SAS4A/SASSYS‑1

SAS4A/SASSYS‑1 is a software simulation tool used to perform deterministic analysis of anticipated events as well as design basis and beyond design basis accidents for advanced nuclear reactors.

Detailed, mechanistic models of steady-state and transient thermal, hydraulic, kinetic, and mechanical phenomena are employed to describe the response of the reactor core, the reactor primary and secondary coolant loops, the reactor control and protection systems, and the balance-of-plant to accidents caused by changes in coolant flow, loss of heat rejection, or reactivity insertion. The consequences of single and double-fault accidents can be modeled, including fuel and coolant heating, fuel and cladding mechanical behavior, core reactivity feedbacks, coolant loop performance including natural circulation, and decay heat removal. Analyses are typically terminated upon demonstration of reactor and plant shutdown to permanently coolable conditions, or upon violation of design basis margins. The objective of the analysis is to quantify accident consequences as measured by the transient behavior of system performance parameters, such as fuel and cladding temperatures, reactivity, and cladding strain. Originally developed for analysis of sodium cooled reactors with oxide fuel clad by stainless steel, the models in SAS4A/SASSYS‑1 were subsequently extended and specialized to metallic fuel clad with advanced alloys and to several other coolant options, including lead, LBE, and water.

For information on the most recent version of SAS4A/SASSYS-1, please contact sas@anl.gov.

Contents

• Part I: Using SAS4A/SASSYS‑1
  • 1. Introduction
  • 2. SAS4A/SASSYS‑1 User’s Guide
• Part II: Whole-Plant Analysis
  • 3. Core Thermal-Hydraulics
  • 4. Reactor Point Kinetics, Decay Heat, and Reactivity Feedback
  • 5. Primary and Intermediate Loop Thermal Hydraulics Module
  • 6. Control System
  • 7. Balance of Plant
• Part III: Fuel Performance
  • 8. DEFORM-4: Steady-State and Transient Pre-Failure Pin Behavior
  • 9. MFUEL: Metallic Fuel Performance Model
  • 10. SSCOMP: Pre-Transient Characterization of Metallic Fuel Pins
  • 11. FPIN2: Pre-Failure Metal Fuel Pin Behavior Model
• Part IV: Failure Modeling
  • 12. Coolant Voiding
  • 13. CLAP: Cladding Motion Model
  • 14. PLUTO2: Non-Voided Channel Fuel Motion Analysis
  • 15. PINACLE: In-Pin Pre-Failure Molten Fuel Relocation Module
  • 16. LEVITATE: Voided Fuel Motion