Applying RISMC Methods, Tools, and Data to Enhance Safety and Economics through Industry Application Demonstrations

Transcription

1 Session 2-2: Economics of Plant Life Management Paper # IAEA-CN Applying RISMC Methods, Tools, and Data to Enhance Safety and Economics through Industry Application Demonstrations Ronaldo Szilard, Ph.D. Light Water Reactor Sustainability (LWRS) Risk-Informed Safety Margin Characterization (RISMC) Idaho National Laboratory Fourth International Conference of Nuclear Power Plant Life Management Lyon, France October 2017

2 RISMC Industry Applications Topics for Discussion Background Economics RISMC Industry Applications Overview LB-LOCA Demonstration Analysis LOTUS Integrated Evaluation Model Approach Plant Demonstration 4 Loop PWR Fuels Performance under LOCA Future Work: Accident Tolerant Fuel & Plant Systems 2

3 Background Economics The existing NPP fleet is facing economic challenges due to: Low natural gas price Rapid deployment of renewable energy sources Additionally, the existing NPP fleet is facing regulatory challenges, e.g. 10 CFR 50.46c 10 CFR Reducing fuel cost is one area that contributes to the improved economic viability and enhanced safety of the existing fleet Higher burnup of the fuel Optimized fuel and loading pattern design Accident tolerant fuel Load following and flexible operating strategies Multi-physics, multi-scale analysis of core/fuel/systems is desired 3

4 RISMC Industry Applications Assisting Margin Management & Sustainability through Realistic Demonstrations RISMC Risk-Informed Safety Margin Characterization Methods Tools Data Industry Applications Nuclear Industry Stakeholders 3-Step Demonstrations: Risk Reliability Multi-physics Multi-scale Nuclear Analysis Dynamic / Combined Analysis Grizzly Materials, Aging RAVEN Advanced Risk Assessment RELAP-7 Next Generation Systems Code External Hazards Seismic, Flood, Wind Assessment, Verification & Validation Experiments Uncertainty Quantification 1. ECCS/LOCA (50.46c) Core and Fuel Multi-physics Systems Demo Problem Definition Preliminary Demo Full Analysis Demo 2. External Hazards Combined Events Demo Seismic & Flooding Helping Demonstrate Game Changers in Delivering the Nuclear Promise Risk- Informed Thinking Accident Tolerant Fuel 4

5 RISMC Industry Applications Purpose: Risk-Informed analysis of realistic, relevant industry problems, with accurate representation of margins for the long term benefit of nuclear assets. Strategy: Develop industry application demonstrations in collaboration with the nuclear industry; Align demonstrations with RISMC methods and tools capabilities; Follow existing industry application structure, starting with existing (legacy codes) which will be replaced with advanced tools as they become available. A Demonstration of Decision Making Tools and Methods 5

6 RISMC Margin Quantification and Risk Assessment Paradigm Risk Simulation Scenario Generator Scenarios Physics Simulation (full physics coupling) Core Design Automation Failure Modes Operational Rules Parameters Fuel/Clad Performance System Analysis Core Design Optimization PCT ECR CWO Margin and Uncertainty Quantification Decision Making 6

7 Industry Application LOCA Integrated Cladding/ECCS Performance Motivation Based upon recent experiments, NRC proposed new regulations (10 CFR 50.46c) Peak-clad temp. and embrittlement oxidation more restrictive than current limits LWRS program will help industry by using RISMC to demonstrate safety margins for loss-of-coolant-accident (LOCA) analysis including emergency core cooling system (ECCS) performance under realistic plant conditions Coupled analysis has core physics, cladding behavior, thermal-hydraulics, and scenario-based risk analysis in order to quantify safety margin Potential Impact: Cost of re-analysis ~65 License Amendment Requests, > $100M (U.S. plants) 7-year implementation plan Loss of margin Increased fuel costs Operation flexibility impact Increased complexity 7

8 Integrated Cladding/ECCS Performance LB LOCA Analysis Demonstration Proposition: Re-analysis can be used to better understand/manage margins Efficient assessment of margins (through advanced methods/tools) Opportunity for reload design and operations processes improvements Proposed 50.46c Limits Assessment Optimization A targeted value proposition for vendor and/or owner-operator stakeholders Goal: Industry adoption via pilot/demos/tools 8

9 RISMC Application for LOCA Analysis LOTUS (LOCA Toolkit U.S.) 5. Core Design Optimization (CD-O) Optimized Fuel/Core Design Probabilistic PCT/ECR margins, Data analysis 4. Risk Assessment (RA) Methods BEPU, Reduced Order Models, Surrogate Models, Limit Surfaces, etc. Fuel/Core Design Assembly/pin power, exposure, etc. Industry Application Demonstration (LOTUS) RELAP Output Pin power, Fuels performance data, safety limits 3. Systems Analysis (SA) 1. Core Design Automation (CD-A) Fuel/Core Design Assembly/pin power, exposure, etc. 2. Fuels/Clad Performance (FP) Stored energy, Rod internal pressure, Clad oxidation and perforation, etc. 9

10 PWR Core Design Generic Design Based on STP Coupled RELAP5/PHISICS 1 T/H channel per assembly Developed PWR core similar to STP core 3.8 GWth 14 feet Westinghouse core Design Criteria 18 month cycle High energy/low leakage design Equilibrium assumed after 8 cycles Enrichment 4.2%-4.6 % IFBA distribution obtained by optimization process 10

11 Fuel and Assembly Design 17 x 17 pins 25 GT positions Top and bottom blanket (assumed low enriched) Top of active fuel 7 top blanket 2.6% enriched 4.2%/4.6% enriched fuel 7 bottom blanket 2.6% enriched Assembly example with 128 IFBA Bottom of active fuel 11

12 Fuels/Clad Performance (Baseline) Fuel mechanics RELAP5-3D includes rupture model and ballooning model But we need detailed analysis of fuel rods behaviors such as the fission gas released, rod internal pressure, and fuel-cladding mechanical interaction, cladding H content etc., FRAPCON The power history data is automatically retrieved by LOTUS from the core design results going into a FRAPCON input Power history for the hot rod (one assembly) Cladding hydrogen content vs. rod average burn-up (all assemblies) fresh 1-burned 2-burned 12

13 Safety Analysis Core Hydraulic Homogenization and Heat Structures An existing RELAP5 PWR model is modified to analyze typical fourloop PWR cores: A core hydraulic homogenization is performed Heat structures for the hot assembly in each group are connected to the hot channel in that group (2 sets of heat structures for each assembly) 13

14 RELAP5 nodalisation for a typical four-loop PWR An existing RELAP5 PWR model is modified to analyze the typical fourloop PWR cores: Reactor Vessel Downcomer Bypass Lower/Upper plena Core Upper head Reactor coolant system 4 primary loops Secondary side up to turbine governor valves ECCS Low pressure injection (LPI) High pressure injection (HPI) 14

15 PCT & ECR Results by Fuel Type (Burnup) for a HE-LL Core Reload and Design Strategy Equivalent Cladding Reacted (ECR) Peak Clad Temperature (PCT) 15

16 An Advanced Toolkit to Inform Design and Operations Understand Simulation Envelope Optimization Better Economics / Operational Flexibility Similar concept can be used for other safety/operational limits to support ATF and BU extension 16

17 Evaluating Potential Cost Benefits Associated with Accident Tolerant Fuel and Plant Enhancements Analyze the problem from a plant/systems level Core Fuels Risk-Informed Engineering Leverage RISMC methods and tools + 10CFR to provide flexibility to reduce cost and improve plant operations & safety margins Evaluation of ATF benefits in terms of changes in success criteria of systems, structures, and components (SSCs) Look at fixed coping time to determine RISC 1 RISC 2 Safety Related Non Safety Related Positive component & system changes at fixed coping times Sequence-level information & associated risk analysis insights High Safety Significance Safety Related Low Safety Significance High Safety Significance Non Safety Related Low Safety Significance Positive implications for components under 10CFR RISC 3 RISC 4 RISC = Risk Informed Safety Class Investigate design elements (fuel, core, clad, plant SSCs) 17

18 Summary RISMC Industry Application Demonstrations The LOTUS framework is being developed to provide a multi-physics simulation capability to better quantify safety margins. The LOTUS capability has been demonstrated by integrating baseline tools in reactor physics, fuels performance, thermal-hydraulis, and safety analysis Future work will continue on coupled systems/fuels performance simulations under steady state and transient conditions by incorporating modern simulation tools developed by DOE R&D Programs Future applications include simulation based plant performance analysis of accident tolerant fuel concepts 18

19 Helping to Sustain National Assets 19