The RELAP/SCDAPSIM code, designed to predict the behavior of reactor systems during normal and accident conditions. Code is being developed as part of the international SCDAP Development and Training Program (SDTP). RELAP/SCDAPSIM uses the publicly available SCDAP/RELAP5 models developed by the US Nuclear Regulatory Commission in combination with proprietary advanced programming and numerical methods, user options, and models developed by ISS and other members of the SDTP. The RELAP5 models calculate the overall RCS thermal hydraulic response, control system behavior, reactor kinetics, and the behavior of special reactor system components such as valves and pumps. The SCDAP models calculate the behavior of the core and vessel structures under normal and accident conditions. RELAP/SCDAPSIM is being used for a variety of applications. The code is used for the analysis of research reactors and nuclear power plants.

Primary differences between RELAP/SCDAPSIM and RELAP5

•  RELAP5/SCDAPSIM has detailed core component models for typical LWR/HWR designs
  •  LWR fuel rods
  • Control rods (made by Ag-In-Cd/B₄C)
  • BWR control blade model
  • Electrically-heated furl rod simulator
• RELAP5/SCDAPSIM has upper and lower plenum models for typical LWR designs (detailed 2D finite element model for lower head instead 1D heat structure model to describe all structures including core and vessel in RELAP5)
• RELAP5 limited to transients that will not result in core damage
  •  Peak fuel cladding temperatures <1500K
  • Limited cladding oxidation
•  RELAP5 radiation exchange heat transfer model neglects absorption by fluid.

User: Maciej Skrzypek