KEK

1
Preliminary ANSYS thermal/stress simulations of
JPARC-nu Beam Dump

• Outline of current work
• Proto-collaboration between KEK and RAL
• Translate MARS 2D-axisymmetric data file from T.
  Ishida
• Build corresponding ANSYS model
• Input MARS power deposition results
• Apply baseline cooling Boundary Conditions
• Calculate equilibrium temperatures and stresses

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Preliminary ANSYS thermal/stress simulations of
JPARC-nu Beam Dump

• Purpose of current work
• Benchmark previous simulation
• Make increasingly realistic simulations e.g.
• Thermal gaps/joints between material blocks
• Temperature dependent and orthotropic material
  (graphite) properties
• Highlight problem areas (high temperatures/stresse
  s)
• Propose and investigate potential solutions e.g.
• Change material/distribution new MARS simulation
• Change cooling path
• Sub-divide/shape material

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Heat Load (Normal Operation, 4MW)
Max. Heat Load 14.0 J/cm3 4.1?/spill
Fe 0.15J/cm3
Total Heat Load 1.1MW sr 15cm
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Concrete
Cu
Fe
Water cooling path between Cu and Fe h 600
W/m2K (water at 30C)
Free convection around Mupit surface h 6.1
W/m2K (30C) (air at 30C)
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Static thermal stresses in unconstrained copper
block only. Von Mises equivalent stress 316 MPa
at 4MW (gt2 x Ultimate Tensile Strength!) NB Beam
pulse thermal shock is additional to this
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Temperatures in Aluminium Copper Hybrid Beam
Dump Max. temp of Al 628C (cf MP 660C!)
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Graphite Cu Hybrid design Anisotropic PSG-332
graphite
Copper
Separated but convection linked graphite and
copper surfaces qhfA(T1-T2), Value used hf5
W/m2K
Graphite
Health Warning Thermal conductivity drop for
graphite probably pessimistic Convection link
value pessimistic measured value (Tada) is much
more effective
Temperature
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Graphite Cu Hybrid design Anisotropic PSG-332
graphite, sub-divided
Separated but convection linked graphite and
copper surfaces qhfA(T1-T2), Value used hf5
W/m2K
Health Warning Thermal conductivity drop for
graphite probably pessimistic Convection link
value pessimistic measured value (Tada) is much
more effective
Temperature
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Graphite Cu Hybrid design Sub-divided
anisotropic PSG-332 graphite Sub-divided copper
Copper
Graphite
Health Warning Thermal conductivity drop for
graphite probably pessimistic Convection link too
poor measured value (Tada) is much more
effective
Temperature
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Summary of results so far
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Preliminary conclusions

• Can successfully translate MARS simulation data
  file into ANSYS model.
• Success with modeling air/He gaps by convection
  links between different modules and material
  blocks.
• Introducing low z material before copper reduces
  peak power density in Cu and consequently reduces
  thermal stress.
• Current design still limited by maximum thermal
  stress in Cu
• May be necessary to reduce cooling radius from
  1.5 m water activation issues

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Next steps

• Use better material (graphite) data
• Use measured (M.Tada) convective heat link data
  between separate material blocks much higher
  value than used in simulations so far
• Further sub-divide graphite and copper blocks
• Optimise cooling radius
• Calculate thermal shock (LS Dyna code)
• Perform full 3-D analysis
• Generate conceptual engineering designs get
  more people involved at RAL

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