Systems Modeling for IFE Power Plants

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Systems Modeling for IFE Power Plants
Rob Schmitt, Wayne Meier LLNL High Average Power
Laser Program Meeting Los Angeles, CA June 2,
2004 Work performed under the auspices of the U.
S. Department of Energy by Lawrence Livermore
National Laboratory under Contract W-7405-Eng-48.
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Introduction

• Update on lithium-cooled blanket model
• W/FS interface ?T constraint not yet included
  waiting for resolution of discrepancies in W
  surface temperature calculated by different codes
• Costing for FW and blanket now included (need to
  add shield/reflector)
• Progress on the helium-cooled solid breeder
  concept
• 1-D heat transfer calculations and temperature
  constraints for first wall have been added
• Breeding blanket details to be added next
• Modular Rankine cycle unit efficiency scaling as
  function of He outlet temp included

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Systems code of Li-cooled blanket is based upon
ARIES design

• Material masses needed for cost scaling are
  roughly based on an ARIES-type blanket.
• First wall unit includes first wall (W/FS), Li
  coolant, and coolant channel outer wall
  (FS/SiC/W). (See detail on far right)
• Remainder is considered as the breeding blanket,
  mostly Li (98) with FS structures (2).
• Shield has not yet been included (requirements
  likely different for IFE since no superconducting
  magnets to protect).

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Costing for Li-cooled blanket is based on ARIES
unit costs (escalated to 2004)
Material Mass (Mg) Unit costs (/kg) (2004) Approximate cost (M)
Tungsten 48 111 5.3
Ferritic steel 152 91 13.8
SiC 3.2 544 1.7
Liquid lithium 337 67 22.6

• Example Y 300 MJ, p 10 mtorr, Rwall 8.9 m
• FW unit 1.5 mm W / 3.5 mm FS / 2 cm Li / 3 mm
  FS / 1 mm SiC / 1 mm W
• Blanket 60 cm thick, 98 vol Li, 2 vol FS
• Will use updated unit costs from Les Waganer
  (ARIES) when they are available.

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He-cooled first wall has been modeled

• Temperature Constraints
• Tungsten Wall 2400 oC
• Ferritic Steel 800 oC
• Steady-state heat flux
• Includes 3.5 heating from neutrons
• Heat transfer coefficient is an important
  parameter to understand. (needs to remove heat
  from system)

temp
2400 oC (max)
800 oC (max)
q
THe
W
FS
Forced He
distance
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Radius of first wall depends on target yield and
chamber gas pressure

• Chamber radius determined by using W temperature
  constraint (2400 C) for single pulse ?T.

Rep-Rate 10 Hz
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A heat transfer code was used to find the
convective heat transfer coefficient

• Dr. Shahram Sharafat (UCLA) has provided us with
  a heat transfer code which calculates the
  convective heat transfer coefficient for helium
  based upon a variety of parameters.
• Heat transfer dependent on pressure, velocity,
  temperatures, pipe diameter and roughness.
• Using a fixed velocity (v 50 m/s) and
  fractional roughness (10 of pipe diameter) a
  parameter study was done in Mathcad to find a
  curve-fit for the heat transfer coefficient.

2.5 mm lt D lt 2 cm
Curve fit within 10 for
2 MPa lt P lt 30 MPa
350 K lt T lt 1100 K
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The heat transfer coefficient needed is within
reasonable limits of engineering design

• Need adequate cooling of the steady-state fluence
  using convection of the helium along the ferritic
  steel surface.
• Constants 10 mtorr Xe, Dpipe 1.7 cm, P 8 MPa,
  V 50 m/s

• At fixed He pressure, HT coefficient decreases
  with increasing temperature
• 154 MJ case allows Tmax 860K ? HT coeff 8200
  W/m2K
• 300MJ case allows Tmax 830K ? HT coeff 8400
  W/m2k

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The max allowable FS temp is the limiting
constraint and sets the max He outlet temp

• The FS temp (1073 K at the W/FS interface) is the
  most constraining temp, therefore helium
  temperature is set for given yield and rep-rate.
• As shown on graph, the He outlet temp is given
  for a specific yield and radius.

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A modular Rankine cycle model is being developed
to couple with the blanket designs

• Curve fits have been created to model the
  efficiency of the steam cycle based upon chamber
  outlet helium temperature, as this is the most
  important parameter.
• Cycle efficiencies range from 38-42 for 154 MJ
  and 300 MJ examples. (assuming chamber outlet
  FW outlet temp)
• If blanket materials can operate at higher temps,
  He from FW could be channeled through blanket to
  achieve higher chamber outlet temp and
  efficiency.

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Summary / next steps

• Work on the lithium-cooled blanket design is
  essentially complete
• Helium-cooled first wall scaling complete
• Rankine cycle efficiency scaling now included
• Next steps
• Add solid breeder blanket information.
• Include blanket cooling approach coupled or
  separate from FW cooling?
• Add costing for solid breeder blanket.
• Possibly start on molten salt coolant/breeder
  option.