Post on 05-Apr-2018
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Heat Transfer for a NuclearReactor
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Review Heat Transfer Terms
Conduction-occurs across the medium1
Convection-occurs between a surfaceand a moving fluid
2
Radiation Heat Transfer-occursbetween two surfaces
3
q kdt
dx
q h(Tc Tb )
q Ts4 T
sur
4
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Heat Generation
200 MeV/ fission (ER)
Ed = Energy deposited in locally ~180MeV
Number of fissions in a core are afunction of the FLUX(f
FLUX is a function of position in thecore fr,z
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Heat Generation
H
R
r
z
qr(r) 2.32PE
d
nERJ0
2.405r
R
qmax 1
2Ha2qr(0)
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Decay heat
Heat is released asthe accumulated
fission productsdecay
The amount of heatis fission products to the power level
P t0,ts P
P ts P
P t0 ts
P
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Coolant Flow q=w(hout-hin)
Steam
Tout
Water
Tin
Tin
Tout
q
q
Recirculating
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Plate fuel
X
a a+ba
a+b
Tfuel Tmax q a2
2kf
Tclad Ts x a
bTs Tc
q TmaxTc
a2kfA
bkcA
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Cylinder
z
Tmax
Ts
Tc
TF
Tfuel Tmax q r2
4kf;
Tclad Ts ln(a b) Tc ln a (Ts Tc )ln r
ln 1b
a
a
a+b
q 2Hkc (Ts Tc )
ln 1b
a
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Coolant Channels
Now you need toremember more
heat transfer andfluid mechanics
The heat transfer fora channel is
h Ck
De
Re
mPr
n
C 0.042P
D
0.024
Re D
;Pr
;Nu
hL
kf
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Other coolants
Gas cooled Helium
Pebble bed in development
Liquid sodium and potassium
Need corrosive resistant structure
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The Boiling Crisis
ln q
T
Annular flow
Partial film
Full film
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LOCA
Address component breakdown or acombination of component breakdowns
that lead to interruption of normalcooling
When an interruption occurs, the fission
process is terminated, however heatgeneration continues
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Classifications of operation
Normal
Operational transients
Upsets
Emergencies
Limiting Fault Conditions includesDesign basis accident DBA
Unprotected or beyond DBA
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Engineered Safety Systems
The actions aredone as a result of
instrument signalsReliability
Duplication
Diversity
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Most common ESS
Alternate cooling
SCRAM - Tripping - insert control rodsto stop fission
Control
Cool
Contain
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Some examples
Millstone 1(660 MWe BWR) - corrosion ofcondensers leads to sea water to enter
primary cooling circuitBrowns ferry fire -(2 1065 MWe BWR 1 inconstruction) fire affected 2000 cables causeabout $10 M
Three mile island- relief valve stuck openGinna 490 MWe PWR- rupture in a steamgenerator tube
Mihama-2 - 500 MWe PWR rupture in a
steam generator tube
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More examples
Chornobyl-Chernobyl
Chalk River - NRX- control rod/ operator error
forerunner to the CANDUWindscale fire- UK large air cooled piledesigned for Pu burst fuel cartridge
St. Laurent - French
Hunterston scotland - Seawater in the reactorvessel
Hinckley point
EBR-1 and Fermi -1 fast breeder.