Severe Accident Modeling and 3D Graphic Visualization Authors: Dr. Vladimir Nosatov, WSC Dr. Wei Huiming, CNPSC

Contents Company Brief Introduction Severe accidents’ (SA) phenomena Integral Codes available for SA simulation Using MELCOR-2.1 models for SA Real-Time simulation on BARAKAH FSS Examples of SA model using in FSS 2D and 3D Graphical Visualization of SA results

WSC Company Overview Technology Driven Company Research Oriented – over 20% of gross profit goes into R&D Employees: ≈ 85; Multidisciplinary team of nuclear, mechanical, electrical, chemical engineers, physicists and computer scientists, 30% with advances degrees. Headquarters in Frederick, Maryland, USA Main Business - Power Plant Simulation Nuclear Power Plant Simulators 40% Conventional Power Plant Simulators 30% Simulation Assisted Engineering 20% Navy and Marine Simulation 5% Process and Pipelines 5% ISO 9001:2015 Certified

WSC HQ Location

WSC Simulation Technology High Fidelity Simulation for use in: Development of Replica Training Simulators Nuclear, Coal, Combined Cycle & Gas Plants, Solar, Process, Pipeline… Part-Task and Full-Scope Simulators Classroom Simulators Web based simulators Simulation Assisted Engineering (SAE) System Analysis and Design Human Factors Engineering Logic and Control Testing, V&V Plant Optimization Plant Test and Operating procedures – e.g. commissioning procedures

WSC Simulator Installations 6

Our Customers

Nuclear Full Scope Replica Simulators China, CNPSC Ningde Korea and UAE KHNP Shin Kori and Barakah APR1400 Taiwan, TPC Lungmen Northrop Grumman Ship Building Bettis / Knolls Atomic Power Laboratory General Dynamics Electric Boat USA, APS Palo Verde 8

Barakah Three (3) MCR Full Scope Simulators

WSC Training and Engineering Simulators 3KEYSOFTWARE

Simulation Technology Overview Software Products Suite for Comprehensive Plant Coverage 3KEYMASTER™ Simulation Platform and Modeling Tools - Flagship for this Suite Graphical Engineering Station for Simulation Development and Control / Instructor Station 2-Phase Flow network Tool Electrical Network Tool Logic & Control and Relay Tools Component Tool and Library 3KEYRELAP5-RT™ – Adaptation of INEEL’s RELAP-3D©, including NESTLE, to run in real-time with visualization, provides best-estimate engineering grade modeling for Thermal-hydraulics and Neutron Kinetics 3KEYSAA™ – Severe Accident Analysis Models MELCOR / MAAP 3KEYDCS™ – is our solution for Distributed Control Systems that provides accurate emulation for Control and Logic, Man-Machine Interfaces, including trend and alarm displays 3KEYSAFE™/3KEYCATALOG ™ – Configuration Management Solution for managing the simulator configuration to the reference plant design through various stages of plant design evolution 3KEYTOUCH™ – Alternative Training Delivery Platform 3KEYITS/3KEYSTUDENT™ – Web and Classroom based Simulator Lesson delivery

MELCOR Tutorial Schematic of Test Problem

Physical Phenomena Inherent in Severe Accidents Thermal-hydraulic response of the primary, secondary and containment; Thermo-mechanical and chemical processes in the Core: fuel heat-up, cladding oxidation, fuel degradation, and core material melting and relocation; Heat-up of reactor bottom head, mechanical loading and failure, and transfer of core materials to the reactor cavity; Core-concrete attack in reactor cavity and ensuing gases and aerosols generation; In-vessel and ex-vessel hydrogen production, transport, and combustion; Fission product release (aerosol and vapor), transport, and deposition, including scrubbing in water pools, particle agglomeration and gravitational settling; Impact of engineered safety features on thermal-hydraulic and radionuclide behavior.

Integrated codes available for Severe Accident simulation MELCOR MAAP SCDAP/RELAP5 MELCOR-2.1 code was chosen base on 3 main criteria: Possibility to get license; Code ability to simulate severe accidents in real-time; Code ability to simulate all main phenomena during severe accident.

Visualization of Core Components (PWR) in MELCOR Code Control Rods (NS) Fuel Assemblies (FU + CL) Core Baffle or Shroud (SH) Core Formers (FM) Core Support Barrel (HS) Vessel Cylinder (HS) Particulate in Channel (PD) Particulate in Bypass (PB)

Switching Real-Time Simulation between RELAP and MELCOR Using MELCOR-2.1 models for SA simulation on BARAKAH FSS Switching Real-Time Simulation between RELAP and MELCOR Logical event causing automatic switch to the severe accident model Transferring data from TH (RELAP) model to SA (MELCOR) model Switching signals and indications to the SA model

RELAP and MELCOR Nodalization of BARAKAH RCS

FB and MELCOR Nodalization of BARAKAH Containment

BARAKAH Core region nodalization in Relap

Transferring data between RELAP and MELCOR

Scheme of data Conversion from RELAP to MELCOR Data base MELCOR Data base

RELAP - MELCOR Transition Functionality Seamless transition between RELAP and MELCOR severe accident model is performed “on the fly”. At that point in time the following has to be done: The physical parameters specific to the current simulation state (such as fuel temperatures, moderator densities etc.) have to be communicated to MELCOR model. This has to be done in such a way that the MELCOR model will start the computation using the actual physical parameters. The other modeling tool (RELAP) has to stop its modeling because both perform modeling of the same parts of the nuclear power plant. MELCOR has to start the computation using the physical parameters specific to the current simulation state that have been transferred to the MELCOR model. RELAP application is halted

3KEYMASTER Settings before and after switchover

Examples of SA model using in FSS MCR personal, Technical Support Engineers, Emergency response Team training for response in conditions of core severe damage; Drills for Emergency response Team and Accident management participating in severe accident mitigation; Verification of Emergency Operation Procedure and Severe Accident Management Guidelines

Scenarios for SA model verification on BARAKAH FSS SA initiated by SBO event; SA initiated by LB LOCA; SA initiated by SB LOCA; SA initiated by TLOFW; SA initiated by TLOCCW

Pressure in Secondary Side

Pressure in Pressurizer

Cladding temperature in Core

Hydrogen concentration in Containment

2D Graphical Visualization of SA results

2D Graphical Visualization of SA results

2D Graphical Visualization of SA results

3D Graphical Visualization of SA results

Questions

WSC invites YOU

WSC Contact Information Thank You! Dr. Vladimir Nosatov WSC, Inc. 7196 Crestwood Blvd, Suite 300 Frederick, MD 21703 www.ws-corp.com