**1. NAME AND TITLE**

PIGG: A Multigroup One-Dimensional P-1 Radiation Transport Code System.

**AUXILIARY ROUTINE**

BIGLIB: Cross Section Handling Code.

**DATA LIBRARY**

BIGLIB Data: Cross Sections.

**2. CONTRIBUTORS**

Institut for Atomenergi, Kjeller Research Establishment, Kjeller, Norway via the OECD Nuclear Energy Agency Data Bank, Gif-sur-Yvette, France.

**3. CODING LANGUAGE AND COMPUTER**

FORTRAN 63; CDC 3600.

**4. NATURE OF PROBLEM SOLVED**

PIGG solves the P1 equations in a Greuling-Goertzel approximation for the spatially dependent multigroup neutron flux in both slab and cylindrical geometry. The resonance absorption and fission are calculated using single-pin resonance and fission integrals, Dancoff factors, and resonance-distribution functions. The thermal region can be treated either as one group or as few groups to which diffusion equations are applied. Logarithmic boundary conditions are applied at the external boundaries. The output is very extensive and includes the criticality factor, point-wise group spectra and macrogroup constants, region-averaged macrogroup constants, and epithermal reaction rates for selected isotopes in different mesh points and macrogroups. Interesting applications include calculation of space-dependent epithermal spectra in BWR-fuel elements, spectrum transients near core-reflector interfaces, and effective macrogroup boundary conditions on control absorbers.

**5. METHOD OF SOLUTION**

Three point difference equations for the group flux are obtained using box integration. The equations are solved using power iteration accelerated by Chebyshev extrapolation of the normalized source. Matrix factorization technique is used for solving the inhomogeneous equations.

BIGLIB is a data library containing macrogroup lethargy structure and Watt's normalized fission spectrum, resonance integral distribution functions and cross sections for 28 materials and a program to update the library tape.

** 6. RESTRICTIONS OR LIMITATIONS**

The following limitations apply: epithermal and 6 thermal groups; 100 mesh points in 20 regions, and 10 homogeneous compositions; 28 different materials may be used for calculation of macroscopic cross sections in 6 macrogroups. For special calculations of reaction rates, 10 selected nuclides in 6 selected mesh points may be used.

**7. TYPICAL RUNNING TIME**

Required to compute each iteration on the CDC 3600: 10 to 20 seconds.

**8. COMPUTER HARDWARE REQUIREMENTS**

The code was designed for a 32K CDC 3600 computer with standard input-output devices, 4 scratch units on drums and up to 3 tape units.

**9. COMPUTER SOFTWARE REQUIREMENTS**

The packaged version was compiled and executed on the CDC 3600 FORTRAN 63 Monitor System DRUM SCOPE V2.0.

**10. REFERENCE**

J. O. Berg, G. E. Fladmark, T. Kulikowska, and O. P. Tverbakk, "PIGG, A Multigroup One-Dimensional P-1 Code," KR-129 (May 1968).

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced document and one (1.2MB) DOS diskette which contains the source codes, data library, and input for two sample problems.

**12. DATE OF ABSTRACT**

August 1971; revised July 1982.

**KEYWORDS:** ONE-DIMENSION; SPHERICAL HARMONICS; NEUTRON; GAMMA-RAY;
MULTIGROUP