Nuclear Fusion…..
Icarus
Icarus flies
flies too
too close
close to
to aa
fusion
fusion reactor
reactor. .
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
Bringing Fusion Down To
Earth?
A talk by Robin Stafford Allen FIMechE
Monday 10th February 2014
For Cranbrook and District Science and Astronomy Society
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
Within our grasp?
• Purpose and outcomes.
– Explain the basics of Plasma and Fusion Physics.
– Introduce the JET, MAST and ITER machines.
– Explain some of the terminology and technology.
– But first – WHY?
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
12.5 TCE
6 TCE
1.4 TCE
0.7 TCE
Present annual consumption / person
mbh
Fossil Fuels
All-world conventional oil production will peak in 5-15 years
GLOBAL WARMING
And then there is
Global Warming …
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
Summary
• We need base-load energy for the future
– Fossil fuels reserves (oil and gas) are running low
– Global Warming means
•
•
•
•
Fossil Fuel with total carbon capture.
Fission.
Fusion (magnetic or laser).
A technology yet to be found.
• “Renewables” are not the answer, they are a
diversion.
• And now to Physics…..
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
Structure of the average atom.
The
Thenumber
numberofofprotons
protonsdefine
definethe
theelement
element
Hydrogen
Hydrogenhas
hasONE
ONEproton
proton
Helium
Heliumhas
has22protons
protons
Lithium
Lithiumhas
has33protons
protons
Beryllium
Berylliumhas
has44protons
protons
……………..
……………..
Carbon
Carbonhas
has66protons
protons
……………..
……………..
Iron
Ironhas
has26
26protons
protons
……………..
……………..
Uranium
Uraniumhas
has92
92protons
protons
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
Isotopes.
•
The same element can have other forms.
•
Hydrogen (1) has a proton and no neutron.
– Usually called simply Hydrogen; Sometime termed “protium”
•
Hydrogen (2) has 1 proton and 1 neutron.
– Usually called “Deuterium”
•
Hydrogen (3) has 1 proton and 2 neutrons.
– Usually called “Tritium”.
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
Fusion Process Introduction
• Fusion
A fusion reaction occurs when two
light nuclei (ions) approach each
other so closely that they fuse.
Methods being investigated include:
– Magnetic Confinement fusion
(Tokamak’s)
– and Inertial Confinement fusion
(Lasers).
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
Sir Arthur Eddington
Picture courtesy of
the SOHO/EIT
collaboration
Transit of Venus
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
Fusion Process Introduction
•Lawson’s Criterion
Usable Fusion is feasible if Lawson
criterion is exceeded
“Plasma density”,
“Plasma temperature” and
“Confinement Time” are all sufficient at
the same time).
Typical numbers required are:
•Plasma density ~0.000001
atmospheres (million times less than
atmosphere),
•Plasma temperature 150 million
degrees C (million times room
temperature)
•Confinement time ~5-10s.
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
A PLASMA A ”soup” of ions, and electrons,
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
D + T Fusion
D + T
α (3.5 MeV) + n (14.1 MeV)
Ash
Plasma
heating
Energy
production
11gram
gramof
ofDDand
andTTreacted
reactedisisequivalent
equivalentto
toburning
burning10,000,000
10,000,000grams
gramsof
ofcoal
coalor
orgas.
gas.
On
Onaagallon
gallonof
ofDDand
andTTaacar
carwould
wouldgo
go300,000,000
300,000,000miles
milestheoretically.
theoretically.
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
Mass
deficit
In the process of fusion,
0.4% of the mass of the
nuclei is lost and released as
energy.
E=∆ mc2
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
Plasma, Magnetic Confinement and Interaction
with the Wall
Motion in all directions
Particle contact with
the wall
Motion of ions and electrons without magnetic field
Ordered particles
motion
Reduced (minimised)
contact with the wall
With magnetic field
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
Bend it around into a Torus
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
Ohmic Heating.
•
•
•
•
•
The first of three forms of
“Additional Heating”
The transformer effect.
This is used to drive a huge
current through the plasma.
Used in the early stages of
heating the plasma.
Not much use once the
temperature is up to
50 million °C as the plasma is
too good a conductor by then.
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
RF Heating (Radio Frequency)
•
Cyclotron frequency
– Charged particles in a magnetic field have a natural frequency of
gyration in the plane perpendicular to the field - the cyclotron
frequency. For electrons in a tokamak, the cyclotron frequency is
typically a few tens of GHz, and for ions, a few tens of MHz.
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
Neutral Beam Heating
• A beam of VERY
energetic fast particles.
• Ions, can be accelerated
but cannot penetrate to
magnetic field without
being recombined with
electrons to make
electrically neutral
particles.
– Analogy is a blow-lamp!
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
A Divertor
Divertor:
A separate chamber in the vacuum vessel to
which escaping particles are exhausted by
means of extra magnetic coils.
The magnetic configuration inside the
vessel is divided in two zones separated by
Separatrix (= LCFS)
JET divertor
BΘ= 0
at X-point
LCFS: The last closed flux surface. This may be created by
last
closed flux
surface.
This may be created by
a LCFS:
limiter, The
or the
presence
of an
X-point.
a limiter, or the presence of an X-point.
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
A pulse on JET
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
Disruptions
• Disruption
– Sudden loss of the plasma – it “goes out” with, usually a bang!
• Disruption information
– During a disruption forces of over 600 tonnes have been recorded. It
is an audible bang!
– Vessel movements up to 8 or 9mm have been seen. (JET weighs
2,800 tons, and is now restrained on hydraulic dampers) .
– Anecdotally, there is a seismic station north of Oxford which can
detect the vibrations from a JET disruption. Apparently the spectrum
is different from the spectrum of an earthquake.
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
A pulse on JET
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Power to site
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Flywheel Generators
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The Next Step - ITER
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
ITER
Construction costs €13 Billion in 10 years
Construction in Cadarache - France
Construction began in 2007/8
Operation in 2019
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
ITER site in early 2013
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
Transporter
•
•
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
A dummy load of 360
concrete blocks will
be loaded onto the
special self propelled
platform (88 axles,
352 wheels) to travel
the whole length of
the itinerary..
Its weight and dims. –
800 tons, 40 metres
long, 9 metres wide,
11 metres high –
mimic the most
exceptional ITER
load.
Can we improve the
tokamak?
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
MAST
MAST
Spherical
Tokamak
Meg
a
Amp
Spherica
l
Tokamak
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
A Fusion Powerplant
Lithium blanket captures
energetic neutrons from the
fusion process and serves two
purposes.
Boils water in a heat
exchanger to produce
steam to drive a generator.
The Lithium and neutron
react to produce Tritium, one
of the primary fuels in the
fusion process.
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
Hydrogen from Fusion?
•
•
•
High temperature catalytic thermo-chemical cracking of water
Heat (800C or more) + 2H2O  2H2 + O2
Only real candidate technologies are solar thermal, electric, or
nuclear power. Fusion is safer, cleaner than fission.
HTR-10
Source: Solar Developments
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
Progress
Progress on
on JET
JET
JET over the years
1983
1987
All metal wall and limiters
1991
Beryllium tiles,
open divertor
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
Graphite limiters
JET over years
1994
Carbon -- in
the form of
Carbon-fibre
reinforced
material lining
the vessel.
1997
2001
Several
configurations
of divertor.
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
Remote Handling of In-Vessel Components in Radioactive and
Beryllium Containing Environment
A robotic arm used for in-vessel
operations at JET:
•Exchange and repair of components
•Installation of diagnostics
•2010 Shutdown: Installation of
Beryllium tiles faced with a coating to
Tungsten. The “ITER-Like” wall.
An image shows the exchange of divertor
tiles: the operation aiming at the
restructuring of the divertor configuration.
So what’s holding us back?
•
Money – limited funding.
– The big experiments are being done in sequence
JET → ITER → DEMO
Results in the “30-year-rule”!
– D-T experiments: 1997, 2017, and 2025?
•
Technical Limitation.
– Materials, and materials research.
– The high-energy neutrons generally damage materials and
can only realistically be studied within fusion machines.
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
“We know how to do fusion
as physicists, how it works.
It is an engineering solution
that is within our grasp.”
(Professor Brian Cox)
“Nuclear fusion…would
provide an inexhaustible
supply of energy without
pollution or global warming.”
(Professor Stephen Hawking)
Advantages of Fusion …
•
Fusion has little or no environmental impact – No greenhouse gasses.
•
Fusion will not produce any ‘long-lived’ radioactive waste.
•
There is no risk of critical safety events e.g. ‘meltdown’.
•
The fuels are abundant. Lithium in the earth’s crust, and…
Deuterium is freely available in …. Water.
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
Advantages of Fusion …
•
Fusion has little or no environmental impact – No greenhouse gasses.
•
Fusion will not produce any ‘long-lived’ radioactive waste.
•
There is no risk of critical safety events e.g. ‘meltdown’.
•
The fuels are abundant. Lithium in the earth’s crust, and…
Deuterium is freely available in …. Water.
Any Questions?
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority