1. NAME AND TITLE

PRESTO: Point Kernel Calculation for Complex and Time-Dependent Gamma-Ray Source Spectra.

2. CONTRIBUTORS

Zentralinstitut F. Kernforschung, Dresden, Germany; OECD Nuclear Energy Agency Data Bank, Gif-sur-Yvette, France.

3. CODING LANGUAGE AND COMPUTER

FORTRAN; VAX.

4. NATURE OF PROBLEM SOLVED

PRESTO is written especially for simple shielding design studies. The chosen approximation is due to calculations of shielding for piping and spherical/cylindrical containers. Surface sources built up by radioactive deposits can be estimated. PRESTO I treats cylinder sources with shields at the side, such as pipelines or containers in radioactive facilities. PRESTO II is the analogous code for spherical sources. The programs consider volume sources or a combination of volume and surface sources. To describe the source spectrum, one begins with the nuclides contained in the source mixture or (with the aid of PRESTO IA) from energy group sets. The internal data set contains 5 common shield construction materials.

5. METHOD OF SOLUTION

The solution method is based on point kernel integration, extended by the ``self absorption distance'' concept. The approximation mentioned before reduces the spatial flux calculation to a plane problem. The dose buildup factor is taken into account by Taylor's formula. Some functions necessary for the integration are calculated inside the program by means of extrapolation based on the internal data sets.

PRESTO calculates: 1) required shield thicknesses for a given dose rate level or the allowed activity concentration of the source for a given shield thickness, both time dependent. 2) the contribution to the dose rate by single nuclides.

6. RESTRICTIONS OR LIMITATIONS

1) Energy range from 0.1 to 10 MeV.

2) Contents of internal nuclide library: 100 nuclides with 428 energy lines. One run can use 30 of them (up to 280 energy lines)

3) PRESTO I: 1 shielding material per job 4) PRESTO II: up to 5 shielding materials per job 5) PRESTO IA: 40 energy groups, taken from the nuclides contained in the data set, or up to 250 free energy groups.

7. TYPICAL RUNNING TIME

NEADB ran the different modules of the test case included in this package on a VAX 8810 computer in less than 6 seconds of CPU time.

8. COMPUTER HARDWARE REQUIREMENTS

PRESTO was developed on a BESM-6 computer and was converted to run on a VAX at the NEADB. The test case runs on a VAX 8810 computer in 5054 K bytes (9872 pages) of main storage.

9. COMPUTER SOFTWARE REQUIREMENTS

The package was tested at NEA-DB under VMS 5.0.

10. REFERENCE

W. Weidemann, U.E. Michaelis, and G. Siewczynski, "PRESTO - A Program System for Shielding Calculations of Cylindrical and Spherical Gamma Sources," (In German) (1984).

11. CONTENTS OF CODE PACKAGE

Included are the referenced document and one (1.2MB) DOS diskette which includes source files, sample input and output.

12. DATE OF ABSTRACT

April 1990.