Research and Development with Regard to Severe Accidents in Pressurised Water Reactors: Summary and Outlook
Total Page:16
File Type:pdf, Size:1020Kb
Research and development with regard to severe accidents in pressurised water reactors: Summary and outlook Rapport IRSN-2007/83 Rapport CEA-2007/351 FOREWORD This report was produced conjointly by the French Institute for Radiological Protection and Nuclear Safety (IRSN) and the French Atomic Energy Commission (CEA). The French electric utility EDF also contributed to Section 8.2. The following individuals participated in writing or editing all or part of the report: For the IRSN: Ahmed Bentaïb, Hervé Bonneville, Cataldo Caroli, Bernard Chaumont, Bernard Clément, Michel Cranga, Florian Fichot, Joëlle Fleurot, Richard Gonzalez, Vincent Koundy, Bruno Laurent, Jean-Claude Micaelli, Renaud Meignen, Frédérique Pichereau, Delphine Plassart, Emmanuel Raimond, Anne Tenaud and Jean- Pierre Van-Dorsselaere. For the CEA: Gérard Ducros, Michel Durin, Christophe Journeau, Daniel Magallon, Jean-marie Seiler, Etienne Studer and Bruno Tourniaire. For EDF: William Ranval and EDF's Severe Accident Teams. CONTENTS CHAPTER 1 : INTRODUCTION .................................................................... 6 1.1 SEVERE ACCIDENTS — DEFINITION AND RESEARCH OBJECTIVES ...................................................... 6 1.2 RESEACH FRAMEWORK ................................................................................................ 7 1.3 REPORT OBJECTIVES .................................................................................................. 8 CHAPTER 2 : SCENARIOS .......................................................................10 2.1 ACCIDENT TYPES POTENTIALLY LEADING TO CORE MELTDOWN ......................................................10 2.1.1 LEVEL 1 PSA ACCIDENT CLASSES ................................................................................... 10 2.1.2 MELTDOWN FREQUENCY BY CLASS IN EDF’ S 900-MW E LEVEL 1 PSA .............................................. 16 2.1.3 ACCIDENT PROGRESSION ............................................................................................ 17 2.2 GENERAL PROGRESSION OF SEVERE ACCIDENTS .....................................................................19 2.2.1 PHYSICAL PHENOMENA POSTULATED FOR PWR S .................................................................... 19 2.2.2 DIFFERENCES BETWEEN 900-MW E AND 1300-MW E PWR S WITH REGARD TO SEVERE ACCIDENTS .................. 21 2.2.3 EPR SPECIFICITIES ................................................................................................. 21 2.2.4 SEVERE ACCIDENT MANAGEMENT .................................................................................... 22 CHAPTER 3 : IN-VESSEL ACCIDENT PROGRESSION ...............................................26 3.1 IN-VESSEL CORE DEGRADATION ......................................................................................26 3.1.1 DEFINITION , OVERALL PHENOMENOLOGY ........................................................................... 26 3.1.2 PHYSICAL PHENOMENA ............................................................................................. 26 3.1.3 EXPERIMENTAL PROGRAMMES , MODELLING AND COMPUTER CODES .................................................. 29 3.1.4 SUMMARY AND OUTLOOK ........................................................................................... 32 3.2 CORIUM BEHAVIOUR IN THE LOWER HEAD ...........................................................................33 3.2.1 DEFINITION , OVERALL PHENOMENOLOGY ........................................................................... 33 3.2.2 PHYSICAL PHENOMENA ............................................................................................. 33 3.2.3 EXPERIMENTAL PROGRAMMES , MODELLING AND COMPUTER CODES .................................................. 37 3.2.4 SUMMARY AND OUTLOOK ........................................................................................... 40 3.3 VESSEL RUPTURE ....................................................................................................41 3.3.1 DEFINITION , OVERALL PHENOMENOLOGY ........................................................................... 41 3.3.2 PHYSICAL PHENOMENA ............................................................................................. 41 3.3.3 EXPERIMENTAL PROGRAMMES , MODELLING AND COMPUTER CODES .................................................. 42 3.3.4 SUMMARY AND OUTLOOK ........................................................................................... 46 3.4 HIGH -PRESSURE CORE MELTDOWN ...................................................................................47 3.4.1 DEFINITION , OVERALL PHENOMENOLOGY ........................................................................... 47 3.4.2 PHYSICAL PHENOMENA ............................................................................................. 48 - 2 - 3.4.3 EXPERIMENTAL PROGRAMMES , MODELLING AND COMPUTER CODES .................................................. 48 3.4.4 SUMMARY AND OUTLOOK ........................................................................................... 54 CHAPTER 4 : PHENOMENALIABLE TO INDUCE EARLY CONTAINMENT FAILURE ...................63 4.1 DIRECT CONTAINMENT HEATING .....................................................................................63 4.1.1 DEFINITION , OVERALL PHENOMENOLOGY ........................................................................... 63 4.1.2 PHYSICAL PHENOMENA ............................................................................................. 63 4.1.3 EXPERIMENTAL PROGRAMMES , MODELLING AND COMPUTER CODES .................................................. 65 4.1.4 SUMMARY AND OUTLOOK ........................................................................................... 70 4.2 HYDROGEN RISK AND MITIGATION STRATEGIES ......................................................................72 4.2.1 HYDROGEN RISK — BACKGROUND ................................................................................... 72 4.2.2 OVERALL PHENOMENOLOGY AND PROBLEM AREAS ................................................................... 72 4.2.3 EXPERIMENTAL PROGRAMMES ....................................................................................... 74 4.2.4 MODELLING AND SIMULATION CODES ................................................................................ 79 4.2.5 SUMMARY AND OUTLOOK ........................................................................................... 80 4.3 STEAM EXPLOSIONS ..................................................................................................82 4.3.1 DEFINITION , OVERALL PHENOMENOLOGY ........................................................................... 82 4.3.2 PHYSICAL PHENOMENA ............................................................................................. 83 4.3.3 EXPERIMENTAL PROGRAMMES , MODELLING AND COMPUTER CODES .................................................. 87 4.3.4 SUMMARY AND OUTLOOK ........................................................................................... 91 CHAPTER 5 : PHENOMENATHAT COULD LEAD TO ALATE CONTAINMENT FAILURE ...............98 5.1 MOLTEN CORIUM -CONCRETE INTERACTION (MCCI) .................................................................98 5.1.1 BACKGROUND TO MCCI AND THE OBJECTIVES OF THE R&D PROGRAMME ........................................... 98 5.1.2 PHENOMENOLOGY OF MCCI AND THE RESULTING PROBLEMS ........................................................ 98 5.1.3 EXPERIMENTAL PROGRAMMES , MODELLING AND COMPUTER CODES .................................................100 5.1.4 SUMMURY AND OUTLOOK ..........................................................................................106 CHAPTER 6 : IN-VESSEL AND EX -VESSEL RETENTION AND COOLING OF CORIUM ................ 111 6.1 IN-VESSEL RETENTION ............................................................................................. 111 6.1.1 DEFINITION , PHENOMENOLOGY AND SAFETY CHALLENGES ..........................................................111 6.1.2 IN-VESSEL RETENTION BY FLODING THE PRIMARY CIRCUIT ..........................................................112 6.1.3 IN-VESSEL RETENTION BY FLOODING THE RACTOR PIT ..............................................................115 6.2 COOLING OF THE CORIUM UNDER WATER DURING THE MOLTEN CORIUM -CONCRETE INTERACTION ................ 124 6.2.1 DEFINITION AND OVERALL PHENOMENOLOGY .......................................................................124 6.2.2 EXPERIMENTAL PROGRAMMES , MODELLING AND COMPUTER CODE S .................................................124 6.2.3 SUMMARY AND OUTLOOK ..........................................................................................128 6.3 CORIUM SPREADING (EPR) ........................................................................................ 129 - 3 - 6.3.1 DEFINITION AND OVERALL PHENOMENOLOGY .......................................................................129 6.3.2 PHYSICAL PHENOMENA INVOLVED ..................................................................................129 6.3.3 EXPERIMENTAL PROGRAMMES , MODELLING AND COMPUTER CODE S .................................................130 6.3.4 SUMMARY AND OUTLOOK ..........................................................................................134 6.4 EX-VESSEL CORE CATCHER ........................................................................................ 135 6.4.1 TYPES OF EX -VESSEL CORE CATCHER ..............................................................................135