vhtr saclay 5 28 03
TRANSCRIPT
Materials forVery-High-Temperature Reactor
Bill Corwin, DirectorBill Corwin, DirectorNational Gen IV Materials Technology ProgramNational Gen IV Materials Technology Program
Oak Ridge National LaboratoryOak Ridge National Laboratory
Presented atPresented atCEA, CEA, SaclaySaclay
SaclaySaclay, France, FranceMay 28, 2003May 28, 2003
Advanced Materials Development andQualification Essential for All Gen IV Reactors
• Process-Heat Use for Large-ScaleHydrogen Generation Will Also RequireMaterials Compatibility with Heat-Transfer Media and Reactants
• Research Will Build upon ExtensivePrevious Materials Development forOther Reactor Systems
• Materials Will Be Exposed to HighTemperatures, Neutron Exposures, andCorrosive Environments
• 60-Year Operating Lives for Gen IVReactors Will Require Very Long-TermMaterials Stability
Preliminary Survey of Materials Needsfor VHTR Demonstration Plant Performed
Assumed Characteristics•He coolant•1000°C outlettemperature
•600 Mth
•Prismatic graphite blockcore based
•SiC-coated TRISO fuel•Direct cycle electricalproduction
•Process heat forhydrogen generation
Similar survey plannedfor pebble bed version
•Boundary Conditions•Deploy VHTR in 2015 - 2018•Very quick survey schedulerequired expert opinion
•Materials for hydrogengeneration plant notincluded
PreliminaryMaterials Survey
Used GT-MHRas Baseline
Cutaway DrawingShowing ReactorVessel and Power
ConversionArrangement
Reactor Pressure Vessel System CanLikely Use Code-Approved Material
• 9Cr-1Mo steel most likely near-term candidate material
• Extensive industrial fabricationand high-temperature serviceexperience
• Requires additional very long-term creep and creep-rupturedata
• High-temperature designmethodology needs updatingfor nuclear service
PCV
Crossvessel
RPV
Very Large Vessel Sizes Will RequireScale-up of Fabrication Methods
PWR ABWR GT-MHRPCV & RPV
• Nuclear service will also require:– Irradiation effects testing
– Emissivity verification
– Very high-temperature
fatigue and crack-growth
testing in helium
• Forging and joining of very large rings
• Transportation
• On-site welding, PWHT, and NDE
Previous Nuclear-GradeGraphites Are Unavailable
• Extensive properties and modelsdeveloped for H-451 for FSV, butprecursors no longer exist
• Data needs to be updated formodern, available grades
• Molded and extruded fine-grained, isotropic graphitesavailable for core and supportapplications
– Used in Japanese HTTR,Chinese HTR-10, and SouthAfrican PBMR
– Samples currently beingirradiated could acceleratequalification
Graphite FuelElement Blocks
Irradiation Data Needed to Validateand Benchmark Existing Behavior
• Graphite data needs include:– Physical, mechanical, and oxidation properties– Variability within and among billets– 200°C higher temperatures
• Qualification will build upon very large bases of data andexperience
• Possible to incrementally adjust existing design models• Must complete and approve ASME Sec III, Div 2,
Subsection CE, Design Requirements for Core andSupport Structures, issued for comment in 1990
Internal Reactor Metallic Components Will Be Significantly Challenged in VHTRs• Alloy 800H sufficient for most
GT-MHR needs, highertemperatures for VHTR willrequire higher temp matls
– Advanced metallic alloys• Hastalloy X or Alloy 617
– Carbon-Carbon Composites
• High-temperature metallicshave extensive design databases but cannot handle off-normal conditions, up to1200°C
• C-C composites maturetechnology but needarchitectures tailored to eachcomponent
ReserveShutdown
System
Core Barrel
Lower Core Supports
Control Rod Drive Guides
Hot Duct
C-C Composites Needed for HigherTemperature Internals in VHTRS
• Control rods, upper corerestraints, interior insulationcovers and supports
• Radiation effects data anddesign models must bedeveloped for C-Ccomposites
– VHTR will need to extend to200°C higher than current data
C-C compositemicrostructure
Fiber bundles
Very High-Temperature InsulationWill Be Required for Pressure
Boundaries and Turbomachinary• Fibrous Mats Supported by
Cover Structures
• In contact with hottest gas inreactor system
• Kaowool with Alloy 800Hcontainers adequate for lowertemperature GCRs
• VHTRs will need new coverstructure materials andcharacterization of ceramicinsulation
– Physical, mechanical,corrosion, and irradiationproperties
ContainerCover
Joint
Ceramic FiberInsulation
InsulatedStructure
Gap
1000°C Input Temperatures in VHTRsWill Strongly Challenge IHX Materials
• Varied materials compatibilityneeds (e.g. He, N2, molten salt, etc.)
• Containment within pressurevessel may minimize stress levels
– Secondary gas circuit for PCU
– Molten salts for gas generationmay operate at much lowerpressure
• Very high-temperature alloysrequired
– Hastelloy X or Alloy 617– Mechanical and corrosion
properties needed– Fabrication and joining
technology critical
Pump
Blower
IHX
REACTOR
H2
GEN
or
PCU
Heatric® Microchannel Printed-Circuit-TypeTechnology One Possible Approach for IHX
• Very compact and efficientindustrial design with currentASME Section VIII approval
• Already demonstrated– to 900°C– large units– > 1000 psi
• Fabrication technology for veryhigh-temperature alloys must bedemonstrated
– Diffusion bonding
• Assurance of primary circuitintegrity requires validated NDE orpressure testing
Structure of“Printed Circuit”Heat ExchangerAlternate Designs
Must Be Evaluated
Materials for Power Conversion SystemsLess Challenged than Fossil Plants
• Inlet turbine shroud, turbine diskand blades, and recuperator mostcritical components
• Nickel-based alloys (617) orC-C composites can be used forinlet shroud
– Properties at 950-1000°C needed
• Existing turbine blade and diskmaterials may work for VHTR butwill require property verification orcoating development
• Stainless steels likely okay for VTHRrecuperator for but scale-up of thin-sheet fabrication technologyrequired
VHTR Materials Needs Addressed by BothCrosscutting and Reactor-Specific Gen IV Tasks
• Crosscutting Materials Tasks–Materials for radiation service–Materials for high-temperature service–Microstructural analysis and modeling–High-temperature design methodology
• Reactor-Specific Materials Tasks–Graphite–Materials compatibility
• Reactor coolants• Hydrogen production
Collaboration with RelatedDomestic and ForeignPrograms Is Essential
Gen IV Materials Needs Are CurrentlyBeing Evaluated and Plans Developed
• Initial Focus Will Be on Commercial or Near-Commercial Materials for VHTR Applications
• Longer Term Focus Will Be on MoreAdvanced Materials for Other Reactor Needs
• Initial Study of Materials Needs for PrismaticVHTR Completed
• Similar Studies for Pebble-Bed VHTR, GFR,SCWR, and LFR Beginning
• Results Will Form Basis for Detailed ProgramPlan to Be Completed by Late Summer ‘03
• Experimental Work to Begin This Year, Basedon Overall Program Priorities