What is Fusion and Why We Need It and Introduction to ITER Mohamed Abdou (web: http://www.fusion.ucla.edu/abdou/) Distinguished Professor of Engineering and Applied Science Director, Center for Energy Science and Technology (CESTAR) (http://www.cestar.seas.ucla.edu/) Director, Fusion Science and Technology Center (http://www.fusion.ucla.edu/) University of California, Los Angeles (UCLA) Lecture 1 at the Xi’an Jiaotong University, Xi’an, China August 2007 1 Outline Lecture 1 • World Energy Scene • What is fusion and Why we need it • ITER Lecture 2 • Fusion Nuclear Technology (FNT) and Blanket Concepts – Principles – Concepts – Issues • Framework and Facilities for FNT Development – ITER Test Blanket – CTF/VNS 2 Global Economics and Energy Population GDP Energy Demand Billions Trillion (2000$) 10 80 Average Growth / Yr. 2000 - 2030 70 8 0.9% 60 MBDOE 350 2.8% 1.6% 300 250 50 6 4.7% 40 4 2 1.1% OECD 0 1950 1990 0.4% 100 2030 2.2% 10 0 1950 2.4% 150 30 20 Non-OECD 200 0.7% 50 1990 2030 0 1950 1990 2030 3 Carbon dioxide levels over the last 60,000 years - we are provoking the atmosphere! Source: University of Berne and US National Oceanic and Atmospheric Administration 4 Energy Situation • The world uses a lot of energy – Average power consumption = 13.6 TW (2.2 KW per person) – World energy market ~ $3 trillion / yr (electricity ~ $1 trillion / yr) • The world energy use is growing - to lift people out of poverty, to improve standard of living, and to meet population growth • Climate change and debilitating pollution Concerns are on the rise – 80% of energy is generated by fossil fuels – CO2 emission is increasing at an alarming rate • Oil supplies are dwindling – Special problem for transportation sector (need alternative fuel) 5 Solving the Energy Problem Requires a Diversified Portfolio and Pursuing Several Approaches • Develop major new (clean) energy sources (e.g. fusion) • Expand use of existing “clean” energy sources (e.g. nuclear, solar, wind) • Develop technologies to reduce impact of fossil fuels use (e.g. carbon capture and sequestration) • Improve energy efficiency • Develop alternate (synthetic) fuels for transportation 6 Incentives for Developing Fusion • Fusion powers the Sun and the stars – It is now within reach for use on Earth • In the fusion process lighter elements are “fused” together, making heavier elements and producing prodigious amounts of energy • Fusion offers very attractive features: – Sustainable energy source (for DT cycle; provided that Breeding Blankets are successfully developed) – No emission of Greenhouse or other polluting gases – No risk of a severe accident – No long-lived radioactive waste • Fusion energy can be used to produce electricity and hydrogen, and for desalination 7 What is Nuclear Fusion? • • Nuclear Fusion is the energy-producing process taking place in the core of the Sun and stars The core temperature of the Sun is about 15 million °C. At these temperatures hydrogen nuclei fuse to give Helium and Energy. The 8 energy sustains life on Earth via sunlight Energy Released by Nuclear Reactions • Light nuclei (hydrogen, helium) release energy when they fuse (Nuclear Fusion) • The product nuclei weigh less than the parent nuclei • Heavy nuclei (Uranium) release energy when they split (Nuclear Fission) • The product nuclei weigh less than the original nucleus 9 Energy Released by Nuclear Fusion and Fission • Fusion reactions release much higher energies than Fission reactions 10 Fusion Reactions • Deuterium – from water (0.02% of all hydrogen is heavy hydrogen or deuterium) • Tritium – from lithium (a light metal common in the Earth’s crust) Deuterium + Lithium → Helium + Energy This fusion cycle (which has the fastest reaction rate) is of interest for Energy Production 11 Plasmas • A Plasma is an ionised gas. A mixture of positive ions and negative electrons with overall charge neutrality • Plasmas constitute the 4th state of matter, obtained at temperatures in excess of 100,000 degrees • Plasmas conduct electricity and heat 12 Self-Sustaining or ‘Ignited’ Plasmas • Deuterium – tritium fusion reaction: D + T → 4He + n + Energy The 4He nuclei (‘a’ particles) carry about 20% of the energy and stay in the plasma. The other 80% is carried away by the neutrons and can be used to generate steam. Plasmas become Self-sustaining or Ignited when there is enough a power to balance losses from the plasma • In stars plasma particles (including a’s) are confined mainly by gravity and high plasma densities achieved • On Earth: – hot dense plasmas can be confined in Magnetic fields (Magnetic Confinement Fusion) – superdense plasmas can be obtained by imploding solid deuteriumtritium pellets (Inertial Confinement Fusion) 13 Inertial Confinement • Laser implosion of small (3mm diameter) solid deuterium–tritium pellets produces fusion conditions • Pressure generation • Compression Fuel is compressed by rocket-like blow off 200,000 million atmospheres in core • Ignition and burn – Peak compression fuel reaches 1000-10000 times liquid density for extremely short time (10–11 seconds) – Core is heated and ‘spark ignition’ occurs 14 Magnetic Confinement • Magnetic fields cause charged particles to spiral around field lines. Plasma particles are lost to the vessel walls only by relatively slow diffusion across the field lines • Toroidal (ring shaped) system avoids plasma hitting the end of the container • The most successful Magnetic Confinement device is the TOKAMAK (Russian for ‘Toroidal Magnetic 15 Chamber’) The Tokamak: A Transformer Device 16 How Large a Device? • For fusion power to ignite a plasma: – There has to be sufficient density of deuterium and tritium ions (ni); – The reacting ions have to be hot enough (Ti); – The energy from the fusion a’s must be confined for long enough (tE). tE increases with the square of the device size – a large machine is needed. • The fusion triple product (niTitE) and the ion temperature (Ti) must both be large enough (below a certain temperature the fusion reaction probability is too small) pressure (niTi) ≥ 2 atmospheres confinement time > 5 seconds plasma ion temperature ≈ 100-200 Million °C 17 Controlling Impurities • Fuel Impurities are a major threat to reactor success • Two primary sources of impurities exist: – Helium “ash” from the fusion reaction – Material impurities from plasma-wall interactions • Impurities must be controlled since they: – Radiate energy, and reduce the plasma temperature – Dilute the fuel, thereby preventing ignition • The “Magnetic Divertor” is a device for controlling impurities. 18 Pumped Divertor in JET • Impurities (C, Be) are produced by ion impact on target 19 and are ionised in the plasma and returned to target The Deuterium-Tritium (D-T) Cycle • World Program is focused on the D-T cycle (easiest to ignite): D + T → n + α + 17.58 MeV • The fusion energy (17.58 MeV per reaction) appears as Kinetic Energy of neutrons (14.06 MeV) and alphas (3.52 MeV) • Tritium does not exist in nature! Decay half-life is 12.3 years (Tritium must be generated inside the fusion system to have a sustainable fuel cycle) • The only possibility to adequately breed tritium is through neutron interactions with lithium – Lithium, in some form, must be used in the fusion system 20 Tritium Breeding Li-6(n,alpha)t and Li-7(n,n,alpha)t Cross-Section 1000 Natural lithium contains 7.42% 6Li and 92.58% 7Li. 100 6Li (n,a) t Li-6(n,a) t Li-7(n,na)t 10 6 Li n t a 4.78MeV 7 Li n t a n 2.47 MeV 1 The 7Li(n;n’a)t reaction is a threshold reaction and requires an incident neutron energy in excess of 2.8 MeV. 0.1 7Li (n;n’a) t 0.01 1 10 100 1000 10 4 10 Neutron Energy (eV) 5 10 6 10 7 21 Shield Blanket Vacuum vessel Radiation Plasma Neutrons First Wall Tritium breeding zone Coolant for energy conversion Magnets 22 The world needs large scale deployment of fusion by mid-century! • 1950-2010 – The Physics of Plasmas • 2010-2030 – The Physics of Fusion – The “Fermi Demonstration” - Fusion-heated and sustained • Q = (Ef / Einput )~10 • 2010-2040 – Fusion Nuclear Technology for Fusion – DEMO by 2040 • 2050 ? – Large scale deployment! 23 The World Fusion Program has a Goal for a Demonstration Power Plant (DEMO) by ~2040 Poloidal Ring Coil Cryostat Coil Gap Rib Panel Blanket Maint. Port Plasma Vacuum Vessel Center Solenoid Coil Toroidal Coil 24 JAEA DEMO Design ITER • The World is about to construct the next step in fusion development, a device called ITER • ITER will demonstrate the scientific and technological feasibility of fusion energy for peaceful purposes • ITER will produce 500 MW of fusion power • Cost, including R&D, is 15 billion dollars 25 ITER Objectives Programmatic • Demonstrate the scientific and technological feasibility of fusion energy for peaceful purposes. Technical • Demonstrate extended burn of DT plasmas, with steady state as the ultimate goal. • Integrate and test fusion technologies • Demonstrate safety and environmental acceptability of fusion. 26 ITER is a collaborative effort among Europe, Japan, US, Russia, China, South Korea, and India 27 ITER Design - Main Features Central Solenoid Outer Intercoil Structure Blanket Module Vacuum Vessel Cryostat Toroidal Field Coil Port Plug (IC Heating Poloidal Field Coil Divertor Machine Gravity Supports Torus Cryopump 28 ITER Magnet System The magnet system for ITER consists of 18 toroidal field (TF) coils, a central solenoid (CS), six poloidal field (PF) coils and 18 correction coils (CCs). The magnet system creates a doughnut-shaped magnetic field to confine charged particles plasma. 29 ITER Blanket System The basic function of the blanket system is to provide the main thermal and nuclear shielding to the vessel and external machine components. FW Panel Total number of blanket modules: 421 Shield module 30 FW leg Coaxial connector ITER Divertor Cassette (Total: 54 Cassettes in ITER) The main function of the divertor system is to exhaust the major part of the alpha particle power as well as He and impurities from the plasma. Dome 31 ITER Parameters Total fusion power Q = fusion power/auxiliary heating power Average neutron wall loading Plasma inductive burn time Plasma major radius Plasma minor radius Plasma current (inductive, Ip) Vertical elongation @95% flux surface/separatrix Triangularity @95% flux surface/separatrix Safety factor @95% flux surface Toroidal field @ 6.2 m radius Plasma volume Plasma surface Installed auxiliary heating/current drive power 500 MW (700MW) ≥10 (inductive) 0.57 MW/m2 (0.8 MW/m2) ≥ 300 s 6.2 m 2.0 m 15 MA (17.4 MA) 1.70/1.85 0.33/0.49 3.0 5.3 T 837 m3 678 m2 73 MW (100 MW) 32 Schedule LICENSE TO CONSTRUCT ITER IO 2005 2006 2007 2008 TOKAMAK ASSEMBLY STARTS 2009 2010 2011 2012 FIRST PLASMA 2013 2014 2015 2016 EXCAVATE Bid Contract TOKAMAK BUILDING OTHER BUILDINGS Construction License Process First sector Complete VV TOKAMAK ASSEMBLY Install PFC cryostat MAGNET Bid Install CS COMMISSIONING Vendor’s Design Contract VESSEL Complete blanket/divertor Bid Contract PFC TFC CS fabrication start First sector Last TFC Last CS Last sector 33 First D-T Burning Plasma in ITER in 2021 ITER Schedule 1st 10 yrs Hybrid operation Phase Flat top pulse length (s) Equivalent number of nominal burn pulses Neutron fluence at TBM FW (MW-y/m2) PER YR 1~3 4 5 6 7 8 9 10 H-H D-D D-T D-T D-T D-T D-T D-T 400 400 400 3000 3000 3000 100-200 0 1 750 1000 1500 2500 3000 3000 0.0 0.0 0.008 0.011 0.017 0.028 0.033 0.033 34 New Long-Pulse Confinement and Other Facilities World-wide will Complement ITER Japan (w/EU) China EAST JT-60SA (also LHD) Europe South Korea W7-X (also JT-60SA) India SST-1 ITER Operations: 34% Europe 13% Japan 13% U.S. 10% China 10% India 10% Russia 10% S. Korea KSTAR U.S. Being planned Likely Fusion Nuclear Technology Testing Facility