005 - Fuel Design Requirements_Al Manzer

CNS Fuel Technology Course:Fuel Design Requirements

CANDU FUEL TECHNOLOGY COURSE2008 JanuaryAl Manzer CANTECH Associates

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OutlineOriginal Design Criteria and CANDU Fuel History

Fuel Element Design Features (see notes)Fuel Bundle Design Features (see notes)Fuel Design Requirements for 1970s

Fuel Design Requirements for 1980s

Fuel Design Requirements for 1990s+

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Introduction (cont.)

The design is verified by a number of methods: Engineering analysisSimulation by modelling.Materials tests.Type testing.

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Birth of CANDU Fuel (1950s)Original NPD Reactor Design in 1954:10 MW PlantVertical pressure vesselOff-power refuellingLong fuel assemblies (= core length)Uranium metal as fuel materialStainless steel fuel cladding being consideredNPD redesigned, construction halted in 1957:20 MW PlantHorizontal with Zr alloy pressure tubesOn-power refuellingShort fuel bundles (19.5 inches long)Uranium Oxide ceramic as fuel materialZr alloy fuel cladding

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Criteria for Fuel Development (1950s)W.B. Lewis stated that CANDU Fuel: Must be safe, reliable, low risk of release of radioactive fission

products no systematic fuel failures

Must have good neutron economy, i.e., low neutron absorption materials

Must meet power specifications, i.e., 1 MW per fuel bundle no distortion in 1-4 years in-reactor

Must be easily handled Must be cheap

1 mils/kWh (0.1 cents/kWh)

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CANDU Fuel Bundle Types (Past)

7 Element NPD (1st Charge)

19 Element (9 reactors)

18 Element CANDU BLW(1 reactor)

NPD

Raps 1

NPD Raps 2

KANUPP Maps 1

Douglas Point Maps 2

Naps 1 Naps 2

Gentilly 1

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CANDU Fuel Bundle Types (Present)

28 Element Pickering(8 reactors)

37 Element Bruce/Darlington

(12 reactors)

37 Element CANDU 6(10 reactors)

Pickering 1 Pickering 5Pickering 2 Pickering 6Pickering 3 Pickering 7Pickering 4 Pickering 8

Bruce 1 Bruce 5 Darlington 1Bruce 2 Bruce 6 Darlington 2Bruce 3 Bruce 7 Darlington 3Bruce 4 Bruce 8 Darlington 4

Pt Lepreau Gentilly 2 Embalse Wolsong 1-4Cernavoda Qinshan 1-2

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CANDU Fuel Bundle Types (Present)

43 Element CANFLEX LVRF(replacing 37 Element in Bruce B)

AECL/KAERI/Bruce Power Project

Demonstration Irradiation started 2006 in Bruce B

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Fuel Design Requirements (1970s)

CANDU Fuel must meet the requirements imposed by the reactor interfacing systems:

Heat Transport System (or Primary Coolant Circuit)

Fuel Channels Fuel Handling Systems Fuel Management (Nuclear Design, or Reactor

Physics)

Reactor interfacing systems must meet requirements imposed by CANDU Fuel

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Fuel Duty Cycle

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Heat Transport System Requirements on Fuel Design

1. The pressure drop over fuel bundles in each fuel channel must be compatible with the design allowance of the heat transport system.

2. The fuel must withstand flow induced vibration.3. The thermal performance of the bundle must be acceptable for

all normal operating conditions.4. The fuel elements must withstand the coolant pressure during

normal operation. 5. The fuel elements must contain fission products during normal

operation.6. The uranium contamination on surfaces of the as-manufactured

fuel bundles must be minimized.

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Fuel Channel

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Fuel Channel Requirements on Fuel Design

1. The bearing pads must not reduce the wall thickness of the pressure tube below the design allowance.

2. The fuel bundle must withstand the loads caused by the coolant hydraulic drag (and the fuelling machine ram).

3. The fuel bundle must not jam in the fuel channel.

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Full Length Fuel Channel

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CANDU 6 Fuelling SchemeFLOW --->

1 2 3 4 5 6

SHIELD PLUG REMOVED, 1st BUNDLE PAIR LOADEDN N 1 2 3 4 5 6

1st NEW BUNDLE SWEPT BY COOLANT REFUELLING IMPACTN N 1 2 3 4 5 6

2nd NEW BUNDLE PUSHED INTO POSITIONN N 1 2 3 4 5 6

2nd BUNDLE PAIR LOADEDN N N N 1 2 3 4 5 6

3rd BUNDLE PAIR LOADEDN N N N N N 1 2 3 4 5 6

FUEL COLUMN DISPLACED TO ALLOW F/M MAGAZINE ROTATIONN N N N N N 1 2 3 4 5 6

4th BUNDLE PAIR LOADEDN N N N N N N N 1 2 3 4 5 6

N N N N N N N N

N N N N N N

F/M RAM STOPS AT CORE LINE, COOLANT DRAG PUSHES FUELN N N N

N N

SHIELD PLUGS RELOADED AND LOCKEDN N N N N N

FUELLING MACHINE ENDFITTING

AXIAL F

7 8 9 10 11 12

SHIELD PLUG UNLOCKED7 8 9 10 11 12

7 8 9 10 11 12

7 8 9 10 11 12

7 8 9 10 11 12

7 8 9 10 11 12

6 7 8 9 10 11 12

6 7 8 9 10 11 12

SIDESTOPS INSERTED SHIELD PLUG UNLOADED1 2 3 4 5 6 7 8 9 10 11 12

1st BUNDLE PAIR UNLOADEDN N 1 2 3 4 5 6 7 8 9 10 11 12

2nd BUNDLE PAIR UNLOADEDN N N N 1 2 3 4 5 6 7 8 9 10

3rd BUNDLE PAIR UNLOADEDN N N N N N 1 2 3 4 5 6 7 8

4th BUNDLE PAIR UNLOADEDN N N N N N N N 1 2 3 4 5 6

SHIELD PLUG READY FOR LOADINGN N N N N N N N 1 2 3 4

N N 1 2 3 4

CORE ENDFITTING FUELLING MACHINE

FLOW REGION

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Fuel Loading Sequence (Upstream End)

SHIELD PLUG REMOVED, 1st BUNDLE PAIR LOADEDN N 1 2 3

1st NEW BUNDLE SW EPT BY COOLANT REFUELLING IMPACTN N 1 2 3

2nd NEW BUNDLE PUSHED INTO POSITIONN N 1 2 3

2nd BUNDLE PAIR LOADEDN N N N 1 2 3

3rd BUNDLE PAIR LOADEDN N N N N N 1 2 3

FUEL COLUMN DISPLACED TO ALLOW F/M MAGAZINE ROTATIONN N N N N N 1 2 3

4th BUNDLE PAIR LOADEDN N N N N N N N 1 2 3

FLOW --->

1 2 3 4 5 6 7 8 9 10 11 12

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Fuel Unloading Sequence (Downstream End)

Bundle 12 loaded against Sidestops

Bundle 4 loaded against Sidestops

SIDESTOPS INSERTED SHIELD PLUG UNLOADED5 6 7 8 9 10 11 12

1st BUNDLE PAIR UNLOADED3 4 5 6 7 8 9 10 11 12

2nd BUNDLE PAIR UNLOADED1 2 3 4 5 6 7 8 9 10

3rd BUNDLE PAIR UNLOADEDN N 1 2 3 4 5 6 7 8

4th BUNDLE PAIR UNLOADEDN N N N 1 2 3 4 5 6

SHIELD PLUG READY FOR LOADINGN N N N 1 2 3 4

2 3 4

N N N N N N N N 1 2 3 4 5 6 7 8 9 10 11 12

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Fuel Unloading Sequence (Upstream End)

Bundle 12 loaded against Sidestops

Coolant Drag > Friction

Bundle 4 loaded against Sidestops

N N N N N N N N 1 2

N N N N N N N N

N N N N N N

N N N N

N N

N N N N N N N N 1 2 3 4 5 6 7 8 9 10 11 12

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Fuel Handling System Requirements on Fuel Design

1. The fuel bundle must not jam in the fuel handling systems.2. During refuelling, the fuel bundle must withstand the loads caused

by cross flow in the liner hole region of the endfittings.3. The fuel bundle must withstand refuelling impacts.4. The fuel bundle must have sufficient flexibility to allow for differential

expansion of the fuel elements and parallelogramming (or tilt of bundle) within a sagged pressure tube.

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Fuel Management Requirements on Fuel Design

1. The ends of the fuel bundles must minimize neutron absorption and withstand end flux peaking due to the gap between the UO2 in adjacent bundles.

2. The fuel bundles must be able to operate at high powers continuously.

3. The fuel bundle must withstand power changes due to refuelling and movement of the reactivity control mechanisms refuelling impacts.

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Fuel Design Requirements on Other Systems

1. The interfacing systems must not cause systematic fuel failures.(translates to at least 22 specific requirements!)

2. The components of the fuel channel and fuel handling systems must have sufficient allowance to protect against damage due to the interaction of fuel. (translates to at least 4 specific requirements!)

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Fuel Design Requirements (1980s)

1. In response to the seismic requirements of a potential CANDU reactor client, AECL agreed to include one more fuel design requirement

2. Fuel bundle must be able to withstand seismic loads while inside the pressure boundary of the heat transport system. For a design basis earthquake, the fuel must maintain coolable geometry and the fuel elements must contain fission products.

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Fuel Design Requirements (1990s+)

In recent years some CANDU users (Bruce Power) have developed new requirements for fuel which may require new design features:

1. Higher operating margins for dryout.2. Lower power pulses during Loss of coolant accidents.3. Lower coolant void reactivity (Fuel enrichment, burnable

poisons)

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CNS Fuel Technology Course:Fuel Design RequirementsOutlineIntroduction (cont.)Birth of CANDU Fuel (1950s)Criteria for Fuel Development (1950s)CANDU Fuel Bundle Types (Past) Fuel Design Requirements (1970s)Fuel Duty CycleHeat Transport System Requirements on Fuel DesignFuel ChannelFuel Channel Requirements on Fuel Design Full Length Fuel ChannelCANDU 6 Fuelling Scheme