Nuclear refugees after large radioactive releases

International audienceHowever improbable, large radioactive releases from a nuclear power plant would entail major consequences for the surrounding population. In Fukushima, 80,000 people had to evacuate the most contaminated areas around the NPP for a prolonged period of time. These people have been called "nuclear refugees". The paper first argues that the number of nuclear refugees is a better measure of the severity of radiological consequences than the number of fatalities, although the latter is widely used to assess other catastrophic events such as earthquakes or tsunami. It is a valuable partial indicator in the context of comprehensive studies of overall consequences. Section 2 makes a clear distinction between long-term relocation and emergency evacuation and proposes a method to estimate the number of refugees. Section 3 examines the distribution of nuclear refugees with respect to weather and release site. The distribution is asymmetric and fat-tailed unfavorable weather can lead to the contamination of large areas of land; large cities have in turn a higher probability of being contaminated. © 2015 Elsevier Ltd

Entwicklung, Realisierung und Erprobung der Automatisierungsstruktur- und -technik einer GF-Einkristallzuechtungsanlage mit Dampfdruckofen unter #mu#g-Bedingungen (Bodenmodell) Abschlussbericht

A control structure for multi zone furnaces has been developed with the aim to carry out the fully automated single crystal growth of GaAs. Accordingly, the crystallization process is performed by an electronically controlled temperature field. The high precision temperature control requires precisely working temperature measurement systems, well stabilized power supply devices and an advanced control strategy. In this project, temperature measurement systems and DC voltage power supplies are used in combination with PC based PID software controllers. After installing and testing all the necessary hardware components, the determination of specific operating characteristics and critical process stages was carried out, for example with respect to permitted temperature ranges and maximum heating and cooling rates. These investigations form the basis for heater identification and furnace modeling. Thus, the PID multivariable control design was realized and the software control algorithm was developed. The algorithm functionality and correctness were tested by computer simulation and numerous experiments. In this way, the control precision was improved to #+-#0.1 K at an operating point of 1238 C. A safety control system using supplemental thermocouples was developed for process supervision and detection of critical situations, for example violation of maximum temperature limits and thermocouple breaks. In addition, the development and implementation of a manual controller were realized. This allows to manually control the process at any time. Finally, it can be stated that the developed and implemented control structure guarantees a single crystal growth with high productivity and vry good accuracy and robustness features. (orig.)SIGLEAvailable from TIB Hannover: F96B1228+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany); Deutsche Agentur fuer Raumfahrtangelegenheiten (DARA) GmbH, Bonn (Germany)DEGerman

Indikation von Strukturelementen durch Dimensionsbetrachtungen

The report describes a new method and two criterions of quality for the estimation of structure elements of continuous linear dynamic systems. With the usual system identification methods it is necessary to pretend a fitting system order. In contrast to that, our method is able to estimate a single structure element in a system with many structure elements (e.g. a single zero of a linear dynamic system with four poles and two zeroes). For our method the knowledge about the order of the system is not necessary. (orig.)SIGLEAvailable from TIB Hannover: ZA 5141(6327) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDeutsche Forschungsgemeinschaft (DFG), Bonn (Germany)DEGerman

Strukturmatrizen basierte Synthese der MIMO-Zustandsraumdarstellung

The report considers linear time invariant multi-input/multi-output state space systems without delay time and with concentrated parameters. The state space description is ambiguous. The structure of different models in the class of equivalent systems is more or less decipherable. Decipherable structures are desired. Therefore an equation is developed to calculate the structure of a multi-input/multi-output state space description from a given, decipherable structure consisting of single-input/single-output systems. So we are able to recognize decipherable structures in state space description, e.g. P-canonical, V-canonical and other combined systems with forward and backward directed subsystems. Examples illustrate the procedure. (orig.)SIGLEAvailable from TIB Hannover: ZA 5141(6458) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDeutsche Forschungsgemeinschaft (DFG), Bonn (Germany)DEGerman

Zuechtung von defektarmen dotierten und undotierten GaAs-Einkristallen mit dem vertikalen Gradient-Freezing-Verfahren Kurze Darstellung der Ergebnisse und Abschlussbericht

Multi zone furnaces, automation concepts and laboratory technologies have been developed using the Vertical Gradient Freeze technique for single crystal growth of GaAs with the aim to produce a low dislocation density. The crystallization prozess is performed by an electronically controlled temperature field without moving the furnace or the sample. A command variables generator free programable yields the temperature time programs for the fully automatized growth process. On the basis of a complex process simulation the crystal growth rate, the As partial pressure as well as the temporal and local temperature gradients could be adjusted with high precision and optimized by systematic growth experiments. The crystals grown are characterized by dislocation densities up 1 to 3 x 10"3 cm"-"2, a large area cellular structure and a low density of microdefects. Si-doped and semi-insulating crystals with reproducible physical properties were grown both in (100) and (111) orientation, respectively. The possibility of affecting the crystal properties by post-growth annealing was shown experimentally. (orig.)SIGLEAvailable from TIB Hannover: F95B346+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman