RSICC CODE PACKAGE CCC-691

1. NAME AND TITLE

SIMMER-II: Code System for Two Dimensional Sn-Neutronics and Fluid Dynamics.

2. CONTRIBUTOR

Los Alamos National Laboratory, Los Alamos, New Mexico, through the Energy, Science, and Technology Software Center, Oak Ridge, Tennessee.

3. CODING LANGUAGE AND COMPUTER

Fortran; Cray1; DEC Vax11/780 (C00691MFMWS00).

4. NATURE OF PROBLEM SOLVED

SIMMERII is designed to predict the neutronic and fluid-dynamic behavior of an LMFBR during a hypothetical core-disruptive accident. Cross sections depend on temperature and background cross sections. The structure, liquid, and vapor fields are modeled to predict the fluid-dynamic behavior of the reactor. Each field consists of density components to follow the material motion and energy components to predict the material temperatures. For typical accident calculations, the materials are fertile fuel, fissile fuel, stainless steel, sodium, control material, and fission gas. Heat, mass, and momentum transfer among the three fields and their components are calculated.

5. METHOD OF SOLUTION

Either the time-dependent multigroup neutron diffusion or neutron transport equation is solved by the quasistatic method to predict reactor neutronic behavior during the accident.

6. RESTRICTIONS OR LIMITATIONS

None to report.

7. TYPICAL RUNNING TIME

This is highly problem dependent, but a large CRBR calculation was completed in 1.7 seconds.

8. COMPUTER HARDWARE REQUIREMENTS

The Cray version of SIMMER2 required 65K (octal) words of SCM and 50-300K (octal) words of LCM. The DEC Vax required 65K (octal) words of SCM and 50-300K (octal) words of LCM.

9. COMPUTER SOFTWARE REQUIREMENTS

LTSS (CDC7600); CTSS (Cray1)

10. REFERENCES

a) Documentation on CD:

W. R. Bohl, L. B. Luck, "SIMMER-II: A Computer Program for LMFBR Disrupted Core Analysis," LA-11415-MS, UC-000 (June 1990).

L. L. Smith and N. N. Sheheen, "SIMMER-II: A Computer Program for LMFBR Disrupted Core Analysis," NUREG/CR-0453 (LA- 7515-M, Rev.) (June 1980).

F. R. Parker, "SIMMER Postprocessor Manual," NUREG/CR-4396 (LA-10549-M), with Errata (October 1985).

W. R. Bohl, "SIMMER-II Hydrodynamics Update Spring 1983," Los Alamos National Laboratory Memorandum, received July 5, 1983.

b) background reference:

L. B. Luck, "SIMMER-II Neutronics Update, Spring 1983," Los Alamos National Laboratory Memorandum, NESC received July 5, 1983.

J. F. Dearing, "SIMMER-II Analysis of Short-Risetime, Two-Component, Transient Boiled-Up Pool Simulation Tests," LA-9736-MS (May 1983).

G. P. DeVault, S"IMMER II Analysis of the CAMEL II C6 and C7 Experiments (Simulated Fuel Penetration into a Primary Control Assembly)," LA-10280-MS (February 1985).

11. CONTENTS OF CODE PACKAGE

Included are referenced documents in 10a. and software on one CD which contains source codes and test cases.

12. DATE OF ABSTRACT

July 2003.

This distribution was first released by NESC in April 1986. Notes indicate SIMMER II ran on Cray 1, DEC Vax and CDC. The package was not modified or tested when it was transferred to RSICC and released in July 2003. Source code, corrections, cross section data, and sample problems are included in this version. The first SIMMER-II release was packaged by NESC in July 1983.

KEYWORDS: LOCA; REACTOR PHYSICS; REACTOR SAFETY