1 hee cheon no nuclear system/hydrogen lab. kaist chapter 3: fuel thermal analysis
TRANSCRIPT
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Hee Cheon NO
Nuclear System/Hydrogen Lab.
KAIST
Chapter 3: Fuel Thermal Analysis
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Contents
3.1 Basic heat transport modes3.1.1 conduction heat transport3.1.2 convective heat transport3.1.3 radiation heat transport
3.2 Fuel irradiation effects3.2.1 Fission gas release3.2.2 Thermal expansion, densification, swelling 3.2.3 Clad creepdown and lift-off3.2.4 Fuel-cladding interaction3.2.5 Fuel failure mechanisms 3.3 Fuel thermal analysis3.3.1 Fuel pellet thermal analysis3.3.2 Fuel cladding thermal analysis3.3.3 Fuel gas gap thermal analysis3.3.4 Heat transfer in the fluid channel
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Conduction heat transport
3.1 Basic heat transport models
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Convection heat transport
heat transfer coefficient
3.1 Basic heat transport models
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Radiation heat transport
Black medium: emissivility=1; perfect emiiter and absorber
Grey medium(practical medium): emissivility<1
3.1 Basic heat transport models
4 41 2
1 2
( )
: 1) inf
eff
eff
Q A T T
for inite parallel planes
where
eff ecti ve emi ssi vi ty=1/ (1/ 1/
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3.2 Fuel irradiation effects
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Fission gas release: recoil & knockout
3.2 Fuel irradiation effects
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Fission gas release: diffusion mechanism
3.2 Fuel irradiation effects open tunnel network
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Fission gas release: grain size effect
3.2 Fuel irradiation effects
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Thermal expansion
3.2 Fuel irradiation effects
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Densification and swelling
3.2 Fuel irradiation effects
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Clad creepdown and lift-off
3.2 Fuel irradiation effects
creep: long-term transient deformation given load
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Fuel-cladding interaction
3.2 Fuel irradiation effects
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Fuel failure mechanism
3.2 Fuel irradiation effects
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Fuel failure mechanism
3.2 Fuel irradiation effects
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Example of fuel temperature radial distribution in fuel pellet
3.3 Fuel thermal analysis
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Fuel thermal analysis
3.3 Fuel thermal analysis
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Fuel pellet thermal analysis:
Fuel cladding thermal analysis:
3.3 Fuel thermal analysis
~17 /
0.6 ~ 0.9cl
cl
k non oxided thermal conductivity W mK
cladding thickness mm
2 2"'( ) / 4p f fsT q r r k T
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Fuel gas gap thermal analysis(open gap):
3.3 Fuel thermal analysis
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Fuel gas gap thermal analysis(closed gap):
3.3 Fuel thermal analysis
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coolant T with cosine power profile:
3.3 Fuel thermal analysis
,/2 /2
, /2
' ', max max
' ;
' ( ( ) );
( ) ' / ( )
/ ( )[sin( / ) sin( / 2 )]; ' cos( / )
( )[ ( ) ( )] ''( ) '( ) / (
b p b
z z
p b p b b inH H
z
b b in pH
b in p
cladding b
q dz mdh mc dT
q dz mc dT mc T z T
T z T q dz mc
T q H mc z H H H if q q z H
h z T z T z q z q z d
); ( ) ( ) ''( ) / ( )
; ( / 2) '( / 2) 0;
( ) :
cladding cladding bT z T z q z h z
where
H extrapolated length H q H
h z heat transfer coefficient
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cladding T for subcooled non-boiling
cladding T for subcooled boiling: Jens-Lottes correlation
3.3 Fuel thermal analysis
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CHF concept
3.3 Fuel thermal analysis
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CHF correlation(W-3)
3.3 Fuel thermal analysis
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HW#3: Chapter 3: Probelms 4, 5