**
1. NAME AND TITLE**

BERMUDA: Discrete Ordinates Code System for Shielding Analysis for Use with Fusion and Fission Reactors.

**DATA LIBRARY**

BERMJ3: 125 Group Library for Use with Neutron Codes. (JAERI-Data/Code 95-006)

BERMJ3G: 41 Group Library for Use with Gamma-Ray Codes (JAERI-Data/CODE 96-021)

**2. CONTRIBUTORS**

Japan Atomic Energy Research Institute, Tokai-mura, Naka-gun, Japan.

Research Organization for Information Science & Technology, Tokai-mura, Naka-gun, Japan.

**3. CODING LANGUAGE AND COMPUTER**

Facom/VP2600; Fortran 77 (C00616/FV260/03).

**4. NATURE OF PROBLEM SOLVED**

Nine computer codes are included to solve the time-independent neutron and gamma-ray transport equation for a given fixed source in a variety of geometries. The neutron codes mentioned in Part I have been modified since the original RSIC release, and codes in Parts II and III were added in the January 1995 update. The neutron group constants library BERMJ3 is based on the Japanese Evaluated Nuclear Data Library version 3.2 (JENDL-3.2) the version 2 of JENDL-3. In January 1996 the BERMUDA-2DN, BERMUDA-2DN-S16, and BERMUDA-3DN codes were modified; and the BERMJ3 neutron data library replaced BERM125X. In November 1996 the BERM1DG, BERM2DG, and BM2DGS16 codes were modified; and the BERMJ3G data were added. BERMJ3G is a new gamma-ray group constants library of 30 nuclides based on JENDL-3.2 and DLC-136/PHOTX. These data are in a 41 energy-group structure (14 MeV ~ 10 keV).

Part I. Neutron transport codes

BERMUDA-1DN: One-dimensional sphere and infinite slab geometries.

BERMUDA-2DN and BERMUDA-2DN-S16: Two dimensional cylindrical geometry.

BERMUDA-3DN: Three-dimensional rectangular parallelpiped geometry.

Part II. Gamma-ray transport codes

BERMUDA-1DG: One-dimensional sphere and infinite slab geometries.

BERMUDA-2DG and BERMUDA-2DG-S16: Two dimensional cylindrical geometry.

BERMUDA-3DG: Three-dimensional rectangular parallelpiped geometry.

Part III. Adjoint neutron transport code

BERMUDA-1DNA: Adjoint neutron transport code for one-dimensional spherical geometry.

**
5. METHOD OF SOLUTION**

Neutron transport calculation architecture in the present code system has become a combination of the following models:

(a) Direct integration method for obtaining space-angle distribution of flux,

(b) Numerical integration of double-differential cross section of elastic and inelastic (discrete levels) scatterings for obtaining group-angle transfer matrices,

(c) Group dividing method into fine energy groups (grids) with a few iterations for each grid for the groups except thermal energy group (For the thermal group, the usual energy group model is adopted with iteration procedure for scattering source from the self group.),

(d) Neutron balance adjustment in each grid or group by renormalizing the obtained flux after space-angle calculation sweep in each spatial region called a coarse mesh,

(e) First collision source method in case of a point source, in which the flux is obtained as the sum of the solution and the uncollided flux and

(f) Scalar flux calculation after all angular fluxes are obtained by numerically integrating them over the angular space for each spatial mesh point and for each energy grid or group.

**
6. RESTRICTIONS OR LIMITATIONS**

Restrictions are noted on the individual code abstracts which are included in the RSICC documentation.

**7. TYPICAL RUNNING TIME**

See the individual code abstracts for execution times on the FACOM.

**8. COMPUTER HARDWARE REQUIREMENTS**

BERMUDA was developed on the FACOM VP2600 vector computer.

**9. COMPUTER SOFTWARE REQUIREMENTS**

BERMUDA was developed on the FACOM M780/20 OS-IV/F4 MSP operating system and uses the Fortran EXVP compiler.

**10. REFERENCES**

Code Abstracts by RIST (1994 and 1996).

T. Suzuki, A. Hasegawa, S. I. Tanaka and H. Nakashima, "Development of BERMUDA: A Radiation Transport Code System Part I. Neutron Transport Codes," JAERI 1327 (May 1992).

T. Suzuki, A. Hasegawa, S. I. Tanaka and H. Nakashima, "Development of BERMUDA: A Radiation Transport Code System Part II. Gamma Rays Transport Codes," JAERI-M 93-143 (July 1993).

T. Suzuki, A. Hasegawa, S. I. Tanaka and H. Nakashima, "Development of BERMUDA: A Radiation Transport Code System Part III. A One-Dimensional Adjoint Neutron Transport Code," JAERI-Data/Code 94-002 (July 1994).

H. Nakashima, A. Hasegawa, and T. Suzuki, "A New Library of Neutron Group Constants for BERMUDA Based on JENDL-3.2 Nuclear Data File," JAERI-Data/Code 95-006 (April 1995). (In Japanese).

H. Nakashima, A. Hasegawa, and T. Suzuki, "A New Library of Gamma Rays Group Constants for BERMUDA Based on JENDL-3.2 Nuclear Data File," JAERI-Data/Code 96-021 (1996) (In Japanese).

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced documents and one tape cartridge which contains the source codes, JCL, data library, and sample case input and output written in compressed mode for UNIX.

**12. DATE OF ABSTRACT**

April 1993, January 1995, February 1996, January 1997.

**KEYWORDS:** COMPLEX GEOMETRY; CTR; DISCRETE ORDINATES; NEUTRON; ONE-
DIMENSION; TWO-DIMENSIONS; GAMMA-RAY; CROSS SECTIONS