RSICC CODE PACKAGE PSR-519
1. NAME AND TITLE
ENTREE 1.4.0: BWR Core Simulation System for Space and Time Dependent Coupled Phenomena.
2. CONTRIBUTORS
TEPCO Systems Corporation, Shinbashi, Minato-ku, Japan, and Tokyo Institute of Technology, Tokyo, Japan.
3. CODING LANGUAGE AND COMPUTER
Fortran 77; Intel PC-Linux, Sun, and Compaq Alpha workstations (P00519MNYWS00).
4. NATURE OF THE PROBLEM SOLVED
ENTRÉE is a plant simulation code system that can be applicable to operational transients, coupled neturonic-thermal hydraulic instability and reactivity insertion accidents. The main objectives of ENTREE are development, verification and application of the three-dimensional plant simulation system TRAC/BF1-ENTRÉE-ACCORD-N for boiling water reactors (BWRs). The coupling phenomena considered in the BWR design field were reviewed in terms of their phenomenological natures. Basic specifications of existing three-dimensional plant simulation codes were compared with regard to modeling of neutron kinetic, two-phase flow dynamic and fuel heat conduction.
ENTRÉE is a three-dimensional neutron kinetic code based on the modern nodal methods. The assembly discontinuity factor (ADF) and the pin power reconstruction capabilities are also implemented for transient calculations, and they permit evaluation of detailed local pin power transition. The fully implicit scheme is implemented to deal with not only slow but also fast power transients based on the same formulations.
The modal analysis code ACCORD-N solves the two or three-dimensional higher neutron flux modes based on the two energy group diffusion equation. The higher neutron flux modes supply basic information for understanding space-dependent neutron kinetics. Specifically, they are fully utilized in regional instability evaluation as the shape function of external disturbance used for evaluating core stability. They are also useful in quantifying inter-modal interaction.
This ENTREE package includes the ENTRÉE and ACCORD-N codes; it does not include TRAC/BF1, which is proprietary. TRAC/BF1 is a state-of-the-art plant simulation code based on the two-fluid model. Non-equilibrium two-phase fluid dynamics permits one to analyze not only slow, moderate transients but also fast transients without switching the basic governing equations.
5. METHOD OF SOLUTION
The high-speed and accurate three-dimensional neutron kinetic code ENTRÉE was developed based on polynomial and semi-analytical nonlinear iterative methods (PNLM and SANLM) including the discontinuity factor. Several numerical techniques were introduced to enhance transient calculation efficiency.
The CCCMA (Correction Coupling Coefficient Modal Analysis) has been proposed to improve spatial resolution of neutron flux modal analysis. The improvement was achieved by including the NLM (Nonlinear Iterative Method)-correction coupling coefficient. The new complex code system, ENTRÉE-ACCORD-N was introduced based on this methodology.
Adequacy and performance of the coupling system TRAC/BF1-ENTRÉE was demonstrated based on the BWR cold water injection transient proposed by NEA/NSC, the Peach Bottom 2 turbine trip test and the BWR-5 one-pump trip test.
The applicability of TRAC/BF1-ENTRÉE-ACCORD-N to the regional instability was extensively discussed. Fundamental aspects of regional instability were studied first based on the extended frequency-domain model that is suitable for systematic parameter studies. Fidelity of TRAC/BF1 was studied next based on the FRIGG-4 loop test with regard to the thermal hydraulic mechanism (density-wave oscillation) underlying in the regional instability. Following this purely thermal hydraulic study, methodology of TRAC/BF1-ENTRÉE has been established for regional instability evaluation from the viewpoint of the reactivity feedback mechanism. Furthermore, core stability was estimated under the pseudo numerical noise that simulates the actual in-core random noise disturbance. This noise analysis technique gave realistic and reliable decay ratios.
6. RESTRICTIONS OR LIMITATIONS
ENTRÉE was designed to be coupled with TRAC/BF1, which is not included in this distribution. This coupling version of TRAC/BF1 was modified from the 1998 Users' Group Version. TEPSYS can supply some proprietary information and the modified TRAC/BF1 under some conditions. See section 2 of the Users Manual for details. The format of the multi-table binary cross sections is proprietary information of Studsvic of America. Proprietary information, and *.sum and *.xsec files are omitted from this package.
7. TYPICAL RUNNING TIME Running time is depended on the size of problem and operating system.
8. COMPUTER HARDWARE REQUIREMENTS
ENTREE runs on Intel PC under Linux and on Compaq Alpha and Sun workstations.
9. COMPUTER SOFTWARE REQUIREMENTS
These codes run under Linux on Intel personal computers, on Compaq Alpha-TRUE64 V4.0F UNIX workstations, and on Sun under Sun OS5.5.1. Fortran 77 and C compilers are required. The package contains post-processing codes for PC Windows environment. GNUPLOT 3.8 and PVM version 3.4 software is included.
10. REFERENCES
A. Hotta, "ENTREE User Manual," TEPCO Systems Corp., Tokyo Institute of Technology (May 2002).
A. Hotta, "Theory and Verification Manual - Development and Verification of a BWR Core Simulation System for Space and Time Dependent Coupled Phenomena," Thesis for Tokyo Institute of Technology (March 2001).
11. CONTENTS OF CODE PACKAGE
Included are the referenced documents and a CD which contains source code, installation files, test cases, and documentation.
12. DATE OF ABSTRACT
November 2002.
KEYWORDS: BWR; THERMAL HYDRAULICS; REACTOR SAFETY