**1. NAME AND TITLE**

PALLAS-2DCY-FX: Multigroup Neutron/Gamma-Ray Direct Integration Transport Code System for Two-Dimensional Cylindrical Geometry.

**2. CONTRIBUTOR**

Japan Atomic Energy Research Institute, Tokyo, Japan.

**3. CODING LANGUAGE AND COMPUTER**

Fortran IV; FACOM M380. (C00391FM38000)

**4. NATURE OF PROBLEM SOLVED**

PALLAS-2DCY-FX is a code for direct integration of the transport equation in two-dimensional (r,z) geometry. It solves the energy and angular-dependent Boltzmann transport equation with general anisotropic scattering in cylindrical geometry. Its principal applications are to neutron or gamma-ray transport problems in the forward mode. The code is particularly designed for and suited to the solution of deep penetration radiation transport problems with an external (fixed) source.

**5. METHOD OF SOLUTION**

PALLAS-2DCY-FX is based on a method of direct integration of the transport equation in which the equation is solved by integrating along a flight path of radiation in the direction of motion at each discrete ordinate direction. The scattering calculations are made directly using the differential scattering cross-section for neutrons and the Klein-Nishina formula for gamma-rays. No iteration and convergence techniques are used for the determination of the flux. To improve the accuracy of duct and void streaming calculations a special option has been added whereby the uncollided angular flux from a point source or any cylindrical surface sources is calculated analytically based on point kernel integration.

**6. RESTRICTIONS OR LIMITATIONS**

The code was written using fixed dimensioning which restricts the number of energy meshes (100), material regions (10 10), nuclides (25), angular meshes (28), and spatial meshes (75 75) which can be used as input.

**7. TYPICAL RUNNING TIME**

Approximately 0.0030 second/spatial mesh/group is required as CPU time on the FACOM M380.

**8. COMPUTER HARDWARE REQUIREMENTS**

The code is operable on the FACOM M380 computer. Approximately 3350 Kb of core storage are required for (75 75) spatial and 28 fixed directional meshes. Disks and/or tapes are needed for auxiliary storage.

**9. COMPUTER SOFTWARE REQUIREMENTS**

A Fortran IV compiler is required.

**10. REFERENCE**

K. Takeuchi, N. Sasamoto, and Y. Kanai, "PALLAS-2DCY-FX: A Code for Direct Integration of Transport Equation in Two-Dimensional (R,Z) Geometry," JAERI-M 84-244 (February 1985).

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced document and one DS/HD 3.5-in. (1.44 MB) diskette in self-extracting compressed DOS files which contains the source codes, data libraries, and sample problem input and output.

**12. DATE OF ABSTRACT**

February 1982; revised April 1987.

**KEYWORDS:** TWO-DIMENSIONS; CYLINDRICAL GEOMETRY;
MULTIGROUP; NEUTRON; GAMMA-RAY; INTEGRAL
BOLTZMANN EQUATION