Nuclear Fusion

The Possibility

Introduction

• “Every time you look up at the sky, every one of those points of light is a reminder that fusion power is extractable from hydrogen and other light elements”

-Carl Sagan, 1991

The Future of Fusion

• While renewables may be the “energy source of tomorrow,” fusion will likely be needed for “the day after tomorrow”

Overview

• Fusion will solve future energy shortfalls• Viable fusion power plants will solve pollution

problems• Investment in fusion research and development

will set the stage for future energy independence• U.S. involvement in International Thermonuclear

Experimental Reactor (ITER) will aid development of fusion technology

The Problems

• Enormous monetary investment

• Possibility of failure

Conclusion

The answer is fusion– Although the monetary investment involved is

daunting the future benefits of establishing fusion as a viable power source for the U.S. and the world rise far above the obstacles that stand in the way

Why Fusion?

• Problems with current energy producing fuels• It is hypothesized that by 2050 we will have run

out of economically recoverable fossil fuels

Coal

• Abundant• Burns dirty• Causes acid rain and

air pollution– Greenhouse gas

problems

Oil

• Flexible fuel source with many derivatives

•Transportable

•Finite supply

•Causes air pollution

Natural Gas

• Burns cleanly• Transportable• Finite supply• Dangerous to

handle

Growing Population

No More Fossil Fuel? Need For New Energy Sources

• If we continue to burn fossil fuels for energy, they will only last another few hundred years.

• This means that an energy shortfall could occur within the next fifty years.

Nuclear Power

• Clean

• No CO2

• No immediate pollution

• Problems with waste disposal

• Safety concerns

Other Alternative Sources

• Water Power

• Solar Power

• Tidal Power

• Wind Power

• Geothermal Power

20% of the energy needed for an estimated world population of 10 Billion in 2050

An Answer

Nuclear Fusion

Our Sun

Fusion Advantages• Abundant fuel, available to all nations

– Deuterium and lithium easily available for thousands of years

• Environmental Advantages– No carbon emissions, short-lived radioactivity

• Modest land usage– Compact relative to solar, wind and biomass

• Can’t blow up– Resistant to terrorist attack– Less than 5 minutes of fuel in the chamber

• Not subject to daily, seasonal or regional weather variation– No large-scale energy storage nor long-distance transmission

• Can produce electricity and hydrogen– Compliments other nearer-term energy sources

Fusion Disadvantages

• Huge research and development costs• Radioactivity

Background

Fusion Basics

Basic Physics

Energy-Releasing Reactions

Chemical Fission Fusion

Sample Reaction

C + O2 -> CO2 n + U-235 -> Ba-143 + Kr-91 + 2 n

H-2 + H-3 -> He-4 + n

Typical Inputs

(to Power Plant)

Bituminous Coal

UO2 (3% U-235 + 97% U-238) Deuterium & Lithium

Typical Reaction Temp. (K)

700 1000 108

Energy Released per kg of Fuel (J/kg)

3.3 x 107 2.1 x 1012 3.4 x 1014

What is an atom?

Nuclear Power

• Nuclear fission– Where heavy atoms,

such as uranium, are split apart releasing energy that holds the atom together

• Nuclear fusion– Where light atoms,

such as hydrogen, are joined together to release energy

States of Matter

• Plasma is sometimes referred to as the fourth state of matter

Plasma makes up the sun and the stars

Plasma Atoms

• In plasma the electrons are stripped away from the nucleus

• Like charges repel

– Examples of plasma on earth:

• Fluorescent lights

• Lightning

• Aurorae

• Neon signs

Typical Plasmas

• Interstellar

• Solar Corona

• Thermonuclear

• Laser

• Air Density

Characteristics of Typical Plasmas

Basic Characteristics

• Particles are charged

• Conducts electricity

• Can be constrained magnetically

Fusion Fuel

• Tritium

• Deuterium

The fuel of fusion

Inexhaustible Energy Supply

• Deuterium– Constitutes a small percentage of the hydrogen in water

• Separated by electrolysis• 1 barrel (42 gallons) water = ¾ oz. D = 32,000 gallons of oil

• Tritium– n + Li T + He– Lithium is plentiful

• Earth’s crust• Oceans

– Savannah, Georgia– Canada, Europe, Japan

Fusion Fuel: Deuterium

Other Possible Fusion Fuels

Helium-3 Nuclear Fusion

Proton Proton NeutronProton

Where is Helium-3?

• Helium-3 comes to us from the sun on the solar wind

• It cannot penetrate the magnetic field around the earth, so it eventually lands on the moon

• One shuttle load- 25 tons- would supply the U.S. with enough fuel for one year– China

HOW FUSION REACTIONS WORK

E=mc2

• Einstein’s equation that equates energy and mass– E= energy– M= mass– C= speed of light (3 x 108 m/sec)

• Example: – energy from one raisin = 10,000 tons of TNT

Two Main Types of Fusion Reactions: P-P

"P-P": Solar Fusion Chain

Two Main Types of Fusion Reactions: D-T

D + T => He-4 + n

More on Fusion Reactions

An enormous payoff

• The fraction of “lost” mass when H fuses into He is 38 parts out of 10,000

• This lost mass is converted into energy

• The energy released from 1 gram of DT = the energy from about 2400 gallons of oil

The result

• Inexhaustible fuel source– Seawater & Lithium

• The MOST “bang for your buck”• Inexpensive to produce• Widely distributed fuel source

– No wars

• No pollution– Helium is not polluting

• Fuel that is non-radioactive– Residue Helium-4 is non-radioactive

• Waste reduction

More on Fusion Radioactivity

• Aneutronic Fusion Fuels– More costly– Not enough science yet

• Neutronic Fusion Fuels– D-T Reaction

• Most of the neutrons are absorbed into a lithium blanket which is then used to replace the tritium fuel

• Stray tritium atoms• The Reactor Structure

More of Fusion Radioactivity

• Stray Tritium– Relatively benign

• Doesn’t emit strong radioactivity when it decays– So only dangerous when ingested or inhaled

• Shows up in one’s body as water– Easily and frequently flushed out

• Half-life of 12 years– No long-term waste problem– Won’t decay while in one’s body

– Less than natural exposure to radon, cosmic rays and much less than man-made x-rays

More on Fusion Radioactivity

• Reactor Structure– Development of special “low-activation”

structural materials• Vanadium• Silicon-carbide

– Wait ten to fifteen years after shutdown• The reactor will be less radioactive than some

natural materials (particularly uranium ores)• Recycle into a new fusion reactor

Waste Reduction

Power Source Total Waste (m3) High-Level RAD Waste

Coal 10,000 (ashes) 0

Fission 440 120

Fusion:

Today’s Materials 2000 30

Advanced Materials 2000 0

So why aren’t fusion plants already in operation?

How fusion works and the obstacles in the way

The Problems

• Harnessing the Energy

• Achieving & sustaining high temperatures– The reaction takes place at a temperature hotter

than the surface of the sun– 0.1 seconds

• Containing the fuel & the reaction

• Money for research and development

Harnessing the Energy

Achieving ignition temperatures

45

Methods to Heat Deuterium-Tritium Fuel

• Compressing the Fuel

• Internal Electric Current

• Neutral Particles

• Microwaves

• Lasers

• X-rays [recent development]

Plasma Confinement & Heating

Magnetic•Electromagnetic Waves

•Ohmic Heating (by electric currents)

•Neutral Particle Beams (atomic hydrogen)

•Compression (by magnetic fields)

•Fusion Reactions (primarily D+T)

Tokamak Schematic Laser-beam-driven Fusion

Inertial•Compression (implosion driven by laser or ion beams, or by X-rays from laser or ion beams)

•Fusion Reactions (primarily D+T)

Gravity•Compression (gravity)

•Fusion Reactions (such as the p-p chain)

Stars & Galaxies

Inertial Confinement Fusion

Recent Developments: Sandia National Laboratories

• Two Purposes:– Weapons research– Pursue the ignition of fusion

• Z Accelerator (inertial confinement)– Wagon wheel-like design– Uses blasts of X-rays crashing into a hydrogen (deuterium)

capsule at the center• 200 trillion watts of x-rays (10 x electrical energy than

entire generating capacity of the world)• 15 million degrees centigrade

– Likened to an internal combustion engine

• Cheaper than Tokamaks and Lasers

The Z Accelerator

• Challenges: A machine that can detonate controlled thermonuclear explosions and survive

• Timeline: electricity on a national grid in 35 years• Dr. Stewart C. Prager, “It’s premature to judge

which is the winner”• Dr. Quintenz says, “We’re in the game”• For More Information: The New York Times, April 8, 2003

“New Fusion Method Offers Hope of New Energy Source”

Fusion By Magnetic Confinement

Where are the Current major Fusion Energy Projects?

• JET from the European Community• JT-60U in Japan• NOVA at Lawrence Livermore Labs in

California• TFTR at PPL in Princeton, New Jersey• DIII-D at General Atomics in San Diego, CA• Sandia National Laboratories in Albuquerque,

NM

NOVA Machine- Inertial Confinement

TFTR is located at PPPL (Princeton, NJ)

DIII-D is located at General Atomics (San Diego, CA)

International Thermonuclear Experimental Reactor (ITER)

• Cooperative Effort by European Union, Japan, U.S. and Russia

• First proposed in 1986

• (Hopefully) Operational 2014

• Magnetic confinement design concept

                                                                                    

Energy Secretary Abraham Announces U.S. to Join Negotiations

on Major International Fusion Project

ITER Design

• To achieve extended burn in inductively driven plasmas with the ratio of fusion power to auxiliary heating power (Q) of at least 10 for a range of operating scenarios and with a duration sufficient to achieve stationary conditions on the timescales characteristic of plasma processes;

• To aim at demonstrating steady-state operation using non-inductive current drive with a ratio of fusion power to input power for current drive (Q) of at least 5.

ITER Physics Design Principal Physics Goals

Issues still unresolved

• Site Selection

• Construction of components

• Timeline

Site Selection: Enter Politicians

• European Union– Cadarache, France– Vandellos, Spain

• Canada– Clarington (near Toronto)

• Japan– Rokkasho (northern tip of Honshu, the main

island)

Financial Commitment

• Total Construction Costs= 5 Billion• Total Operating Costs= 5.5 Billion (twenty years)• Dismantling Costs= 450 million• Countries offering to host the site

– EU, Canada, Japan– 20%-25%

• Countries offering to be full partners– Russia, China, U.S– 10%

Component Construction

• Superconducting coils

• Plasma-heating system

• Vacuum pumps

• Cryogenics

• Diagnostic devices

Timeline

• May 20 & 21– Negotiation session of ITER partners in Vienna

• End of 2003/early 2004– Ratify an agreement amongst participating

nations

• 2005-2006– Construction begins– Ten years

• 2014– Facility operational

Concluding Remarks

“We definitely need more physics”

Concluding Remarks

• Fusion is possible

• Fusion will solve many environmental problems

• Fusion will solve political problems

• Fusion will solve future fuel needs

• Fusion is the answer

Questions