News
Complex analysis of the voltage and current of the switchgear input for monitoring of the powered device condition
TES s.r.o. in cooperation with the Brno University of Technology, the Department of Theoretical and Experimental Electrical Engineering, have been working on the project aiming to enable remote evaluation of the connected electrical devices, for example electrical motors, by measuring of the current and voltage waveforms at the power input of the switchgear. The use of the methods for measurement, signal processing, spectral analysis by the fast Fourier transformation and the MCSA analysis (Motor Current Signature Analysis) are used to fulfil above mentioned goals. Project outputs include methods and procedures for regular analysis of measured quantities and the innovation of the software for data analysis. The connected devices, such as large asynchronous motors, requires complex non-destructive diagnostic method of the technical condition which can be performed during operation without need of any interruption. The ability of data monitoring at the switchgear offers a potential for a significant increase of frequency of data measurement which improves the chances for early detection of the change or early stage malfunctions of the connected device. The innovation of the software tools for data processing of a wide range of connected devices is a key instrument for quick and effective detection of changes in measured quantities.
The Memorandum of Understanding between TES and KHNP signed
The next step in the development of further cooperation between TES s.r.o. and the South Korea company Korea-Hydro & Nuclear Power (KHNP) is the conclusion of the Memorandum of Understanding. The Memorandum was signed at the beginning of September during the visit of Mr Jae Hoon Chung, the KHNP President & CEO, in the Czech Republic. This act declares the intention of parties to support joint projects in the area of operation, service and maintenance, research and development and design and engineering of nuclear power plants. The Memorandum envisages joint participation in the construction of new nuclear power units in the Czech Republic as well as abroad.
TES activities at the NPP sites continue as scheduled under the strict preventive measures due to coronavirus pandemic
TES workers carry up in planned activities, despite difficulties caused by coronavirus pandemic. They fully comply with time schedule according to the requirements of our customer (ČEZ, a.s.) in the area of service and maintenance of the electrical and machinery equipment at the NPP Dukovany and NPP Temelín. ČEZ, a.s. has implemented many necessary measures ensuring continuing production and safe operation of both nuclear power plants. Some of them will definitely have a negative economic impact on our company. It is mainly the postponement or even cancellation of some works which in the short term do not significantly affect the operation or safety of the NPP. The reason for such changes is to reduce number of people working in the area of the NPP site. We face some other challenges. For example work overload of the key specialists, difficulties in commuting to workplace or limited number of people during meetings. There is necessary to keep distance and follow all administrative changes. We respect all the measures and strictly observe all the rules. The Unit 3 of the NPP Dukovany is currently undergoing planned outage, other units are at full operation. TES workers provide all standard activities regarding regular service and maintenance of the electrical equipment at all units. In particular, it is the maintenance of the diagnostic and monitoring system for the plant electrical equipment (MSE), transformer monitoring systems (MST) and other relevant subsystems. Our specialists at the Temelín NPP currently participate on the planned outage of the Unit 1.They provide service and maintenance, testing, diagnostic monitoring, measurements and analyses of the plant electrical systems. Among others, the most important works provided by TES during the outage is the inspection of the monitoring and diagnostic systems of turbo-generators, transformers and on-line monitoring system of the plant electrical equipment (NEMES).
TES developed an in-house methodology for modelling Passive Autocatalytic Recombiners in MELCOR
TES experts from the Nuclear Safety Department have developed a methodology for modelling a Passive Autocatalytic Recombiners (PARs) in MELCOR code, which is used in TES for modelling severe accidents. The PARs are located in the containment and are designed to passively remove the hydrogen, which can be released into containment atmosphere during severe accidents and may become a safety threat. The methodology describes how to prepare a model of a specific PAR by arbitrary vendor and how to implement it in the system MELCOR model. The methodology was successfully validated against the data from the experimental facility THAI (Germany).
Nuclear safety assessment of the APR1000 discussed with KEPCO E&C at joint workshop
The experts from Korean company KEPCO E&C visited Třebíč to participate in a workshop, held from 18 to 21 February, 2020 in TES headquarters. The participants addressed the issues of assessment of AMS (Accident Management System) and determination of the source term. These topics are part of the broader project framework, where TES participates in the safety assessment of APR1000 reactor, as this type possibly can be used for the construction of new units in the Czech Republic. The workshop was another example of successfully developing cooperation between TES and Korean partners.
TES experience in discharge measurement of batteries during simulated SBO accident conditions at the IAEA Technical Meeting
TES experts participated in Technical Meeting on the Management of Direct Current Power Systems and Application of New Devices in Safety Electrical Power Systems for Nuclear Power Plants held at the IAEA’s Headquarters in Vienna, Austria, from 2 to 6 December 2019. The topic covered the issues encountered in direct current (DC) safety power systems due to accelerated ageing of batteries and the use of new devices and technology including power electronic and smart devices. Mr. Frelich presented TES field experience with the discharge measurement of batteries during simulated station blackout (SBO) accident conditions.
TES in negotiations with South Korea partners about cooperation in R&D
South Korea KHNP (Korea Hydro& Nuclear Power) and KEPCO E&C representatives visited TES headquarters in Třebíč on 5 September, 2019. Both parties informed about their activities in nuclear industry and discussed areas of possible future cooperation. Among all bidders, South Korea ´s KHNP is considered to have the best references to win the competition for the supplier of additional nuclear units in Dukovany NPP and now is in search for local sub-suppliers. Except future construction of nuclear power units KHNP is calling on know- how of Czech engineering and industrial companies for other KHNP projects (KHNP operates 24 reactors and 9 more is under the construction). Discussions with KHNP representatives opened the way for TES to further cooperation in the research and development of new technologies and interconnections with KHNP partners.
Upgrade of NEMES Diagnostic and Monitoring System at Temelín NPP
An article addressing the importance of NEMES monitoring system and its upgrading appeared in the corporate newspaper issued by ČEZ, a.s - Temelín NPP (No.23/2019). Key HW and SW components for the system have been supplied by TES s.r.o. as mentioned by Mr. Trubka, the head of profession support of electrical group at Temelín NPP. The system ensures processing of thousands of different signals and monitoring of all important electrical equipment at the power plant. Data provided by the system are considered to be very important for LTO program at Temelín NPP. The „ nonstandard monitoring system“ has been under major up-grading since the beginning of this year. It should be finished by 2025. The system provides continuous monitoring of voltage and electrical currents parameters of the key electrical equipment. „ Nonstandard monitoring system “(shortly NEMES) watches, for instance, generator, transformer, main circulating pumps or diesel- generators. Provided data are available especially for managers and operating personnel of electrical equipment. The system is not directly involved in the control of the power unit; however its importance increases at the moment when any failure occurs. „It is thanks to the system that the cause of the problem can be detected very quickly". Such information can reduce tens of hours, in particular, during period of very tight shutdown timetable. The testing of diesel-generators performed a few weeks ago can be mentioned as an example. The system enabled that within half an hour we could identify the cause of unplanned shutdown of the important power source“, explained Mr. Trubka, the head of profession support of electrical group in ČEZ, a.s., Temelín NPP. In 2019 its 6 year modernisation project was launched. It lies in complete replacement of hardware. The modernization includes replacement of diagnostic units, ensuring processing up to 30 thousand signals, some of which has already been in operation for almost 20 years. The technicians try to schedule works to fit the shutdown plan of the power plant: „The works could also be performed when the equipment is in service, however we could lose the data important to LTO of the power plant. Based on the information on history and current condition of the equipment we can set down conditions of future operation”, Mr. Trubka underlined the significance of the diagnostic system (author of this article is Marek Sviták).
Partial Discharge Monitoring of the Generator in Operation at NPP Temelín
Since 2000 both generators at NPP Temelín have been monitored by on-line diagnostic system MOSAD®–6 (integrated into plant information system under NEMES name). Benefits of the MOSAD®–6 system to the service and maintenance of the electrical equipment are explained by Oto Mareček, executive director of TES company in the interview for All For Power magazine. Monitoring system MOSAD®–6 is developed and supplied by TES. MOSAD®–6 is designed to continuous monitoring of all important electrical equipment for power output and house load of both NPP Temelín units. Among others, the partial discharge in stator winding of the generator is a key parameter for early detection of emerging failure. It is of a great importance for the NPP operator, that the monitoring of the generator is performed without interrupting its operation. Partial discharge monitoring is facilitated with TurboGuardII TC device. Data communication ensures the transfer of recorded data to MOSAD®–6 system where the data are evaluated, archived and synchronised with other measured analogue and binary signals. MOSAD®–6 is equipped with web interface for visualization allowing customer friendly access to measured data and quick assessment of the current status including time trends. Such diagnostics has been regularly provided by TES since 2015. The operator obtains valuable information on the equipment condition and ground for maintenance planning.
Critical Heat Flux Calculation by ALTHAM C12 Code
The second stage of the project no. CZ.01.1.02/0.0/0.0/17_102/0011478 "Application of Codes and Correlations for the Calculation of Critical Heat Flux in Nuclear Reactors" was started on January 1st, 2019. The project is co-financed by "Operational Programme Enterprise and Innovations for Competitiveness (OPPIK)". In the framework of the project TES experts in cooperation with the Brno University of Technology have developed and evaluated methodology procedures for safety analyses related to the critical heat flux in nuclear reactors of PWR type with square geometry of nuclear fuel. The computation will be performed with ALTHAM C12 program developed by ALVEI. Experimental data for the validation of the computational code and related methodology was obtained from international NEA and EPRI databases.
