**1. NAME AND TITLE**

SHREDI: Multigroup Two-Dimensional (x-y, r-o geometry) Neutron Removal-Diffusion
(Spinney Method) Shielding Code System.

**2. CONTRIBUTOR**

Comitato Nazionale Energia Nucleare, Bologna, Italy, through the OECD NEA Data Bank,
Gif-sur-Yvette, France.

**3. CODING LANGUAGE AND COMPUTER**

FORTRAN IV; IBM 360/370.

**4. NATURE OF PROBLEM SOLVED**

SHREDI is a shielding code system which executes removal-diffusion computations for bi-dimensional shields in r-z or x-y geometries. It may also deal with monodimensional problems
(infinitely high cylinders or slabs).

**5. METHOD OF SOLUTION**

Given the spatial fission density distribution in the core of a reactor, the geometry, the compositions and the macroscopic removal cross sections, SHREDI computes removal fluxes in some points of the reactor shield for each removal energy group.

The removal fluxes are utilized to calculate the removal sources for diffusion energy groups. These sources are obtained in all the diffusion mesh points by interpolation. SHREDI may also compute diffusion fluxes or adjoint diffusion fluxes. The former are used for calculating the total neutron fluxes and activations; the latter can be utilized by Monte Carlo codes as a guess for the importance function.

The anisotropic diffusion approximation (1) is adopted in diffusion flux computation. The anisotropic diffusion coefficients must be supplied as input. These coefficients can be computed by means of the TRUD code (2) in the case of x-y geometries. For these geometries it is also possible to take into account rectangular cavities since TRUD calculates diffusion coefficients in these regions.

SHREDI is organized so as to executeseparatelyremoval, diffusion, and activation computations, memorizing the partial results on peripheral units.

**6. RESTRICTIONS OR LIMITATIONS**

None noted.

**7. TYPICAL RUNNING TIME**

No study of typical running time has been made by RSIC.

**8. COMPUTER HARDWARE REQUIREMENTS**

The code system is operable on the IBM 360/370 computer.

**9. COMPUTER SOFTWARE REQUIREMENTS**

An IBM FORTRAN IV compiler is utilized.

**10. REFERENCES**

**a. Included in the documentation:**

A. Daneri, L. Martelli, G. Toselli, "SHREDI: A Removal-Diffusion Shielding Code for X-Y
and R-Z Geometries."

**b. Background information:**

(1) M. Michelini, *Nucl. Sci. Eng.* 47 No. 1 (1972).

(2) A. Daneri, M. Michelini, C. Toselli, "TRUD: An Anisotropic Diffusion Code for XY Geometry," RT/FI(72)1 - CNEN - Roma.

(3) R. G. Jaeger, et al. (eds.), "Engineering Compendium on Radiation Shielding," V1.2. Berlin: Springer-Verlag (1968).

(4) A. Daneri, L Martelli, G. Toselli, "ATTOW-B: A New Version of Removal Diffusion Shielding Code ATTOW," RT/FIMA - CNEN, Roma (to be published).

(5) C. Ponti, H. Preusch, H. Schubart, "SABINE: A One-Dimensional Bulk Shielding
Program," EUR 3636e (1967).

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced document (10.a) and one (1.2MB) DOS diskette which contains the
source code and sample problem input and output.

**12. DATE OF ABSTRACT**

December 1981.

**KEYWORDS: ** MULTIGROUP; TWO-DIMENSIONS; SPINNEY METHOD; NEUTRON;
REMOVAL-DIFFUSION