ABSTRACl The SCDAP/REtAPS code has been developed for best-estimate transient simulation of light water reactor coolant systems during a severe accident. The code models the coupled behavior of the reactor coolant system, the core, and the fission products and aerosols In the system during a severe accident transient as well as large and small break loss-of-coolant accidents, operational transients such as anticipated transient without SCRAM, loss of offslte power, loss of feedwater, and loss of flow. A generic modeling approach Is used that permits as much of a particular system to be modeled as necessary. Control system and secondary system components are Included to permit modeling of plant controls, turbines, condensers, and secondary feedwater conditioning systems. The modeling theory and associated numerical schemes are documented In Volumes I and II to acquaint the user with the modeling base and thus aid In effective use of the code. Volume III contains detailed instructions for code application and Input data preparation. In addition. Volume III contains user guidelines that have evolved over the past several years from application of the REtAP5 and SCDAP codes at the Idaho National Engineering taboratory, at other national laboratories, and by users throughout the world. The light water reactor (LWR) severe accident transient analysis code, SC0AP/RELAP5, has been developed at the Idaho National Engineering Laboratory (INEL) for the U. S. Nuclear Regulatory Commission (NRC) to provide an advanced best-estimate predictive capability for use In severe accident applications In support of the regulatory process. Code uses Include analysis required to support rulemaking, licensing audit calculations, evaluation of accident mitigation strategies, and experiment planning and analysis. Specific applications of this capability have Included analytical support for the loss-of-fluld test (LOFT), Power Burst Facility (PBF), ACRR, MISl, ROSA IV, and NRU experimental programs, as well as simulations of transients that lead to severe accidents, such as loss of coolant, anticipated transients without scram (ATWS), and operational transients In LWR systems. SCDAP/RELAP5 Is a highly generic code that. In addition to calculating the behavior of a reactor coolant system (RCS) during a severe accident transient, can be used for simulation of a wide variety of hydraulic and thermal transients In both nuclear and nonnuclear systems Involving steam-water noncondenslble solute fluid mixtures. SC0AP/RELAP5 was developed by Integrating three separate codes, RELAP5/M0D2, SCDAP, and TRAP-MELT. These codes were combined to model the coupled Interactions that occur between the core, the RCS, and the fission products during a severe accident. For example, blockage In the core, caused by fuel rod ballooning and meltdown, can have a significant effect on RCS flows. Fission products released from the core can have a significant effect on the RCS because of the heat produced during decay. These and many other coupled effects can have a sig...

This report documents ten developmentalassessmentproblems which were " used to test the multidimensionalcomponent in RELAP5/MOD2.5,Version 3w. The problems chosen were a rigid body rotation problem, a pure radial symmetric flow problem, an r-0 symmetric flow problem, a fall problem, a rest problem, a basic one-dimensionalflow test problem, a gravity wave problem, a tank draining problem, a flow through the center problem, and coverage analysis using PIXIE. The multidimensionalcode calculationsare compared to analytical solutions and one-dimensionalcode calculations. The discussion section of each problem contains informationrelative to the code's ability to simulate these problems. iii Idaho, Inc., managers during the development and assessment of this capabilitywho provided coordination,direction,and resources.

process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to an)' specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

No abstract