**1. NAME AND TITLE**

RICANT: A Computer Code for 2-D Transport Calculations in x-y Geometry Using the Interface
Current Method.

**2. CONTRIBUTOR**

Indira Gandhi Center for Atomic Research, India, through the NEA Data Bank, France.

**3. CODING LANGUAGE AND COMPUTER**

Fortran IV; VAX 8810.

**4. NATURE OF PROBLEM SOLVED**

RICANT performs 2-dimensional neutron transport calculations in x-y geometry using the interface
current method. In the interface current method, the angular neutron currents crossing region surfaces
are expanded in terms of the Legendre polynomials in the two half-spaces made by the region surfaces.

**5. METHOD OF SOLUTION**

The integral form of the neutron transport equation is solved by the interface current method. The
region of interest is divided into small regions with constant material properties. The regions are
connected by neutron currents crossing the interfaces. The outgoing current in one region is the
incoming current in the adjacent region. The region sizes have to be very small so that spatial
dependence can be ignored. Associated Legendre polynomials are used to represent the angular
dependence of the fluxes. The weighted residual method is used to find the expansion coefficients of
the angular fluxes. Making use of the superposition principle of neutron currents, inner iterations are
performed over current components. Outer iterations are performed over groups.

**6. RESTRICTIONS OR LIMITATIONS**

The total number of angular flux expansion terms is limited to 10.

**7. TYPICAL RUNNING TIME**

The sample input was tested on the VAX 8810 at NEA Data Bank. It took 3 minutes of CPU time.

**8. COMPUTER HARDWARE REQUIREMENTS**

RICANT runs on the VAX 8810.

**9. COMPUTER SOFTWARE REQUIREMENTS**

The code was written in Fortran IV. On the VAX 8810, the compiler used was VAX Fortran
under the VMS version 5.1 operating system.

**10. REFERENCE**

**a. Included in the documentation:**

P. Mohanakrishnan, "A Guide to the Use of Computer Code -- RICANT," RG/RPD-311,
(December 1987).

**b. Background information:**

P. Mohanakrishnan, "Choice of Angular Current Approximations for Solving Neutron Transport
Problems in 2-D by Interface Current Approach," *Ann. Nucl. Energy*, Vol. 9, pp. 261-274, 1982,
Great Britain.

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced document and one DS/DD (360 K) 5.25-inch diskette.

**12. DATE OF ABSTRACT**

December 1990.

**KEYWORDS: ** NEUTRON; POLYNOMIAL APPROXIMATION; TWO DIMENSIONS