Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

The code DYN3D/M2 is used for investigations of reactivity transients in cores of thermal power reactors with hexagonal fuel elements. The 3-dimensional neutron kinetics model HEXDYN3D of the code is based on a nodal expansion method for solving the two-group neutron diffusion equation. The thermo-hydraulic part FLOCAL consists of a two-phase flow model describing coolant behaviour and a fuel rod model. The fuel elements are simulated by separate coolant channels. Additional, some hot channels with power peaking factors belonging to chosen fuel elements can be considered. Several safety parameters as temperatures, DNBR and fuel enthalpy are evaluated. Macroscopic cross sections depending from the thermo-hydraulic parameters and boron concentration are input data of the code. The stationary state and transient behaviour can be analyzed. The arrangement of input data are descibed for using the different option of the code.

The code DYN3D/M2 consists of a the 3-dimensional neutron kinetic model of the code HEXDYN3D and the thermohydraulic model of the code FLOCAL. The neutron kinetics of DYN3D/M2 is calculated by using a nodal expansion method (NEM) for hexagonal geometry. The developed method solves the neutron diffusion equation for two energy groups. Stationary state and transient behaviour can be calculated. By help of the code PREPAR-EC parameterizid neutron physical constants of given burnup distribution can be transferred from the MAGRU library to an input file of DYN3D/M2. The code FLOCAL consisting of a two-phase coolant flow model, a fuel rod model and a heat transfer regime map up to superheated steam is coupled with neutron kinetics by the neutron physical constants. One coolant channel per fuel assembly and additional hot channels are considered. The activities for code validation and the range of application are described.

The report summarizes the present state of the 1000-Roof-Photovoltaic-Programme (sponsered by the BMFT and the Federal States) in the five new German Federal states. After some starting problems the programme is well accepted also in East Germany now, especially in Brandenburg, Saxony and Thuringia. Statistical data are given on the siutation in the single states.
Some operation results are discussed in more detail. A final yield of 2 kWh/kWp.a seems to be possible, at least in the region of Saxony. The share of the direct used solar energy by the plant owner strongly depends on the individual energy consumption and on the season. During the winter only a share of 10 % is realistic, but in summer the value can reach 50 % or more. The average performance ratio of several systems is estimated to 68 %.

The paper dealt with the first results of the 1000-Roof-Photovoltaic Programme in the German Federal States of Saxony and Thuringia. Experiences in designing and mounting the pv-plants are discussed. Up to the end of 1992 totally 70 small pv-plants were coupled to the grid in both states. From the first results a mean energy production of about 700 kWh per installed power of 1 kWp can be extrapolated. The most technical difficulties resulted from the used DC-AC-inverters. Additional problems were caused by the grid itself, which was still integrated in the East European Network.

Der derzeitige Entwicklungsstand bei netzgekoppelten Photovoltaikanlagen wird dargestellt. Basierend auf einer Darstellung der eingesetzten Anlagentechnik und ihrer Besonderheiten werden aktuelle Betriebsergebnisse von kleinen (1 bis 5 kWp) Anlagen diskutiert. Die Ergebnisse wurden vorwiegend an Anlagen gewonnen, die im Rahmen des 100-Dächer-Programms in Sachsen errichtet wurden. Abschließend wird auf künftige Entwicklungen eingegangen.

At a lithium metal ion source two concentric emission bundles with sharp outlines are observed, which may indicate two different kinds of emitted ions and/or emission mechanisms. The angular intensity of the narrow bundle is the highest yet reported for liquid metal ion source.