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Table of Contents,Getting Started 3,Installation 3. Running the Program 4,Basic Geometry 5,Surface Cards MCNP5 Manual Vol II Page 3 12 5. Macro Bodies MCNP5 Manual Vol II Page 3 18 7,Cell Cards MCNP5 Manual Vol II Page 3 9 7. Advanced Geometry 10,Universes MCNP5 Manual Vol II Page 3 26 10. Lattices MCNP5 Manual Vol II Page 3 28 10,Materials MCNP5 Manual Vol II Page 3 122 12.
Source Terms and Criticality MCNP5 Manual Vol II Page 3 53 13. Tallies MCNP5 Manual Vol II Page 3 81 14,Flux and Energy Tallies 15. Mesh Tallies MCNP5 Manual Vol II Page 3 118 17,Burn up MCNPX Manual Page 5 77 19. Further Study 20,Getting Started, This section will cover basic set up of the MCNP5 X This involves installing the program setting up an. environment and running the program If there are any questions about this process please contact me It is. not very easy to get started with this process if you have never dealt with installing software in this way before. Installation, There are several different versions of MCNP that a person can obtain from RSICC One can get only the. executables the full source code and also the newest beta release The only reason for needing the source. code is if you plan on compiling the source code yourself to enable different options or even to modify the. code to suit your needs I will not discuss this here as it is not a trivial process to learn how to compile code and. set up environment without having ever used the MCNP at all The following will discuss how to install the ex. ecutables data and set the environments up The data libraries will take a while to install as they are extremely. large files remember back to the Brookhaven National Lab cross sections you used to look up in NE405 408. and imagine these cross sections for different temperatures etc and the amount of data starts multiplying. fast It is possible to add in new cross sections for MCNP to read if you have data from an outside source that. you d like to use but I will not discuss that here. For the windows users there is a simple installation program that uses the windows install wizard to. guide you through the process On the disk you received from RSICC you will want to go into the MCNP5 direc. tory and then the windows installer directory and run the setup exe file This should guide you through the rest. of the way of installing MCNP5 The code needs cross sections to compute the nuclear interactions and there. fore the MCNPDATA folder should be opened and similarly followed to install the data libraries. You should now have MCNP5 and the data libraries installed This is able to run problems now but. there is also MCNPX that can be installed as well MCNPX will be installed in a similar way except that the file to. install MCNPX is a windows batch file located in that directory. NOTE Do NOT try this if you are not experienced with what you are doing in this environment It can. cause problems if you do not install files properly and set permissions accordingly. The linux installation is a lot more exciting in that you are required to do some work and must know. your way around a terminal window During the linux installation readme files will be your best friend MCNP5. and MCNPX tell you to do things differently and don t agree on the installation process and thus installing both. of them for the first time can be rather confusing I would first recommend installing the data libraries some. where that you can reference later These libraries are used by both programs and need to be extracted only. once An important feature is that you need to set your DATAPATH variable to wherever you installed your da. ta libraries This is where I prefer linux in that you can do things your own way without being forced to install. them to a directory structure you don t like, After installing the data libraries and setting your DATAPATH variable one can move onto the programs.
themselves For a variety of machines and set ups there are executables that are included on the disks These. executables need to be put into a folder for you to run from later Note that you will have to know your com. puter architecture etc to choose the proper binary file. Your system should now have a folder with binary executables and also a location storing all the data. libraries The next step is to set all the environment variables that you will need The location that the executa. ble files are located should be added to your PATH variable This will now allow MCNP5 X to be executed To. visualize the geometry for MCNP an x windows server is required To set this up you will need to set your DIS. PLAY variable up properly to an output for an x window These three variables DATAPATH PATH DISPLAY. are the three variables that you will need almost every time you want to run MCNP and thus I would recom. mend putting these in your profile so that they will be around every time you run your machine. Running the Program, The first thing that I will mention is that the User s Manuals are extremely helpful These manuals have. loads of information in them and can help you through the entire process that this tutorial takes you through. They are very dense though and it is helpful to know what you are looking for before beginning to read 500. pages from a manual which is what I will try and help with. You should now have an executable version of MCNP and data libraries installed The next step now is. getting the program to actually run This is done by executing the program through a command prompt if. you re on windows or by executing the binary file on a linux machine To run a problem the basic syntax is. mcnp5 i filename options, where i is short for inp and indicates to look for the given input file This can also be replaced by n which. will label all files the same way For example let s say my input file is named test I could run the program like. mcnp5 i test, which produces a file called outp and several others with the data from the problem Each subsequent run. with the syntax like this will produce new output files with the last letter changed outq outr If instead I. ran the program like this,mcnp5 n test, which produces a file called testo and several other test files This is helpful if you have several input files. and want to separate the output in a unique way The drawback here is that if the output files already exist the. program will terminate without executing, The options available for running your problem allow you to process different aspects of the execution.
in a unique order If no options are specified as above then the default options are given to the program. which are ixr,The options are as follows,i process input file. p plot geometry with the built in plotter NOT vised. x process cross sections,r transport the particles run the program. z plot tally results or cross section data, You can see that the default of ixr will first process the input file then process the cross sections that are. needed for the problem and finally transport the particles specified in the problem Another typical option that. I use frequently in my executions is ip This will process the input and then plot the geometry I personally pre. fer this plotter to vised but each person has their own personal preferences. Basic Geometry, In MCNP every input file contains three sections which are cell cards surface cards and data cards. The geometry is only concerned with the cell and surface cards Cell cards are used to specify volumes and sur. face cards are obviously used to specify the surfaces that enclose the volumes MCNP allows the user many. different options of specifying the different parameters but does require an order to every input file The. layout for an input file is as follows Cell cards followed by a blank line then surface cards followed by a blank. line then the data cards followed by a blank line,A typical input file looks something like this.
c Cell Cards,Different cells that are specified,blank line. c Surface Cards,Different surfaces that are specified. blank line,c Data Cards,Any data that is needed for the problem. blank line, Every file is organized in that way but the way that you specify the individual components can vary based on. personal preferences and ease of specifying different geometries One note is that MCNP does not allow any. blank lines other than one after the three sections This means that if you want your input file to be more read. able you will have to put a c at the beginning of the line to indicate that the line is commented This shows the. Fortran heritage of the code,Surface Cards MCNP5 Manual Vol II Page 3 12.
Parameters and options j n a,j surface number integer value from 1 99999. n coordinate transformation information,a equation mnemonic. Surfaces are objects that can be combined in unique ways to create enclosed volumes which we discovered in. the cell cards There are many different surface types listed in the manual that one is able to use and I will. briefly introduce a plane A common plane equation is this Ax By Cz D 0. To specify this plane surface in MCNP the following would be used j p A B C D. where j is the surface number p indicates that it is the equation of a plane and A B C D are the plane parame. ters To create a surface parallel to the Z axis at a height of 5 the following two lines could be used. j p 0 0 15, The following chart contains all the surfaces that MCNP can handle and their input options. Macro Bodies MCNP5 Manual Vol II Page 3 18, Another way to specify multiple surfaces at once is with the use of macro bodies Macro bodies are simply. combinations of multiple surfaces that MCNP has already predefined One such macro body is a box The. mnemonic for creating a box is the following,BOX Vx Vy Vz A1x A1y A1z A2x A2y A2z A3x A3y A3z.
where the V s are the coordinates of a corner and the A s are the vector s of the sides leaving that corner De. pending on the math that you use to create your volumes it could be advantageous to use macro bodies as a. quicker method of specifying many surfaces The standard way of specifying six surfaces and combining these. with cell cards to create a box is valid as well and this method of specifying every surface will be used in all the. Cell Cards MCNP5 Manual Vol II Page 3 9,Parameters and options j m d geometry parameters. j cell number 1 99999,m number of material card 0 if void. d density if a material is present nothing if void. geometry definition of how surfaces are arranged, parameters optional input to specify importances universes etc which will be discussed later. In the geometry section surfaces that are used in this cell think volume are listed which includes how these. surfaces interact with each other Surfaces have a negative and positive sense to them that one can talk about. The positive sense is the side of the surface that is pointing toward the positive axes A plane with the equa. tion z 0 xy plane has orientation with a negative side below the xy plane and positive side above the xy plane. This is important to note because a cube enclosed by 6 surfaces has to be specified using the correct orienta. tions of the surfaces otherwise it will be an infinite volume outside the cube with nothing in the cube Here is. an example of this,C Cell cards,1 0 1 2 3 4 5 6 void region outside box. 2 0 1 2 3 4 5 6 cube,C Surface cards Notice the blank line above.
One thing to note is that the code above doesn t produce the results expected at first glance Think about. what is actually specified though and you ll discover that the program did exactly what we indicated it should. do The cell was specified by going to the left of surface 1 and above surface 2 These must always hold true. and therefore the program interprets the input as a quadrant In logic this is an AND clause Left of surface 1. AND Above surface 2 To get everything outside the cube logic tells us that it has to be an OR clause Left of. surface 1 OR Above surface 2 This is accomplished in MCNP by putting a colon between the surfaces It is. often advantageous to group things together to make the geometry more clear for yourself which can be done. with parenthesis The above example should look like this to get a cell outside of a cube. C Cell cards, 1 0 1 2 3 4 5 6 void region outside box parenthesis are optional. 2 0 1 2 3 4 5 6 cube,c Surface cards, A cell can be everything except for a certain cell For example a cube within a cube example will build upon our. previously developed cube To create the second cube we could specify all the surfaces of the first cube and. also all the surfaces our second cube 12 surfaces in all To make life a little simpler one could just specify the 6. new surfaces of the outside cube and then use the command and the cell number to indicate that you want. to exclude the cell number For this example it could look like this. C Cell cards,1 0 10 11 12 13 14 15 void region outside box. 2 0 1 2 3 4 5 6 inner cube,3 0 10 11 12 13 14 15 2 outer cube. c Surface cards,OR this will produce the same geometry.
C Cell cards,1 0 10 11 12 13 14 15 void region outside box. 2 0 1 2 3 4 5 6 inner cube,3 0 10 11 12 13 14 15 1 2 3 4 5 6 outer cube. c Surface cards,Advanced Geometry, To create many of the objects that are of interest in MCNP it would be very tedious to constantly speci. fy new volumes for each fuel pin in an entire reactor core mock up This problem can be solved by writing a. NOTE Do NOT try this if you are not experienced with what you are doing in this environment It can cause problems if you do not install files properly and set permissions accordingly The linux installation is a lot more exciting in that you are required to do some work and must know your way around a terminal window During the linux

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