Smaller Sooner ASP

7/31/2019 Smaller Sooner ASP

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1ASP Whyte June 2012

Smaller & Sooner:How a new generation of

superconductors can accelerate

fusions development

Dennis WhyteMIT Nuclear Science & Engineering

Plasma Science Fusion CenterJune 2012

American Security ProjectFusion Energy Workshop


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Fusions development is impeded by itslarge single-unit cost

The overnight cost of a ssion power plant is ~ $4/W.

First of kind fusion plants at least $10-20/W

Which implies that developing fusion reactors at ~GWe scalerequires 10-20 G$ per try.

Chance of fusion development signicantly improved if net thermal/ electrical power produced at ~5-10 x smaller.


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Fusion at smaller size requires highermagnetic elds

What do you need? High energy gain ~ ignited Robustly steady-state as far as

possible from physics limits

Linear size ~ R Volume ~ Cost ~ R 3

Magnetic eld strength ~ B

Connement quality, H, cannot bebudged much The safety factor q>3, or as high

as possible since suddenterminations of plasma areunacceptable for materials

H

q R B C

Ignition requirement

$$ 1 / B 3


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Economically efcient fusion reactorsrequire higher magnetic elds with

~loss-free superconductors Stability parameter, Beta, hasknown intrinsic limits

Limits must be avoided since, unlike in present devices, violationleads to probable end-of-lifedamage to internal components

Solution in present designs? Violatethe intrinsic stability limit by factorof two!

$ IN $ OUT

~P

Fusion

Volume~

2 B 4

Power produced per unit cost


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Economically efcient fusion reactorsrequire higher magnetic elds with

~loss-free superconductors Stability parameter, Beta, hasknown intrinsic limits

Limits must be avoided since, unlike in present devices, violationleads to probable end-of-lifedamage to internal components

Solution in present designs? Violatethe intrinsic stability limit by factorof two!

Transiently demonstrated buttaking very high risk to end-of-lifeof very costly and difcult to repairinternal components

$ IN

$ OUT ~

PFusion

Volume~

2 B 4

Power produced per unit cost

The way out of this contradiction is high B eld..

B 2 R

Damage to components fromViolating operating limits


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New high-T superconductors can provide thepath to smaller & sooner fusion:

Higher B + Detachable coils

Can nearly double B (up tostress limits of structure)

Sub-cooled YBCO tapes

R/2 Volume/8 $/8 !

Away from operating limits

Small tape-to-tape joints coils can be demounted

Eliminate sector (pie-wedge)maintenance

Modular replacement of smaller internal parts

More easily constructed and maintained fusiondevice at small size but with reliable high gain


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Recent MIT Design Effort*Rules

Develop a robust conceptual design based on YBCO magnetsof a high gain, net electricity producing magnetic fusion powerplant at substantially reduced total thermal power ~ 500 MW(factor of ~5 reduction from typical designs).

No violation of basic core limits: kink, no-wall Troyon Beta, Greenwald to assure stable operation.

Fully non-inductive scenarios but robust external control Minimize solid waste Minimize capital cost ~ Surface area of plasma/blanket to assure

best fusion economic outlook. Q_electric > 4

*22.63 MIT fusion design course Spring 2012


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Key innovations towardsachieving design goals

Integrated YBCO +structure to achieve9.2 T on axis withoutlarge electrical costs

R=3.2 m


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Demountable coils Modular replacementof vacuum vessel +components fulloff-site construction+ QA of all internalcomponents

No connection evermade inside TF= Paradigm shift tostandard sectormaintenance


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Immersion liquidFLIBE blanket Nomaterials radiationdamage in blanket ~50-fold reduction insolid waste fullcoverage high-TBR

blanket

FLIBE


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Demountable coils Attractiveliquid immersion blanket

Key Features

Tritium breeding ratio: 1.15Excess T in FPY: ~3 kg

High thermal efciencyLow recirculating power

30+ year lifetime of coils fromradiation damage

Solid waste reduced x50compared to standard blanket

Liquid FLIBE@ 900 K


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Lower Hybrid CDwith high-eld sidelaunch neartheoretical max. forCD efciency at mid-radius ~20%external control of

current prole


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Inside RF launch robust theoretical max.sustainment ~3-4x more external control

Enabled by- high B- compact size

=10 keV

Provides only ~4% of plasma heating but~20% of plasmacurrent.


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~4 keV pedestal notregulated by ELMs + high CD efciency high fusion gainwith moderatebootstrap fraction= Robust steady-state

scenarios producing~250 MWe


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