atw 2018-09v3

More documents

Recommendations

Info

atw Vol. 63 (2018) | Issue 8/9 ı August/September 464 AMNT 2018 | YOUNG SCIENTISTS' WORKSHOP | | Award winners, sponsors and jury of the 49 th Annual Meeting on Nuclear Technology (AMNT 2018) Young Scientists Workshop: (from left): Dr. Wolfgang Steinwarz, Prof. Dr. Marco K. Koch (Ruhr-Universität Bochum), Dr. Katharina Stummeyer (Gesellschaft für Anlagen- und Reaktorsicherheit gGmbH), Vera Koppers, Winner of the 2018 Young Scientists' Award, Dr. Jens Schröder (GNS Gesellschaft für Nuklear- Service mbH), Katharina Amend (2 nd ranked young scientist), Prof. Dr. Jörg Starflinger ( Universität Stuttgart), María Freiría López 3 rd ranked young scientist. several different sections, each of them modelled separately with different correlations. A comparison with experimental data showed fairly reasonable results which are subject for improvement as a next step. Tobias Jankowski (Ruhr-Universität Bochum, mentoring: Prof. Koch) reported about Development and Validation of a Correlation for Droplet Re-Entrainment Estimation from Liquid Pools. The correlation is based on a dimensional analysis and therefore considers thermohydraulic boundary conditions by dimensionless quantities, which are quantified by empirical constants. These constants are obtained by four nearly steady test phases, taken from two experimental facilities of different scale. The correlation results are in a good agreement with experimental data. The presentation entitled Comparison of Different Wash-off Models for Fission Products on Containment Walls was given by Katharina Amend (Universität der Bundeswehr München, mentoring: Prof. Klein). A parameter variation was conducted with in the setting of a simplified geometry and with the geometry of the laboratory tests. One key influencing parameter for the resulting washed off mass is the percentage of area covered by water in each case, which differs with inclination and mass flow rate. First simulations with the laboratory geometry show satisfactory agreement, when compared to the experiments. Moritz Schenk (Karlsruhe Institute of Technology (KIT), mentoring: Prof. Cheng) gave a presentation about CFD Analysis of centrifugal Liquid Metal Pumps. Using the open-source software OpenFOAM the influence of the physical properties of liquid metals on the performance of a pump impeller and on the flow field is investigated. In general, the simulations show a relatively strong negative influence on head and efficiency for much higher viscosities and nearly no effect for lower viscosities compared to water. This qualitative behaviour is in good agreement with the literature. The optimization of the liquid metal pump is ongoing, focussing on the corrosion potential of the liquid metal. Summarizing, the scientific quality of papers presented by the young scientists in this year reached again a very high level. Therefore, all participants of the workshop should get honourable recognition. The jury awarded Vera Koppers (Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) gGmbH) the 1 st price of the 2018 competition. Her compact as well as those of both the 2 nd ranked author, Katharina Amend (Universität der Bundeswehr München) and the 3 rd ranked author Maria Freiria (Universität Stuttgart) are published in this issue of atw – nucmag. Author Prof. Dr.-Ing. Jörg Starflinger Institute of Nuclear Technology and Energy Systems (IKE) Pfaffenwaldring 31 70569 Stuttgart, Germany Young Scientists' Workshop WINNER Vera Koppers was awarded with the 1 st price of the 49 th Annual Meeting on Nuclear Technology (AMNT 2018) Young Scientists' Workshop. Heuristic Methods in Modelling Research Reactors for Deterministic Safety Analysis Vera Koppers and Marco K. Koch 1 Introduction The national and international fundamental nuclear safety objective is to protect the public from ionising radiation [IAEA2016]. Although research reactors may have a smaller risk potential to the public than nuclear power plants, operators and researchers are at a higher risk [IAEA2016]. Deterministic safety analyses using thermal-hydraulic system codes are a prevalent and important instrument to evaluate the safety of nuclear power plants and research reactors. A wide range of safety analysis codes that are used for simulations of nuclear power plants are applicable to simulations of research reactors. The application range of the thermal-hydraulic system code ATHLET (Analysis of thermal-hydraulics of leaks and transients) – developed by GRS (Gesellschaft für Anlagen- und Reaktorsicherheit gGmbH) – was extended to simulated subcooled nucleate boiling processes at low pressure in 1994 [GRS2009]. AMNT 2018 | Young Scientists' Workshop Heuristic Methods in Modelling Research Reactors for Deterministic Safety Analysis ı Vera Koppers and Marco K. Koch
atw Vol. 63 (2018) | Issue 8/9 ı August/September After that, research reactor simulations using ATHLET were successfully performed at national and international research institutes. ATHLET uses the finite volume method and solves the partial differential equations matrix at discrete meshed volumes. In order to simulate a plant system, the user has to build up a network of thermal hydraulic volumes. This approach allows a wide range of code application due to free thermal-hydraulic nodalisation, but it takes large amount of human resources and requires detailed plant descriptions. In ATHLET, the main modules are thermal fluid dynamics (TFD), heat transfer and heat conduction (HECU), neutron kinetics (NEUKIN) as well as plant control (GCSM). The user has to choose adequate input options out of a wide range of possibilities for each module. Analysing foreign research reactors, technical support organisations and research institutes might be confronted with limited available information of plant data. In case of emerging safety related questions, the complex input data structure of safety analysis codes impede a fast response. The present paper describes the development of a new method for rapid input deck development in the light of limited available data. Due to high diversity of research reactor designs, a rule-based software system is engineered to support the modelling process for deterministic safety analysis utilising the system code ATHLET. The use of heuristic rules allows an adequate input deck generation despite limited data. The fundamental elements of the input deck are generated automatically by few input data necessary. In the case of unavailable data and urgently safety related questions, the user is supported by this software. In the following, the applied heuristic rules realising the new strategy of modelling are described. After that, first functionality of the new modelling system is demonstrated. 2 Heuristic methods in modelling research reactors In this paper, heuristic methods are defined as an approach to achieve an appropriate modelling quality of research reactors despite incomplete data. For this purpose a new software is developed that is structured in the following main modules: • process of user input • build the research reactor model • transform to ATHLET input format • export as input deck The required key data, which the user has to provide to run the software, are constricted to publicly available data. Detail technical documentations, such as safety analysis report, operating manual, system descriptions and schematics as well as technical drawings are assumed to be not accessible. The next text section describes the main steps of the strategy that are implemented in the modelling software. medicine, research reactors have a wide range of designs and operation modes. Realising a heuristically process for research reactor modelling, the number of reactor types considered in this study was restricted. To date, 241 research reactors are operated around the world [RRDB2018]. The TRIGA (Training, Research, Isotopes, General Atomic) and MTR (Material Testing Reactors) reactors represent the most widely installed research reactor types. About 25 % of the research reactors are of MTR type and 21 % are of TRIGA design [RRDB2018]. Consequently, these types are selected as a model design basis. The considered reactor designs are abstracted to open core and tank-in pool reactors as pictured in Figure 2-1. The TRIGA design is currently limited to reactors with natural convection cooling. To structure the research reactor types, a modularisation approach is used. The first level of modularisation is also shown in Figure 2-1. On the second level, the reactor components are decomposed into their further elements. Focusing on the central component, the “reactor core”, typical MTR research reactors have a cluster of multiple assemblies installed at the lower part of the reactor pool. The assembly consists of several parallel arranged fuel plates and the assembly feet. The basic TRIGA core design (Mark I and II) consists of a cylindrical geometry and uses fuel moderator rods. The TRIGA core is also located at the lower part of the reactor pool. The fuel elements of both types (MTR or TRIGA) are made of a fuel meat section containing the fissile material and outside cladding material. Within this work, the fuel meat and cladding material are the smallest units of which a fuel element is made of. In Figure 2-2 the modularization of an MTR core is shown. | | Fig. 2-1. Generic design sense of TRIGA and MTR research reactors and modularisation of main components. 465 AMNT 2018 | YOUNG SCIENTISTS' WORKSHOP 2.1 Abstraction and modularisation of research reactor designs Due to their different applications in the field of science, technology and | | Fig. 2-2. Modularisation of the reactor core (MTR example). AMNT 2018 | Young Scientists' Workshop Heuristic Methods in Modelling Research Reactors for Deterministic Safety Analysis ı Vera Koppers and Marco K. Koch
Page 1 and 2: nucmag.com 2018 8/9 437 Akademik Lo
Page 3 and 4: atw Vol. 63 (2018) | Issue 8/9 ı A
Page 5 and 6: Kommunikation und Training für Ker
Page 39: atw Vol. 63 (2018) | Issue 8/9 ı A
Page 67 and 68: Kommunikation und Training für Ker

atw 2018-09v3

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?