The Dynomak Reactor System

An economically viable path to fusion power

Derek Sutherland HIT-SI Research Group

University of Washington November 7, 2013

Outline• What is nuclear fusion?

• Why do we choose to pursue fusion?

• Current leading methods towards controlled fusion energy.

• The case for the spheromak configuration.

• The Dynomak reactor system .

• Next steps and conclusions…

Fusion is the fundamental energy source of the universe • Fusion is a nuclear process that combines light elements into heavier

ones, which releases large amounts of energy via E = mc2.

• Proton-proton fusion occurs in the sun and sustains life on earth — very slow process. !

• Require fast fusion (i.e. DT) on Earth since we cannot use gravitational confinement — magnetic and inertial fusion are two main choices.

Gravitational FusionMagnetic Fusion Inertial Fusion

DT fusion is the easiest type of fusion to achieve, though requires production of tritium

Image source: La Fusion Magnetique, Euratom-CEA, Link

• Quantum resonance between deuterium and tritium provides large fusion cross section.

• D(t,n)4He — helium heats the plasma and neutrons must be captured.

• Fast neutrons from fusion undergo reaction with lithium-6 to make tritium — closed fuel cycle.

Magnetic fusion energy requires low densities and long confinement times

• Charged particles exhibit helical motion due to Lorentz force — q(v x B).

• Lawson criterion dictates what product of density, temperature and confinement time is required for “ignition”.

• Anomalous transport and plasma instability has inhibited commercial fusion thus far.Image source: ITER and Fusion Energy,

Link

Helical magnetic fields are required for toroidal confinement due to particle drifts

• Wrapping magnetic fields into a torus enables confinement of charged particles — requires helical fields.

• This magnetic structure is common to most magnetic fusion approaches — method of generating fields differs.

• Plasma currents and/or external coils provide helical fields required for confinement.

Image source: Hong Kong Institute of Engineers, Link

Fusion has many motivating qualities as ultimate green energy source• A nearly unlimited fuel supply on the planet that is mostly

harvested from sea water — no scarcity of resources.

• Zero greenhouse-gas emissions — only unused product is helium.

• No risk of meltdowns and no long-lived radioactive waste like fission reactors.

• Intrinsic safety of fusion makes it attractive from an industrial safety standpoint.

• Need fusion propulsion to get to other solar systems in a reasonable amount of time.

High fusion power densities requires high pressure or large magnetic fields • Pfusion ~ β2 B4 — high pressure or large magnetic

fields can be used to reach attractive power densities.

• Large fields are “safe,” but require expensive coils.

• High beta is “cheap,” but are more dangerous plasma instability wise — need to limit instability.

• A high-beta fusion reactor with a small amount of superconducting coils is ideal for fusion energy economics.

Current leading approaches to fusion are large, expensive machines with lots of complex superconducting coils

ITER Tokamak - $25+ billion in Cadarache, France. 500 MWth. Link

W7-X Stellarator - ~ $5-6 billion in Griefswald, Germany Link

• Both of these experiments are as expensive or an order of magnitude more than a 1 GWe power plant — no electricity!

Spheromaks use plasma currents to generate magnetic fields instead of expensive superconducting coils • Reduction of superconducting coil set to one, circular equilibrium

coil set simplifies reactor design.

• Due to less superconducting coils to shield from neutrons in difficult areas, reactor is able to be shrunk down.

• Smaller reactors require less superconducting coils, along with less material overall.

• A spheromak reactor system enables economical fusion power, but requires clever sustainment that avoids instability — poor confinement was typical in previous spheromak experiments.

• Need sustainment discovery to make spheromak fusion energy possible!

Imposed-dynamo current drive is discovery required for spheromak based magnetic fusion

• Previous spheromak experiments had poor confinement since sustainment required plasma instability to drive dynamo action — instability degrades confinement.

• IDCD perturbs and sustains a stable magnetic equilibrium with small, non-axisymmetric magnetic fluctuations.

• Pressure-driven interchange and micro-tearing modes may be responsible for core current drive and impurity regulation.

The Dynomak Reactor System — Imposed-dynamo current drive (IDCD) enables the spheromak for controlled fusion energy

Thermonuclear plasma

YBCO superconductors

ZrH2 neutron shielding

Dual-chambered, molten-salt

blanket system

IDCD helicity injectors for sustainment

ITER developed cryopumps for

helium removal

Fuel injection

Prescribed superconducting coil set provides toroidal force balance required for steady-state operation

Coil Set MA-turns

A -16.3

B -5.2

C 0.4

D -11.0

E 16.8

F 2.6

β wal

l [%

]

Major Radius [m]

Z [m

]

IDCD discovery provides a factor of 10 reduction in fusion capital cost

ITER – Large “present” fusion power producing experiment (≈ $25 billion)

Dynomak – 2.5 GWth, 1 GWe fusion reactor (≈ $2.7 billion)

Dynomak reactor system is competitive with conventional power sources

Energy Source $ USD for 1 GWe

Fuel Energy Density (MJ/kg)

Annual Fuel Costs for 1 GWe

Coal Fire > 3 billion 24 $267 millionNatural Gas + No CO2 Capture < 1 billion 53 $175 million

Natural Gas + CO2 Capture ~1.5 billion 53 $175 million

Gen III+ Nuclear Plant > 3 – 4 billion 79.5 million $67 million

Dynomak Reactor System 2.7 Billion 330 million $36,000

Schlissel, D. et al. Coal-Fire Power Plant Construction Costs, Synapse Energy Economics Inc., Cambridge, MA. July 2008. www.synapse-energy.com!!Schlissel, D. and Biewald, B. Nuclear Power Plant Construction Costs. Synapse Energy Economics Inc., Cambridge, MA. July 2008. www.synapse-energy.com !!Black, J. et al., Cost and Performance Baseline for Fossil Energy Plants, Volume 1: Bituminous Coal and Natural Gas to Electricity. National Energy Technology Laboratory, sponsored by U.S. DOE, November 2011.!!Updated Capital Cost Estimates for Electricity Generation Plants, U.S. Energy Information Administration: Independent Statistics and Analysis, U.S. Department of Energy, November 2010. ! 

An economical fusion development path is proposed to reach a dynomak scale device • Exciting experimental results and computer simulations

along with economic attractiveness of the dynomak justifies a Proof-Of-Principle (PoP) experiment.

• HIT-PoP will serve as the primary risk reduction experiment of development path — confirm good confinement with IDCD on an inexpensive, pulsed machine.

• With a successful PoP experiment, remainder of development path entails steady-state operation and confirmation of satisfactory nuclear engineering.

PoP experiment is the genesis of an economical fusion energy development path

R

a

Parameter Value Parameter ValueMajor radius (R) 1.5 m Density (ne) 4 x 1019 m-3

Minor radius (a) 1.0 m Max Temperature 3.0 keVPlasma Current (Ip) 3.2 MA Coil Material Copper

Shot Length 10.0 s Plasma Type Deuterium

Conclusions • Fusion is the energy of the future: zero greenhouse-gas

emissions, nearly unlimited fuel, high energy density and is inherently safe.

• The spheromak, enabled by the IDCD mechanism, provides an economical path to fusion power — The Dynomak reactor concept.

• The discovery of IDCD experimentally and encouraging computer simulations justifies a Proof-of-Principle Experiment (HIT-PoP).

• HIT-PoP will demonstrate the compatibility of IDCD and good confinement in a spheromak configuration.

Questions and Discussion

Experimental evidence of IDCD on HIT-SI

• Published, peer-reviewed IDCD model matches experimental measurements on HIT-SI very well. !• Simulations suggest IDCD will provide plasma rotation in HIT-

SI3 that is presently under construction.

HIT-PoP cost breakdownComponent Cost ($M)

Vacuum tank assembly 3.8

Injectors and mounting ring 6.7

Copper equilibrium coils 2.3

Power supply and controls 9.2

Building preparations 1.7

Contingency 7.8

Total Experiment Cost 31.5

Overnight capital cost breakdown for dynomak reactor Subsystem Cost ($M USD)Land and land rights 17.7Structures and site facilities 424.3Reactor structural supports 45.0First wall and blanket 60.0ZrH2 neutron shielding 267.3IDCD and feedback systems 38.0Copper flux exclusion coils 38.5Pumping and fueling systems 91.7Tritium processing plant 154.0Biological containment 50.0YBCO superconducting coil set 216.0Supercritical CO2 cycle 293.0Unit direct cost 1696Construction services and equipment 288Home office engineering and services 132Field office engineering and services 132Owner’s cost 465Unit overnight capital cost 2713

PoP

Pilot

Reactor

Tritium breeding

Power Gen

Power GenDD-water DT-FLiBe

Revenue

Cost estimate(Includes Science and engineering programs)

$130 M

$800 M

$1.5 B

Design activity

Construction and operations

year 0 5 10 15 20

Time lines to fusion power

Evidence that IDCD imposed fluctuations are compatible with good plasma confinement

• Computer simulations suggest that confinement degradation occurs due to plasma instabilities, not magnetic fluctuations as previously thought. !!

• IDCD does not drive the equilibrium unstable, but simply imposes the magnetic fluctuations required for sustainment → good confinement expected to be compatible with this method of sustainment. !!2-fluid MHD simulation a = 0.62 m,

T = 100 eV, Zero pressure!