a life power requires the integration of several packing 25% perforated walls. ... –h = 35 kw/m2/k...

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


This talk covers top-level thermal and mechanical features key to LIFE performance• Central chamber

• Active cooling systems

• Static structural stresses

• Power systems


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


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


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


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


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


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


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


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.


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


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


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


Back ups


Layouts have also been composed for low illumination angle fast ignition systems

a life power requires the integration of several packing 25% perforated walls. ... –h = 35 kw/m2/k...

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