UCBTH 08 - 003 Risk - informed Design

.......................................................................................................................................... 2 1 Introduction ............................................................................................................................. 5 1.1 History of Domestic Commercial Reactor Development and Licensing ......................... 5 1.1.1 Governing Code of Federal Regulations ................................................................... 6 1.2 Transition to Licensing Generation IV Reactors .............................................................. 7 1.2.1 Licensing of the PBMR ............................................................................................ 8 2 Case Study: Modular PB-AHTR Reactivity Control ............................................................ 18 2.1 PB-AHTR Overview ...................................................................................................... 18 2.1.1 Key Safety Features ................................................................................................ 20 2.1.2 State of Technology ................................................................................................ 21 2.3 Description of PB-AHTR Reactivity Control System (RCS) ........................................ 22 2.3.1 Reactivity Control and Protection System Functionality and Modes of Operation 24 2.3.1 Buoyant Shutdown Rod Concept ............................................................................ 26 3 Phenomena Identification and Ranking ................................................................................. 31 3.1 PIRT Generation Procedure ........................................................................................... 31 3.1.1 Application of PIRT to Shutdown Rod System Response ..................................... 32 3.1.2 Selection of Nucleus Set of Event and Primary Safety Criteria ............................. 33 3.1.3 Identification of Associated Components ............................................................... 34 3.1.4 Identification of Major Processes and Phenomena ................................................. 36 3.1.5 Ranking by PIRT Panel ........................................... Error! Bookmark not defined. 3.1.6 Evaluation of Knowledge Level Ranks .................................................................. 42 4 Passive Rod Insertion Shutdown Model (PRISM) Experiment ............................................ 43 4.1 Sizing of the PRISM Experiment ................................................................................... 43 4.1.1 Geometric similarity ............................................................................................... 43 4.1.2 Kinematic similarity ................................................................................................ 44 4.1.3 Dynamic similarity .................................................................................................. 44 4.2 PRISM Description ........................................................................................................ 45 4.3 Experimental Results ...................................................................................................... 50