Design Study for Passive Shutdown System
of the PGSFR
2015. 10. 20
Lee, Jae-Han
Koo, Gyeong-Hoi
20151021 IAEA TM on passive shutdown system
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– Start up, power control and reactivity
compensation through the CRA’s position
movement driven by AC servo motor
– Shutdowns
• Normal shutdown – Plant Control System
 Rod insertion by AC servo motor
• Scram – Reactor Protection System, RPS
 Rod insertion by gravity (EM power off)
and then the insertion confirmed by fast
drive-in motor
Seal Bellows
6 Primary CRDMs
Drive Motor
1. Reactor Control and Shutdown Concepts of PGSFR
Electromagnet
[EM]
Eq. Diameter = 158 cm
Inner core F.A.
52
Outer core F.A.
60
6
Primary control rod
3
Secondary control rod
Reflector
B4C shield
78
114
– Scram – RPS
• 1 : Rod insertion by gravity (EM power off)
and confirmed by fast drive-in motor
– Passive shutdown function of relaxing ATWS
• Use of thermal expansion difference of two
metals, when the coolant temperature rises
up at certain level
20151021 IAEA TM on passive shutdown system
ElectroMagnetic gripper,
SASS
3 Secondary CRDMs
Bushing
313
Eq. Diameter = 253 cm
2
2. Components and Materials of Passive Shutdown System
 System components
– Electromagnet, which is attached to the bottom end of CRA
driveline, to hold or trigger off the CRA
– Armature, attached to the top of the CRA extension rod head
– Thermal expansion device (structure), material of a relatively large
thermal expansion coefficient
– Coil enclosure structure for protecting the coil from hot sodium
– Flow guide structure supported by upper internal structure (UIS)
Sodium level
Components
Materials
Electromagnet cores /
armature
SS410 or soft iron /
SS410 or 2.25Cr1Mo
Thermal expansion device
SS316
Thermal
Expansion
device
Coil
enclosure
structure
Armature
Drive shaft
corresponding to the
thermal expansion device
20151021 IAEA TM on passive shutdown system
9Cr-1Mo-V
or Inconel 718
Drive Shaft
 Materials
Electro
magnet
Flow
guide
structure
Control rod
assembly
(CRA) head
3
3. Basic Actuation Concepts of Passive Shutdown System
 Use of thermal expansion differences
25oC
Thermal
Expansion
device
(SS316)
Thermal expansion device
(SS316)
Drive shaft
(9Cr-1Mo-V (Inconel718))
Thermal
Thermal
Thermal
Thermal
Temp
Conductivity
Conductivity
Expansion
Expansion
[oC]
[10-6 mm/mm/oC] [W/(moC)] [10-6 mm/mm/oC] [W/(moC)]
~ 650oC
~ 545oC
Drive Shaft (Inconel 718)
– Behaviors at three situations
• Fabrication, 25oC
• Operating condition, ~ 545oC
• One of ATWS conditions, ~ 650oC
Electro
Electro
magnet
magnet
~ 9.7 mm
Magnet
flux gap
Electro
magnet
~ 0.8 mm
Gap size,
~ 1 mm
Electro
magnet
CRA
head
425
19.6
20.1
13.4(14.13)
27.9(17.7)
525
20.4
21.5
14.0(14.4)
27.9(19.4)
 1.8 mm = (~ 6.0 x 10-6 /oC) x ( 105oC) x (~2.86
625
21.4
22.9
14.9(14.9)
27.5(21.2)
m)
 9.0 mm = (~ 6.0 x 10-6 /oC) x ( 520oC) x (~2.86
m)
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Temperature rising
range
Gap size to the
CRA release armature
Maximum
electromagnetic force
Allowable length of
thermal expansion device
20151021 IAEA TM on passive shutdown system
~ 50Kg
100 ~ 150oC
~ 1 mm
(TBD)
Coil
enclosure
Structure
(option)
Seal Bellows
Weight of secondary control rod
assembly (CRA)
Targets
Thermal
Expansion
Device
Drive
Shaft
< 300 N
~ 3.0 m
(TBD)
ElectroMagnet gripper
Design conditions
Bushing
 Initial design values for building
up the design concept
Drive Motor
4. Design Conditions of Passive Shutdown System
Electromagnet
Gripper
2nd CRA
(~50 Kg)
5
 Monitoring the CRA release
– CRA head contact rod through a central hole in
electromagnet
– Electrical way using an eddy current
20151021 IAEA TM on passive shutdown system
Diameter,
100 mm
Drop height
Seal Bellows
Length of
thermal expansion device
 Layout of DC power line
– Length : ~ 12 m
Bushing
 High temperature(545oC) and radiation
environments
– Core material of electromagnet
• Permeability
– Coil insulation
• Insulation materials and methods
• Coil design life
ElectroMagnetic gripper
 Installation space of electromagnet
– Limited diameter => Limited electromagnetic force
– Limited length of thermal expansion device
Drive Motor
5. Design Issues of Passive Shutdown System
6
6. Electromagnet Designs of Passive Shutdown System
 Two design types are studied, Type 1
is an initial design, Type 2 is an
improved design concept.
Type 1
Type 2
rectangular,
4~ 6 layers, 2 x 6 mm 2
circular,
1.4 mm in diameter
Coil insulation
materials
fiber glass in
interspaces
mineral (MgO)
insulation
and seamless SS316
sheath
Coil seal from
sodium
SS316 enclosure
structure
weld seal at gaps of
the electromagnet
cores
Coil wire (Cu)
Size of coil
enclosure
structure
Size of outside
core
Type 1
OD : 80 mm,
thickness : ~ 2 mm
OD : 75 mm
20151021 IAEA TM on passive shutdown system
OD : 80 mm
Type 2
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7. Calculation of Electromagnetic Force (Type 1)
Design parameters of electromagnets
•
Gap size between the electromagnet core and the
armature of the CRA head, 0.5 ~ 3 mm
•
Size of the electromagnet core,
Length, 200 ~ 300 mm
Thickness of cores
Thermal
Expansion
Device
•
No. of coil turns, 100 ~ 320 turns
Coil
enclosure
structure
•
Fixed value
Outer core
Outer core outside diameter : 75 mm
Power supply
•
•
DC ~ 6V, 17A ~ 20A
~ 3,200 Ampere Turns
 Calculation software
•
Coils
Inner core
Armature
2nd CRA head
Redan
ANSYS Emag.
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8. Electromagnetic Forces on CRA head (Type 1)
 The electromagnet forces on the CRA head are
calculated by changing the design parameters.
 The electromagnetic forces on the CRA with 1
mm gap and the 160 coil turns are in the range
of ~ 250 N for the several core thicknesses.
 The results in Table 6 show that the increase of
the core thickness is proportional to the
electromagnetic force even if the ampere turns
are decreased in the certain range.
20151021 IAEA TM on passive shutdown system
Table 5 Electromagnet forces induced by design variations
Gap size
between
fixed core
and
armature
mm
1
1
1
1
1
1
1
2
3
0.5
Electromagnet
Inner core
Electromagnet
armature
Inner
Outer
diameter diameter
Thickness
Axial
length
Ampere
Force
turns
mm
20
20
20
20
10
10
10
20
20
20
mm
185
185
185
185
385
185
185
185
185
185
AT
N
17x 160 177
17x 160 217
17x 160 231
17x 160 251*
17x 320 290
17x 160 245
17x 220 463
17x 160
86
17x 160
48
17x 160 490
mm
15
11
9
5
5
5
5
5
5
5
mm
27
27
27
27
27
27
27
27
27
27
Coil (6 layers)
Table 6 Electromagnet forces for magnetic core thicknesses
Gap size
between
fixed core
and armature
Inner core
thickness
Outer core
thickness
Coil
space
Layer
no
Ampere
turns
Force
mm
1
1
1
1
1
mm
12
14
17.5
17.5
17.5
mm
4
5
5.5
5.5
5.5
mm
19.5
16.5
12.5
12.5
12.5
6
5
4
5
5
AT
20x150
20x125
20x100
20x125
25x125
N
253*
310
384
456
532
Coil
Electromagnet
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9. Calculation of Electromagnetic Force (Type 2)
Design parameters of electromagnet
• Gap size variations to the armature : 0.25~ 2 mm
• Different core materials
• Fixed values
Outer core outside diameter : 80 mm,
thickness : 3 mm, length : ~ 300 mm
Coil turns : 264
Thermal
expansion
device
• No coil enclosure structure
The role is replaced with
the sealed outer and lower cores
Power supply
• DC ~ 15V, 7.5 A
• 1,980 AT
Outer core
enclosure coils
Coils
Inner core
(inside)
Armature
2nd CRA head
 Calculation software
• ANSYS Emag.
20151021 IAEA TM on passive shutdown system
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10. Electromagnetic Forces on CRA head (Type 2)
 The electromagnetic forces on the CRA
head are calculated when the outer core
outside diameter is enlarged to 80 mm,
and the calculated results for the
different core materials and the gap size
variations to the armature are suggested
2500
in Figure 4.
 The electromagnetic forces on the CRA
within 0.5 mm gap are strong enough to
hold the CRA.
 The electromagnetic forces with 1 mm
gap are in the range of ~ 300 N, it
makes the CRA drop into the reactor
core by gravity.
20151021 IAEA TM on passive shutdown system
Magnetic force (N)
2000
Low carbon & SS410 25 deg.(Lc 10 mm)"
1500
Soft iron & 2.25Cr-1Mo (Lc 10 mm)
1000
500
0
0
0.25
0.5
0.75
1
1.25
1.5
1.75
2
Gap size between fixed magnet and armature (mm)
Figure 4 Electromagnetic force variations to air gap size to the armature
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11. Summary
 The thermal expansion difference of the 2.86 m long expansion device
is calculated about 1.7 mm for the temperature rise of 100oC.
 The electromagnetic forces on the CRA with 1 mm gap are in the range
of ~ 300 N.
 The thermal expansion difference of the thermal expansion device to
trigger off the CRA shall be controlled within 1 mm at a set
temperature ( ~ 650oC).
 Additional design study to trigger off the CRA by utilizing the limited
length of thermal expansion device is going on.
 The design feasibility tests for a passive shutdown concept of the
PGSFR are being performed by using several test mockups of the
thermal expansion device.
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A1. Design feasibility tests for Electromagnets
 Type 1 Design
– Use of rectangular coated coil
– Electromagnet forces for gap
size 1 ~ 0 mm
• 20 ~ 260 kgf
Electro-
Thermal
Magnet
Expansion
Device
 Type 2 Design
– Use of mineral insulation coil
– Electromagnet forces for gap
size 1 ~ 0 mm
• 20 ~ 240 kgf
Coated
coil
2nd CRA
head
MI coil
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A2. Design feasibility tests for passive shutdown device
 Under the fabrication of a
medium size test facility
• Type 2 design
• Use of shorten thermal
expansion device : 0.7 m
• Initial position of expansion
device
 Passive Function tests
• CRA drop test for
temperature 600 ~ 650 (oC)
• CRA weight variations
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Thanks for your attention !
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