At the Applied University Zittau/Görlitz studies within the scope of nuclear safety research are perfomed together with the TU Dresden and the Helmholtz Centre Dresden-Rossendorf (HCDR). They serve clarification of physicochemical mechanisms and their influence on thermofluid-dynamical processes, which may follow Loss-of-Coolant-accidents (LOCA).
Because of corrosion of zinc-coated components zinc ions can be dissolved in boron-treated coolant. In focus of the first set of investigations were the properties of the coolant on hot surfaces, like they are in hot reactor cores of PWR. It became apparent that turbidity can happen, followed by precipitation of zinc borate particles. The latter may not only have different appearances, but may also affect the dissipation of heat from the surfaces.
Currently under investigation are states and conditions which can cause a threat to core cooling. They will be reproduced in test stands in semi-technical scale. With it emerging chemical and thermodynamic effects of zinc dissolution and the precipitation and deposition behaviour of the zinc corrosion products can be detected.
The projects are funded by the Federal Ministry of Economic Affairs and Energy (BMWi). Technically they are accompanied by representatives of the research supervision of the project sponsor and by consultants, manufacturers and operators.
The results will be used, among other things, in simulations that serve to assess the safety of plants for various accident scenarios.
This project was/is funded by the Federal Ministry of Economic Affairs and Energy (BMWi) using the funding sign FKZ 150 1491 and 150 1585A because of the decision of the German Federal Parliament (Deutscher Bundestag).
Machine transformers represent an important link in the power supply chain. Damage to these large components leads to high repair costs. In addition, when transformers are damaged, block units are no longer available to the power supply network. This leads to high consequential costs, which can exceed the amount of the actual damage many times. Condition monitoring is therefore necessary to ensure the operational reliability of machine transformers and to increase their availability.
Numerous parameters of the transformers are recorded and monitored by the monitoring systems installed for this purpose. The data volume can vary with regard to the number of recorded parameters and sampling rate. Based on these recorded parameters a software tool will be created by the Applied University Zittau/Görlitz in cooperation with the Lausitz Energie Kraftwerke AG to estimate the actual state (diagnosis) and to predict future states (forecast) of a machine transformer.
For provision of diagnostic assertions the processing of data takes place using so-called unsharp fuzzy algorithms, which contain expert knowledge in form of rules. Based on the provided data future parameter values are estimated using a prediction method. From that, however, guidance for further monitoring of transformer components can be derived.
Diagnostic and prediction algorithms were provided as modules of a software tool, which accesses and processes data directly from a company-internal database. If requested by the operator the software provides an evaluation of the actual state of the machine transformer and a prediction for selected parameters. The latter one allowing estimation of the remaining lifetime and prescient planning of maintenance tasks.
At the Zittau/Görlitz University of Applied Sciences, together with the TU Dresden and the Helmholtz-Zentrum Dresden-Rossendorf, investigations are being carried out as part of nuclear safety research. These serve to clarify physicochemical mechanisms and their influence on thermofluid-dynamic processes that can occur after loss-of-coolant accidents in a pressurized water reactor (PWR).
Zinc in the form of ions can be dissolved in the borated coolant on galvanized installations as a result of corrosion. The initial investigations therefore focused on the behavior of this coolant on hot surfaces, such as those present in the hot reactor core of PWRs. It was found that turbidity of the coolant can occur here, followed by precipitation of zinc borate particles. The latter can not only exhibit different forms of appearance, but may also influence the removal of heat from the surfaces.
States and conditions are currently being determined in which a risk to core cooling could occur. These are then simulated in test facilities on a semi-industrial scale. In this way, the chemical and thermodynamic influences on zinc release and the precipitation and deposition behavior of zinc corrosion products occurring in the PWR can be recorded.
The projects are funded by the BMWi. They are technically supervised by representatives of the project sponsor's research department as well as by experts, manufacturers and plant operators.
The results will be used, among other things, in simulations that serve to assess the safety of the plants for various accident scenarios.
This work was/is funded by the Federal Ministry for Economic Affairs and Energy (BMWi) under the funding codes FKZ 150 1491 and 150 1585A on the basis of a decision by the German Bundestag.
Generator transformers are an important link in the power supply chain. Damage to these large components leads to high repair costs. Furthermore, in the event of transformer damage, block units are no longer available to the power supply network. This leads to high follow-up costs that can exceed the actual damage many times over. Condition monitoring is therefore necessary to ensure the operational reliability of generator transformers and increase their availability.
Numerous transformer parameters are recorded and monitored by the monitoring systems installed for this purpose. The scope of data can vary in terms of the number of parameters recorded and the sampling rates. Based on these recorded system parameters, the Zittau/Görlitz University of Applied Sciences, in cooperation with Lausitz Energie Kraftwerke AG, is developing a software tool for assessing the current condition of a transformer (diagnosis) and predicting future conditions (prognosis).
To provide diagnostic statements, the data is processed using so-called "fuzzy" fuzzy algorithms, which contain expert knowledge in the form of rules. Future parameter values are estimated from the available time series using forecasting methods. This in turn can be used to derive recommendations for further monitoring of the transformer components.
The diagnostic and forecasting algorithms were made available as modules of a software tool that obtains and processes the data directly from a company-internal database. At the user's request, the tool also provides an assessment of the current condition of a machine transformer and a forecast for selected parameters. The latter allow the remaining service life of a transformer to be estimated and maintenance measures to be planned in advance.
