1. NAME AND TITLE

COMPRASH: Spinney Removal-Diffusion Shielding Code.

The code was originally programmed under the name RASH B for the Ferranti Mercury computer and has undergone a series of developmental changes, each carrying the RASH name. It was rewritten for the IBM 7090, later for the CDC 3600, and for the IBM 360/370.

The code package is also available in the OECD NEA Data Bank, abstracted as E126.

2. CONTRIBUTOR

Shielding Group, Reactor Physics Division (AEEW), Atomic Energy Research Establishment, UKAEA, Winfrith, England.

3. CODING LANGUAGE AND COMPUTER

FORTRAN IV; IBM 360/75/91.

4. NATURE OF PROBLEM SOLVED

Fast neutron spectra, thermal neutron flux densities, and the secondary gamma-ray dose rates are calculated for reactor shields in slab geometry.

5. METHOD OF SOLUTION

The Spinney removal-diffusion method of calculating neutron transport is a two-step model. The basic assumption is that the penetrating component from a point source can be calculated by a kernel. The removal flux density, a function of energy, is given by the product of the fission neutron spectrum and an exponential attenuation function which depends on an energy-dependent removal cross section.

The removal source function, a product of the energy-dependent removal cross section and the removal flux density, is then made the source term in a conventional multigroup age-diffusion calculation to calculate the diffusing neutron spectra, including a thermal neutron group.

The value of the removal cross section is taken to be the usual transport cross section which is justified by the remarkable success of the model in predicting the thermal neutron flux densities measured in bulk concrete shields.

The secondary gamma-ray transport is calculated with the use of an analytic form of the buildup factor.

6. RESTRICTIONS OR LIMITATIONS

There are no known restrictions implied by storage allocation.

7. TYPICAL RUNNING TIME

No study has been made to determine typical running time.

8. COMPUTER HARDWARE REQUIREMENTS

The code is operable on the IBM 360/75/91.

9. COMPUTER SOFTWARE REQUIREMENTS

The code will compile and operate in the IBM FORTRAN IV Monitor System. A special expanded I-O table and several routines from the Risley library have been packaged with the code.

10. REFERENCES

J. Butler, "The Status of Theoretical Methods for Reactor Shield Design," AEEW-R361 (March 1964).

A. F. Avery, J. Clarke, and Mrs. A. Hartley, "COMPRASH - (A Preliminary Users Guide Prepared for the ENEA Seminar-Workshop on Shielding Programmes Held at Ispra, April 1966)," AEEW-M 648 (March 1966).

11. CONTENTS OF CODE PACKAGE

Included are the referenced documents and one (1.2MB) DOS diskette which contains the source code, non-standard library routines, input and output for a sample problem and a library of cross sections.

12. DATE OF ABSTRACT

January 1968; updated July 1981.