1 Review on Conventional and Innovative Fuel Burning Schema for HTGRs Peng Hong Liem, Ismail, Yasunori Ohoka, Takashi Watanabe and Hiroshi Sekimoto Research Laboratory for Nuclear Reactors Tokyo Institute of Technology COE-INES Indonesia Symposium March 2-4, 2005 Bandung, Indonesia 2 Contents • Brief introduction on the conventional and innovative fuel burning schema for HTGRs – Block Fuel Element – Pebble Fuel Element • Procedures for solving fuel burning problems under core equilibrium condition • Some examples of analysis results • Impact of fuel burning schema on HTGR safety
Transcript
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Review on Conventional and Innovative Fuel Burning Schema
for HTGRsPeng Hong Liem, Ismail, Yasunori Ohoka, Takashi Watanabe and Hiroshi Sekimoto
Research Laboratory for Nuclear Reactors Tokyo Institute of Technology
COE-INES Indonesia SymposiumMarch 2-4, 2005
Bandung, Indonesia
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Contents• Brief introduction on the conventional and
innovative fuel burning schema for HTGRs– Block Fuel Element– Pebble Fuel Element
• Procedures for solving fuel burning problems under core equilibrium condition
• Some examples of analysis results• Impact of fuel burning schema on HTGR safety
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1. Brief introduction on the conventional and innovative fuel
burning schema for HTGRs
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Block-Type Fuel Element (1/2)
Coated Fuel Particle
Fuel Kernel
Fuel Compact
SiC/PyC Coated Layers (4)
1 mm
26 mm
39 mm
8 mmT 580 mm
End Plug
Fuel RodFuel Assembly
(HTTR: Pin-In-Block)
Graphite Sleeve
Fuel Compact
Dowel
Fuel Rod
Burnable Poison Hole
34 mmD
360 mm
Other Block-type (GA): Multihole(Fuel and Coolant Holes)
Coolant flows between fuel compact and graphite sleeve
Source: JAERI-HTTR
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Block-Type Fuel Element (2/2)
• Past Experimental/Demonstration Reactors– Dragon (OECD, Winfrith, UK)– Peach Bottom 1 (GA, Peach Bottom, Pa., US)– Fort St. Vrain (GA, Platteville, Co., US)
• Currently Operating Experimental/Research Reactors– High Temperature Test Reactor, HTTR (JAERI, Oarai, Japan)
CANDLE Burning Scheme (1/3)Applied to Block-type HTGRs
• Constant Axial Shape of Neutron Flux, Nuclide Densities and Power Shape During Life of Energy Producing Reactor (Sekimoto, H. et. al., Nucl. Sci. Eng. 139, 2001)
• Features:– No need for burnup reactivity control mechanism– Constant reactor characteristics (simple reactor
operation)– Reactor height is proportional to core lifetime– kinf of fresh fuel < 1 (optimal use of BP); small risk of
criticality accident
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CANDLE Burning Scheme (2/3)
BurningDirection
(Axial)
Spent Fuel
Discharge
Loading
Fresh Fuel
Loading
Fresh Fuel
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CANDLE Burning Scheme (3/3)
• Fresh Fuel Region (k<1)– BP is burnt slowly by
neutrons leaked from the burning region
• Burning Region (k>1)– BP is almost completely
burnt– Fissile material is depleted
for producing energy and neutrons
– Fertile material is converted to fissile material
• Spent Fuel Region (k<1)– Fission products are
accumulated– Depleted fuel
BurningDirection
BP Fissile
FP
Flux
BP：Burnable PoisonFP：Fission Products
Steady-State(Equilibrium)
Burning Region
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Pebble-Type Fuel Element (1/2)
SiC/PyC Coated Layers (4)
Fuel Kernel
1mm
6 cm
Coolant flows between pebbles
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Pebble-Type Fuel Element (2/2)• Past Exp/Proto Reactors
j is core cycle, S is reshuffling and refueling matrix. Example:
)(EOC),(BOC),( 1Fresh
)()1( rNrSNrN ++ += jjj
NTN ),,(1 σλΦ=∂∂
svs
vs is pebble flow velocity or burning region velocity
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Φ=Φ ),(1),( σσ NFNMk
NTN ),,(1 σλΦ=∂∂
svs
SOR-Newton Method
Φ∂Φ∂Φ
−Φ=Φ Φ+
),(),()()1(
NfNfωll
NNgNgNN
∂Φ∂Φ
−=+
),(),()()1(
Nll ω
Good guesses for
Given
)0(N )0(Φ
sv
Sekimoto, H., et. al., J. Nucl. Sci. Tech. 24(10), 1987Obara, T. and Sekimoto, H., J. Nucl.Sci. Tech. 28(10), 1991
PREC Algorithm
0Nf =Φ),(
0Ng =Φ),(
Acceleration parameter similar to SOR method
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Φ=Φ ),(1),( σσ NFNMk
NTN ),,(1 σλΦ=∂∂
svs
Liem, P.H., Ann. Nucl. Energy 21(5), 1994Liem, P.H., Ann. Nucl. Energy 23(3), 1996
Given sv
)0()0(
)0( ),(1),( Φ=Φ σσ FreshFresh
kNFNM
)()()1(
),,(1 ll
s
l
vsNTN σλΦ=
∂∂ +
),(1),( )1()1()1(
)1()1( +++
++ Φ=Φ lll
ll
kNFNM
Batan-MPASS Algorithm (1/2)
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Annals of Nuclear Energy 29 (2002) 1345–1364Direct deterministic method for neutronicsanalysis andcomputation of asymptotic burnupdistribution in a recirculating pebble-bed reactorW.K. Terry*, H.D. Gougar, A.M. OugouagIdaho National Engineering and Environmental Laboratory
Asymptotic=Equilibrium
Recirculating=Multipass
Batan-MPASS Algorithm (2/2)Comparison with Other Codes
PREC
PREC2
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Φ=Φ ),(1),( σσ NFNMk
)()()(
)1(
),,(1 lll
z
l
vzNTN σλΦ=
∂∂ + )()(
)(
)1(
),,(1 lll
z
l
vzNTN σλΦ=
∂∂ +
)0(zvGood guesses for )0(Φ
Ohoka, Y. and Sekimoto, H., Nucl. Eng. Design 229(1), 2004
),(1),( )1()1()1(
)1()1( +++
++ Φ=Φ lll
ll
kNFNM
∫∫Φ
Φ=+
dV
dVzz
l
ll
C )(
)()1(
)1( +lzvCorrect )()1( l
Cl
C zz −+based on
SRAC-CD Algorithm
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3. Examples of Analysis Results
• Case Study: Small-Size HTGRs (25 MWth)• Burning Schema:
