A web-based nuclear simulator using RELAP5 and LabVIEW
Contents
1. see front matter 2007 Elsevier B V All rights reserved doi 10 1016 j nucengdes 2007 01 004 GUIs have been developed so that the system codes can be used like a conventional nuclear plant analyzer NPA Bartsoen et al 1997 Maselj et al 1997 Kim et al 2001 2003 In addition to the user friendly interfaces real time web casting of results obtained using these codes in GUIs is also desirable With easy accessibility and fast Internet communica tion a greater degree of freedom in simulation and or analyses of nuclear transient conditions can be achieved if computer codes and their output are accessible from anywhere in the world through the web Such a web based interactive interface can also be very useful for team work when there is a need to share real time data With increasing emphasis on team work with teams often located in geographically distant locations such a capabil ity can act as the bridging interface allowing better collaboration and interactive exploration of real time data Using mostly off the shelf technology development of such a capability a web based nuclear reactor simulator based on a best estimate code and with user friendly interface is reported here Specifically a user friendly graphical interface is devel oped to execute and to display the voluminous output of the widely used best estimate code RELAPS Moreover a capability to web cast that I O interface in real time is also a2. ELSEVIER Available online at www sciencedirect com ScienceDirect Nuclear Engineering and Design 237 2007 1185 1194 Nuclear Engineering and Design www elsevier com locate nucengdes A web based nuclear simulator using RELAPS and LabVIEW K D Kim Rizwan uddin gt Korea Atomic Energy Research Institute KAERI Dukjin 150 Yusung 305 353 Taejon Republic of Korea gt University of Illinois at Urbana Champaign UIUC Department of Nuclear Plasma and Radiological Engineering 103 S Goodwin Ave Urbana IL 61801 USA Received 20 September 2006 received in revised form 7 January 2007 accepted 8 January 2007 Abstract A web based nuclear reactor simulator has been developed using the best estimate nuclear system analysis code RELAPS as its engine and LabVIEW for graphical user interface and web casting Simulator retains the accuracy of the best estimate code Results are displayed in user friendly graphical format Color coded nominal values are displayed along with the current status of different variables in tab activated windows Some variables of interest are also shown as a function of time All graphical outputs are displayed in web browsers making the simulator s front end independent of the operating system The interactive simulation feature allows the users to simulate specific reactor transients such as LOCA scram etc using a single click Simulator s graphical output can be web casted and is
3. Fig 6 Flow rates window K D Kim Rizwan uddin Nuclear Engineering and Design 237 2007 1185 1194 1191 Nodalization for Typical Two Loop Westinghouse PWR m hoe jma LJ Problem ine 170 314 Tewpera taro Fig 7 Nodalization window 3 2 4 Flow rate window Flow rates for the primary loop and charging letdown flows and various secondary flows are included in this window shown in Fig 6 Primary loop flows are essential for reactor cooling and charging letdown is used to maintain water inventory on the primary side On the secondary side main and auxiliary feedwater flow steam flow for each steam generator and turbine isolation flow and steam depressurizing valve flow are shown in the window These flows are also shown in trend graphs as a function of time 3 2 5 Nodalization window Conventional simulators are often based on simplified models and coarse computational cells This does not permit evaluation and display of spatial distributions of quantities of interest Since RELAPS a code that calculates fairly detailed spatial distribu tions is the engine behind the simulator developed here it is pos sible to display the evolution of spatial distribution of quantities of interest such as temperature or void fraction etc The nodal ization window is designed to show void distribution in nuclear steam supply system Color is used to show the level of void frac tion in each cell D
4. Main Control Nodalization Pressure amp Level Temperature Row Cold Leg T Temperaturel K Temperaturel K 8 8 as Fig 5 Temperature window such reactor operating conditions as thermal power generated on the primary side reactor over cooling and under cooling etc This window also shows for each leg the saturation tempera tures with red bars on the upper part of the thermometers This Title of Web Page OF D2IOMNA NZE Windows Internet Explorer Tai Bae BY SASIKA FAD SBSH x 2 p24 yman http A2S 5m33_23 html information is crucial in determining the level of sub cooling margin that must be maintained to protect the reactor coolant pump These temperatures are also shown in trend graphs as a function of time mZ O BSO Loop Flow Loop 2 Flow Hr Loop Im Loop 2 Bag Main Feedwater 1 kg s Aux Feedwater 1 kg s Steam Flow 1 kg s 515 88 Main Feedwater 2 kg s Aux Feedwater 2 kg s Steam Flow 2 kg s 199 200 300 400 eog 199 200 300 400 eag 199 200 300 400 0 600 0 600 0 515 377 0 Turbine Flow kg s SDV Flow kg s on 400 600 800 1000 400 600 800 1000 1200 200 1200 P Yo 1019 28 fo Main Control Nodalization Pressure amp Level Temperature Flow lt DES 19 2 0 S 19 OD en 199 200 90 oy Time sec 0 509 536 500 600 Flow kg s anaes sBeegeeees esse 20 40 Time sec o SEEEN
5. lt Auto Manual Cie Cc RCP I RCP 2 Accident Initiation Auto Manual Fig 2 Main control page mination by LabVIEW intrinsic function without following the proper termination procedure Few frequently used transient simulation scenarios such as LOCA steam generator tube rup ture and built in trip control functions such as reactor scram and reactor coolant pump ON OFF are made available as single click switches Since current work is only to demonstrate the capabilities and feasibility of a web based simulator using Lab VIEW the GUI currently does not provide interactive features to control all aspects of a reactor However additional interac tive controls can be added without significant effort The red button is used as a reactor scram switch as well as an indicator to show the reactor s current status Two toggle switches show the current status of the reactor coolant pumps and two push buttons above these switches are used to select the auto manual mode Access to reactor output data in graphical form is available by clicking on the tabs at the bottom left of the window shown in Fig 2 which results in display of the clicked module in the same window replacing the control window User can also elect to view the data in newly opened windows by clicking on the desired module button on the left edge of the control module buttons under the heading Stand alone Pages shown in Fig 2 3 2 Data visual
6. KOSEF for partially supporting the visit to UIUC Work was performed while K D Kim was a visiting scientist at UIUC 1192 K D Kim Rizwan uddin Nuclear Engineering and Design 237 2007 1185 1194 Appendix A Slight changes are made in seven RELAPS subroutines and six new subroutines are added to generate the dynamic link library to couple RELAPS with LabVIEW VI Two examples of the changes made to RELAPS code are shown and described below RELAPS5 main program was changed to a sub program for LabVIEW Modified parts of program Change to sub program instead of main program subroutine relap5_main ictrl_ varstr_ Export this sub program to LabVIEW IDEC ATTRIBUTES DLLEXPORT RELAP5_MAIN New module files USE GUI dat USE ICV_mod Define control variables integer ictrl_ 0 19 i Define minor edit variables and void distribution to real 8 varstr_ 0 99 voidf_ 500 be passed to LabVIEW do i 0 10 Initialize the control variables ictrl 0 0 enddo Close input file close 11 Sub program to transfer data to LabVIEW call r5m33_data ictrl_ varstr_ voidf_ Return instead of stop return Sub program set_files shown below is added to set up the I O files Description Program list Change to sub program instead of main program subroutine set_files Export this sub program to LabVIEW This routine sets up the I O files implicit none RELAP5 common block to save I O file names integer nflsch parameter nflsch 18 common ufilef filsch nfls
7. during loss of coolant or steam line break accidents Trend graph shows the change of reactor power with time 3 2 2 Pressure and level window Pressure and water levels on the primary and secondary sides are very important parameters for reactor operation and reactor K D Kim Rizwan uddin Nuclear Engineering and Design 237 2007 1185 1194 1189 F 5m33_16 Microsoft Internet Explorer De PMZ IWW SAATA FAD TESH x 2 Pax Rmn amp D http kdkim nb mshome net r5m33_16 htm v ndk Reference YS Highighh SS Edi Qperate 2 Reactor Power Fission Power Power MWth sdo oho sho 2b0 2sho 3 0 Time sec Total Reactivity Moderator SS ath HTST Fuel T Scram Core Liquid Level m 10 10 6 5502 Fuel Center Temperature K from the bottom Ao 12th HTST 16th HTST 18th HTST 2 uaa Initialization amp SS Nodalization POWer Pressure amp Level lt 2 28 Fig 3 Reactor power module safety evaluation This window shows pressures and collapsed water levels for the pressurizer and two steam generators using meters for pressure level indicators for water level and trend graphs See Fig 4 The state of the primary side pressure and water inventory is shown using the pressurizer pressure and pres surizer water level Steam dome pressure and narrow range water levels show the state of the pressure and water inventory of the secondary sid
8. thus available to anybody with access to the web Moreover if permitted the simulator can be operated remotely from another site connected to the server via the World Wide Web 2007 Elsevier B V All rights reserved 1 Introduction Large system analysis computer codes such as RELAPS US NRC December 2001 RETRAN Computer Simulation amp Analysis 2001 TRAC M US NRC April 2001 CATHARE Farvaque 1992 MARS Jeong et al 1999 etc have played an important role in evaluating nuclear reactor systems for a wide range of planned and accidental conditions Most of these codes required high performance computers to simulate compli cated reactor phenomena However rapid advances in computer technology now enable these codes to run on personal comput ers or workstation in real or nearly real time This has helped in more widespread use of these codes One limitation that still restricts their use on an even wider scale is that these codes often have complicated I O structure User friendly graphical user interfaces GUI will not only help in their increased use they are also likely to help in better and efficient interpretation of the results obtained using these codes This has motivated the development of easy to use GUI tools for best estimate codes such as SNAP Jones 2000 and PEGAS YS Agee 1996 Some Corresponding author E mail addresses kdkim kaeri re kr K D Kim rizwan uiuc edu Rizwan uddin 0029 5493
9. 0000 Steam Line 1 Pressure 303 p 770010000 Steam Line 2 Pressure 1194 K D Kim Rizwan uddin Nuclear Engineering and Design 237 2007 1185 1194 References Agee L J 1996 Status of EPRI software In Presented at Korea Electric Power Corp Electric Power Research Institute Bartsoen L Mandy Cs Stubbe E 1997 Nuclear plant analyzer an efficient tool for training and operational analyses In Proceedings of the Second CSNI Specialist Meeting on Simulators and Plant Analyzers Finland Computer Simulation amp Analysis Inc 2001 RETRAN 3D A Program for Transient Thermal Hydraulic Analysis of Complex Fluid Flow Systems vol 1 Theory and Numerics Electric Power Research Institute EPRI NP 7450 Farvaque M 1992 Users manual of CATHARE 2 V1 3E CEA STR LML EM 91 61 Jeong J J Ha K S Chung B D Lee W J 1999 A multi dimensional thermal hydraulic system analysis code MARS 1 3 1 J Korean Nucl Soc 31 3 344 363 Jones K R 2000 Symbolic nuclear analysis package In Proceedings of the 2000 ANS ENS International Mtg Embedded Topical Mtg 2 Best Esti mate Methods in Nuclear Installation Safety Analysis Washington DC November 12 16 Jurcevic M Malaric R Sala A 2006 Web based platform for dis tance training on Electrical Measurements Course Measurement Science Review vol 6 Sec 1 No 4 2006 Available via Web at http www measurement sk 2006 S 1 Jurcevic pdf K
10. S Nuclear Regulatory Commission Report NUREG CR 5535 Washington USA White J R 2006 Available via web at http nuclear101 com
11. ark blue represents 100 water and decreas ing intensity of blue shows an increasing amount of void Fig 7 shows the change in void fraction distribution during a large loss of coolant accident The figure on the left shows the void distri bution during normal operating conditions and the one on the right shows void distribution about 100s after the accident Windows and variables shown in the figures above are for a specific two loop PWR However the target plant can be easily replaced by another plant by simply changing the RELAPS input file Data windows showing scalars for a different plant design for example for a four loop plant will however require some minor modifications to display the additional variables for the different plant design In the current version of the simulator nodalization window is the only window that displays spatial distribution of a variable void fraction Since geometry and number of cells may vary from plant to plant and from one sim ulation to another the nodalization window must be tailored for each plant geometry and the number of cells This may require a moderate amount of effort to tailor the simulator s nodalization window for the geometry and the number of cells used in any plant simulation 4 Summary and conclusions A web based nuclear reactor simulator based on RELAPS has been developed using LabVIEW VIs RELAP5 was selected as the engine for this simulator since it is a very widely use
12. ch character filsch 80 RELAP5 common block to save property file names include mxnfcd h Definitions for I O file names to obtain from integer parameter nfiles_p1 15 LabVIEW VI character len 256 mars_file nfiles_p1 character mars_ 96 integer 4 i j is mars_file 1 1 3 ftb File stored user defined O file names through open unit 1818 file filenames txt main control window amp status old iostat is Error recovery routine if is ne 0 then write 1819 1017 is filenames txt 1017 format open error number i8 on file a stop output endif Read O file names read 1818 1819 mars_file 2 read 1818 mars_file 3 read 1818 mars_file 5 mars_file 15 1819 format a Set the variables for RELAP5 I O file name to file do i 1 nfiles_p1 1 names given by user filsch i mars_file i end do property files Include the file path to RELAPS property file name i scan mars_file nfiles_p1 back true do j 1 26 tpfnam j mars_file 15 1 i tpfnam j enddo Close input file close 1818 return end subroutine set_files K D Kim Rizwan uddin Nuclear Engineering and Design 237 2007 1185 1194 1193 To minimize the changes in RELAPS input the values of parameters graphically shown in the LabVIEW VI are obtained from the RELAPS minor edit variables A sub program named r5m33_data is added to get the values of the minor edit variables and to pass the information for the control parameters including intera
13. ctive control function program control between RELAPS DLL and LabVIEW VI Following part of sub program r5m33_data is to export the values of minor edit variables to LabVIEW for graphical representation and web casting sub program transferring information between SUBROUTINE r5m33_data ictrl_ varstr_ voidg_ LabVIEW and RELAP5 DLL Export this sub program to LabVIEW IDEC ATTRIBUTES DLLEXPORT R5M33_DATA New module files USE GUI dat USE ICV_mod Define size of global common block size INCLUDE fast h Define the index of dynamic block for specific INCLUDE comctl h information blocks Information block for minor edits INCLUDE miedtc h Initialize the variables to export to LabVIEW that Initial_call IF ictri O eq 0 then saves minor edit variables DO i 0 99 varstr_ i 0 0 END DO END IF Initial _call index of dynamic file in fast block starting index of 11 filndx 16 minor edit block number of items to be saved per time step n mipck 2 11 increment for each minor edit variables 11a mipck 2 11 1 loop for saving all minor edit variable to sequential DO i 1 n i 1 time vector varstr_ varstr_ i fa micode 2 11 1 IF not unito THEN IF miconv i ge 0 0d0 THEN varstr_ i mplot i miconv 1 varstr_ i mplot i miconv I1 1 8d0 ENDIF ENDIF 1 I1 Il1a END DO Following is the part of RELAPS input to define minor edits A4 Minor Edits Requests a Pressure 301 p 290080000 PZR Pressure 302 p 67001
14. d best estimate code that has been well verified over several years Moreover RELAPS input decks for most nuclear power plants are already available which makes it relatively easy to tailor the simulator for these power plants Although the web based simulator was developed for a particular PWR plant it can be developed for other nuclear plants and experimental facilities by changing the input deck of the RELAPS code and making minor modifications in the data display windows The simulator engine RELAP5 can also be switched with any other system analysis code since the interface between the simulator engine and graphical user interface program is well defined and the two are coupled by dynamic link libraries LabVIEW has been used as a development environment and as generic graphical user interface because LabVIEW is based on a graphical language which is easy to use provides excellent graphics capabilities and moreover it has the ability to make all results available in real time on the World Wide Web Such web based simulation capabilities can also be very useful for team work such as international and or distance collaborations Future work will focus on adding additional interactive fea tures for operator actions as well as extending the development to GEN IV reactor designs Acknowledgements This work was supported in part by the US DOE INIE grant K D Kim acknowledges the support from Korea Science and Engineering Foundation
15. e of the two steam generators These instruments also show reactor s normal operating range in green color above Title of Web Page Microsoft Internet Explorer Hh Bae VIY sas SAD Sse h x 2 ea sya E http fk dkim nb mshome net r 33_23 htm high high set point in red color and below low low set point in yellow color thus making it very easy to assess reactor s current operating status This window also includes the trend graphs for pressures and water levels for pressurizer and secondary side of steam generators 3 2 3 Temperature window This window shown in Fig 5 shows hot leg cold leg and average temperatures for each loop These temperatures indicate gos BBC BD FWO SG 1 Pressue MPa SG 2 Pressure MPa PRZ Level SG 1 Level SG 2 Level Main Control Nodalization Power Pressure amp Level Temperature Pressure 20 Pressure MPa sesogagei 5 p 7 Fig 4 Pressures and water levels 1190 K D Kim Rizwan uddin Nuclear Engineering and Design 237 2007 1185 1194 3 Title of Web Page Microsoft Internet Explorer REE BSCE SIV BARIA S40 Sew d A G Pax kaan http kdkim nb mshome net r5m33_23 html MZE S0 gt 2 6 Average T Hot Leg T LOOP 1 m i Upper slider Saturate T K I Lower slider Loop T K Average T Upper slider Saturate T K Lower slider Loop T K
16. e parameters for the interactive control features 3 Main features Main features of this web based nuclear simulator are explained using an example of a typical Westinghouse two loop PWR Pressurized Water Reactor modeled as the target plant for this application While results shown here are for one spe cific nuclear power plant the simulator can easily be adapted for other plants Specific details for adapting this tool to other LWRs are given later in this section 3 1 Control module Fig 2 shows the main window a LabVIEW virtual instru ment of the web based nuclear simulator It consists of a main tool bar and five tab sheets The tab sheets include the main con trol nodalization reactor power pressure amp level and temperature Each tab sheet is developed as a separate mod ule or virtual instrument Output data can be seen in graphical format by selecting appropriate tabs at the bottom of the sim ulator window This leads to the display of the selected data in the currently open window Option is also available to open new windows to display the selected data Hence a user can select to view the data in a separate window or web browser open in new window by clicking on the buttons on the left side of the main window under stand alone pages Contents of these tab sheets are discussed in more detail below User can control the execution mode using the buttons for run stop and pause o
17. im K D Lee S W Jeong J J 2001 A visual environment for system analysis codes Prog Nucl Energy 39 3 4 335 344 Kim K D Lee S W Jeong Lee Y J Chung B D Hwang M G 2003 Devel opment of a nuclear reactor transient analyzer based on the best estimate codes RETRAN and MARS Trans ANS 89 MacLaren S Faltens A Ritchie G Seidl P 1999 Preliminary Results from a Scaled Final Focus Experiment for Heavy Ion Inertial Fusion In Proceedings of the 1999 Particle Accelerator Conference New York Maselj A Vonjovic D Gregoric M 1997 NPA applications develop ment in the nuclear safety authority framework In Proceedings of the Second CSNI Specialist Meeting on Simulators and Plant Analyzers Finland National Instruments 2003 LabVIEW Getting Started with LabVIEW Oliveira V A Aguiar M L Silva Jr W 1998 User friendly computer soft ware in control and instrumentation teaching and learning In Proceedings of the International Conference on Engineering Education ICEE98 Rio Othon Palace August 17 20 p 1998 US Nuclear Regulatory Commission Office of Nuclear Regulatory Research April 2001 TRAC M FORTRAN 90 version 3 0 Theory Manual US Nuclear Regulatory Commission Report NUREG CR 6724 Washington USA US Nuclear Regulatory Commission Office of Nuclear Regulatory Research December 2001 RELAPS5 MOD3 3 Code Manual Volume 1 Code Struc ture System Models and Solution Methods U
18. imulator can reside on a server Users who are permitted to be connected to the server through the Internet can interactively simulate the transient in interac tive mode using control features through their web browser and examine the results on line Each user interface screen in the web based simulator which will be called a module is a LabVIEW virtual instrument Each module consists of elements such as a windows meters switches etc Since LabVIEW VI is a graphical language the graphic elements within each module can be replaced by other instruments or modified using such simple mouse operation as drag and drop User interface screens in the web based nuclear simulator developed here consist of six modularized LabVIEW VIs a main control module for problem set up and interactive control and five RELAPS output visualization modules Local or remote master user can select the code I O files exe cute the code and simulate operator s action through the main control page which appears in their web browser when they connect to the server The main control window as well as other windows displaying the data can be web casted over the Inter net However only one master user or client can control the transient simulation It should be noted that the RELAPS input data can be used without any changes However to fully utilize the capabilities of this tool additional input cards must be added into the existing RELAPS input deck to specify th
19. ization modules RELAP5S produces a large amount of text based output in a transient simulation Web based nuclear simulator is designed to provide graphical displays of the results during or after a transient simulation so that the users can easily follow plant dynamics There are five data modules that can be accessed to display a wide range of data These are described below 3 2 1 Reactor power module A picture of the reactor power module is shown in Fig 3 It shows major reactor power related parameters through indi cators and trend graphs Specifically this module shows total reactor power fission power major contributions to the reactiv ity worth fuel centerline temperatures along five different axial positions and reactor core collapsed water level This module is designed to display important reactor power related variables as well as parameters that lead to change in power For exam ple user can easily analyze the contributions to a change in reactor power by examining the reactivity effects and fuel tem peratures which affect Doppler feedback Operating range for reactor power is indicated with green color in the reactor power indicators and the power levels above the high reactor power set point are marked in red RELAPS input model was prepared to automatically scram the reactor if reactor power is above the high power set point Core water level is included to show the increase in fuel temperature due to uncovered core
20. n the main tool bar see inset in Fig 2 The main control module is designed to set up the I O files code execution accident initiation simulation of reactor control and to open other output pages in separate browser windows The main control module has three edit boxes and associated buttons to browse and select the input output and restart data files User can execute start the RELAP5 code or pause resume the execution by clicking a button in the main tool bar on top of the window shown Fig 2 User can terminate the execution by clicking the stop button on the top right corner of the win dow shown in Fig 2 Although there is an alternate method to terminate the execution by clicking the stop button in the main tool bar it is not recommended because it forces the ter 1188 K D Kim Rizwan uddin Nuclear Engineering and Design 237 2007 1185 1194 gt Pause r51 33_23 vi it View Brojght Operate Jools Window Help gt E Input File 4 C WResearc hy UC r5m334lv sample _rel apse mide mo 7 oOo Output File R CW Research UIUC HrSm334lv sample _relapst outdta Restart File 4 C WResearch WUIUCWrom3ssivWsample_relapsWrstpit Stand alone Pages Problem Time 32 118 Open Pressure amp Level Page Open Power Page Open Temperature Page REACTOR SCRAM Open Flow Page Open Nodalization Page Main Control Nodalization Power Pressure amp Level Temperature Student Edition
21. r These paths and file names are transferred to RELAPS DLL when user clicks on the run but ton in the main control module The simulator runs using these files as input decks Local or remote master user who has the control of the simulator can simulate operator s actions through the main control page and this control action is also passed to RELAPS5 DLL through LabVIEW VIs During the transient cal culation the RELAPS DLL transfers the results to LabVIEW and the Lab VIEW VIs show the data in graphical form Through Internet the users connected to the server running the simulator can access the graphical output of LabVIEW VIs LabVIEW VIs which are coupled with RELAPS as DLLs make it possible to run RELAPS from a web browser through the network without the code and or input file being present in K D Kim Rizwan uddin Nuclear Engineering and Design 237 2007 1185 1194 1187 3 Master a user ee Graphic Visualization Module output e Reactor Power Module e Temperature Module e Pressure and Level Module e Mass Flow Module Interactive e Void Distribution Module input Web Server Main Control Module results Dynamic Link Lib q Best Estimate System Code Interactive control Calculation e I O File Setup Select I O files e Open separated VI s e Interactive Control Textbasedhput Fig 1 Schematic diagram of a web based nuclear simulator the end user s computer The s
22. ronment For LabVIEW programming a modular approach was adopted Each module is encapsulated with well defined interfaces The modules such as the core power temperature pressure etc are then simply assembled together to create the complete simula tor This modular approach reduces the programming effort and the complexity of the design Because each component is inde pendent and self contained with well defined interfaces it can be repeatedly used saving time and effort in future development work The simulator developed here taps into the data directly from the RELAPS arrays for the variables to be plotted This allows the display of data while simulation is still continuing LabVIEW VIs are coupled with RELAPS as dynamic link library DLL RELAPS main program is changed into a sub program and is exported to LabVIEW The changes made to accomplish this are shown in Appendix A The same appendix also shows a new sub program set_files added to set up the I O files Also as an example the part of RELAPS minor edit input and the related part of a new sub program to graphically show the output of RELAPS in the LabVIEW VI are shown and described in Appendix A Fig 1 shows a schematic diagram of the web based engineer ing simulator The user provides the input and output file names for RELAPS DLL via the main control module by either entering the path and name of the file or by simply browsing through the storage media on the compute
23. st in lab oratories Oliveira et al 1998 MacLaren et al 1999 and is routinely used to process experimental data It has recently been used to develop web based virtual laboratory Jurcevic et al 2006 White 2006 but it has not been used as a front end of a large system analysis nuclear simulation software as is done in the application reported here The sub programs added for the DLL programming are located in a separate directory and maintained as an indepen dent static library The RELAPS files that have been modified to implement the interactive control feature are also saved in a directory different from the one where these sub programs or subroutines are saved in a standard version of RELAPS The number of variables for the interface between RELAPS dynamic link library DLL and virtual instruments VIs in LabVIEW is minimized to simplify the interface Standard input decks of RELAP5 are used as input for this simulator Since interac tive control feature has been added control parameters for this new feature however must be provided along with the standard RELAPS input The interactive web based user interface is developed using the virtual instruments feature in LabVIEW LabVIEW virtual instrument LabVIEW VI is a powerful and flexible graphic programming language It provides a platform to efficiently develop user interfaces and to display data Moreover with the click of a mouse it provides a web based running envi
24. ulations The simulator is developed using RELAPS as its engine However the methodology used here for the web based nuclear simulator is very general and it can be easily extended to other system analysis codes The tools and methodology used to develop the web based nuclear simulator are presented in the next section 2 Tools and methodology Development of a web based simulator can be broken into two steps identification of an engine and development of a GUI A personal computer with Windows OS was used as the developmental platform This choice was primarily dictated by the fact that the dynamic link library DLL for RELAPS which was chosen as the engine for the simulator was gen erated in the Windows environment However since the user interaction is via a web browser the simulator can be used with other machines and operating systems other than Windows RELAPS is selected as the engine of this simulator because of its widespread use worldwide RELAPS input decks for most nuclear plants are already available and can be directly or with very minor modifications used with the simulator devel oped here The choice was also at least partly dictated by the desire to develop a means to graphically display the voluminous text based output generated by RELAP5S LabVIEW 8 0 National Instruments 2003 was used to develop the graphical user interface GUI of the web based nuclear simulator LabVIEW has been used in the pa
25. vailable This has been achieved using the virtual instruments VIs feature available in LabVIEW Laboratory Virtual Instrument Engi neering Workbench a commercially available package for data 1186 K D Kim Rizwan uddin Nuclear Engineering and Design 237 2007 1185 1194 acquisition and visualization In addition to the graphical dis play of the large quantity of data that is generated by such codes interactive control functions have also been added that allow simulation of operator actions such as scram etc Operator actions can be initiated by the local user as well as if permitted by the distant user through the web The key features of this web based nuclear simulator are summarized below e RELAPS forms the engine of this simulator Hence all standard RELAPS5 features are available in this simulator Moreover existing RELAPS input data files can be used e A LabVIEW based graphical user interface has been devel oped to display the large amount of output data during as well as after the transient simulations e Simulator can be run on a server by users who are allowed to access the server through the web Since all interactions take place via a web browser it is machine independent Remote users accessing running the simulator see the results in windows that open in the web browser e Interactive control functions are provided so that users local as well as remote can perform operator actions during the sim
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