RSICC CODE PACKAGE PSR-411

1. NAME AND TITLE

MORECA: Computer Code System for Simulating Modular High-Temperature Gas Cooled Reactor Core Heatup.

2. CONTRIBUTORS

Oak Ridge National Laboratory, Oak Ridge, Tennessee through the Energy Science and Technology Software Center, Oak Ridge, Tennessee.

3. CODING LANGUAGE AND COMPUTER

FORTRAN 77; IBM PC (P00411/PC386/00).

4. NATURE OF PROBLEM SOLVED

MORECA was developed for analyzing postulated long-term core heatup scenarios for which active cooling systems used to remove afterheat following the accidents can be assumed to be unavailable. Simulations of long-term loss-of-convection accidents, both with and without depressurization of the primary coolant, have shown that maximum core temperatures stay below the point at which any significant fuel failures and fission product releases are expected. Sensitivity studies also have been done to determine the effects of errors in the predictions due both to uncertainties in the modeling and to the assumptions about operational parameters. MORECA models the U.S. Department of Energy reference design of a standard modular high-temperature gas-cooled reactor (MHTGR). It is based on the ORNL ORECA code system.

5. METHOD OF SOLUTION

The method of solution used was Modified Euler.

6. RESTRICTIONS OR LIMITATIONS

None noted.

7. TYPICAL RUNNING TIME

The sample problem runs in less than 1 minute on a Pentium II 266 Mhz PC.

8. COMPUTER HARDWARE REQUIREMENTS

A 386 or better processor, with 3 MB or more free disk space.

9. COMPUTER SOFTWARE REQUIREMENTS

FORTRAN 77 compiler, MS DOS 6.0, WINDOWS 3.1 or higher versions. An executable created with the Digital Visual Fortran Vers. 5.0 compiler is included in the package.

10. REFERENCES

RSICC, "README.TXT" (May 14, 1999).

S.J. Ball, "MORECA: A Computer Code for Simulating Modular High-Temperature Gas-Cooled Reactor Core Heatup Accidents," NUREG/CR-5712, ORNL/TM-11823 (October 1991).

11. CONTENTS OF CODE PACKAGE

Included are the reference document and the software program source and executable with sample problem input and output on one 3.5" diskette in a self-extracting compressed DOS file.

12. DATE OF ABSTRACT

May 1999.

KEYWORDS: LOCA; REACTOR SAFETY