Transcript PowerPoint 프레젠테이션 - Nuclear Safety and Security

International Conference for Spent Fuel Management from
Nuclear Power Reactors
May 31- June 4, 2010, Vienna, Austria
IAEA-CN-178/08-04
Demonstration Drop Test and Design Enhancement
of the CANDU Spent Fuel Storage Basket in
MACSTOR/KN-400
Woo-Seok Choi*, Jae-Yeon Jeon, Ki-Seog Seo(KAERI)
Jung-Eun Park (KHNP)
2010. 6. 2
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Contents
1. Introduction
2. Demonstration test
3.1 Devices to measure an impact velocity
3.2 Accelerometers and strain gauges
3.3 Leak test
3. Drop test results
3.1 Deformations
3.2 Impact velocity
3.3 Leak rate
4. Design enhancement
5. Conclusion
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1. Introduction
 A dry interim storage facility named MACSTOR/KN-400 for
CANDU type spent fuels has been constructed at the Wolsung
Power Plant(WSPP) in Korea.
 The MACSTOR/KN-400 has 7 modules.
 400 cylinders/module, 10 baskets/cylinder
 Under the process of licensing this facility, KINS(Korea
Institute of Nuclear Safety) recommended the demonstration
drop test of the basket in this facility.
 KAERI(Korea Atomic Energy Research Institute) conducted
this test with the support of KHNP (Korea Hydro & Nuclear
Power Co.).
Macstor/KN-400
A basket test
model
A drop test facility consisting of a
cylinder and tower
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1. Introduction (Performance requirements)
 Drop Conditions
 Dropping a basket into a cylinder
 Dropping a basket onto the other basket loaded in
cylinder
 Performance requirements
Performance
requirement
1. Deformation
2. Leakage rate
Allowable criteria
< 1,102 mm
(for outer diameter of basket)
< 10-5 atm·cm3/sec (He)
 Deformation requirement is for the retrievability.
 Leak rate requirement is for maintenance of containment
boundary.
 Geometric dimension
 Inner diameter of cylinder : 1,117.6 mm
 Outer diameter of basket : 1,066.8 mm
Schematic drawing of a drop test
facility and drop conditions
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2.1 The first device to measure an impact velocity
 Two devices invented and installed to measure the impact velocity of a basket
 The first device uses two laser displacement sensors installed with a distance difference.
 Calculates the time difference between the measured times when the basket passes over
each sensor
 The distance difference divided by the measured time difference yields the impact velocity.
Schematic drawing for the laser
sensor arrangement
Arrangement of two installed laser sensors
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2.2 The second device to measure an impact velocity
 The second device uses a fan shaped rotation device and a laser displacement sensor.
 The invented device is installed above the cylinder.
 A fishing string is rolled around the circulated object and one end of string is attached to
the top of a basket.
 When the basket starts to drop, the string becomes unfolded and the object starts to
circulate. A laser sensor acquire the pulse data when it circulates.
 From this pulse data, the RPM of the circulated object is calculated.
 Consequently, an impact velocity is calculated from this RPM.
Schematic drawing for the second device
Arrangement of the second device
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2.3 Accelerometer and strain gauge
 Accelerometers and strain gauges are attached to
basket only.
 Accelerometers: 4 each
 On spacer pad blocks by the space of 90 degree
 Impact acceleration acquisition
 Evaluate which bottom region drops first
 Strain gauges: 8 each
 4 strain gauges attached to the neighborhood of an
upper welded part between the top plate and the
post.
 4 strain gauges to the neighborhood of a lower
welded part between the side wall and the bottom
plate.
 Strain acquisition before and after impact
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2.4 Leak test
 Measuring the leakage rate after drop test
 Procedure
 Basket is charged with helium gas
 A Sniffer test is conducted.
 After basket is kept for 15 minutes, a leakage rate is measured by the helium mass
spectrometer.
Basket under charging helium gas
Leakage test by helium mass spectrometer
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3.1 Drop test results (deformation)
 After the drop test, both of the dropped basket and the loaded basket were withdrawn by a
grappler.
 The retrievability of both baskets was maintained.
Dimension of a basket before/after the first drop test
Before
After
Diameter (0º-180º)
Diameter (90º-270º)
Height (0º)
Height (90º)
Height (180º)
Height (270º)
1067.2
1067.1
557.22
557.36
557.65
557.74
1065.8
1065.6
557.75
558.06
557.90
557.66
Dimension of a basket before/after the second drop test
Dropping basket
Loaded basket
Before
After
Before
After
Diameter (0º-180º) 1067.1 1067.0 1067.0 1066.0
Diameter (90º-270º) 1067.0 1067.0 1066.3 1066.2
Height (0º)
557.67 558.18 557.35 556.06
Height (90º)
557.37 557.61 557.92 555.89
Height (180º)
557.37 557.47 557.69 557.09
Height (270º)
557.40 560.37 557.29 557.64
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3.2 Drop test results (impact velocity)
 Case 1: Drop to the cylinder bottom
 Case 2: Drop onto the other basket
 Theoretical free drop velocity: 12.13 m/s
 Theoretical free drop velocity: is 11.67 m/s
 Velocity reduction: 22.3% ~ 23.7%
 Velocity reduction: 21.0% ~ 21.6%
Drop test
Using 2 laser
sensors
Using rotation
device
Drop test
Using 2 laser
sensors
Using rotation
device
case 1
drop test
case 1
2nd drop test
9.43 m/s
9.26 m/s
9.15 m/s
9.17 m/s
9.42 m/s
N/A
case 2
drop test
case 2
2nd drop test
9.22 m/s
N/A
1st
30
1st
2nd
40
20
Magnitude [mm]
Magnitude [mm]
1st
0
-20
Rev_Pulse
20
10
-40
1.806
1.808
1.810
1.812
1.814
Time [sec]
1.816
1.818
1.820
0
1.70
1.72
1.74
1.76
1.78
1.80
1.82
1.84
1.86
1.88
1.90
Time [sec]
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3.3 Drop test results (leak rate)
Impacted area to the post of
stacked basket (45 degree)
Dropped basket figure 1
Dropped basket figure 2
Loaded basket figure 1
Loaded basket figure 2
Leak rate: 1.5×10-2
atm· cm3/sec (HE)
Leak from welding part between the
top plate and the post (225 degree)
Leak happening region (PT)
Leak happening region (PT)
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4. Design enhancement
 Clear understanding of the problem has been done by drop analysis.
 Drop analysis showed that a large plastic strain happened locally at the welding part.
The bottom plate of a dropping
basket impacts to the post of a
loaded basket
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4. Design enhancement (Cont’d)
 Direction of design enhancement
(1) To enhance the welding performance of welding region itself
(2) To afford the deflection of the bottom plate of the dropped basket
(3) To increase the bending rigidity of the top plate of the basket
(4) To increase the bending rigidity of the bottom plate of the basket
 Six revised designs based on the design direction were generated
Revised designs
Design
direction
1. Increase of the welding thickness at top welding region
(1)
2. Addition of extra spacer pads and increase of rib height
(2)
3. Increase of the thickness of side wall
(4)
4. Increase of the thickness of bottom plate
(3)
5. Increase of the thickness of top plate
(4)
6. Decrease of the height of central post
(2)
The revised basket designs
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4. Design enhancement (Cont’d)
 Among 6 proposed designs, the final revised design was achieved by the evaluation of many FE
analysis and the specimen test.
 The final revised design was the one, which is decreasing the height of the central post.
 And the revised design was achieved by the minimum design change from the original design.
 Demonstration test with the revised basket satisfied all the performance requirements.
Enhancement
Strain (%)
(Previous:28.07%)
1. Welding thickness increase
▲
27.35
2. Addition of extra spacer pads and rib height
increase
▲
25.87
3. Side wall thickness increase
▲
25.40
4. Bottom plate thickness increase
△※
25.55
5. Top plate thickness increase
▼※
Over than elongation
6. Central post height decrease
▲
24.89
Revised designs
Post of the previous basket
※Collision between fuel dummy and top plate
Post of the revised basket
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5. Conclusion
Data Acquisition
During Test
Deformation
Basket impact
velocity
Acceleration history
Strain history
Performance
Requirements
Deformation
(Retrievability)
criteria satisfied
Leak rate criteria not
satisfied for the
loaded basket
Verification through
PT
Evaluation of FE
Analysis and
Specimen Test
Comparison between
Test and Analysis
Results
Design
Enhancement
Needed
Demonstration test with the revised basket satisfied all the
performance requirements.
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