IFE Reactor Chamber Design and Blanket Issues Some Comments

1
IFE Reactor Chamber Design and Blanket
IssuesSome Comments

• Presented by A. René Raffray
• UCSD
• TITAN Workshop on System Integration Modeling on
  MFE and IFE
• University of California, Los Angeles
• Los Angeles, CA
• February 5, 2008

2
IFE Based on Lasers, Direct Drive Targets and
Solid Wall Chambers
3
Example of IFE Energy Source Based on Lasers,
Direct Drive Targets and Solid Wall Chambers
(HAPL)
Target (fabrication at lt20K, survival in chamber
during injection)
Blanket
Chamber conditions (0.1-1 eV depending on
pre-shot conditions)
Dry wall chamber (armor must accommodate
ionphoton threat at up to 2000-3000K)
4
What are the Threats on the Chamber Wall?
Example energy partitioning for 350 MJ-class
direct drive target (HAPL reference from J.
Perkins, Oct. 2005)
Chamber wall
Target micro-explosion
X-rays Fast debris ions Neutrons

• X-ray, ion and neutron fluxes to the chamber wall
  several times per second.
• Neutron flux penetrates deeper and not an issue
  for armor.
• Need to develop armor that can accommodate X-ray
  and (more importantly) ion threats.

5
Ion and Photon Threat Spectra Cover Appreciable
Energy Ranges
Example spectra for 350 MJ-class direct
drive target (HAPL reference, J. Perkins,
Oct. 2005).
6
Ion Power Deposition Occurs in a Very Thin Armor
Region (?ms) over a Few ?s
Example case for 10.75 m chamber without
protective gas to avoid target survival and
placement issues. Only thin armor region sees
large energy deposition and temperature
transients (next slide). This led to the
configuration choice of a thin armor layer ( 1
mm) on a FS substrate. Blanket at the back
sees quasi steady state (similar to MFE). W
chosen as preferred armor material
(high-temperature capability, no tritium
concern). Armor lifetime is a key issue and
is the focus of the RD in this area.
7
Temperature History and Gradient for W Armor in a
10.75 m Chamber Subject to the 350 MJ-Class
Baseline Target Threat Spectra (from HAPL)
1-mm W on 3.5 mm FS at 580 C. No chamber
gas. Time-of-flight spreading of ion energy
deposition results in much lower temperature
rise than assumption of instantaneous energy
deposition. Peak temperature 2400C.
8
Impact of Threat Spectra on W Armor Lifetime

• Several possible mechanisms could lead to
  premature armor failure
• - Ablation.
• - Melting (is it allowable?).
• - Surface roughening fatigue (due to cyclic
  thermal stresses).
• - Accumulation of implanted helium.
• - Fatigue failure of the armor/substrate bond.

Because the exact IFE ion and X-ray threat
spectra on the armor cannot be duplicated at
present, experiments are performed in simulation
facilities as part of the HAPL program - Ions
(RHEPP_at_SNL). - Laser (Dragonfire_at_UCSD). - Fatig
ue testing of the W/FS bond in ORNL infrared
facility. - He management is addressed by
conducting implantation experiments (UNC, UW)
along with modeling of He behavior in tungsten
(UCLA).
9
Armor Survival Constraints Impact the Overall IFE
Chamber Design and Operation
W temperature limit of 2400C assumed for
illustration purposes (1.2 J/cm2 roughening
threshold from RHEPP results) Limit to be
revisited as RD data become available
Desirable to avoid protective chamber gas
based on target survival and injection
considerations
Large chamber maintained as baseline for
HAPL Possibility of advanced chambers
explored, in particular use of magnetic
intervention to stir away the ions and help
achieve a more compact chamber
Example chamber parameters for 0 gas
pressure - Yield 350 MJ R10.5 m Rep. rate
5 for 1750 MW fusion
10
Self-Cooled Li Blanket for Large HAPL Chamber

• Large chamber size (R10-11 m) led to the
  division of blanket modules in two (upper and
  lower halves).

The design is based on an annular geometry
with a first Li pass cooling the walls of the
box and a slow second pass flowing back
through the large inner channel. Optimized
for good performance when coupled to a
Brayton cycle via a HX (? up to 49 for ODS FS
and TBR gt 1.1). Other designs considered as
back-up options.
11
Magnetic Intervention Utilizing a Cusp Field to
Create a Magnetic Bottle Preventing the Ions from
Reaching the Wall and Guiding them to Specific
Locations at the Equator and Poles

• Utilization of a cusp field for such magnetic
  diversion has been experimentally demonstrated
  previously
• - 1980 paper by R.E. Pechacek et al.,
• Following the micro-explosion, the ions would
  compress the field against the chamber wall, the
  latter conserving the flux. Because of this flux
  conservation, the energetic ions would never get
  to the wall.
• One possibility would be to dissipate the
  magnetic energy resistively in the FW/blanket,
  which reduces the energy available to recompress
  the plasma and reduces the load on the external
  dumps
• - about 50-70 of ion energy dissipated in
  blanket
• - about 30-50 of ion energy in dump region

More details in SOFE 2007 presentation D. V.
Rose, A. E. Robson, D. R. Welch, T. C. Genoni, J.
L. Guiliani and J. D. Sethian, "Computational
Analysis of the Magnetic Intervention Concept for
First Wall Protection from Energetic Ions in KrF
Laser Driven IFE,
12
Biconical Chamber Well Suited to Cusp Coil
Geometry and Utilizing SiCf/SiC for Resistive
Dissipation
SiCf/SiC blanket with Pb-17Li or flibe as
liquid breeder (tight assembly of
submodules). Armored ion dumps schematically
shown inside chamber, but preferably placed
outside for easier maintenance access.
Water-cooled steel shield is lifetime component
and protects the coil (can also be locally placed
around coils).
Example Chamber Parameters
13
Self-Cooled Pb-17Li or Flibe SiCf/SiC Blanket
Optimized for High Cycle Efficiency
Simple annular submodule design builds on
ARIES-AT concept.
Coolant flows in two-pass first pass through
the annular channel to cool the structure and a
slow second pass through the large inner channel
where it is heated to a high temperature
(gt1000C) while the SiCf/SiC temp. is maintained
lt1000C. High Brayton cycle efficiency
( 50-60). For flibe, 1 cm Be layer needed
at front of module for tritium breeding and
chemistry control.
Magnified View of Schematic Cross-section
14
Self-Cooled Pb-17Li (or flibe) SiCf/SiC Blanket
Coupled to a Brayton Cycle through a He HX
3 Compressor stages (with 2 intercoolers) 1
turbine stage DP/P0.05 1.5 lt rplt 3.5

• - DTHX 30C
• - hcomp 0.89
• - hturb 0.93
• - Effect.recup 0.95

15
Self-Cooled Blanket Concept Coupled to a Brayton
Cycle (Pb-17Li SiCf/SiC and Flibe SiCf/SiC)
Pb-17Li
From simple estimate for flibe with same
blanket configuration as Pb-17Li - Flibe low
Re and poor heat transfer properties result in
lower cycle ? and higher ?P for given
SiCf/SiC Tmax constraint. Need to perform
analysis for optimized flibe configuration
16
Integrated Chamber Core (work in progress)

• Vertical maintenance for core components.
• Horizontal maintenance for equatorial ion dump
  (described later).
• Magnets inside VV and protected by local
  shield around them.
• Vacuum pumping done through shielded vertical
  ducts below the chamber.
• - An array of 32 turbo-molecular pumps can
  keep the chamber pressure lt0.5 mTorr
  (low pressure desired for both
  target survival during injection and to
  prevent charge exchange with the
  expanding ions).

17
IFE Based on Heavy Ion Beam Driver,
Indirect-Drive Target and Thick Liquid Wall
Chamber
18
Example of Thick Liquid Wall Concept with Heavy
Ion Beam Driver and Indirect Drive (HYLIFE-II)
Schematic of liquid jets that make up TLW
protection
CAD model of HYLIFE-II chamber for the RPD (S. YU
et al., An Updated Point Design for Heavy
Ion Fusion, Fusion Sci. Technol., 44, 266, 2003)
19
Energy Partitioning and Photon Spectum for
Example 458-MJ Heavy Ion Indirect-Drive Target
20
Physical Processes in X-Ray Ablation
Volumetric heat deposition in a flibe wall or
curtain at 0.5m from the microexplosion for the
458-MJ indirect-drive photon spectra,
illustrating the region where explosive boiling
is likely to occur.
From A.R. Raffray, S. I. Abdel-Khalik, D.
Haynes, F. Najmabadi, P.Sharpe, M. Yoda, M.
Zaghloul and the ARIES-IFE Team, "Thermo-Fluid
Dynamics and Chamber Aerosol Behavior for Thin
Liquid Wall under IFE Cyclic Operation," Fusion
Science Technology, 46, 438-450, November 2004.
21
Summary of Simulation Capabilities of Different
Models and of Simulation and Measurement
Capabilities of DifferentExperimental Facilities
in Addressing IFE Liquid Wall Mechanisms