CBBI-14 20060907 JHF 1

Thermomechanical Model developed for the Pebble Bed Assembly applied to other Pebble Bed

Mock-Up Tests

J.H. FokkensNRG PPT

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• thermomechanical pebble bed model

• application to HCPB in-pile test element

• results HELICA analyses

• next steps

Contents _______________________________________________________________________________________________________________________

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• reliable temperature prediction- feasibility in-pile test module- determination test matrix

• engineering tool- lay-out in-pile test module- determination of gas gap dimensions- determination of pre-compaction procedure- safety evaluation

Thermomechanical Pebble Bed Model (1) _______________________________________________________________________________________________________________________

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• describe observed behaviour- non-linear elasticity- initial compaction behaviour- creep compaction behaviour- strain dependent thermal conductivity of pebble bed

• based on available test data- oedometer experiments

Thermomechanical Pebble Bed Model (2) _______________________________________________________________________________________________________________________

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Thermomechnical Pebble Bed Model (3) _______________________________________________________________________________________________________________________

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HCPB In-Pile Test Element _______________________________________________________________________________________________________________________

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HCPB In-Pile Test Element _______________________________________________________________________________________________________________________

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HELICA Geometry and FE-model _______________________________________________________________________________________________________________________

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HELICA Thermal boundary conditions (1) _______________________________________________________________________________________________________________________

h = 10 W/m2K Tsink = 20oC

h = 145 W/m2K Tsink = 250oC

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HELICA Thermal boundary condition (2) _______________________________________________________________________________________________________________________

h = 84 W/m2K Tsink = 250oC

h = 84 W/m2K Tsink = 250oC

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HELICA Mechanical boundary conditions _______________________________________________________________________________________________________________________

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HELICA Loading conditions _______________________________________________________________________________________________________________________

Schnorr springs (p = 0.09 MPa)

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• thermomechanical model for pebble bed- non-linear elasticity- initial compaction- creep compaction

• generalized plane strain• MSC.Marc Version 2005• gap development at interfaces pebble bed - solids• heat transfer through gaps by purge gas conduction• analysis of complete loading cycles

HELICA Summary of analysis _______________________________________________________________________________________________________________________

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HELICA TC-positions (1) _______________________________________________________________________________________________________________________

2.70

16.5

102.70

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HELICA Results (1) _______________________________________________________________________________________________________________________

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HELICA Results (2) _______________________________________________________________________________________________________________________

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HELICA Results (3) _______________________________________________________________________________________________________________________

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HELICA Results (4) _______________________________________________________________________________________________________________________

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HELICA Results (5) _______________________________________________________________________________________________________________________

mean initial compaction strain

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HELICA Results (6) _______________________________________________________________________________________________________________________

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HELICA Results (7) _______________________________________________________________________________________________________________________

mean creep compaction strain

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HELICA Results (8) _______________________________________________________________________________________________________________________

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HELICA Results (9) _______________________________________________________________________________________________________________________

mean total compaction strain

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HELICA Results (10) _______________________________________________________________________________________________________________________

gap development after cooldown

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HELICA Results (11) _______________________________________________________________________________________________________________________

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• comparison calculated results with TC measurements

• comparison calculated results with deformation measurements

• optimisation of boundary conditions

• improvement of thermomechanical pebble bed model

HELICA Next steps _______________________________________________________________________________________________________________________

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