Download - Review on Conventional and Innovative Fuel Burning Schema ......2 3 1. Brief introduction on the conventional and innovative fuel burning schema for HTGRs 4 Block-Type Fuel Element

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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)

• On-going Design (Near/Far Future)– Gas-Turbine Modular Helium Reactor, GT-MHR (US/Russia)– Gas-Turbine High-Temperature Reactor, GTHTR-300 (JAERI,

Japan)– Gas-Turbine HTR Cogeneration, GTHTR-300C (JAERI, Japan)– New Generation Nuclear Power Plant, NGNP (Pebble ? Block ?, US-

DOE)– Very High Temperature Reactor VHTR ANTARES (Framatome ANP

Demo, French)

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HTTR (1/4) Main Data

UO2 (FC 3-10 %)TRISO Fuel

22 GWD/TBurnup (Ave.)

1 Batch (Off-line)Fuel Loading

395/850 (950) ℃Inlet/Outlet Temp

2.5 W/ccPower Density

2.9/2.3 mCore Height/Diam.

-Electric Power

30 MWthThermal Power

Source: JAERI-HTTR

Burning Scheme

Whole core is removed at EOC and replaced by new FE

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HTTR (2/4) Burnup Control

Core Center

BP (B4C-C)

Effe

ctiv

e M

ultip

licat

ion

Fact

or (k

eff)

Burnup (days)

Keff of core without Burnable Poison

Reactivity compensated by BP

Keff of core with Burnable Poison

Excess reactivity (BOL)4.6 %Δk Excess reactivity (EOL)

2.6 %Δk

Yamashita, K et al., NSE 122 (1996)

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HTTR (3/4) Radial Power Control

Core Center

¼ Core1-st Layer

6.7 % 7.9 %

9.4 %

9.9 %U-235 Enrichment

Yamashita, K. et al.,NSE 122 (1996)

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Layer number of fuel blocks

Pow

er D

ensi

ty (W

/cc) U-235

6.7-9.9 %U-235 5.2-7.9 %

U-235 4.3-6.3 %

U-235 3.4-4.8 %

HTTR (4/4) Axial Power Control

Burnup10 days (BOL)

440 days

660 days (EOL)

Yamashita, K. et al.,NSE 122 (1996)

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GTHTR-300 (Japan)

2 Batch/Off-line (Sandwich Reshuffling)

Fuel Loading

120 GWD/TBurnup

UO2 (LEU)Fuel

587/850℃Inlet/Outlet Temp



279 MWElectric Power


Source: JAERI-HTTR

Burning Scheme

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• Gas-Turbine Modular Helium Reactor

3 Batch/Off-lineFuel Loading

640 GWD/tBurnup

Ex Weapon PuTRISO Fuel




286 MWElectric Power


GT-MHR(US/Russia)

Burning Scheme

Level of Pu-239 burning 90 % (Deep Burn)

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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

– Arbeitsgemeinschaft Versuchsreaktor, AVR (BBC/HRB, Hamm-Uentrop, FRG)

– Thorium High-Temperature Reactor, THTR-300 (BBC/HRB, Hamm-Uentrop, FRG)

– High-Temperature Reactor Modul, HTR-M (Siemens/Interatom, Design Only, FRG)

• Currently Operating Res Reactors– HTR-10 (Tsinghua Univ.-INET, China)

• On-going Design Proto/Demo/Commercial Reactors– Pebble Bed Modular Reactor, PBMR (Escom, South Africa)– HTR-PM (INET, Beijing, China)

• Near/Far Future Design– Peu-A-Peu, PAP-80, PAP-20, PAP-20-H (KFA-Julich, FRG)– Advanced Atomic Cogenerator for Industrial Application, Acacia/Incogen

(ECN, Petten, Netherland)– Modular Pebble Bed Reactor, MPBR (MIT, US)– New Generation Nuclear Power Plant, NGNP (Pebble ? Block ?, US-DOE)

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HTR-M Main Data

76He Gas Flow (kg/s)

6He Pressure (Mpa)

250/700He Temp (℃)

1020Fuel Residence Time (day)

80Fuel Burnup (GWD/t)

MultipassFuel Burning Scheme

UraniumFuel Cycle

TRISOCoated Fuel Particle

8Fissile Enrichment (%)

7HM loading/ball (g)

9.6Core Height (m)

3Core Diameter (m)

3Ave. Pow. Dens. (W/cc)

200Thermal Power (MWth)

Reutler, H. and Lohnert, G.H., Nucl. Technol. 62, 22 (1983), 78, 129 (1984)

Burningscheme

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OTTO Burning Scheme

• Once-Through-Then-Out (OTTO)

• Features:– No recycling of FE (Simpler

than Multipass )– No burnup measurement

devices and recycle mechanism

– Good axial power density profile for steady-state condition (power density is strongly tilted towards the top)

Spent

Fresh

Depleted CoreRegion

Reactive Core Region

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Multipass Burning Scheme (1/3)

• HTR-M• Features:

– Better neutron economy– Higher fuel burnup– Low max. power density– Low max. fuel temp.

during depressurization accident

Spent

Fresh

Small BU

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Multipass (2/3) - Inner Refl.

• PBMR (Nominal) Design• Features:

– Two pebble types (fuel and graphite)

– Central and peripheral loading tubes

– Higher max. power density at the graphite-fuel interfaces

– Better neutron economy (FC 8%) than alternative design

Fresh

Spent

Small BU

Graphite Ball

Graphite Ball

Inner ReflectorRegion

Core Region

H. D. GOUGAR, W. K. TERRY, and A. M. OUGOUAG(INEEL)

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Multipass (3/3) Out-In

• PBMR alternative design• Features:

– Central and peripheral loading tubes

– Control on the radial distribution of fuel burnup

– Radial power distribution flattening

– Worse neutron economy (FC 10%) than the nominal design

Fresh

Spent

Small BU

High BU

Depleted CoreRegion


H. D. GOUGAR, W. K. TERRY, and A. M. OUGOUAG(INEEL)

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Peu-a-Peu Burning Scheme (1/3)

• PAP-80, PAP-20, PAP-20H

• Acacia (Incogen)• Features:

– Simplest fuel loading scheme

– Axial power density is similar to OTTO and CANDLE

– Large difference of core pressure drops between BOC and EOC


Fresh

BOL(Critical)Depleted Region

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Peu-a-Peu Burning Scheme (2/3)Acacia/Incogen

18.0 MWthHeat Cogen


16.5 MWElectric Power


Source: NRG-Petten

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Peu-a-Peu Burning Scheme (3/3)Example: Small-Size HTGR

1.6Fissile Loading (kg/GWD)

250 / 700He Inlet/Outlet Temp. (C)

4.8 / 1.5Max. Pow. Dens. BOL/EOL (W/cc)

871 / 750Max. Fuel Temp. BOL/EOL (C)

28 / 17Neut Leakage BOL/EOL (%)

49.8 / 69.2Ave. and Max. BU (GWD/t)

8.0Uranium Cycle FC(%)

10Core Life Time (year)

1.2 / 6.9Core Height BOL/EOL (m)

3.0Core Diameter (m)

25Power (MWth)

Liem, P.H., Ann. Nucl. Energy 23(3), 1996

Max. Pow. Dens.

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2. Procedures for solving fuel burning problems under core

equilibrium condition

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Criticality

Φ=Φ ),(1),( σσ NFNMk

NTN ),,( σλΦ=∂∂

t

Non-Moving FE(Off-line, Batch refueling)

Moving FE, Burning Region(On-line, Cont. refueling)

NTNN ),,( σλΦ+∂∂

−=∂∂

sv

t sEquilibrium Core Conditions

0=∂∂

tN

Batan-EQUIL

PREC, PREC2 (OTTO)Batan-MPASS (Multipass)SRAC-CD (CANDLE)

Problem Statement

EOCBOC ),(),( )()1( ≤≤=+ ttt jj rNrN

jjj all )()1( SS =+

jjj all BOC),(BOC),( )(Fresh

)1(Fresh rNrN =+

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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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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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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)()()(

)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:

– Multipass– OTTO– Peu A Peu– CANDLE

• Fuel Cycle (Fissile Content 8 %)– Uranium– Thorium

Pebble Fuel Element

Block Fuel Element

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Burning Schema Comparison for Small-Sized HTGRs

BURNING SCHEME Multipass OTTO Peu-a-Peu CANDLE HTTRFuel Element Type Block Block

Fuel Loading Method - Off-line, Batch

Calculation Code Batan-Peu SRAC-CD NDCSThermal Power (MWth) 30Core Diameter (m) 2.3Fissile Content (%) 3-10Active Core Height (m) 4.5 4.5 6.9 4.0+2.0 2.9

4.5 4.5 4.0 3.0+2.0Core Life Time (year)/ 11.0 9.4 10.0 10.0 1.8Residence Time (year) 16.5 14.0 10.0 10.0Velocity (cm/day)/ 1.8 0.14 1774.0 0.108Fueling Rate (ball/month) 1.2 0.09 703.0 0.080Ave. Burnup (GWD/t) 78.5 67.2 49.8 48.3 22.0

117.0 99.4 71.1 76.4Max. Power Density (W/cc) 0.99 1.53 4.78 3.30 4.50

1.02 2.10 7.33 4.96

8.0

Batan-MPASS

Pebble

On-line, Continuous

25.03.0

Uranium Thorium Just for reference

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4. Impact of Burning Schema on the HTGR Safety

• Case Study: HTR-M (200 MWth)• Burning Schema

– OTTO– Multipass

• Fuel Cycle (Fissile Content 8 %)– Uranium– Thorium

• Accident Analysis: Depressurization Accident

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Burning Scheme Impact on Steady-State Power Dist.(Uranium Fuel)

200

300

400

500

600

700

800

0 200 400 600 800 1000 1200

Distance from top (cm)

Temperature (℃)

0

2

4

6

8

10

12

14

Power Density (W/cc)

OTTO

Multipass

HePebble

He Flow

Pow Dens

Top

Ref

l

Bot

tom

Ref

l

Upp

er V

oid


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0

2

4

6

8

10

12

14

16

0 200 400 600 800 1000 1200

Distance from top (cm)

Power Density (W/cc)

Fuel Cycle Impact on Power Distribution

He Flow

Top

Ref

l

Bot

tom

Ref

l

Upp

er V

oid

OTTO

Thorium

Uranium

MultipassThorium

Uranium


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HTR-M (OTTO)Max. Fuel Temp. During Depressurization Accident

He Flow

Top

Ref

l

Bot

tom

Ref

l

Distance from top of the core

Fuel Limit Temperature

Hiroshe, Y, Liem, P.H., Suetomi, E., Obara, T., Sekimoto, H, Journ. Of Nucl. Sci. Tech. 26 (1989)

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HTR-M (Multipass) Max. Fuel Temp. During Depressurization Accident

He Flow

Top

Ref

l

Bot

tom

Ref

l

Distance from top of the core

Fuel Limit Temperature

Hiroshe, Y, Liem, P.H., Suetomi, E., Obara, T., Sekimoto, H, Journ. Of Nucl. Sci. Tech. 26 (1989)

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Keywords to Memorize

• HTGR• Coated Fuel Particle• Block, Pebble-type FE• On-line, Off-line Refueling• Batch, Continuous Refueling• Multipass, OTTO, Peu-A-Peu• CANDLE• Uranium, Thorium, Ex Weapon Pu

Fuel• Fissile Content (enrichment)• Burnable Poison• Fuel Burnup• Max. Power Density• Max. Fuel Temperature• Depressurization Accident

• CANDLE– Large-Size CANDLE

Reactor Design– Radial Optimization– Thermal-Hydraulic

Design– Accident Analyses– Etc.

• Analysis Code Development

Future Works

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Terima kasih !