1. NAME AND TITLE

SCRELA: Code System for LOCA Analysis of Supercritical Light Water Reactors.

2. CONTRIBUTORS

Nuclear Engineering Research Laboratory, University of Tokyo, Tokyo, JAPAN

OECD, Nuclear Energy Agency Data Bank, Issy-les-Moulineaux, France.

3. CODING LANGUAGE AND COMPUTER

Fortran 77; Sun (P00408/SUN05/00).

4. NATURE OF PROBLEM SOLVED

The new SCRELA code was developed to analyze the LOCA of the supercritical water cooled reactor. Since the currently available LWR codes for LOCA analysis could not analyze the significant differences in reactor characteristics between the supercritical-water cooled reactor and the current LWR, the first objective of this code development was to analyze the uniqueness of this reactor. The behavior of the supercritical water in the blowdown phase and the reflood phase is modeled.

5. METHOD OF SOLUTION

A simple thermal-hydraulic model was adopted to analyze the blowdown phase. The high flowrate and high pressure conditions of the blowdown use a homogenous equilibrium model. The mass flowrates between the system nodes are calculated from the coolant expansions due to evaporation and depressurization during blowdown. The system pressure at certain time steps is determined to satisfy the flow-balance between nodes.

The reflood phase models the cold-leg break LOCA since it has the most severe results. The overall calculational model for the system thermo-hydraulics is based on the model for a system momentum calculation and the model for a core mass-energy calculation.

6. RESTRICTIONS OR LIMITATIONS

None noted.

7. TYPICAL RUNNING TIME

SUN ULTRASPARC 60: Blowdown module: 10 minutes; Reflood module: 5 hrs.

8. COMPUTER HARDWARE REQUIREMENTS

SCRELA was written for workstations and tested on a SUN ULTRASPARC 60 with 128 MB RAM and at least 20 MB free hard disk space.

9. COMPUTER SOFTWARE REQUIREMENTS

A FORTRAN compiler is required. The f77 version 4.2 FORTRAN compiler was used on the test computer running SUN OS 5.6.

10. REFERENCE

J. H. Lee, S. Koshizuka, and Y. Oka "Manual of SCRELA (Supercritical-Water Cooled Reactor LOCA Analysis Code)," Nuclear Engineering Research Laboratory, University of Tokyo, Japan (September 1996).

11. CONTENTS OF CODE PACKAGE

Included are the referenced document and the SCRELA source code with sample problem input and output. The package is transmitted on one 3.5" DOS diskette as a UNIX tar file.

12. DATE OF ABSTRACT

October 1999.

KEYWORDS: HEAT TRANSFER; LOCA; LWR; WORKSTATION