an overview of the doe advanced gas reactor fuel development and qualification program
DESCRIPTION
An Overview of the DOE Advanced Gas Reactor Fuel Development and Qualification Program. David Petti Technical Director AGR Program. Outer Pyrolytic Carbon. Silicon Carbide. Inner Pyrolytic Carbon. PARTICLES. Porous Carbon Buffer. Coated Particle. COMPACTS. Fuel Kernel (UCO, UO 2 ). - PowerPoint PPT PresentationTRANSCRIPT
US Department of Energy (DOE) Advanced Gas Reactor (AGR) Fuel Development and Qualification Program
UT-BATTELLEORNL
An Overview of the DOE Advanced Gas Reactor Fuel Development
and Qualification Program
David PettiTechnical Director
AGR Program
US Department of Energy (DOE) Advanced Gas Reactor (AGR) Fuel Development and Qualification Program
UT-BATTELLEORNL
Coated Particle Fuel Performance Is at the Heart of Many of the Key Pieces of the Safety
Case for the NGNPNormal Operation
Source Term
Fuel SafetyLimits
Fuel Kernel(UCO, UO2)
Coated Particle
Outer Pyrolytic CarbonSilicon CarbideInner Pyrolytic CarbonPorous Carbon Buffer
SevereAccidentBehavior
ContainmentAnd
BarriersAnd
Defense inDepth
Mechanistic Accident
Source Term
PARTICLES
COMPACTS
FUEL ELEMENTS
US Department of Energy (DOE) Advanced Gas Reactor (AGR) Fuel Development and Qualification Program
UT-BATTELLEORNL
Why Additional Fuel Work is Needed Comparison of German and US EOL Gas Release Measurements from Numerous Irradiation Capsules
1.0E-101.0E-091.0E-081.0E-071.0E-061.0E-051.0E-041.0E-031.0E-021.0E-01 U.S.
TRISO/BISO
U.S. WARTRISO/BISO
U.S.TRISO/TRISO
U.S. TRISO-P
German(Th,U)O2TRISOGerman UO2TRISO
U. S. Fuel German Fuel
U.S. GermanIrradiation temperature ( C) 930 - 1350 800 - 1320Burnup (%FIMA) 6.3 - 80 7.5 - 15.6Fast fluence (1025 n/m2 ) 2.0 - 10.2 0.1 - 8.5
Only German fuel had excellent EOL performance
US Department of Energy (DOE) Advanced Gas Reactor (AGR) Fuel Development and Qualification Program
UT-BATTELLEORNL
Key Differences between German and US fuel are related to coating not performance
• Coating rate used to make PyC (affects permeability and anisotropy of layer; US is low which reduces permeability and increases anisotropy; German is high which reduces anisotropy and increases permeability)
• Nature of the coating process. US used interrupted coating. Germans used uninterrupted coating. Interrupted coating and tabling led to metallic inclusions (from the tabling screens) in the SiC layer creating weak particles
• Nature of the interface between SiC and IPyC (German fingered interface is strong and US is weak which causes debonding)
• Microstructure of SiC (German is small grained and US is large columnar grained; difference is largely due to temperature used during SiC coating step)
• US had significant iron contamination of compact matrix which attacked the SiC and caused failures
USGerman
Weak interfaceStrong interface
Columnar SiCSmall grained SiC
Isotropic PyC Anisotropic PyC
US Department of Energy (DOE) Advanced Gas Reactor (AGR) Fuel Development and Qualification Program
UT-BATTELLEORNL
NGNP/AGR Fuel Program Priorities, Requirements and Approach
• The gas reactor in the US must demonstrate high integrity in-reactor and accident performance at any operating envelope envisioned the VHTR to have a chance of being commercialized. The fuel is the sine qua non of the VHTR.
• Qualify fuel that demonstrates the safety case for NGNP– Manufacture high quality LEU coated fuel particles in compacts
– Complete the design and fabrication of reactor test rigs for irradiation testing of coated particle fuel forms
– Demonstrate fuel performance during normal and accident conditions, through irradiation, safety testing, and PIE
– Improve the understanding of fuel behavior and fission product transport to improve predictive fuel performance and fission product transport models
• Build upon the above baseline fuel to enhance temperature capability• Lowest risk path to successful coated-particle manufacturing is to “replicate” the proven German coating
technology to the extent possible in an uninterrupted manner on the AGR particle design (350 m UCO), incorporating the lessons learned from prior U.S. fabrication and irradiation experience
• Irradiations of more that one type of fuel (variants) are required to provide improved understanding of the linkage between fabrication conditions, coating properties and irradiation performance
US Department of Energy (DOE) Advanced Gas Reactor (AGR) Fuel Development and Qualification Program
UT-BATTELLEORNL
Qualification of TRISO fuel requires two important conditions to be demonstrated
• Production of high quality fuel at a manufacturing scale with very few manufacturing defects (~ 1E-05) - this is the difficult part
– Disciplined control of coating process– Statistical demonstration (nature of the CVD process) of irradiation and
accident behavior– Currently cannot establish satisfactory fuel product specification to cover all
aspects of fuel behavior» Some process specifications are required. Thus, we are qualifying the
coater and the process.• Satisfactory performance for the service/performance envelope. The historical
database suggests this is attainable.– Normal conditions (temperature, burnup, fast fluence, packing fraction and
power density)– Accident conditions (hundreds of hours @ 1600°C with no fission product
release)
US Department of Energy (DOE) Advanced Gas Reactor (AGR) Fuel Development and Qualification Program
UT-BATTELLEORNL
Why Do Additional AGR Fuel Work? - Comparison of Fuel Service Conditions
• Germans qualified UO2 TRISO fuel for pebble bed HTR-Module
– Pebble; 1100°C, 8% FIMA, 3.5 x 1025 n/m2, 3 W/cc, 10% packing fraction
• Japanese qualified UO2 TRISO fuel for HTTR
– Annual compact; 1200°C; 4% FIMA, 4x1025 n/m2, 6 W/cc; 30% packing fraction
• Eskom RSA is qualifying pebbles to German conditions for PBMR
• Without an NGNP design, the AGR program is qualifying a design envelope for either a pebble bed or prismatic reactor
– 1250°C, 15-20% FIMA, 4-5x1025
n/m2, 6-12 W/cc, 35% packing fraction
– UCO TRISO fuel in compact form
Burnup (% FIMA)Fast Fluence (x 1025 n/m2)
Temperature(C)
Packing Fraction
Power Density(W/cc)
30
50
10 1250
1100
5.0
3.0
10
2
25 10
GermanNGNP
US Department of Energy (DOE) Advanced Gas Reactor (AGR) Fuel Development and Qualification Program
UT-BATTELLEORNL
Coated Particle Coated Particle Fuel FabricationFuel Fabrication
Fuel Fuel QualificationQualification
Analysis Analysis Methods Methods
Development Development && ValidationValidation
Fuel Fuel Performance Performance
ModelingModeling
Post Post Irradiation Irradiation
Examination & Examination & Safety TestingSafety Testing
Fuel SupplyFuel Supply
Program Participants
INL, ORNL BWXT, GA
NGNP/AGR Fuel Program Elements
Fission Product Fission Product Transport & Transport & Source TermSource Term
Fuel and Materials
Irradiation
US Department of Energy (DOE) Advanced Gas Reactor (AGR) Fuel Development and Qualification Program
UT-BATTELLEORNL
Overview of AGR Program ActivitiesPurpose Irradiation Safety Tests &PIE Models
AGR-1
AGR-2
AGR-3&4
AGR-5&6
AGR-7&8
Early lab scale fuelCapsule shakedown
Coating variantsGerman type coatings
Fuel and FissionProduct Validation
Fuel QualificationProof Tests
Failed fuel to determineretention behavior
Production scale fuelPerformance Demonstration
AGR-1
AGR-2
AGR-3&4
AGR-5&6
AGR-7&8
Update &Fuel
PerformanceAnd Fission
ProductTransportModels
ValidateFuel
PerformanceAnd Fission
Product Transport
Models
feedback
feedback
US Department of Energy (DOE) Advanced Gas Reactor (AGR) Fuel Development and Qualification Program
UT-BATTELLEORNL
AGR-1 Related ActivitiesFab baseline & variant
particlesCharacterize
Particles
Fab & CharacterizeCompacts
Ship toINL
Inspect & insertinto capsules
Complete test train fab
Complete, install & checkout gas control system
Complete checkout & install fissionproduct monitor
Complete cubiclecleanout
Safety analysisand training
BeginAGR-1
Irradiation
Critical dimensions & HMloadings to size gas gap
Ready to Insert
AGR-1
Certified Data Package
Confirmatory analysis,update pretest prediction,
finalize test plan
Characterization Data
Complete
QA Hold
US Department of Energy (DOE) Advanced Gas Reactor (AGR) Fuel Development and Qualification Program
UT-BATTELLEORNL
AGR-1 Baseline and Coating Variants (on 350 µm diameter UCO kernels)
CGF = 0.3T = 1265°C =1.91 g/cc
1500°C1.5% MTS
~1425°C~1.5% MTS
OPyC Layer: Same as IPyC baseline
All continuous
coating
Note: Choice of Variant 3 selection to be based on TCT recommendation supported by batch characterization data.
Goal: PyC with low anisotropy
and low permeabilityAnd acceptable
Surface connected porosity
CGF = 0.3T = 1290°C =1.85 g/cc
CGF = 0.45T = 1265°C =1.92 g/cc
CGF = 0.3T = 1265°C =1.91 g/cc
Baseline2 capsules in
AGR-1
Variant 1Increase
Coating Temp
Variant 2Increase
Coating GasFraction
Variant 3aDeposit
SiC with Ar
1500°C1.5% MTS
1500°C1.5% MTS
1500°C1.5% MTS
CGF = 0.3T = 1265°C =1.91 g/cc
Goal: fine grained SiC
Variant 3bInterrupted between
IPyC & SiC
US Department of Energy (DOE) Advanced Gas Reactor (AGR) Fuel Development and Qualification Program
UT-BATTELLEORNL
Optimize Sintering ConditionsProduction Line
Kernel improvement is primarily due to better carbon dispersion during kernel forming, and less grain growth most likely due to the shorter sintering time at 1890oC.
69302 (AGR-1) 59307 59308 LEUCO for AGR-1 Improved carbon dispersion 1890 4 Hours 1890 4 Hours 1890 1 Hour
US Department of Energy (DOE) Advanced Gas Reactor (AGR) Fuel Development and Qualification Program
UT-BATTELLEORNL
AGR-1 Fabrication
LEUCO coated particles
Fuel Compact
Loose kernelsSintered kernels
US Department of Energy (DOE) Advanced Gas Reactor (AGR) Fuel Development and Qualification Program
UT-BATTELLEORNL
All required characterization capabilities have been established
Density
Dim
ensions
Microstructure/
Ceram
ography
Sphericity
BET Surface A
rea
Anisotropy
Permeability
Crystallite/G
rain Size
Porosity
Uranium
Dispersion
Heavy M
etal Contam
ination
Missing B
uffer Fraction
Defective SiC
Fraction
Defective O
PyC Fraction
Impurities
KernelBufferIPyCSiCOPyCParticleCompact
– Completed – In Progress – Not applicable/required
US Department of Energy (DOE) Advanced Gas Reactor (AGR) Fuel Development and Qualification Program
UT-BATTELLEORNL
14March06 Status
ProductTRISOBatch
Fabrication
TRISOBatch
Characterization
Blend toForm
Composite
TRISOComposite
Characterization
CompactFabrication
CompactCharacteriza
tion
Baseline - pass - pass In Process
Variant 1 - pass - pass In Process
Variant 2 - pass In Process
Variant 3 In Process
US Department of Energy (DOE) Advanced Gas Reactor (AGR) Fuel Development and Qualification Program
UT-BATTELLEORNL
AGR-1 Experiment Block Diagram
Vessel Wall
CapsulesIn-core
HeNeHe-3
SilverZeolite
ParticulateFilters
H-3Getter
Grab Sample
FPMS
US Department of Energy (DOE) Advanced Gas Reactor (AGR) Fuel Development and Qualification Program
UT-BATTELLEORNL
AGR-1 Capsule Design Features• 6 Capsules with individual
temperature control and fission product monitoring
• Fuel compacts– 3 fuel compacts/level – 4 levels/capsule– Total of 12 fuel
compacts/capsule – Encased in graphite
containing B4C• 3 thermocouples/capsule• Thermal melt wires for
temperature back-up• Fast and thermal flux wires• Hafnium & SST shrouds
ATR Core Center
Graphite
Fuel Compact Gas Lines
Thermocouples
Flux Wire
Hf Shroud
SST Shroud
Stack 1
Stack 3
Stack 2
US Department of Energy (DOE) Advanced Gas Reactor (AGR) Fuel Development and Qualification Program
UT-BATTELLEORNL
Experiment Conditions• Minimum compact average burn-up > 14 %
FIMA (134.5 GWd/t)
• Maximum capsule burn-up > 18 % FIMA (172.8 GWd/t)
• Maximum fast neutron fluence < 5 x 1025 n/m2 (E>0.18 MeV)
• Minimum fast neutron fluence > 1.5 x 1025
n/m2 (E>0.18 MeV)
• U-235 enrichment 19.7 wt%
• Packing Fraction 35% (about 1410 particles/cc)
Gas Line
Thermocouple
Fuel Stack
Hafnium Shield
SST Holder
Capsule Spacer
Nub
US Department of Energy (DOE) Advanced Gas Reactor (AGR) Fuel Development and Qualification Program
UT-BATTELLEORNL
1
2
3
NT11
+1.605e+03+1.662e+03+1.718e+03+1.775e+03+1.832e+03+1.888e+03+1.945e+03+2.001e+03+2.058e+03+2.115e+03+2.171e+03+2.228e+03+2.285e+03
Experiment Conditions• Maximum temperature
<1400 ºC
• Time average peak temperature of 1250 ºC
• Time average volume average temperature of 1150 +30/-75 ºC
• Particle power not to exceed 400 mW/particle
• Only graphite (with boron carbide) may contact fuel specimens
US Department of Energy (DOE) Advanced Gas Reactor (AGR) Fuel Development and Qualification Program
UT-BATTELLEORNL
Welding of mockups of an AGR-1 capsule and brazing of tubes to the end cap
These two mockup capsules are straight within about .010 inch
US Department of Energy (DOE) Advanced Gas Reactor (AGR) Fuel Development and Qualification Program
UT-BATTELLEORNL
Fission Product Monitors: Assembled equipment for checkout and calibration
US Department of Energy (DOE) Advanced Gas Reactor (AGR) Fuel Development and Qualification Program
UT-BATTELLEORNL
AGR Fuel Program High Level Schedule
US Department of Energy (DOE) Advanced Gas Reactor (AGR) Fuel Development and Qualification Program
UT-BATTELLEORNL
Summary• AGR Fuel Development and Qualification needed to support NGNP• Highest priority is to demonstrate the safety case for NGNP
• Fuel is based on reference UCO, SiC, TRISO particles in thermosetting resin (minimum development risk consistent with program objectives)
• Based on Lessons Learned from the past - German coating is the baseline. Limit acceleration level of the irradiations.
• ‘Science’ based--provides understanding of fuel performance. Modeling is much more important than in the past US programs.
• Provides for multiple feedback loops and improvement based upon early results
• Improves success probability by incorporating German fabrication experience