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 = mc 2. 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 Fusion Magnetic Fusion Inertial Fusion
DT fusion is the easiest type of fusion to achieve, though requires production of tritium Quantum resonance between deuterium and tritium provides large fusion cross section. D(t,n) 4 He helium heats the plasma and neutrons must be captured. Image source: La Fusion Magnetique, Euratom- CEA, Link 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. Image source: ITER and Fusion Energy, Link Anomalous transport and plasma instability has inhibited commercial fusion thus far.
Helical magnetic fields are required for toroidal confinement due to particle drifts Image source: Hong Kong Institute of Engineers, Link 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.
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 P fusion ~ β 2 B 4 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 W7-X Stellarator - ~ $5-6 billion in Griefswald, Germany Link ITER Tokamak - $25+ billion in Cadarache, France. 500 MWth. 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 Imposeddynamo current drive (IDCD) enables the spheromak for controlled fusion energy ITER developed cryopumps for helium removal Fuel injection Thermonuclear plasma YBCO superconductors IDCD helicity injectors for sustainment ZrH2 neutron shielding Dual-chambered, molten-salt blanket system
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 Z [m] βwall [%] F 2.6 Major Radius [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 million Natural Gas + No CO 2 Capture < 1 billion 53 $175 million Natural Gas + CO 2 Capture Gen III+ Nuclear Plant Dynomak Reactor System ~1.5 billion 53 $175 million > 3 4 billion 79.5 million $67 million 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 Value Major radius (R) 1.5 m Density (ne) 4 x 10 19 m -3 Minor radius (a) 1.0 m Max Temperature 3.0 kev Plasma 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 breakdown Component 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 17.7 Structures and site facilities 424.3 Reactor structural supports 45.0 First wall and blanket 60.0 ZrH2 neutron shielding 267.3 IDCD and feedback systems 38.0 Copper flux exclusion coils 38.5 Pumping and fueling systems 91.7 Tritium processing plant 154.0 Biological containment 50.0 YBCO superconducting coil set 216.0 Supercritical CO2 cycle 293.0 Unit direct cost 1696 Construction services and equipment 288 Home office engineering and services 132 Field office engineering and services 132 Owner s cost 465 Unit overnight capital cost 2713
Time lines to fusion power PoP Cost estimate (Includes Science and engineering programs) $130 M Power Gen Pilot DD-water DT-FLiBe Power Gen $800 M Tritium breeding Reactor year 0 5 10 15 20 Revenue $1.5 B Design activity Construction and operations
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.! 2-fluid MHD simulation a = 0.62 m, T = 100 ev, Zero pressure!! 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.!!