Development of 3D CAD System as a Design Tool for PEACER Development

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1 Development of 3D CAD System as a Design Tool for PEACER Development Kwang Jin Jeong*, Hyoung Won Lee, Seung Ho Jeong, Jong Gye Shin, and Il Soon Hwang NUclear Transmutation Energy REsearch Center of Korea (NUTRECK), , Seoul National University, Shillim-dong, Kwanak-gu, Seoul, , Korea *Tel: , Fax: , jkj@plaza1.snu.ac.kr In an effort to resolve generic concerns with current power reactors, PEACER has been developed as a proliferation-resistant waste transmutation reactor based on a unique combination of technologies of a proven fast reactor and the heavy liquid metal coolant. In order to develop engineering design and visualize its performance, a three-dimensional computer aided design (3D CAD) method has been devised. Based on conceptual design, system, structure and components of PEACER are defined. Using results from finite element stress analyzer, computational fluid dynamics tool, nuclear analysis tool, etc, 3D visualization is achieved on the geometric construct based on CATIA. A 3D visualization environment is utilized not only to overcome the integration complexity but also to manipulate data flow such as meshing information used in analysis codes. The 3D CAD system in this paper includes an open language, Virtual Reality Modeling Language (VRML), to deliver analyses results on 3D objects, interactively. Such modeling environment is expected to improve the efficiency of designing the conceptual reactor, PEACER, reducing time and cost. Results of 3D design and stress analysis simulation will be presented as an example case. KEYWORDS: PEACER, 3D CAD, CATIA, Virtual Reality Modeling Language (VRML) Introduction The recent research progress in the area of plant design and simulation modeling highlighted the importance of integrating plant design and simulation models with other models. As far as documentation for Nuclear Power Plants (NPPs) were concerned, the range varies from NPPs designed in the 1960s in which documents are all papers and hand-drawings to a modern French Chooz-B plant in which the plant was completely designed by CAD. For those reactors currently under design, either for power production or for research, they have totally embraced impressive state-of-the-art information and automation technology [1]. A computer-aided modeling environment is required to overcome the integration complexity among the enterprise models. The purpose of this paper is to set up an integrated design tool for PEACER, a proliferationresistant waste transmutation reactor [2]. To promote efficiency in design process by coupling design, analysis, and post-processing jobs, to minimize the repetitive jobs followed by design changes, and to present three-dimensional visualization in postprocessing are the major goals of this paper. In designing PEACER, it is also important to show proliferation-resistance and structuralthermal behaviors besides in addition to show geometric shape. To achieve this end with effective manner an integrated design tool has been set up that is composed with commercial CAD software, analysis codes, and visualization code. Using this system, repetitive jobs in design process can be minimized and this approach is being applied to PEACER design. This method is divided two processes, how to relate designs with analyses and how to visualize the analysis output. The one is to use design data directly to analysis tools and the other one is to grasp the design to analysis process at a glance detecting a possible problem easily. 1. Design automation by CATIA Figure 1 shows data flow where geometric data produced by CATIA [3] goes in solution codes and in turn the solutions are visualized by a postprocessor. Base Design Supply detail Design Parameter (FEED BACK) Analysis Solution 2 When base design parameter is changed 1 Detail Design CATIA Geom. Data transfer to analysis solution rapidly Fig 1. Integrated design model by CATIA Design flow 1 Post Processing 3 3 2

2 Table 1. CATIA, solution codes, and design changes Parts Functions CATIA provides geometric data to solution codes where preprocessor is not applicable generates VRML data to be used in post-processor Solution codes handle geometric data obtained from CATIA Conceptual design is modified by CATIA using design parameters from solution codes 2. CATIA and solution codes interface REBUS VRML/PLUGIN REFIN MATRA CFX CATIA ANSYS OUT Waste Disposal Codes * Oriented CATIA Figure 2. CATIA and solution codes interface IN Geom. Data Flow Result Data Flow Other Flow Data produced by each solution code are coupled with Virtual Reality Modeling Language (VRML) script produced by CATIA and are simulated in it or in other VRML viewer. Figure 2 shows geometric data interchanged with CATIA. If a solution code does not have a pre-processor then output data should be post-processed first. In order to make an interface flow diagram (Figure 2) between nuclear solution codes and the 3D CAD system, specified data format of each code must be examined. Therefore the diagram illustrates integration of solution codes, portability of geometry data, and interoperability between the 3D CAD system and nuclear solution codes. Object oriented programming technique is also used to build diagram characteristics. 3. Solution codes [4] 1) REBUS-3 - Input processing is automatic in case of triangular cell/ manual process is needed in case of square cell (PEACER) - Manual input processing is prone to error and it usually takes 2 to 3 weeks - Data transformation needs postprocessing jobs - A utility program needs to handle geometric information changes 2) CFX - Geometric input data produced by CAD is needed - Plots of vector field and contour are needed to visualize fluid characteristics 3) MATRA - Channel by channel characteristics - Geometric input data produced by CAD is needed - Output data is visualized by vector field and contour plot - Fluid characteristics should be reflected 4) REFIN - One dimensional code (being modified to three-dimensional code) - Data format should be set up to be interchangeable - To be three-dimensional, realistic geometric description is needed - Input file is created by manually 5) GEN II - Has the same problems with REFIN [5] 6) ANSYS - Pre-processing (geometric) data can be transferred from CATIA to ANSYS - In post-processing the output results, data should be formatted properly 4. Post-processing method in CATIA In this study, CATIA performs two major roles. One is to be used for a design tool of PEACER and the other one is to visualize the output data obtained by analysis codes. To visualize the results, Component Application Architecture (CAA) and VRML can be used. CAA V5 is the Next Generation middleware for implementing 3D Product Life cycle Management (PLM) system. Though CAA has more capability than VRML, VRML has been adopted in this study to visualize more economically and efficiently with flexibility for VRML, which is an open script language. This method can visualize three-dimensional geometric data with output results calculated from analysis codes. In this study, a PEACER-VIEWER program has been made using VRML and will show the results with threedimensional geometry. 4.1 CAA CAA [3] is an application programming interface (API) to handle CATIA internal data. As an example, CFD Hexa CAA V5: Hexahedral Volume Meshing within CATIA V5 (Figure 3) of ICEM, Inc. is a good example of CAA where mesh generation tool of CATIA can be used in CFD.

3 Figure 3. CFD Hexa CAA V5: Hexahedral volume meshing within CATIA V5. Table 2. VRML and viewing methods VRML viewing Examples methods Application CATIA, 3D MAX, MAYA, dependent type LightWave, etc. Web-browser plug-in type ParallelGraphics Cortona VRML Client, Cosmo Player 4.2 VRML 4) Editing tools - VRML cannot be edited in CATIA A script language, VRML, has been made - 3D MAX, MAYA, etc. are the famous to visualize three-dimensional data in web-browser GUI type tools [6, 7]. Figure 4 shows how geometric data produced by CATIA can be coupled with calculation results 5. Pre-design example using CATIA produced by analysis codes. VRML script produced finally enables three-dimensional visualization. Figure 5. Pre-design of PEACER Figure 5 shows reactor vessel, pump, steam generator, and pipes where Pb-Bi coolant flows. Figure 4. VRML simulation flow chart 4.3 VRML characteristics 1) Interface with CATIA - Export Geometric data produced by CATIA can be transformed to VRML data - Import Transformed data in VRML format can be imported but can not be edited by CATIA 2) Post-processing function - Animation Time dependent simulation is possible - User interactive command Reactions to user inputs such as mouse click or scroll can be defined - Navigation Navigation with zooming, rotating, changing view-angle is possible. 3) Viewer There are two types of viewer. One is application dependent where a viewer is activated appropriate application such as CATIA. The other one is for the web-browser. Table 3. PEACER pre-design main part list 1. Head closure 2. Mid shell 3. Bottom closure 4. Fuel rod 5. Pin 6. Assembly 7. Assembly supporter 8. Barrel 9. Reactor supporter 10. Pipe 11. Pump 12. Steam generator 1) Head closure Figure 6. Head closure

4 GENES4/ANP2003, Sep , 2003, Kyoto, JAPAN 2) Mid shell PAPER No ) Barrel Figure 7. Mid shell 3) Bottom closure Figure 11. Barrel 9) Reactor supporter Figure 8. Bottom closure 4) Fuel rod 5) Fuel pin 6) Fuel assembly Figure 12. Reactor supporter 10) Pipe 11) Pump 12) Steam generator Figure 9. Fuel assembly 7) Assembly supporter Figure 13. Pipe, pump, and steam generator 6. Analysis Example Figure 10. Assembly supporter 6.1 Structural analysis To validate the 3D CAD system developed, an example analysis was done. In this case, a reactor vessel geometry drawn by CATIA was imported by ANSYS [8]. Then reactor vessel was meshed in ANSYS and linear elastic analysis has been performed. Corresponding solution was saved in VRML format and post-processed by VRML viewer. The purpose of this example is to see that the system works well across CAD, FEM, and VRML tools.

5 The reactor vessel has a hemispherical bottom head and a flat top head, attached to a cylindrical body. There are two methods to visualize: Method I) As shown in Figure 15, three-dimensional data produced by CATIA has two data flows. One is to VRML for geometric visualization as formatted by VRML 1.0 and the other one is to ANSYS for structural calculation as formatted binary data named with model extension. Final visualization is achieved by combining, element, and stress data produced by ANSYS with VRML data as shown in Figure 16. Method II) Figure 14. An example of PEACER-VIEWER: ANSYS - stress analysis of reactor vessel There are four piping holes, two of which are for inlet nozzles and the other two for outlet nozzles. A file with model extension is created by CATIA to be imported by ANSYS. Automatic meshing function was used in the ANSYS program to mesh the whole reactor vessel, and 10--tetrahedral element was used. 48,490 meshes and 66,460 s were generated. As a loading condition inside reactor vessel, 0.2 MPa of oxygen gas pressure was postulated. Additional pressure of 0.8 MPa was applied which is the equivalent pressure induced by the Pb-Bi coolant mass. Two inlet holes and two outlet holes are assumed fixed as boundary conditions. Figure 14 shows the von Mises effective stress calculated by ANSYS in the VRML program. Maximum effective stress is 146 MPa and corresponding deformation under about 5 mm. Deformation is magnified to show the deformation behavior while actual deformation is negligible. 6.2 ANSYS-to-VRML converting methods CATIA Processor Confirming Model Draw PEACER 550 Vessel Model and S/G Model using CATIA CATIA Export geometry data to ANSYS ANSYS Result ASCII data (Element, Node, xyz position) (Result Property) Converting Programming for inserting result output data in VRML script code VRML Processor VRML export VRML ASCII geometry data Make VRML ASCII data including ANSYS result ASCII data Post processing Programming Figure 15. CATIA-ANSYS-VRML visualization flow After transferring data produced by CATIA to ANSYS, calculation results are obtained as VRML 1.0 format and then converted to VRML 2.0 format. Finally with legend caption bitmap, visualization can be achieved. Node Data Element Data Result Data ANSYS Output Data Element Data Structure Data Structure of ANSYS result data to convert into VRML VRML 2.0 Converter VRML 2.0 Data Figure 16. Data transferring diagram to VRML 2.0 format The result file is converted to VRML 2.0 and to do the job, information related to, element, and solution should be controlled properly. In the controlling system, an element controls its s, and each has stress and strain information. If element information is transferred to VRML as a face information, this face element has information with its stress and strain values and then finally contour plot can be achieved. 6.3 PEACER-VIEWER A systematic application is needed to achieve three-dimensional visualization and to this end an integrated PEACER-VIEWER application is designed. With this application, structural, nuclear, thermal-hydraulic, and waste disposal designs can be integrated together with their analysis results so as to be examined more closely with transparency finally achieving visualization goal.

6 Figure 17. A menu bar of PEACER-VIEWER Figure 17 shows menu bar of PEACER- VIEWER where each function of menu bar corresponds to its design interface. With these functions, a part of PEACER can be visualized with analysis results as illustrated in Figure 14. A reactor vessel of PEACER is illustrated as shown in Figure 14, from CATIA model generation via ANSYS structural analysis to VRML data conversion. 7. Conclusion As a complexity of system design increases, more changes of design parameters are needed. These frequent changes of parameters not only cause changes of geometric designs but also invoke recalculation of related analysis codes. These repetitive changes in design leads to inefficiency of a time schedule making loss of manpower and money. Three-dimensional CAD system in this paper, using CAD software coupling with nuclear, thermal-hydraulic, and structural analysis codes to apply PEACER design, minimizes the repetitive jobs coming from design changes. As an example case, reactor vessel of PEACER is modeled and visualized with analysis results. As a three-dimensional CAD software, CATIA program is used and ANSYS is used for structural analysis tool. To achieve threedimensional visualization with analysis results over CATIA model, a PEACER-VIEWER is programmed with VRML script. With an integrated CAD system developed in this paper, three-dimensional visualization from geometry design to analysis results can be effectively related. Before the development of this 3D CAD system, we would need 48 months of PEACER project to design the PEACER system [2]. While with integrated system developed in this work, the time for the same work would reduce about 30%. Further, this system is highly practical to use for being composed with commercial CAD and FEM software s and open script language. 3) CATIA Version 5 on-line manual, Dassult Systems, Inc. 4) Conceptual design study of proliferation-resistant transmutation reactor (Korean), Contract No. B-25, Final report of ministry of science and technology (MOST), Korea, ) Byung Gi Park, A Time-dependent Simulation of Molten Salt Electrolysis for Nuclear Wastes Transmutation, Ph.D. thesis, Seoul National University ) Rikk Carey, Gavin Bell, "The Annotated VRML 2.0 Reference Manual", Addison-Wesley, ) Andrea L. Ames, David R. Nadeau, John L. Moreland, "VRML 2.0 Sourcebook", 2nd Edition, ) ANSYS Ver. 6, User's Manual, ANSYS Inc. Acknowledgement This work was financially supported by MOCIE through IERC program. REFERENCES 1) Information technology impact on nuclear power plant documentation, IAEA-tecdoc-1284, April ) I.S. Hwang, et al., The concept of proliferationresistant, environment-friendly, accident-tolerant, continual and economical reactor (PEACER), Nuclear Energy, Vol. 37, No. 1-4, pp , 2000