This course is designed to familiarize plant operation personnel and staff members with severe accident phenomena and accident scenarios highlighting the recovery and mitigation actions to prevent and limit core damage, maintain containment integrity and minimize the fission product releases. The Severe Accident Management Guidelines (SAMGs), developed by the Westinghouse Owners Group, are presented and their link with the Emergency Operating Procedures and the Site Emergency Plan is explained.

Introduction

  • Definition of a severe accident 
  • Description of Chernobyl, Three Mile Island, and Fukushima Accidents 
  • Tools for the Study of the Severe Accidents 
    • PSA Terminology and Scope 
    • PSA Example Results 
    • PSA Uses 
    • PSA Decision Making Criteria 
    • Severe Accident Simulation Models 
  • Example Severe Accident Sequence 
  • Introduction to Severe Accident Management 


Plant Behavior prior to Core Damage: Initiating Events, Emergency Operating Procedures (EOPs)

  • Anticipated Transient Without Scram (ATWS) 
  • Loss of Coolant Accidents / Inadequate Core Cooling (ICC) 
  • Loss of Feedwater / Loss of Heat Sink (LOHS) 
  • Loss of AC Power 
  • Severe Overcooling / Pressurized Thermal Shock (PTS) 
  • Response of Instrumentation to Core Uncovery 


Plant Behavior during and after Core Damage: In Vessel Phase

  • Behavior up to Core Uncovery
  • Core Melt Progression 
  • Hydrogen Generation 
  • Natural Circulation and Creep Failure Phenomena 
  • Reactor Vessel Failure 
  • Importance of EOPs and Operator Actions 


Plant Behavior during and after Core Damage: Ex-Vessel Phase

  • Containment Design 
  • Debris Dispersal 
  • Direct Containment Heating 
  • Vessel Thrust 
  • Steam Explosions 
  • Debris Coolability 
  • Core Concrete Attack 
  • Hydrogen Behavior in Containment 
  • Containment Fragility and Failure Modes 


Radiological Aspects

  • Fission Product Inventory
  • Fission Product Release from Fuel 
  • Fission Product Transport 
  • Source Terms 


Severe Accident Mitigation Hardware

  • Filtered Containment Venting 
  • Emergency Containment Spray System 
  • Hydrogen Control Systems 


Severe Accident Management Guidance - WOG SAMG Overview

  • Background 
  • Scope and Philosophy 
  • Technical Basis 
  • Goals 
  • Structure of SAMG 
  • Interface with EOPs ad E-plan 
  • Control Room SAMG 
  • TSC SAMG 
  • Instrumentation 
  • Phenomenology 
  • Computational Aids 
  • Design Variations 
  • Summary

USEFUL LINKS