NEA-1507 WIMSD5.

1. NAME OR DESIGNATION OF PROGRAM:  WIMSD5.

3. DESCRIPTION OF PROGRAM OR FUNCTION

The Winfrith improved multigroup scheme (WIMS) is a general code for reactor lattice cell  calculation on a wide range of reactor systems. In particular, the code will accept rod or plate fuel geometries in either regular arrays or in clusters and the energy group structure has been chosen primarily for thermal calculations. The basic library has been compiled with 14 fast groups, 13 resonance groups and 42 thermal groups, but the user is offered the choice of accurate solutions in many groups or rapid calculations in few groups. Temperature dependent thermal scattering matrices for a variety of  scattering laws are included in the library for the principal moderators which include hydrogen, deuterium, graphite, beryllium and oxygen.
  WIMSD5 is a  successor version of WIMS-D/4.

4. METHOD OF SOLUTION

The treatment of resonances is based on the use of equivalence theorems with a library of accurately evaluated resonance integrals for equivalent homogeneous systems at  a variety of temperatures. The collision theory procedure gives accurate spectrum computations in the 69 groups of the library for the principal regions of the lattice using a simplified geometric representation of complicated lattice cells. The computed spectra are then used for the condensation of cross-sections to the number of groups selected for solution of the transport equation in detailed geometry. Solution of the transport equation is provided either by use of the Carlson DSN method or by collision probability  methods. Leakage calculations including an allowance for streaming asymmetries may be made using either diffusion theory or the more elaborate B1-method.
The output of the code provides eigenvalues for the cases where a simple buckling mode is applicable or cell-averaged parameters for use in overall reactor calculations. Various reaction rate edits are provided for direct comparison with experimental measurements.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

As variable dimensions are used in WIMS, there are no specific limits on such parameters as number of energy groups or mesh intervals other than an overall limit on the core storage of the computer used. The library of cross-sections has only 69 energy groups. Flexibility is provided for running problems with a smaller number of groups.

6. TYPICAL RUNNING TIME:

7. UNUSUAL FEATURES OF THE PROGRAM:

8. RELATED AND AUXILIARY PROGRAMS

WIMS-D/4 (NEA 0329/11) previous version and associated libraries WIMS7 for more "complicated" requirements and 3D calculations LWRWIMS for PWR or BWR cluster geometries.

10. REFERENCES:

- ANSWERS Software Service, AEA Technology:
  WIMSD A Neutronics Code for Standard Lattice Physics Analysis
  (June 1997)
- M.J. Halsall and C.J. Taubman:
  The "1986" WIMS Nuclear Data Library
  AEEW-R 2133 (September 1986)
- T. Kulikowska:
WIMSD-5B Extensions

11. MACHINE REQUIREMENTS:

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:
MVS (IBM), UNIX, VMS, MSDOS.

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

WIMSD5 can now run on a variety of platforms such as IBMs running MVS, SUNs running UNIX and VAXes running MVS. It can be run also on  PCs if compilers are used allowing extended memory.

15. NAME AND ESTABLISHMENT OF AUTHORS

         ANSWERS Software Service
         AEA Technology
         Winfrith
         Dorset DT2 8DH, U.K.

File name	File description	Records
WDN29.ASC	ASCII Library
WILLIE.FOR	Fortran source file to convert library
/SOURCE/	Fortran Source files
/VERIN/	Input data for test cases
/VEROUT/	Output files for test cases
LOADSRCNEA.BAT	Batch file to install the PC version
UPD.FOR	Update program Fortran source file
WIMSD5B.UPD	Upd to generate srce non platform dependent
WIMSD5B.FOR	WIMSD5B source code non platform dependent