1. NAME OR DESIGNATION OF PROGRAM - 
    GRTUNCL 3D                                                                  

 2. COMPUTER FOR WHICH PROGRAM IS DESIGNED AND OTHER MACHINE VERSION            
    PACKAGES AVAILABLE - 
    Program-name         Package-ID     Orig. Computer   Test Computer          
    ------------         ----------     --------------   -------------          
    GRTUNCL 3D           ??????????     Many Computers                          
                                        Sun-EWS, HP-EWS                         

 3. DESCRIPTION OF PROGRAM OR FUNCTION - 
    The existing two-dimensional GRTUNCL code was converted to compute the      
    uncollided fluence at each spatial in an R-theta-Z grid and to generate the 
    associated distributed first-collision source moments for use as a          
    distributed source in the TORT three-dimensional discrete ordinates         
    computed code.  Because there is very little information on the GRTUNCL     
    code, reviews of the essential elements underlying the methods were made    
    and the changes performed to convert the exiting code into R-theta-Z        
    version compatible with the TORT distributed source input option.           

 4. METHOD OF SOLUTION - 
    The representation of the scattering source in discrete ordinates methods   
    stems from the representation of the collisional transfer differential      
    cross section in terms of Legendre expansions.  The scattering transfer     
    integral of the equation can be further simplified by using the Legendre    
    Additional Theorem.  So the scattering transfer source for a transport      
    problem can be and generally is mathematically represented.  This type of   
    representation of the scattering transfer term is standard in most          
    deterministic transport codes although it is generally used in multigroup   
    form with a truncated spherical harmonics expansion of a specified degree.  
    A source in TORT at a spatial mesh in a discrete direction is presented by  
    an expansion of spherical harmonic type with the source moments which the   
    GRTUNCL 3D code needs to calculate.  The values of the source moments for   
    the first-collision source are the quantities produced by the extension of  
    GRTUNCL code to 3D for input into TORT.  Since the code works only for a    
    point source, the uncollided flux in each spatial mesh is a delta function  
    in direction.  As a result, the moments of the flux expansion can be        
    obtained by multiplying the uncollided fluence by the coefficients for      
    the spherical harmonic expansion described above.  The first collision      
    source moments are then computed group by group using the group-to-group    
    transfer Legendre expansion coefficients taken from an appropriate          
    multigroup cross section set.  This quantity is the desired quantity from   
    running the GRTUNCL code.

 5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM - 
    Three-dimensional GRTUNCL 3D is limited in application to appoint source    
    located on Z-axis.

 6. TYPICAL RUNNING TIME - 

 7. UNUSUAL FEATURES OF THE PROGRAM - 

 8. RELATED AND AUXILIARY PROGRAMS - 

 9. STATUS - 

10. REFERENCES -                                                                
    - F. Masukawa, et al.:                                                      
      GRTUNCL 3D: An Extension of the GRTUNCL Code to Compute R-Theta-Z First   
      Collision Source Moments                                                  
      INS/S99-05(M) Institute of Nuclear Safety Code Manual (March 2000)
    - F. MASUKAWA, et al.:                                                      
      GRTUNCL-3D: An Extension of the GRTUNCL Code to Compute R-Theta-Z First   
      Collision Source Moments                                                  
      Proc. of ICRS9, J. of NUCL. SCI. & TECHNOL. Suppl. 1, p.471-474           
      (March 2000)

11. MACHINE REQUIREMENTS - 
    Sun-EWS or HP-EWS                                                           

12. PROGRAMMING LANGUAGE USED. - 
    FORTRAN + C                                                                 

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED - 
    Sun OS 5.6 or HP-UX9000/785                                                 

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS - 

15. NAME AND ESTABLISHMENT OF AUTHORS - 
    Contributed by:                                                             
                    Institue of Nuclear Safety, NUPEC                           
                    Tokyo, Japan                                                
    Developed by:                                                               
        GRTUNCL 3D  CRC Research Institue, Inc.                                 
                    Tokyo, Japan                                                

16. CONTENTS OF CODE PACKAGE - 
    Unix compressed tar files containing source files and sample cases.         
    The referenced documentation in postscript files.

17. CATEGORY. G J 
    KEYWORDS - 
    discrete ordinates, neutron, gammma-ray, first-collision source moments,    
    multigroups, two-dimensions, three-dimensions, cylindrical geometry