed at different values of current, temperature, and reformate feed composition. Purification measurements show that a significant reduction in gas impurities can be obtained. In the performance tests, three different ratios of reformate gas (RG) (H2:carbon dioxide (CO2):carbon monoxide (CO)) as RG-1= (75:25:0), RG-2= (75:22:3), and RG-3= (95:0:5) were used. The highest purification values were observed at 160 °C as 99.999%, 99.931%, and 99.708% for RG-1, RG-2, and RG-3, respectively. The obtained results show that an electrochemical H2 purification (ECHP) based on PBI/UIO-66 composite membrane is promising for H2 purification.
Fabrication and Performance Evaluation of Graphene-Supported PtRu Electrocatalyst for High-Temperature Electrochemical Hydrogen Purification
(International Journal of Hydrogen Energy, 2023-06-26) Bal, İlay Bilge; Durmuş, Gizem Nur Bulanık; Devrim, Yılser
The main aim of this study is to investigate the high-temperature electrochemical hydrogen purification (HT-ECHP) performances of graphene nanoplatelet (GNP) support material decorated with platinum (Pt) and platinum-ruthenium (PtRu) nanoparticles prepared by microwave irradiation technique. Prepared catalysts coupled to the phosphoric acid doped polybenzimidazole (PBI) membrane for HT-ECHP application. The structural and electrochemical properties of the catalysts were examined by thermogravimetric analysis (TGA), X-Ray Diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Transition electron microscopy (TEM) and cyclic voltammetry (CV) analyses. The characterization results indicate that the catalysts provided the necessary properties for HT-ECHP application. The HT-ECHP performances are investigated with reformate gas mixture containing hydrogen (H2), carbon dioxide (CO2) and carbon monoxide (CO) in the range of 140–180 °C. The results show that the electrochemical purification performances of the catalysts increase with increasing operating temperature. The highest H2 purification performance is obtained with PtRu/GNP catalyst. The high electrochemical H2 purification performance of the PtRu/GNP catalyst can be attributed to the strong synergistic interactions between Pt and Ru particles decorated on the GNP. These results advocate that the PtRu/GNP catalyst is a hopeful catalyst for HT-ECHP application.
Editor’s notes on ICENES’2013, 16th International Conference on Emerging Nuclear Energy Systems
(Progress in Nuclear Energy, 2015-08-05) ŞAHİN, Sümer
The 16th ICENES 2013 was held in Madrid (Spain) on May 26e 30, 2013, by Universidad Politécnica of Madrid (UPM), according to a scientific tradition of 35 years, started in 1978 as an autono mous, self-organized event, when a group of independent nuclear scientists met in Graz, Austria in order to find new routes for improving the use of the immense energy of the atomic nucleus. Throughout the years, ICENES became a very important series of well established conferences and acted as an open forum for inno vation and challenges in the field as long as they were based on sound deliberations and were addressing the key issue of providing energy for humankind.
Energy multiplication and fissile fuel breeding limits of accelerator-driven systems with uranium and thorium targets
(International Journal of Hydrogen Energy, 2015-01-25) ŞAHİN, Sümer; ŞARER, Başar; ÇELİK, Yurdunaz
The study analyses the integral 233U and 239Pu breeding rates, neutron multiplication ratio through (n,xn)- and fission-reactions, heat release, energy multiplication and consequently the energy gain factor in infinite size thorium and uranium as breeder material in an accelerator driven systems (ADS), irradiated by a 1-GeV proton source. Energy gain factor has been calculated as Menergy ¼ 1.67, 4.03 and 5.45 for thorium, depleted uranium (100% 238U) and natural uranium, respectively, where the infinite criticality values are k∞ ¼ 0.40, 0.752 and 0.816. Fissile fuel material production is calculated as 53 232Th(n,g) 233U, 80.24 and 90.65 238U(n,g) 239Pu atoms per incident proton, respectively. The neutron spectrum maximum is by ~1 MeV. Lower energy neutrons E < 1 MeV have major contribution on fissile fuel material breeding (>97.5%), whereas their share on energy multiplication is negligible (0.2%) for thorium, depleted uranium. Major fission events occur in the energy interval 1MeV < E < 50 MeV.
Influence of void fraction on BWR spent fuel direct recycling scenario
(International Journal of Hydrogen Energy, 2015-06-10) ŞAHİN, Sümer; WARIS, Abdul; SU'UD, Zaki; ŞAHİN, Hacı Mehmet; KURT, Erol
Preliminary study on influence of changing void fraction (VF) on SUPEL (Straight Utilization of sPEnt LWR fuel in LWR system) scenario for boiling water reactor (BWR) spent fuel direct recycling scheme has been carried out. Several VF values of BWR have been investigated to determine the criticality of reactor. The VF values range from 20% to 60%. The fraction of spent fuel to the total loaded fuel was changed from 5% to 20%. The required uranium enrichment for criticality becomes higher with the increasing of VF as well as the enlarging of the fraction of spent fuel in loaded fuel. The neutron spectra become harder with the augmenting of VF. The plutonium and minor actinides isotopes are produced more in the reactor.
Neutronic investigations of a laser fusion driven lithium cooled thorium breeder
(Progress in Nuclear Energy, 2014-02-02) ŞAHİN, Sümer; ŞARER, Başar; ÇELİK, Yurdunaz
The paper investigates the main parameters of a Laser Inertial Confinement Fusion Fission Energy (LIFE) driven thorium breeder. A similar blanket to the (LIFE) engine design in Lawrence Livermore National Laboratory is chosen in order to allow mutual feedback between two geographically separated teams towards a more advanced and improved design under consideration of totally independent views. In the basic design, frozen (D,T) fusion fuel ice is shot to the center of 5 m diameter spherical fusion reactor chamber cavity in pulsed mode (10e30 Hz). Fusion fuel burns through direct or indirect laser beam irradiation. The first wall surrounds the fusion chamber and is made of S-304 steel (2 cm). The fusion reactor cavity is kept in high vacuum. It is followed by a natural lithium coolant zone. A 2nd S-304 layer (2 cm) separates the lithium zone on the right side from the graphite reflector (30 cm). The outer boundary of the graphite reflector is also covered with a 3rd S-304 layer (2 cm). The calculations have been performed for a fusion driver power of 500 MWth with the last available version of MCNP, namely with MCNPX-2.7.0. In the first calculation phase, the thickness of the natural lithium coolant-tritium breeder zone (DRLi) has been varied as 50, 60, 70, 80, 90 and 100 cm to select the coolant thickness DRLi to have a satisfactory tritium breeding ratio (TBR) for continuous fusion reactor operation. For a pure fusion blanket without any fissionable elements in the coolant, TBR values are calculated as 1.237, 1.312, 1.370, 1.415, 1.449 and 1.476, respectively, for corresponding coolant thick nesses. A DRLi value of 50 cm would keep TBR > 1.05 for self-sustaining tritium supply. These DRLi values lead to blanket energy multiplication values of M ¼ 1.209, 1.216, 1.219, 1.222, 1.223 and 1.224, respec tively, and have been calculated, as a result of exoenergetic neutron absorption in 6 Li. For coolant thickness values >50 cm, the increase of “M” would remain minor. In the second phase, ThO2 has been suspended in the form of micro-size tristructural-isotropic (TRISO) particles in the lithium coolant for 233U breeding. TRISO fuel has the great advantage of high mechanical stability. Furthermore, fission products will be separated from the coolant. TRISO particles have been dispersed homogenously in the lithium coolant with volume fractions Vtr ¼ 1, 2, 3, 4, 5 and 10 vol-%. Calculations with DRLi ¼ 50 cm and by variable Vtr result with TBR ¼ 1.229, 1.222, 1.214, 1.206, 1.1997 and 1.1622, respectively. Parasitic neutron absorption in Thorium decreases the TBR values. For Vtr < 5 vol-% TRISO in the coolant, the increase of the neutron absorption in thorium will be compensated to a great degree through neutron multiplications via 232Th(n,f) and 232Th(n,2n) reactions so that the sacrifice on TBR remains acceptable. However, for Vtr > 5 TRISO vol-%, neutron absorption in thorium reduces TBR drastically. On the other hand, the blanket energy multiplication M increases with thorium volume fraction, namely as M ¼ 1.2206, 1.2322, 1.2426, 1.2536, 1.2636, 1.3112 for respective TRISO volume frac tions due to the contribution of fission energy. Fissile fuel productions in the blanket are calculated as 17.23, 33.09, 48.66, 64.21, 79.77 and 159.71 233U (kg/year), respectively.
Editor’s Report on NURER2012, The III. International Conference on Nuclear and Renewable Energy Resources, _ Istanbul, Türkiye (20–23rd May 2012)
(Energy Conversion and Management, 2012-05-22) ŞAHİN, Sümer
The Journal of Energy Conversion and Management covers a wide range of topics related to energy such as the energy efficiency and management; heat pipes; thermo-siphons and capillary pumped loops; thermal management of spacecraft; space and terrestrial power systems; hydrogen production and storage; renewable energy; nuclear power; conventional power; single and combined cycles; miniaturized energy conversion and power systems; fuel cells and advanced batteries; biomass, and water management and desalination
Hydrogen hazard and mitigation analysis in PWR containment
(Annals of Nuclear Energy, 2012-04-09) ŞAHİN, Sümer; SARWAR, Mohammed Sohail
This paper describes the analytical results for the estimation of hydrogen concentration in the contain ment atmosphere based on zirconium oxidation reaction following a severe accident. The analysis pro vides useful information about the potential challenge of local hydrogen accumulation in the containment, which may be used to reduce the hydrogen detonation risk and to design the capacity and arrangements of mitigation measures. The containment analysis has been performed using computer code COGAP which uses the scenario of loss of coolant accident. The behavior of pressure and hydrogen concentrations in containment as a function of time under the severe accident condition is presented in graphical form. The mitigation measures (recombiners) are essential to maintain containment atmo sphere in the safe stable conditions. A hydrogen control system is to mitigate the hydrogen risk by com paring results from a reference accident sequence with and without recombiners. This comparison show that combustible gas occur in few local areas in the containment for a limited time span and hydrogen concentration is reduced significantly with the use of recombiners.
Evaluation of integral quantities in an accelerator driven system using different nuclear models implemented in the MCNPX Monte Carlo transport code
(Annals of Nuclear Energy, 2012-07-27) ŞARER, Başar; ŞAHİN, Sümer; ÇELİK, Yurdunaz; GÜNAY, Mehtap
The MCNPX code offers options based on physics packages; the Bertini, ISABEL, INCL4 intra-nuclear mod els, and Dresner, ABLA evaporation–fission models and CEM2k cascade-exciton model. This study ana lyzes the main quantities determining ADS performance, such as neutron yield, neutron leakage spectra, heating and neutron and proton spectra in the target and in the beam window calculated by the MCNPX-2.5.0 Monte Carlo transport code, which is a combination of LAHET and MCNP codes. The results obtained by simulating different models cited above and implemented in MCNPX are compared with each other. The investigated system is composed of a natural lead cylindrical target and stainless steel (HT9) beam window. The target has been optimized to produce maximum number of neutrons with a radius of 20 cm and 70 cm of height. The target is bombarded with a high intensity linear accelerator by a 1 GeV, 1 mA proton beam. The protons are assumed uniformly distributed across the beam of radius 3 cm, and entering the target through a hole of 5.3 cm radius. The proton beam has an outer radius of 5.3 cm and an inner radius of 5.0 cm. The maximum value of the neutron flux in the target is observed on the axis 10 cm below the beam window, where the maximum difference between 7 different models is 15%. The total neutron leakage of the target calculated with the Bertini/ABLA is 1.83 1017 n/s, and is about 14% higher than the value calculated by the INCL4/Dresner (1.60 1017 n/s). Bertini/ABLA calcu lates top, bottom and side neutron leakage fractions as 20%, 2.3%, 77.6% of the total leakage, respectively, whereas, the calculated fractions are 18.6%, 2.3%, 79.4%, respectively, with INCL4/Dresner combination. The largest heat deposition density by considering all particles in the beam window calculated with CEM2k model is 104 W/cm3 /mA, which is 9.0% greater than the lowest value predicted with INCL4/Dres ner model (95.4 W/cm3 /mA). The maximum average heat deposition density for all particles in the target is calculated as 6.87 W/cm3 /mA with INCL4/ABLA.
Editorial notes on the 2012 International Youth Nuclear Congress (IYNC), Charlotte, North Carolina, USA (5–11 August 2012)
(Energy Conversion and Management, 2012-08-05) ŞAHİN, Sümer
Primary purpose of the International Youth Nuclear Congress (IYNC) series is to transfer knowledge from the current generation of leading scientists and engineers to the next generation. Scien tific, political, public and corporate views regarding the develop ment of different nuclear issues are presented to provide comprehensive discussions on all sides of the subject. With this aim, The 2012 International Youth Nuclear Congress has been held in Charlotte, North Carolina. IYNC2012 was focused on the use of nuclear energy more than ever after the accident at Fukushima power plant and also in the framework of the nuclear renaissance in many developing countries and world powers as well. IYNC2012 offered the opportunity to share knowledge, experience, best prac tices and information about nuclear energy between generations and also between peers in the ongoing mission to promote the peaceful use of nuclear power.

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