NachhaltigMaschinenbau und Mechatronik
Beitrag (Sammelband oder Tagungsband)
T. Wagner, S. Leyer, Giuseppe Bonfigli, Nadine Kaczmarkiewicz
Performance of the Passive Core Flooding System in the Integral Tests of the Project EASY
49. Jahrestagung Kerntechnik / 49th Annual Meeting on Nuclear Technology (AMNT 2018), Berlin , 29. - 30. Mai 2018
Among nuclear power generation plants, light water reactors are mainly used at present, and are anticipated to be predominant in the future. To improve the light water reactors the development of the LWRs for the next generation is carried out at various organizations. For example, in the USA the Westinghouse AP-1000 is based on proven technology but with an emphasis on passive safety features. The reactor passive core cooling systems include the core makeup tanks system, passive residual heat removal heat exchanger and in-containment refuelling water storage tank. In Russia has been developed the so-called NPP-2006 project of a VVER-1200 nuclear power plant with a V-392M reactor unit. To provide the safety, protection passive systems which don’t depend upon human errors are widely used in this project. Among these are hydrotanks of the second stage and passive heat removal system. In the presented paper an overview of passive core cooling systems for next generation NPPs is given.
NachhaltigElektrotechnik und Medientechnik
X. Jing, E. Grustan-Gutierrez, M. Buckwell, Y. Ji, A. Kenyon, M. Rommel, Y. Shi, A. Mehonic, L. Jiang, A. Paskaleva, F. Hui, Günther Benstetter, S. Chen, W. Ng, M. Lanza
On the Limits of Scalpel AFM for the 3D Electrical Characterization of Nanomaterials
Advanced Functional Materials, vol. 28, no. 52
Conductive atomic force microscopy (CAFM) has been widely used for electrical characterization of thin dielectrics by applying a gentle contact force that ensures a good electrical contact without inducing additional high‐pressure related phenomena (e.g., flexoelectricity, local heat, scratching). Recently, the CAFM has been used to obtain 3D electrical images of thin dielectrics by etching their surface. However, the effect of the high contact forces/pressures applied during the etching on the electrical properties of the materials has never been considered. By collecting cross‐sectional transmission electron microscopy images at the etched regions, it is shown here that the etching process can modify the morphology of Al2O3 thin films (producing phase change, generation of defects, and metal penetration). It is also observed that this technique severely modifies the electrical properties of pSi and TiO2 wafers during the etching, and several behaviors ignored in previous studies, including i) observation of high currents in the absence of bias, ii) instabilities of etching rate, and iii) degradation of CAFM tips, are reported. Overall, this work should contribute to understand better the limitations of this technique and disseminate it among those applications in which it can be really useful.
NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenTAZ Spiegelau
K. Elian, Günther Ruhl, F. Darrer, S. Chiang, T. Mueller, M. Vaupel, S. Auer, J. Dangelmaier, H. Theuss, M. Fries, M. Rose, Wee, T. F. D.
Sensor arrangement, battery cell and energy system
NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenEuropan Campus Rottal-Inn
K. Morita, W. Maschek, Rui Li, C. Matzerath Boccaccini, F. Gabrielli
Investigation on upper bounds of recriticality energetics of hypothetical core disruptive accidents in sodium cooled fast reactors
Nuclear Engineering and Design, vol. 326, no. January, pp. 392-402
One key research goal for GEN-IV systems is an enhanced safety compared to the former Sodium Cooled Fast Reactor concepts. A key issue is built-in safety and the capability to prevent accidents and to demonstrate that their consequences do not violate aimed-at safety criteria. From the beginning of SFR development the Core Disruptive Accident (CDA) has played an outstanding role in the safety assessment. Under core disruptive accident conditions with core melting the fuel might compact, prompt criticality might be achieved and a severe nuclear power excursion with mechanical energy release might be the consequence. Numerous safety analyses accompanied the development and the licensing procedures of past fast reactor projects. A central issue of all analyses was the assessment of a realistic upper bound of energetics especially related to recriticalities in disrupted core configurations. Striving for an even higher safety level for next generation reactors a new strategy focused on the development and introduction of preventive and mitigative measures both to reduce the chance for a severe accident development and to mitigate its energetics. For assessing the effectiveness of these measures the knowledge of the CDA behavior is essential. In this context and on basis of new code developments, new experimental insights and extended studies for many reactor types of different power classes over the recent years, the issue of a realistic upper bound of energetics of the late core melt phases is again of relevance. Of special interest is the identification of natural and intrinsic mechanisms that limit the escalation of energetics. The current paper deals with these issues and tries to add supportive facts on the limits of CDA energetics. The evaluation of results of mechanistic SIMMER-II and SIMMER-III/IV analyses performed for various core designs and power classes and specific model case studies in 2D and 3D geometry indeed supports the idea of a limit of recriticality energetics. Intrinsic mechanisms exist, which limit the escalation energetics even in case of a strong blockage confinement suppressing any fuel discharge and allowing on-going sloshing recriticalities. In the light of the available information and taking into account relevant scientific publications and studies by the international community on the subject, one could conclude that an upper bound for energetics in the range given in the paper can be deduced.
NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenIPH Teisnach
G. Berger, I. Widdershoven, M. Schulz, R. Bergmann, D. Ramm, A. Beutler, J. Asfour, G. Schneider, T. Blümel, C. Elster, R. Meeß, H. Klawitter, R. Schachtschneider, M. Sandner, I. Fortmeier, K. Kubo, F. Löffler, Johannes Liebl, M. Stavridis, M. Wendel, C. Pruss
Interlaboratory comparison measurements of aspheres
Measurement Science and Technology, vol. 29, no. 5
The need for high-quality aspheres is rapidly growing, necessitating increased accuracy in their measurement. A reliable uncertainty assessment of asphere form measurement techniques is difficult due to their complexity. In order to explore the accuracy of current asphere form measurement techniques, an interlaboratory comparison was carried out in which four aspheres were measured by eight laboratories using tactile measurements, optical point measurements, and optical areal measurements. Altogether, 12 different devices were employed. The measurement results were analysed after subtracting the design topography and subsequently a best-fit sphere from the measurements. The surface reduced in this way was compared to a reference topography that was obtained by taking the pointwise median across the ensemble of reduced topographies on a $1000 \times 1000$ Cartesian grid. The deviations of the reduced topographies from the reference topography were analysed in terms of several characteristics including peak-to-valley and root-mean-square deviations. Root-mean-square deviations of the reduced topographies from the reference topographies were found to be on the order of some tens of nanometres up to 89 nm, with most of the deviations being smaller than 20 nm. Our results give an indication of the accuracy that can currently be expected in form measurements of aspheres.
NachhaltigElektrotechnik und MedientechnikTC Freyung
Luis Ramirez Camargo, G. Stoeglehner
Spatiotemporal modelling for integrated spatial and energy planning
Energy, Sustainability and Society, vol. 8, no. 1, pp. 1-29
The transformation of the energy system to a renewable one is crucial to enable sustainable development for mankind. The integration of high shares of renewable energy sources (RES) in the energy matrix is, however, a major challenge due to the low energy density per area unit and the stochastic temporal patterns in which RES are available. Distributed generation for energy supply becomes necessary to overcome this challenge, but it sets new pressures on the use of space. To optimize the use of space, spatial planning and energy planning have to be integrated, and suitable tools to support this integrated planning process are fundamental.
Spatiotemporal modelling of RES is an emerging research field that aims at supporting and improving the planning process of energy systems with high shares of RES. This paper contributes to this field by reviewing latest developments and proposing models and tools for planning distributed energy systems for municipalities. The models provide estimations of the potentials of fluctuating RES technologies and energy demand in high spatiotemporal resolutions, and the planning tools serve to configure energy systems of multiple technologies that are customized for the local energy demand. Case studies that test the spatiotemporal models and their transferability were evaluated to determine the advantages of using these instead of merely spatial models for planning municipality-wide RES-based energy systems.
Spatiotemporal models allow a more detailed estimation of RES potentials and serve to find not only optimal locations but also optimal sizes for individual RES plants. While the potential of variable RES based on yearly energy generation values can be considerably larger than the energy demand, only a fraction of it can be deployed without compromising the quality and reliability of the local energy supply system. Furthermore, when spatiotemporal models are used, it can be seen that technological diversity is beneficial for the supply quality. Similarly, the advantages and limits of the deployment of storage systems and of combinations of RES-based technologies to cover the local demand were determined and evaluated. Finally, the results from the analyses provide sufficient information to define road maps of installations deployment to achieve desired RES penetration objectives.
Luis Ramirez Camargo, Wolfgang Dorner, K. Gruber, F. Nitsch
Mapping minimum technical requirements for electricity self-sufficiency of single-family houses using regional reanalysis data and satellite imagery derived data
Geophysical Research Abstracts, vol. 20, no. EGU2018-12577
Decreasing prices of photovoltaic (PV) and electricity storage systems have popularized the idea of independency from the grid among household's owners. The basic idea is simple: on the one side, PV installations can easily fit in building's roof-tops while producing more energy per year than a household would require; on the other side, the temporal mismatch between energy generated by the PV system and the electricity consumed by the household can be corrected with storage systems. In theory, this basic concept would require the examination of long time series of weather data and an optimization model in order to find a system configuration that actually fulfils the requirements of a household in a particular location. In practice, such detailed studies would be too expensive for small-scale installations and contractors take system sizing decisions based on empirical values or general sizing guidelines. Motivated by the project CrossEnergy, a research project that studies the future of the energy system in rural areas at the border between Germany and Czech Republic, and by the publication of the COSMO-REA high resolution regional reanalysis data sets for Europe in 2017, this study presents a methodology to generate maps indicating minimum battery and PV sizes for self-sufficient single family houses (SFHs). The methodology consist of three parts. First, settlement data extracted from the LUISA Territorial Modelling platform of the European Commission is used together with standard load profiles to generate spatiotemporal data sets of electricity demand for rural and low density urban areas. Second, spatiotemporal data sets of PV potential are generated based on a) a technical PV model, b) instantaneous solar irradiance and temperature data from the COSMO-REA regional reanalysis data, and c) snow cover data from the Land Surface Analysis Satellite Applications Facility. Third, a linear optimization model, relying on the data sets of the two previous parts, serves to define PV and battery systems sizes and to generate the corresponding maps. The resulting maps cover Germany and Czech Republic and are generated for multiple technical and weather dependent scenarios. The results show how complicated it could be to achieve a complete independence from the grid in certain locations and offer a scientifically based source of information for sizing PV-battery systems in the two countries. An outlook how to apply the methodology to the whole CORDEX Euro area and for future work is provided.
Luis Ramirez Camargo, K. Gruber, F. Nitsch
Assessing variables of regional reanalysis data sets relevant for modelling small-scale renewable energy systems
Renewable Energy, vol. 133, pp. 1468-1478
An accurate resource availability estimation is vital for proper location, sizing and economic viability of renewable energy plants. Large photovoltaic (PV) and wind installations undergo a long and exhaustive planning process that would imply unacceptably high costs for developers of small-scale installations. In a context of abolition of feed-in tariffs, electricity feed-in restricted by grid capacity constraints and storage systems being commercialized at lower costs, the acquisition of high quality solar radiation and wind speed data becomes important also for planners of small scale installations. These data allow the characterization of short-term and inter-annual variability of the resources availability. Global reanalysis data sets provide long time series of these variables with temporal resolutions that can be as high as one hour and at no cost for the final user. However, due to the coarse spatial resolution and relatively low accuracy these products only provide an inferior alternative for data retrieval compared to e.g. satellite derived radiation data sets or advanced interpolation methods for wind speed data. The COSMO-REA6 and COSMOS-REA2 regional reanalysis overcome this limitation by increasing the resolution of the reanalysis to six and two kilometres respectively. The accuracy of these data sets for variables with high relevancy for meteorology, such as rainfall, has been assessed with satisfactory results but an independent evaluation for variables relevant for renewable energy generation has not been performed yet. This work presents an assessment of the variables of these data sets that have been made available to the public until November 2017. This assessment is performed for the area of the federal state of Bavaria in Germany and whole Czech Republic using data of the Bavarian agro-meteorological network and the Czech Hydrometeorological Institute. Accuracy indicators are calculated for horizontal global radiation or cloud coverage (depending on data availability from the weather stations) and wind speeds at 10 meters height. While there are important differences between weather stations and cloud coverage data, the results for wind speeds and global solar irradiance are satisfactory for most of the locations. For certain locations widely used indicators such as the Pearson’s correlation coefficient reach values above 0.8 for wind speeds and above 0.9 for global solar irradiance and the mean biased error is consistently lower than 10 W/m2 and can be as low as 0.3 W/m2 for the irradiance data and is, with a few exceptions, lower than 2 m/s in Germany and lower than 1 m/s in the Czech Republic for wind speed data. A total of eight indicators for the hourly data in the period between 1995 and 2015 are calculated, presented, discussed and compared against international literature dealing with data accuracy for solar irradiance and wind speed data sets.
NachhaltigElektrotechnik und Medientechnik
A. Ehrmann, T. Grothe, Grassmann, C. Blachowicz, T., László Juhász, D. Wehlage, R. Döttjer, I. Juhász Junger
Dye-Sensitized Solar Cells with Electrospun Nanofiber Mat-Based Counter Electrodes
Materials, vol. 11, no. 9