Martin Neumann, BAM-III.3 1
USING SCALE MODEL IMPACT
LIMITER IN THE DESIGN SAFETY
ASSESSMENT OF TRANSPORT CASKS
FOR RADIOACTIVE MATERIAL
PATRAM 2007
21st-26th October, Miami, USA
Martin Neumann, Frank Wille, Bernhard Droste
BAM-III.3
Martin Neumann, BAM-III.3 2
Outline
1. Impact-Limiting Devices of RAM-Casks
2. Concept of Proof of Safety
3. Description of the Calculation Tool
1. Theoretical Background
2. Modeling of the Geometry
3. Modeling of the Material
4. Verification
1. GNS CONSTOR® V/TC
2. MHI MSF69BG®
5. Conclusions
Martin Neumann, BAM-III.3 3
Introduction
Impact limiting devices in RAM-Casks
Steel constructions, cavities filled with
wood
Impact limiting devices in RAM-Casks
Steel constructions, cavities filled with
wood
Martin Neumann, BAM-III.3 4
Introduction
9m Drop9m Drop
Safety Evaluation and Assessment Concept of BAM
In accordance to IAEA Regulations
Safety Evaluation and Assessment Concept of BAM
In accordance to IAEA Regulations
1m Puncture1m Puncture 800°C Fire800°C Fire ……
Energy absorption capacity of impact limiter plays extraordinary role in
package integrity and tightness
Energy absorption capacity of impact limiter plays extraordinary role in
package integrity and tightness
Reduced-scale model casks are common in drop tests
Influence of impact limiter is large – crucial for determination of load
for cask body, lid and lid bolts and inventory
Reduced-scale model casks are common in drop tests
Influence of impact limiter is large – crucial for determination of load
for cask body, lid and lid bolts and inventory
Martin Neumann, BAM-III.3 5
General principles of similarity
– Geometric similarity
– Kinematic similarity
– Dynamic similarity
– Gravitational similarity
– Material similarity
IAEA Regulations - Section VII, §701 (c)
“Performance of tests with models of appropriate scale incorporating
those features which are significant with respect to the item under
investigation when engineering experience has shown results of such
tests to be suitable for design purposes.”
Introduction
Similar Mechanical
Response of
the Prototype Cask
and the Scale Model
Similar Mechanical
Response of
the Prototype Cask
and the Scale Model
Total Overall Similarity Impossible to achieveTotal Overall Similarity Impossible to achieve
Martin Neumann, BAM-III.3 6
Parameters affected by scaling
Major Influence
• Strain rate dependency of the material
• Size effects of the material
• Relative target compliance
• Compression mechanisms
• Gravitation
• Further influences (having influence on the earlier mentioned)
Major Influence
• Strain rate dependency of the material
• Size effects of the material
• Relative target compliance
• Compression mechanisms
• Gravitation
• Further influences (having influence on the earlier mentioned)
Precondition here: Model A-4 in Mok (PATRAM95), omitting strain rate
and gravitational similarity
Precondition here: Model A-4 in Mok (PATRAM95), omitting strain rate
and gravitational similarity
Martin Neumann, BAM-III.3 7
Strain Rate
Parameters affected by scaling
Literature: Wood-Tests with Split Hopkinson Bar test arrangement
Large velocity ranges Unsuitable
Literature: Wood-Tests with Split Hopkinson Bar test arrangement
Large velocity ranges Unsuitable
Investigations at different constant strain rates: Investigations at different constant strain rates:
Cube-shaped wooden
samples 100mm edge
length loaded axial
and perpendicular to
the grain
Cube-shaped wooden
samples 100mm edge
length loaded axial
and perpendicular to
the grain
BAM Impact Test Facility
(Max. 1MN, max. 8.5m/s, max. 500mm)
BAM Impact Test Facility
(Max. 1MN, max. 8.5m/s, max. 500mm)
Martin Neumann, BAM-III.3 8
Strain Rate
Parameters affected by scaling
Three Test Velocities: 0.001 m/s
0.3 m/s
3.0 m/s
Longitudinal and perpendicular to the grain
At least 10 samples each
Three Test Velocities: 0.001 m/s
0.3 m/s
3.0 m/s
Longitudinal and perpendicular to the grain
At least 10 samples each
Increase in compressive strength
in a reduced scale model,
compared to a full scale model
(1:2.5 scale):
Approx. 8%
Increase in compressive strength
in a reduced scale model,
compared to a full scale model
(1:2.5 scale):
Approx. 8%
Martin Neumann, BAM-III.3 9
Size Effects
Parameters affected by scaling
Bending and tensile tests indicate higher strength for small scale
specimens factor varies
Bending and tensile tests indicate higher strength for small scale
specimens factor varies
Increase in compressive strength in a reduced scale model (1:2.5
scale), compared to a full scale model according to a estimated
general factor: Approx. 16%
Increase in compressive strength in a reduced scale model (1:2.5
scale), compared to a full scale model according to a estimated
general factor: Approx. 16%
Compression Mechanisms
Biggest inherent structural system size:
Annual growth rings
Compared to wood layer thickness in
impact limiter not negligible
Biggest inherent structural system size:
Annual growth rings
Compared to wood layer thickness in
impact limiter not negligible
Influence on strength unclearInfluence on strength unclear
Martin Neumann, BAM-III.3 10
Relative Target Compliance
Parameters affected by scaling
BAM Drop Test Facility Horstwalde: large unyielding target (2600Mg)
small amount of impact energy is absorbed by the target
BAM Drop Test Facility Horstwalde: large unyielding target (2600Mg)
small amount of impact energy is absorbed by the target
Relative energy
of the target:
Relative energy
of the target:%100
,
,,
,
⋅
+=
totalkin
grdeftkin
totalkin
t
E
EE
E
E
Kinetic energy of the target:
Deformation energy of the ground:
Kinetic energy of the target:
Deformation energy of the ground:
2
2
1vmEkin =
( )∫=
=δ
0
,
x
grdef dxxFE
Acceleration sensors in target (integration)
Force transducers in the target
Acceleration sensors in target (integration)
Force transducers in the target
Martin Neumann, BAM-III.3 11
Target Compliance
Decrease in relative target compliance for a reduced scale model
(1:2.5 scale), compared to a full scale model : Approx. 2%
Decrease in relative target compliance for a reduced scale model
(1:2.5 scale), compared to a full scale model : Approx. 2%
14.7Proportion
0.15%1:2.5 Model
2.20%1:1 Model
Absorbed Energy, relative to Impact Energy
Parameters affected by scaling
Gravitation
Error for a 1:2.5 model compared to a full scale model: 5.9m/s²
Compared to impact deceleration (e.g. 600m/s) negligible
Error for a 1:2.5 model compared to a full scale model: 5.9m/s²
Compared to impact deceleration (e.g. 600m/s) negligible
However, multi-mass interactions are highly affected by gravtitation
and therefore scaling (Quercetti et al. PATRAM 2007)
However, multi-mass interactions are highly affected by gravtitation
and therefore scaling (Quercetti et al. PATRAM 2007)
Martin Neumann, BAM-III.3 12
Friction
Parameters affected by scaling
Annual growth ring structure and early/latewood relation affect friction
coefficient according to literature
Annual growth ring structure and early/latewood relation affect friction
coefficient according to literature
Analysis of friction influence on the energy absorption capacity by FEMAnalysis of friction influence on the energy absorption capacity by FEM
Individual considerations for
each impact limiter essential
Individual considerations for
each impact limiter essential
Martin Neumann, BAM-III.3 13
MSF69BG®
Comparison with Drop Test Results
Vertical Drop (Quercetti et al. PATRAM 2007)
Reduced-scale model showed: 16% lower deceleration
9% higher deformation
24% longer impact duration
Compared to the full-scale model test
Vertical Drop (Quercetti et al. PATRAM 2007)
Reduced-scale model showed: 16% lower deceleration
9% higher deformation
24% longer impact duration
Compared to the full-scale model test
Slap Down Position / Oblique (Quercetti et al. PATRAM 2007)
Reduced-scale model showed: 17% higher deceleration30% lower deformation7% shorter impact duration
Compared to the full-scale model test
Slap Down Position / Oblique (Quercetti et al. PATRAM 2007)
Reduced-scale model showed: 17% higher deceleration30% lower deformation7% shorter impact duration
Compared to the full-scale model test
No ambiguous proof for the direction of differences (harder/softer)
between reduced and full scale drop test – uncertainties remain high
No ambiguous proof for the direction of differences (harder/softer)
between reduced and full scale drop test – uncertainties remain high
Martin Neumann, BAM-III.3 14
Conclusions
Possible factors influencing the energy absorption of wood were
identified.
Possible factors influencing the energy absorption of wood were
identified.
For strain rate, size dependency and target compliance quantitative
estimations were derived.
Gravitation, compression mechanisms and friction are likely to have an
influence, but could not evaluated quantitatively.
For strain rate, size dependency and target compliance quantitative
estimations were derived.
Gravitation, compression mechanisms and friction are likely to have an
influence, but could not evaluated quantitatively.
Comparison between reduced- and full-scale drop tests showed, that
due to “high scatter” results are difficult to interpret.
Comparison between reduced- and full-scale drop tests showed, that
due to “high scatter” results are difficult to interpret.
From assessment point of view: As a result of uncertainties due to
scale-model testing, additional safety factors for drop test results as
well as for the calculations needed to transfer the results, have to be
demanded.
From assessment point of view: As a result of uncertainties due to
scale-model testing, additional safety factors for drop test results as
well as for the calculations needed to transfer the results, have to be
demanded.
Martin Neumann, BAM-III.3 15
Conclusions
Thank you very much!Thank you very much!
