DoE BES Advisory Committee July 9 th 2009 N. Bethesda Md.

1. “Materials’ Issues and Research Needs for Electricity Generating Light Water Reactor Sustainability : An Industrial Perspective”Mike Burke Manager Materials Center of ExcellenceWestinghouse Electric Company DoE BES Advisory Committee July 9th 2009 N. Bethesda Md.

2. Growth of Nuclear Power Generating Capacity LWR Sustainability and New Plant Installations How will we keep the older reactors operating ? What technologies are needed now to support the planned new builds ? What technologies should be put in place to provide for next generation plants ?

3. Materials Implications of the Upcoming Demand for Nuclear Power

4. Issues for Materials Usage in Operating and New Plants • Plants are designed for long lives • No material is “Impervium” • Degradation mechanisms are generally known • Materials response must be predictable • Quantitative precise prediction of materials’ response to service is needed  linear models • Discrimination between material variants is needed  need to quantitatively understand the effects of the major variables • Technologies for inspection, monitoring and repair will always be required

5. Materials Technology Support for Power Generating Reactor Fleet Sustainability Current Issues No integrated models for long time behaviors Limited range of accuracy Limited range of extrapolation – late blooming phases ? Processing and chemistry variable behavior should be understood Excessive conservativism in some cases ? Conservativism, inability to differentiate between material Limited acceptance of alternative technologies, need to undergo stringent validation before implementation is allowed Limited acceptance of new technologies, significant validation and qualification efforts needed for new technologies Industrial Solution Application specific empirical models (PWR, BWR Fast Reactor) Specific alloy performance data Bounding data for material classes Sparse database Materials repair and mitigation processes (Proof of performance data) In place NDE methods and performance monitoring Recognize that nuclear industry is safety driven, changes and data must be validated – and it’s difficult to do !

6. Materials Technology Enhancement Opportunities to Support for Power Generating Reactor Fleet Sustainability Technology Enhancement Improve model accuracy in real (linear) time and extended service prediction capability Discriminate heat to heat and process dependent property variability Improve confidence in predictions Ready to implement effective repair and mitigation technologies More effective plan operations and maintenance Industrial Solution Application specific empirical models (PWR, BWR Fast Reactor) Specific alloy performance data Bounding data for material classes Sparse database Materials repair and mitigation processes (Proof of performance data) In place NDE methods and performance monitoring

7. Basic Science Opportunities to Support for Power Generating Reactor Fleet Sustainability Technology Enhancement Improve model accuracy in real (linear) time and extended service prediction capability Discriminate heat to heat and process dependent property variability Improve confidence in predictions Ready to implement effective repair and mitigation technologies More effective plan operations and maintenance Industrial Solution Application specific empirical models (PWR, BWR Fast Reactor) Specific alloy performance data Bounding data for material classes Sparse database Materials repair and mitigation processes (Proof of performance data) In place NDE methods and performance monitoring Basic Science Support Integrated quantitative models of materials behavior and degradation Understanding of metallurgical effects in alloy behavior (Chemistry, microstructure effects) Property variation with respect to material variants Extension of materials property database New materials repair, coating and surfacing methodologies Advanced sensing and monitoring technologies – application to “materials condition”

8. Ground Rules for Materials’ Selections for Operating and Planned Nuclear Power Plants • Industry has addressed issues with today’s aging plants • NRC GALL (Generic Aging lessons Learned) Report • NEI Materials Initiative 03-08 – “Guideline for the Management of Materials Issues” • Near Term Commercial Plants will be built to already established design practices • Materials selection often based on experience • System design calls for code verified data (materials properties) • Long term and irradiated materials’ properties are only available for established materials • Next Generation plants must be built to the same safety concerns • Assurance of material properties ? • Aging response ? • More potential for (need for ?) new materials Consider materials technology needs for these 3 sets of plants

9. Reactor Materials for Existing and Near Term Plants Assembly by Pinning, Welding and Bolting

10. Key Driver for Existing Plant Technology Needs = Plant Relicensing Process • Plants are Licensed to Operate by the NRC • Licenses are held on a 20 year basis • 2009-2013 Upcoming License Renewals Period for many US PWR Reactors • Relicensing Application Must be Supported by Technical Data Demonstrating Safe Operating Capability • Key Element of Relicensing plan is the Proposed Plant Specific, Inspection and Evaluation Program • Quantitative data are required to properly disposition inspection findings • Accurate data are needed to avoid excessively conservative reaction

11. Materials Issues For Existing Plants • The Nuclear Power Generation Industry Currently Manages All of These Issues to Keep Plants Operating at 90% of Capacity Factor • Technology Developments Must Be Able to Discriminate Between Materials Variants at These Levels for Long Time Behaviors

12. Materials Issues For Existing Plants • Key issue for structural materials is to validate materials survivability to long life (>60 years) • Key issue for fuel related materials is to withstand higher burnup • “improved materials/confidence in materials” will be acceptable for 2-3x lifetime increase - compare to data scatter on log-log plot ! • Consider examples of current technology • Current solution – Enhancement Gap - Basic Science Opportunity • Identify basic science opportunities that may improve materials performance and/or confidence in materials performance • Pressure Vessel Materials, Internals Materials, Ni alloys (piping, tubing), Zr alloys (core structures, cladding)

13. Materials Issues for Existing Plants – Evaluation of Pressure Vessel Materials • Ferritic steels become embrittled in neutron and thermal environments • These changes are manifested in : • Reduction in the toughness during ductile fracture • Tendency to brittle fracture at onsets at increasing temperatures • Plant operations monitor vessel materials for embrittlement and feedback properties into analyses to support operations • Surveillance capsule programs for vessels • License requirement - Pressurized Thermal Shock (PTS) • Operational Limitations – heat up/cool down “curves” Acceleration Factor of Capsule Samples Leads Real Life Material

14. Reactor Containment Vessel MonitoringAgainst “Pressure Vessel Embrittlement” Key Region for Surveillance Programs so called “Beltline”

15. Typical Surveillance Capsule Locations Usually 8 capsules per vessel Capsules are locate in the highest intensity region, attached to the backside of the core barrel

16. Fracture Behavior of Pressure Vessel SteelsContinuing Issues and Research Needs • The industry has a large inventory of tested materials – re-irradiations can be readily performed • Extrapolation of embrittlement curves to higher dpa for >60 year life is a current issue • Resolution of fast reactor data and extrapolation of surveillance capsule data to highest fluences • Complete understanding of chemical effects and cross-interactions • Full utilization of fracture toughness methodologies (c.f. Impact data) • Projections to new steels etc.

17. Technology Enhancement and Basic Science Opportunities for Pressure Vessel Materials Technology Enhancement Improve model accuracy in real (linear) time and extended service prediction capability Discriminate heat to heat and process dependent property variability Improve confidence in predictions More effective plan operations and maintenance Industrial Solution Embrittlement trends available for industry wide database Extensive chemistry information available – data for wrought alloys and weld Conflict between thermal and fast reactor data –flux effects ? Extrapolation to long times  effects of late blooming phases In place surveillance capsule program Basic Science Support Quantitative (Linear) mechanistic based models Understanding of metallurgical effects in alloy behavior (Chemistry, microstructure effects) Property variation with respect to material variants – and processing induced variations Mechanistic aspects of degradation : microstructure  properties Resolve late blooming phases – “optimally conservative” predictions to longer lives Consider other sensing technologies for pressure vessels

18. Materials Issues for Existing Plants – Evaluation of Vessel Internals Materials • Recognize degradation has occurred and effects of degradation are generically known • Plant specific materials extraction and sampling is not feasible • Some opportunities to assess materials from plants do occur • Testing programs are in place e.g. Halden • Testing programs are sparse and expensive to perform • In-core testing • Hot Cell testing of pre-irradiated materials (in environment) • Accelerated irradiation exposures and evaluation/characterizations • Data on exposed materials has been built into advanced modeling systems • Generic Materials Degradation Rules • Systematic Analyses • Key Materials Properties • Allows identification of key issues/areas • Support to I&E Guidelines and relicense applications

19. Materials Degradation Modeling for Reactor Internals Applications Apply modern simulation capabilities to a systematic analysis of all components in plant internals) • Consider failure under 8 Mechanism Thermal Embrittlement IASCC Wear Void Swelling Irradiation Embrittlement SCC Fatigue Irradiation Creep/Relaxation • Calculate materials degradation and continuing response with respect to time, fluence temperature etc. • Model can currently provide self consistent, semiquantitative assessments of failures • Allows identification of Classify Component/Mechanism Pairs and Determine Quantitative Rankings for Each Mechanism… • … Use such rankings as ordered priority to develop inspect and evaluate of components strategy (“Waterfall Charts”)

20. Materials’ Constitutive Modeling for Quantitative Assessment of Reactor Internals Degradation Loads, Temperatures, Environments, Neutron Flux Aged Materials Condition Microstructure Defect Content, Segregation Time step Local Stresses and Strains Initial Materials Condition Microstructure Defect Content, Segregation New Material Response “Modified Compliance matrices” Redefine Local Stresses and Strains FEA Modeling allows iterative reassessments of local conditions – Can model materials degradation and assess potential for failure under local conditions of materials degradation New/Modified Failure Criteria

21. Materials Degradation Modeling for Reactor Internals Applications – Materials Availability • Materials should reflect behavior in LWR situation – effects of accelerated aging ? • Materials available after high dose - from decommisioned plants (or replaced internals ?) • Sufficient fluence and local heating to predict behavior to long plant life ? • Properties : • Stress/Strain Behavior • Fracture Toughness • Stress Corrosion Cracking • Test Environment (with or without neutrons) • Hot Cell Testing • Test Reactor Testing Schematic Extraction Locations for RVI Test Material

22. Materials Degradation Modeling for Reactor Internals Applications Reactor Structural Internals are made from Stainless Steels • Effects of Irradiation on Stainless Steels • Hardening & Loss of Ductility • Stress Corrosion Cracking • Irradiation Induced Creep Both Compliance and Failure Data Must be Developed to Support these Analyses

23. An example of Automated Constitutive Modeling IASCC Susceptibility of Reactor Internals (Bolted Baffle Plates) • IASCC Susceptibility • Blue : No Concern • Yellow : Minimal Concern • Red > Increase Concern Constitutive Modeling of Materials Degradation Provides Rapid Screening of Large Systems and Precise Analysis of Highly Localized Systems but… Provides direct comparison of locations and components Identifies the most likely locations for failure… …Primary locations for inspections

24. Application of Results of Materials Modeling -Waterfall Approach to Inspection Prioritization Goal IASCC Baffle –Former Bolts Aging management strategy based on a prioritized grouping of the expected degradation mechanisms by manifestation. Baffle Plates Baffle –Edge Bolts Relative Ranking From Modeling Former Plates Barrel –Former Bolts Core Barrel – Lower, Upper Task Group components in a manner that will facilitate a common AMS for all items in group. Lower Support Column Bolts Thermal Shield Other Components – AMS Unnecessary for IASCC Waterfall A stream of actions that will provide an appropriate aging management strategy for multiple degradation mechanisms.

25. Materials Degradation Modeling for Reactor Internals Applications – Data Availability Test Data Available for CASS used in Reactor Internals Sparse database prevents full utilization of modeling

26. Technology Enhancement and Basic Science Opportunities for Reactor Internals Materials Technology Enhancement Improve model accuracy in real (linear) time and extended service prediction capability Discriminate heat to heat and process dependent property variability Improve confidence in predictions Ready to implement effective repair and mitigation technologies More effective plan operations and maintenance Industrial Solution Data for 316SS, 304SS and 316SS at 050dpa Tensile and hardness data available Fracture Toughness and SCC (particularly IASCC) are still to be developed Existing data are for old vintage plants (old vintage materials) Knowledge gaps with respect to very high fluence behavior (but data shows plateaus ?) Good service at already high dpa Bolting replacement Existing visual and ultrasonic inspection capabilities for in-situ inspection of components Basic Science Support More extensive property database – compliance and failure criteria vs dpa Understanding of aged (and corroded surface) materials response to continuing long time exposure More precise quantitative data – understanding of scatter Understanding of metallurgical effects in alloy behavior (chemistry, microstructure effects) Property variation with respect to material and processing variants High dose behavior – reality of swelling effects Welding technology for repair of irradiated materials Coating and (re) surfacing technologies ? Advanced sensing and monitoring technologies – application to “materials condition

27. LWR Materials Applications & Degradation Mechanism Issues

28. Technology Enhancement and Basic Science Opportunities for Corrosion Resistant Materials Technology Enhancement Improve model accuracy in real (linear) time and extended service prediction capability Discriminate heat to heat and process dependent property variability Improve confidence in predictions Ready to implement effective repair and mitigation technologies More effective plan operations and maintenance Industrial Solution Stainless steels, (alloy 600) Alloy 690 used for primary and secondary side corrosion resistance Long term data and plant experience based on vintage materials Crack initiation and crack propagation data being developed for some alloys Materials repair and mitigation processes based on welding are available Weld alloys based on wrought alloy effectiveness Visual and ultrasonic NDE available Basic Science Support Quantification of corrosion and SCC data Understanding of metallurgical effects on corrosion and SCC properties (Chemistry, homogeneity microstructure effects) Property variation with respect to material variants and new/replacement parts’ materials More effective materials repair, coating and surfacing techniques Quantitatively understand weld alloy microstructure effects on SCC properties Advanced sensing and monitoring technologies – application to “materials condition”

29. Technology Enhancement and Basic Science Opportunities for Zr Alloys (Fuel Clad, Structures) Technology Enhancement Improve model accuracy in real (linear) time and extended service prediction capability Discriminate heat to heat and process dependent property variability Improve confidence in predictions Ready to implement effective repair and mitigation technologies More effective plan operations and maintenance Industrial Solution Established corrosion database Specific alloy performance data vs burnup proprietary IP for proprietary alloys Post irradiation analysis is difficult to perform (High irradiation doses) Correlations of environmental exposure and reduction in mechanical performance (LOCA ductility criteria) NDE methods for tubing quality inspection and for inplant leakage Basic Science Support Mechanisms of corrosion film growth – alloy effects, retardation Understanding of alloying effects (solute vs 2nd phase) on corrosion film formation Quantitative understanding of corrosion rate vs hydrogen pickup vs mechanical performance (ductility) Quantitative correlations of corrosion vs mechanical properties (effect of hydriding) Advanced sensing and monitoring technologies for Zr components

30. “New Build” Plant Technology – Gen III+ • These plants are already designed ! • Constrained to Fuel/LWR systems • Will be built to already established materials and design practices • Use of ASME code materials and materials proven by existing plant experience • Similar modes of construction welding, bolting etc • Replacement materials justified by plant experience e.g. Alloy 690 for Alloy 600 • Materials will be new vintage materials produced by modern (e.g. steelmaking) methods These plants represent at least those that will come on line up to 2035

31. Reactor Materials Options in New Plants Building on Experience with Existing Plants … The New Plant Designs Use Validated Materials Performance Currently Applied in Existing Plants to Continue to Meet Better than 90% Capacity Factor Operations

32. New Plant Materials Technology Issues • Manufacturing Issues • Product Validation • Degradation Mechanism Understanding • Operational Assessment Capability • Mitigation Approaches • Inspection & Evaluation Needs • Repair / Replacement Options • Regulatory Issues

33. Concern for New Plants :Component Supply Reactor Pressure VesselCore Region Shell • Dimension: (mm) 7,478od X 7,122id X 3,962H • Weight: 127ton. Reactor Pressure VesselBottom Petal • Dimension:(mm) 7,636od X 5,290id X 1,631H • Weight: 80ton Reactor Pressure VesselIntegrated Type Closure Head • Dimension: (mm)4,015od 1,705H • Weight: 38ton • Requirements • Manufacturing Infrastructure • Testing and Validation • Timely Supply

34. Concern for New Plants :Validation of New Component Supply • High Performance Pressure Boundary Components Require : • Uniform Chemistry and Structure • Validated Mechanical Properties – Strength and Toughness • Properties must be Exhibited in All Sections Supplier as well as component development Integrally Forged Piping Segments During Processing High Performance Production Parts Require : Materials Qualification Tests to Support Piece Acceptance

35. Concern for New Plants :Component Fabrication Capability • Large welded Structure need processes to minimize residual stresses etc.

36. Materials Technology and Basic Science Needs for New build Plants Basic science drivers will be similar to those for existing plants – but the lifing technology may need to take us out to service beyond 2100

37. Materials for Next Generation Plants • New systems based on high temperature gas and other coolant media (See Gen IV systems) • Opens up the potential for new materials • Structural • Fuel • Fuel cladding • System design confidence for new installations must compete with existing LWR concepts • Established database • Operating history • Materials capabilities will determine design options and operational capabilities – but this is not the aeroengine industry ! • Materials development for Next Generation plants must provide completely verified design database  competition with existing materials and concepts. • Development of new materials is unlikely to be commercially driven

38. Materials Options for Next Generation Plants Ceramics • Enabler for higher efficiency systems ? • Graphite issues • Graphite as structural material • Aging of graphite • CMC composites will be proven for heat engines • Stability and assurance of new ceramics for radiation applications • Processing effects on CMC performance • Stability of proposed higher temperature materials • Long term compatibility with coolant media High Temperature Metallics • Enabler for higher efficiency systems • GT materials have temperature capability but very low life • Low temperature materials not validated to high temps • Stability of proposed higher temperature materials Fuel Systems • Relax restriction to UO2 • Relax enrichment restrictions ? • New fuel systems to be proven (e.g. TRISO) • Manufacturability • Performance/Durability • Physical properties/design database to be established

39. Materials Technology Needs for Nuclear Power Generation Applications