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NIF-0908-15298.ppt TOFE Conf, R. Abbott, 10/1/2008 2
A LIFE power requires the integration of several major subsystems
Powerconversion
Fuelinspection
Centralchamber
Target production
Tritiumstorage
LaserdriverPassive
cooling
NIF-0908-15298.ppt TOFE Conf, R. Abbott, 10/1/2008 3
This talk covers top-level thermal and mechanical features key to LIFE performance• Central chamber
• Active cooling systems
• Static structural stresses
• Power systems
NIF-0908-15298.ppt TOFE Conf, R. Abbott, 10/1/2008 4
LIFE design parameters can vary depending on chosen plant size and mission
Parameter Value
First wall radius 2.5 - 4.0 m
Target Illumination NIF-like or low-angle illuminationIgnition type Central hot-spot or fast / shock ignition
37.5 - 75 MJ13.3 HzODS ferritic steel (12YWT)
Tungsten-armored ODS ferritic steelPb-17Li (eutectic)Flibe (2 LiF + BeF2)Beryllium pebbles40 - 80 MT DU in pebbles or molten salt2000 - 4000 MWHelium Brayton700 - 1500 MWe
Fusion yieldRep-rateStructural material
First wall materialFirst wall coolantPrimary coolantNeutron MultiplierFuelThermal powerPower cycleNet electric power
NIF-0908-15298.ppt TOFE Conf, R. Abbott, 10/1/2008 5
The LIFE central chamber has nine layers1) Central cavity with inert fill gas
– Absorb fusion ions and x-rays
2) W on ODS first wall with Pb-17Li cooling– Vacuum barrier– Conduct fusion ion and x-ray energy
3) Inner primary coolant injection plenum– Generate isotropic outward radial flow
4) Beryllium multiplier pebble bed– Neutron multiplication and
moderation
1
3 42
1 cm Ø60% packing
25% perforated walls
NIF-0908-15298.ppt TOFE Conf, R. Abbott, 10/1/2008 6
5) Fuel pebble bed
6) Graphite reflector pebble bed
7) Primary coolant extraction plenum
8) Outer primary coolant injection plenum
9) Outer wall– Structural component– Vacuum barrier
56
78 9
The LIFE central chamber has nine layers (cont.)
2 cm Ø60% packing
25% perforated walls
NIF-0908-15298.ppt TOFE Conf, R. Abbott, 10/1/2008 7
x-rays
ions
n
4 μg/cm3 Xe
2.5 m
Thermally robust targets allow for a protective chamber gas to absorb all ions and 90% of x-rays
9− 8− 7− 6− 5− 4− 3− 2−600
800
1000
1200
1400
1600
1800
log(t(s))T(
°C)
Protective background gas re-radiates ion and x-ray energy over a timescale thermal conduction can effectively remove it
NIF-0908-15298.ppt TOFE Conf, R. Abbott, 10/1/2008 8
Pb-17Li enters–Tc = 260 °C–m = 4.5 MT/s–v = 5.5 m/s–h = 35 kW/m2/K–Tw = 450 °C
Dedicated Pb-17Li first wall cooling removes 1.5 MW/m2 of re-radiated ion and x-ray energy
Coolant reaches midpoint–Tc = 352 °C–v = 1 m/s–h = 8 kW/m2/K–Tw = 672 °C
Coolant reaches exit–Tc = 445 °C–v = 5.5 m/s–h = 35 kW/m2/K–Tw = 632 °C
First wall reaches highest temperature of 700°C just beyond the midpoint
NIF-0908-15298.ppt TOFE Conf, R. Abbott, 10/1/2008 9
Flibe coolant is forced radially through the multiplier, fuel, and reflector pebble beds
24 MT/s flibe at 610 °Cdelivered to outer plenum from eight 100 cm Øinjection tubes
24 smaller tubes deliver coolant to inner plenum
Flibe flows through Be, fuel, and graphite pebbles at15 cm/s
Flibe collected in plenum and exits from eight extraction tubes at 640 °C
NIF-0908-15298.ppt TOFE Conf, R. Abbott, 10/1/2008 10
¼ Section
The central chamber is being designed to keep stresses well below ODS stress limits• A 3D shell model has been
implemented in NIKE-3D
• Loads from pebble and coolant hydrostatic pressures applied
• Loads from coolant flow Δp’s applied
• Structure reinforced with ribbing
600 °C 700 °C
Yield strength (MPa) 900 450
5-yr creep rupture strength (MPa)
320 225
Ribbing and other reinforcement will be used to ensure robust safety factors
NIF-0908-15298.ppt TOFE Conf, R. Abbott, 10/1/2008 11
Flibe coolant transfers thermal energy to a helium Brayton cycle achieving 43% efficiency
• Based on designs of General Atomics’ GT-MHR and UCB’s PB-AHTR
• Flinak secondary loop incorporated to allow in-service inspection of shell-and-tube primary HX’s
http://gt-mhr.ga.com/large_image.htmlCommittee, U.S.D.o.E.R.A., A Technology Roadmap for Generation IV Nuclear Energy Systems. 2002.
NIF-0908-15298.ppt TOFE Conf, R. Abbott, 10/1/2008 12
The LIFE power system uses two independentsecondary and helium power cycle loops
Primary pumps
Primary shell-and-tube HX
HP, MP, and LP PCU’sTurbine + Compressor + Intercooler
Secondary pumps
Regenerator
Compact HX reheater
Salt distribution manifolds
Top View
NIF-0908-15298.ppt TOFE Conf, R. Abbott, 10/1/2008 13
Future work will increase the fidelityand accuracy of the LIFE engine design
• Pebble flows studies – routine and off-normal conditions
• Dynamic stresses – neutron isochoric heating and chamber venting
• 2-D and 3-D coolant flow analyses
• Detailed design of pebble handling systems
• Further definition of chamber maintenance systems
NIF-0908-15298.ppt TOFE Conf, R. Abbott, 10/1/2008 14
Several of LIFE’s major thermal-mechanical systems have been self-consistently integrated
• Chamber gas keeps first wall temperature pulses to acceptable levels
• Low temperature Pb-17Li efficiently cools first wall
• Flibe coolant achieves effective heat removal with low pressure drops
• Structural analyses demonstrate robust engineering safety margins
• Helium Brayton cycle achieves high efficiency and a compact footprint
LIFE thermal and mechanical systems maintain materials within temperature and stress limits while enabling neutronics design goals
NIF-0908-15298.ppt TOFE Conf, R. Abbott, 10/1/2008 15
Back ups
NIF-0908-15298.ppt TOFE Conf, R. Abbott, 10/1/2008 16
Layouts have also been composed for low illumination angle fast ignition systems
NIF-0908-15298.ppt TOFE Conf, R. Abbott, 10/1/2008 17