15 june 7 structural_modeling_2016_distribution_klymshyn

1. Nick Klymyshyn
Philip Jensen
Nathan Barrett
UFD Annual Working Group Meeting, UNLV
June 6, 2016
PNNL Structural Dynamic Modeling to
Support ENSA/DOE Rail Test

2. 2
ENSA/DOE Test Summary
• Loading Environments
• Heavy-haul truck
• Coastal shipment (e.g., barge)
• Open ocean transport
• One or Two Fuel Assemblies
• SNL 17x17 test assembly
• Data Collected
• Cladding strain
• Outcomes
• Determination of cladding/UNF loads
• Definition of the fuel assembly loading environment
• Estimate strains and fatigue damage on real UNF
• Validate numerical models to evaluate any combination of
fuel/package/cradle/railcar combination
• Close the UNF loading knowledge gap under NCT rail
• Normal rail
• Inter-modal transfers
• Other 17x17 test assembly
• Acceleration

3. 3
Role of Modeling in the Test
Campaign
 Validated numerical models are necessary to interpret the raw
test data to determine the loading on real UNF.
 Step 1: Expand the response throughout the fuel assembly
 Step 2: Adjust the test data from as-tested to real UNF
conditions
 Step 3: Project the UNF response onto other fuel and
conveyance system designs

4. 4
Modeling Step 1: Expand Response
Limited number of strain gage data collection locations.
Example: 6 Strain gage sites representing 6 to 18 channels of data.
Modeling is used to determine the
response at every fuel assembly location.
Model requires fuel assembly loading conditions as input.

5. 5
Fuel Assembly Loading Conditions

6. 6
Rail Conveyance System Data
Collection to Determine Fuel
Assembly Loading Conditions
Model SpaceTest Space
Accelerometers will be used to collect
rail conveyance system loads at
many locations to provide the data
needed to reconstruct the loads on
the fuel assembly in model space.
• Railcar Deck
• Cradle/Skid
• Cask
• Basket
• Fuel Assembly
NUCARS
LS-DYNA
ANSYS
LS-DYNA

7. 7
Modeling Step 2: Adjust from as-
tested to as-expected conditions
As-Tested
• Copper cladding
• Room
temperature
• Unbonded
Rigidity (EI)
As-Expected
• Irradiated Zirc
• Elevated
Temperature
• Bonded
Composite
Rigidity (EI)Model Space
Test Space

8. 8
Modeling Step 3: Project Response of
other fuel assembly designs/other
conveyance systems.
Model Space
LS-DYNA
ANSYS
LS-DYNA
NUCARS
This project will result in
validated models that can
be modified to account for
differences in…
• Fuel Design
• Package Design
• Cradle/Skid Design
• Railcar Design
… as necessary to close
the cladding load
knowledge gap.

9. 9
Test Campaign Expectations
 The current best estimate of cladding response under NCT rail
transportation shock and vibration based on conservative
numerical models:
• Cladding will not fail (peak stress at all locations remains below yield)
• The single most limiting cladding location uses 18% of its fatigue life.
 The test campaign is expected to:
• Fully quantify the UNF loading environment
• Confirm UNF cladding strains remain below yield throughout transport
• Provide better insight into UNF cladding fatigue usage
– over a full cross country trip
– during intermodal transfers
• Reveal loading phenomena we might have missed

10. 10
PNNL Detailed Fuel Assembly
Select Model Validation Comparisons
Shaker Table Simulated Truck Shock
Over the Road Truck Test
NCT Rail Study
2015
Shaker Test
2013
Modeling
Study(3)
241 µs 545 µs
(752 µs)(4)
(3) FCRD-UFD-2013-000325,
Adkins et al.
(4) Includes stress concentration at
pellet-pellet interface (1.38)
2014
Truck
Test Data
2014
Model
2015
Projected(2)
136 µs 323 µs 277 µs
2013
Shaker
Test
2013
Model(1)
2014
Model
2015
Shaker Test
213 µs 578 µs 744 µs 128 µs to
189 µs
(2) Modifies the excitation to adjust
for a realistic conveyance design.
Strain ends up being approximately
the same.
(1) Average strain error through time was ±10 µs.
Peak instantaneous error was ±480 µs.
Note: 1 µs = 0.000001 mm/mm

11. 11
Additional Model Validation Activity
Under the Structural Uncertainty task, work is being done to determine the best
(most accurate) beam finite element formulation for UNF modeling. We are using
closed form solutions and bench testing of cladding rods to form validation cases.

12. 12
ENSA Cask Comparison to TN-32
 Detailed comparison of ENSA ENUN-32P and TN-32 packages to
demonstrate similarity
ENSA TN-32 %∆
Total Mass ? ? ±1% (guess)
PWR
Capacity
32 32 Identical
Package
Mass
? ? ?
Basket Mass ? ? ?
Trunnion
Length
? ? ?
CG location ? ? ?
Additional… … … …

13. 13
Preliminary Modeling: Basket
Note that basket has
freedom to move within
package.
Two Basket Accelerometer Locations
Where to put the 1 or 2 real
fuel assemblies? - TBD

14. 14
NCT (30 cm) Cask Drop Analyses
Package
Type
Impact
Orientation
Gap
Cladding
Peak Axial
Strain
Peak Bending
Moment
(N-m)
Peak Shear
Force
(N)
Peak Fuel
Assembly RBA
(m/s2)
Rail Horizontal Min 0.000425 4.56 246 235
Rail Horizontal Mid 0.001985 22.21 2306 1263
Rail Horizontal Max 0.003546 38.88 3366 2752
Rail 1° Mid 0.003100 32.79 7879 345
Truck Horizontal Min 0.001454 17.17 1514 885
Truck Horizontal Mid 0.002174 23.67 2766 1649
Truck Horizontal Max 0.002094 29.14 3347 1948
Truck 1° Mid 0.002928 31.58 4386 277
Topfuel2016 paper: Modeling Used Fuel Response to Normal Conditions of Transportation Package
Drops to Assess Geometric Sensitivities, NA Klymyshyn, PJ Jensen, NP Barrett
Nominal Results

15. 15
High Burnup Fuel Considerations
The structural dynamic behavior of high burnup UNF is expected to behave like
lower burnup UNF when loading conditions are relatively low, making it valid to
approximate the cladding and fuel as a composite beam with an equivalent
bending rigidity (EI).
ENSA/DOE testing and modeling will establish the loads on UNF. Materials
testing (e.g., Sister Pin Testing) will determine failure conditions. Comparing
loads to failure conditions is typically done outside the model, but certain failure
mechanisms can also be modeled (element deletion). We are not currently
expecting a high cladding damage environment.

16. 16
END
 Questions?

17. 17
UNF Finite Element Model
S
T
Beam Axes
List of Beam Results
• Axial Force (Fa)
• Bending Moment about S (Ms)
• Bending Moment about T (Mt)
• Shear Force (Fs)
• Shear Force (Ft)
• Torsion (T)Fs
Ft
Beam Properties: Mass, E, I, A
Fa
T
Mt
Element N Element N +1 Element N +2
2x2 Gauss Quadrature
4 integration points arranged
at the beam element centroid
node1 node2
Beam element
mid-plane

18. 18
Cladding Strain Sensitivity to
Surrogate Rod Bending Rigidity (EI)
3 Zircaloy Tubes
EI (N-m2)
Copper Tubes
EI (N-m2)
S2 – 0° Gage Strain
(µs)
Baseline Model (2014) 12.9 24.4 744
3 RT Fuel (2015) 43.2 24.4 1139
All RT Fuel (2015) 43.2 43.2 942
Modeling Answer: Realistic used fuel has a similar response to test loads. Large change in EI has a
small effect on strain results. Loading environment is relatively low.
SNL Surrogate Fuel Assembly [1]
Modeling Question: How does realistic fuel cladding respond to the test excitation?
Note: 2015 test
results for S2-0°
were 128-189 µs.

19. 19
Detailed PWR Fuel Assembly Model
LS-DYNA finite element model for use
in any dynamic or structural loading
scenario to calculate stress and strain.