fuel performance: integrating cms with nnls enigma · fission product e.g. iodine makes crack tip...
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Fuel Performance:Integrating CMS with NNLs ENIGMAA.S. DiGiovine, S. Tarves
A. Worrall, R. Gregg, (National Nuclear Laboratory, UK)
2010 Studsvik Light Water Reactor Seminar
Fukuoka, Japan June 9-11, 2010
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Outline
• Fuel Performance Issues
• CMS Capabilities
• ENIGMA (National Nuclear Lab, UK)
• ONUS - ENIGMA/CMS Integration
• Summary
June 2010 Studsvik Light Water Reactor Seminar
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What is the PCI Phenomenon?
• When power in a rod increases, becomes prone to PCI (pellet clad
interaction)– Induces “stress corrosion cracking” (SCC)
1. Power increase causes a differential thermal expansion in the clad
tensile stress in the cladding (“hoop stress”)
2. A certain power level is also necessary for fuel to fail indication
that high fuel temp. required and release of aggressive, volatile
fission product e.g. iodine makes crack tip brittle
3. Failure is not immediate suggests crack has to develop and
propagate have to be held at power for a period of time
• Power increases alone are insufficient– This has been proven by experimental results with very high increases in rod powers
Requires fuel performance code PLUS power history – look at
“concentrated hoop stress” and “crack length”
June 2010 Studsvik Light Water Reactor Seminar
Stress
Corrosion
Cracking
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Fuel Performance Issues:
INPO PCI Initiative (SOER 07/004)
• Impose local power monitoring to avoid PCI
• Implement operational guidelines to avoid
operating practices that increase PCI
vulnerabilities
June 2010 Studsvik Light Water Reactor Seminar
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Fuel Performance Basics
June 2010 Studsvik Light Water Reactor Seminar
Fuel/Clad
Mechanics
PCMI
Determine
Power
Distribution
Fuel/Clad
Temperature
Distribution
Fission Gas
Release
ModelRadioactive Gap
Inventory
Failure
Probability Rod
Internal
Pressure
Input Data Define Geometry
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Fuel Performance Parameters of Interest
• Calculation against design and licensing criteria:
–fuel centreline temperature
–rod internal pressure
–clad stress
–clad strain
–rod growth
–clad fatigue and ratchetting
June 2010 Studsvik Light Water Reactor Seminar
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Fuel Performance
Capabilities of NNL’s ENIGMA
• Thermo-mechanical fuel performance code
– stress and strain evolution in fuel and clad
– temperature evolution in fuel and clad
– stable and short-lived fission product release
• Applications
– fuel: UO2, MOX, Gd, IMF, Thorium, wafer fuel, ...
– clad: Zircaloy-2, Zircaloy-4, advanced alloys
– PWR, BWR and some test reactor conditions
• Validation– temperature, pressure, FGR, dimensional changes, corrosion, etc
June 2010 Studsvik Light Water Reactor Seminar
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NNL’s Fuel Performance Capabilities:
ENIGMA• 527 rod irradiations currently included
• Test reactor irradiations
– Halden: 18 separate IFAs
– Risø: 1st, 2nd & 3rd fission gas projects
– Studsvik: Various ramp projects (e.g. Trans, Inter)
– BR3/BR2: Tribulation, GAIN, GAP, PRIMO
Callisto projects
– High Burnup Effects Program
– NFIR program
• Commercial reactor irradiations
– Various American and European PWR datasets
June 2010 Studsvik Light Water Reactor Seminar
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ENIGMA Benchmarking – Number of
Irradiated Rods Modeled vs. Exposure
June 2010 Studsvik Light Water Reactor Seminar
Exposure (GWd/t)
No. of
Rods
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Studsvik Capabilities :
Assessing Fuel Performance
• SIMULATE – PCI Extension Module– Account for fuel conditioning and deconditioning on a pin by pin basis
(not node, not “hot pin”)
• CMSOps – Reactivity Management and Operational
Support– Guidance to preclude PCI failures during power maneuvers
– Project planned power maneuvers (before actual maneuver occurs)
• GARDEL – Online Monitoring– Ensure compliance within PCI limits during operations
– Preclude PCI failures during power maneuvers
June 2010 Studsvik Light Water Reactor Seminar
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ONUS – Computational Configuration
June 2010 Studsvik Light Water Reactor Seminar
CMS Model
SIMULATE Pinfile
NEXUS: automated
ENIGMA input generation
NEXUS: executes/collates
ENIGMA results
Presentation of Pin-by-pin
ENIGMA results provided in
format governed by customer
•The “ONUS Cloud” features/benefits
• Hosted solution
• Controlled environment for QA
• Results presented via GUI
• No computational burden on end-user
• Entire analysis of all pins in the entire core takes
less than 10 minutes
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Benefits of a Hosted Solution
“Cloud Computing”
• Quick-Fix or Just-In-Time Services– Since Studsvik has access to the environment and model files, support
and services can be done quickly, meaning less down time for engineers
• User Flexibility– The software installations reside outside of your private network,
allowing users to access the system even when out of the office, without
having to go through your network
• High Availability– Hosted servers use the latest technology for built-in redundancy and
automatic failover to backup hardware, ensuring the system is highly
available
June 2010 Studsvik Light Water Reactor Seminar
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ONUS Example – Clad Hoop Stress
June 2010 Studsvik Light Water Reactor Seminar
• Indicates pins more
“susceptible” to PCI
• Shows bi-modal nature of clad
stress
• Coolant to clad pressure
• Pellet to clad pressure
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PWR PCI Operations Example
Near EOC Load Swing
June 2010 Studsvik Light Water Reactor Seminar
PCI Allowed
Power
Actual Power
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ONUS Example – Rod Internal Pressure
June 2010 Studsvik Light Water Reactor Seminar
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ONUS- Benefits of combining CMS with ENIGMA
• Eliminate uncertainties of approximate modelling, some examples:
– global ramp rates
– limiting pin (“hot-pin”)
– delta kW/ft
• Explicit pin-by-pin thermo-mechanical fuel performance analyses (detailed pin power history from CMS, fuel performance assessment from ENIGMA)
– evaluate fuel loading pattern prior to finalizing core design
– explicitly evaluate and monitor reactor operations and power maneuvers(before they actually occur)
June 2010 Studsvik Light Water Reactor Seminar
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Summary
• Detailed (pin by pin) thermo-mechanical fuel performance
via ENIGMA analysis using CMS pin histories now
available– Hosted solution
• We are in the prototype stage, if you have interest to
have a trial evaluation of your fuel or core design please
let us know
Thank you for your attention!
References:1. “ONUS”: ON-line fUel performance Surveillance – Linking Studsvik’s CMS with UK NNL’s ENIGMA-B,” A. Worral (NNL) A.
DiGiovine (Studsvik), Advances in Nuclear Fuel Management IV (ANFM 2009) Hilton Head Island, South Carolina, USA, April
12-15, 2009, American Nuclear Society
2. “Highly Detailed PCI Evaluations of Actual Operating Power Maneuvers at Southern Nuclear,” A. DiGiovine, et. Al., 2010 LWR
Fuel Performance Meeting/TopFuel/WRFPM (TOPFUEL) Orlando, Florida, USA September 26-29, 2010 – to be published
June 2010 Studsvik Light Water Reactor Seminar
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June 2010Studsvik Light Water Reactor
Seminar