convert

Fusion as an energy source: challenges and opportunities

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Acknowledgements

Introduction

1.1:

The funding landscape

1.2:

The benefits of fusion as an energy source

What is fusion? The basic physics

2.1:

Tokamaks: a technical explanation

The quest for fusion: a history

3.1:

Achievements of the large tokamaks

3.2:

The International Thermonuclear Experimental Reactor

Unconventional magnetic confinement approaches to fusion

4.1:

Spherical tokamaks

4.2:

Beyond tokamaks: the stellarator

Why is fusion research so slow?

5.1:

A strategy for the 21st century

5.2:

Historical, current and future costs

5.3:

Commercial fusion before fusion electricity: faster than fast track?

Fusion – another way?

6.1:

Inertial confinement fusion energy

6.2:

Plasma pinch

6.3:

Cold fusion?

Six challenges for fusion

7.1:

Planned availability

7.2:

Reliability

7.3:

Structural integrity

7.4:

Helium supply

7.5:

High-temperature plasma-facing materials – the divertor

7.6:

Problematic materials

Conclusions

Bibliography

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Introduction

Figure 1: UK domestic

fusion R&D budget and

oil price from 1975 to

2005. Source: UKAEA

Culham.

1 engineers.ihs.com/news/

eu-en-greenhouse-gases-5-07.

htm.

Climate Action: Energy for a

Changing World,

ec.europa.eu/

energy/climate_actions/index_

en.htm.

3 IOP 2004

The Future of

Fission Power: Evolution or

Revolution?

4 A Klix

et al.

2005.

Life on Earth currently faces a threat on a truly global
scale: climate change. A scientific consensus is emerg-
ing that civilisation must reduce its emissions of global
warming gases by more than half in less than 50 years

if we are to stand a chance of achieving a global climate
as stable as that of the past 10 000 or so years.

This pressing need comes at a time when fossil-fuel

prices are high, albeit perhaps for short-term reasons,
giving the world a window of opportunity in which to
make a significant move away from environmentally
harmful fossil-fuel combustion. Thus far, no country has
managed to make significant cuts in greenhouse-gas
emissions as a consequence of rising concern over glo-
bal warming. In Europe, at least, political leaders have
started to put in place policies that, if delivered, would
have sufficient strength to have some impact on the
problem. In January 2008 the EC president José Manuel
Barroso released a major package of policies entitled
“Climate Action”.

The measures consolidated earlier

plans for a 20% cut in EU greenhouse-gas emissions by
2020, even in the absence of any global deal that might
see the EU target become a 30% cut.

To meet its primary energy needs each year, the

world consumes energy roughly equivalent to 12 billion
tonnes of oil. Of this, three-quarters comes from fos-
sil fuels, all of which when combusted release carbon
dioxide (CO

); while around 6% is supplied by the very

low CO

-emitting technology of nuclear power.

All nuclear power stations in operation today rely on

fission – the splitting of large atomic nuclei, in particular
the very heavy elements uranium and plutonium. Most
nuclear power stations are fuelled by uranium, and some
plutonium is produced from uranium by the reactions.

However, fission is not the only type of nuclear reaction
to release energy. An alternative approach to usable
energy production depends on nuclear fusion. The basis
of this is the release of energy when very light nuclei are
brought together to form more stable heavier ones.

As with fission, fusion would be a source of usable

heat-energy producing almost no CO

emissions. The

only greenhouse-gas emissions produced would be
those associated with the construction and manu-
facture of the power station, and the need for exter-
nal energy inputs for start-up and operations. Fusion
research holds out the promise of a clean, sustainable
energy supply to contribute to the increasing needs of
our civilisation.

In the history of fusion, governments have sometimes

emphasised the scientific interest of fusion research. In
the UK, however, the goal is clear: a fusion power sta-
tion producing electricity for a competitive market. This
is a substantial technical challenge but it seems that

none of the technological elements is beyond reach.

1.1: The funding landscape

Despite the growth in global concern about the increase
in atmospheric CO

and average global temperatures

since the 1980s, it is only in more recent years, with
rapidly rising fossil-fuel prices, that support for fusion
research has increased. There is a correlation between
oil price and support for fusion research;

figure 1

implies

that there is a lag of a few years between a change in oil
price and spending on the UK fusion programme.

Figure 2

shows the UK’s investment in fusion research

compared with international investment levels over a
similar timescale. In all countries shown, fusion budg-
ets had declined by the late 1990s, reflecting a period
of inexpensive energy supplies. It is noteworthy that in
the US, decreases in fusion research budgets occurred
most strongly in the late 1970s, only increasing again
modestly following the “second oil crisis”, prompted by
the 1979 Iranian revolution.

1.2: The benefits of fusion as an energy

source

In principle, fusion has several key benefits over conven-
tional approaches to nuclear power based on fission:

The fuel for fusion is abundantly available

●

. Two

isotopes of hydrogen are well suited for fusion:
deuterium and tritium. Deuterium is available from
seawater (and can be extracted by electrolysis)
and it is expected that tritium can be produced
within a fusion power station from small quantities
of lithium.

Lithium has a range of commercial

uses, including, importantly, in modern batteries.
Despite increasing demand, lithium supplies remain

Introduction

UK domestic fusion R&D budget (£m – 1990)

1970

1980

year

1990

2000

2010

100

oil price ($/bbl)

fusion
oil

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Introduction

Figure 2: Public

spend on fusion

RD&D, international

comparison from

1974 to 2006.

Source:

International Energy

Agency, see www.iea.

org/textbase/stats/

rd.asp.

5 Typical annual values, see

R Pitts

et al.

2006.

6 See section 6.

abundant. The long-term fuel security of fusion
would appear to exceed that of fission power and
hence far exceed that of fossil-fuel energy. A fusion
station would use about 100 kg of deuterium and
3 tonnes of lithium to produce the same amount
of energy as a coal-fuelled power using 3 million
tonnes of fuel.

Fusion has a low environmental impact

●

. Whereas

fission stations produce spent fuel with half-lives
of thousands of years, the only radioactive wastes
produced from a fusion station would be from the
intermediate fuel, tritium, and any radioactivity
generated in structural materials. The radioactivity
of tritium is short-lived, with a half-life of around
12 years, and if chosen appropriately the structural
materials have a half-life of around 100 years.

Fusion is inherently safer than fission in that

●

it does not rely on a critical mass of fuel

. This

means that there are only small amounts of fuel
in the reaction zone, making nuclear meltdown
impossible.

Fusion power stations would present no

●

opportunity for terrorists to cause widespread
harm (no greater than a typical fossil-fuelled
station) owing to the intrinsic safety of the
technology

. Fusion in a tokamak relies on a

continuous supply of fuel, without which the process

soon dies away. Furthermore, the process is only
sustained via careful use of the controlling magnetic
fields. While the magnets contain some limited
stored energy, the fusion reactor does not. This is in
contrast with other low-carbon electricity sources,
fission and conventional hydropower, which require
the safe control of large amounts of stored energy,
even when not operating.

As with fission, fusion power stations would

●

provide energy at a constant rate, making them
suitable for base-load electricity supply

. Fusion

electricity will be similar to fission electricity in its
cost structure; a power station will require complex
and expensive engineering, while fuel costs will
be negligible in comparison. Staffing levels will
be roughly constant whether or not the plant is
generating. As such, the majority of costs will
be capital costs and almost all will be fixed. The
marginal cost of electricity generation will be very
small.

Fusion power stations would not produce fissile

●

materials and make no use of uranium and
plutonium, the elements associated with nuclear
weapons

. This reduces proliferation concerns

associated with these elements, although fusion is
not completely free from proliferation risks.

1400

1200

1000

800

400

200

public spend on fusion RD&D ($m)

1974

1976

1978

1980

1982

1984

1986

1988

1990

1992

1994

1996

1998

2000

2002

2004

2006

year

Germany

Italy

Japan

600

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What is fusion? The basic physics

Nuclear reactions are different from chemical reactions
in that they involve the protons and neutrons in the
nucleus, rather than electrons. Like chemical reactions,
nuclear reactions can involve either a net absorption or
a net release of energy. To achieve a release of energy
in a fusion reaction, smaller, less stable nuclei must be
joined together to form a more stable nucleus. Elements
on the far left of the curve in

figure 3

release energy by

fusion, while elements on the far right release energy
via fission.

The energy released arises from the difference

between  the  nuclear  binding  energies  of  the  initial
and  final  components.  In  the  conventional  approach
to  fusion,  no  fundamental  nuclear  particles  are  cre-
ated or destroyed. The energy associated with binding
the initial components is greater than that associated
with the reaction products, and it is this energy differ-
ence that is released during fusion. Interestingly, these
small differences in binding energy are reflected in the
observable masses of the various reaction components;
via  Albert  Einstein’s  famous  equation  describing  the
equivalence of mass and energy:

. This states

that energy = mass

(speed of light)

. That is, the com-

ponents after the reaction actually weigh less than those
before the reaction and the mass difference is released
as energy. Einstein’s equation gives an indication of the
scale of the proportionality between mass and energy,
and it explains why very small changes of mass in nuclear
fuel can release a great deal of usable energy.

Fusion occurs inside the Sun at 15 million °C, and at

more than 100 million °C in manufactured experimental
reactors.

It is interesting to note that, despite the tem-

peratures involved, the pressure inside a fusion tokamak
will actually be quite low, similar to atmospheric pressure.
This is a consequence of the small amounts of fusion fuel
involved. Fusion reactors use specific isotopes of hydro-
gen as fuel because these can react at a useful rate for
power production, allowing a fast reaction at more easily
achievable temperatures. Most reactors use deuterium
and tritium. As shown in

figure 4

, all of these atoms have

a single proton but, while hydrogen has no neutrons,
deuterium has one and tritium has two.

In preparation for fusion, these isotopes are heated

so that they become a plasma. This is an ionised gas
consisting of free electrons and nuclei not bound into
atoms, and it is a distinct state of matter, along with
solids, liquids and gases. This allows the atomic nuclei
to be separated out. Since the deuterium and tritium
ions, like any atomic nuclei, are positively charged, they
repel each other strongly with an electrostatic force.
For fusion to occur, this repulsion must be overcome,
forcing these lighter nuclei close enough together for

long enough to bring them into collision. This involves
confining the plasma at very high temperatures, and at
the same time isolating it from the walls of the container
to prevent impurities. Plasma stability remains an active
area of fusion physics research. The fusion plasma must
be confined and kept clean for the longest possible sus-
tained fusion reaction – ideally in an operating power
station for several hours.

There are two conventional ways of achieving this

in a fusion power station. In magnetic confinement
approaches to fusion (MCF), magnetic fields hold the
plasma in isolation while very high temperatures, cor-
responding to very high speeds for the nuclei, create
the necessary collisions. MCF, in the form of a toka-
mak reactor, is the most common approach to fusion

7 J Bahcall 2005.

8 R Pitts

et al.

2006.

What is fusion? The basic physics

nuclear binding energy per nuclear particle (nucleon) (MeV)

size of nucleus/mass number

100

150

200

yield from fusion

per nucleon

yield from fission

per nucleon

hydrogen

deuterium

tritium

Figure 3: The relationship between binding energy and mass number of

elements.

Figure 4: Hydrogen, deuterium and tritium.

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What is fusion? The basic physics

Figure 5: The fusion

reaction of deuterium

and tritium.

power and magnetically confined fusion energy (MCE).
In inertial confinement approaches to fusion research
and to fusion energy (ICF and ICE), very high pressure is
applied very quickly, initiating a short fusion pulse. Iner-
tial confinement can be achieved using high-powered
lasers. The majority of this report deals with MCE, as
this approach will more probably yield a usable energy
source before ICE does.

Figure 5

illustrates the fusion reaction between deu-

terium and tritium, releasing a helium nucleus and a
single neutron, as well as 17.6 MeV (2.82

–12

J) of

energy. The original energy of convergence is negligible
in comparison. The released energy is taken up by the
two new particles in inverse proportion to their masses.
That is, a fifth is taken up by the kinetic energy of the
helium nucleus and four-fifths by the kinetic energy of
the neutron. As an electrically neutral particle, the neu-
tron is unaffected by any magnetic fields. These fast
neutrons are emitted in all directions and are the pri-
mary means by which energy leaves the fusion reactor.

Many of these neutrons would leave the reactor on its

outer edge and come to rest in a component known as
“the blanket”. This contains material designed to slow
down the fast neutrons and in doing so become heated.
This heat is, in turn, transferred to a medium such as
high-pressure helium or steam. This hot, high-pressure
gas can be used to drive an electricity-generating tur-
bine. Some modules of the power-station blanket would
include lithium, which reacts with the fast neutrons to
generate tritium, one of the two fuels required for the
reaction. In this way a fusion power station could pro-
duce one component of its own fuel

in situ

Unlike the neutron, the helium nucleus is charged,

so in MCF it becomes trapped by the magnetic fields
holding the plasma in place. This allows energy to be
retained in the plasma, helping to maintain high tem-
peratures. If this internal heating effect is sufficient to
sustain the required temperature at the correct density,
the plasma is said to ignite and the reactor to operate
in ignition mode.

However, once the helium nucleus has transferred its

energy to the plasma, it becomes something of a prob-
lem. As a heavy ion it acts to dilute and cool the plasma,
thereby inhibiting the reactions. It becomes helium ash,
and power-station designs incorporate sophisticated
devices known as divertors to extract this residue. Diver-
tors and the associated plasma geometry present sig-
nificant technical challenges. One key challenge is the
choice of high-temperature durable materials for the
divertor target.

In an eventual power station the divertor

would be subject to intense particle bombardment and
reliability will be key to its commercial success.

2.1: Tokamaks: a technical explanation

The tokamak addresses a key challenge for fusion –
sustained operations and plasma stability. The conven-
tional design for an MCF reactor is shown in

figure 6

The plasma is contained in a toroidal vessel and held in
isolation from the walls by a helical magnetic field from
a set of D-shaped toroidal field coils (blue). The process
starts with the high-vacuum reactor vessel being charged
with a small amount of deuterium and tritium gas, which
is then ionised and the electrons are removed.

The voltage applied to the primary circuit (red) is

swept slowly from a large positive to a large negative
value. In near-term research machines, such a sweep
might last for about a minute. In a commercial MCE
power station, such a sweep would last far longer, per-
haps even hours. This magnetises the iron core (orange),
generating a field that induces a current in the plasma
(analogous to the secondary coil of a conventional
electric transformer). Positively and negatively charged
components are not bound together in a plasma, so the
changing field induces a current of two components:
positive nuclei moving in one direction round the torus
and negative electrons moving in the opposite direction.
The key advantage of this geometric arrangement is the
fact that the plasma particles do not follow smooth cir-
cular paths round the ring. While the transformer action
gives rise to a poloidal magnetic field, the coils create a
toroidal magnetic field. The combination of these fields
results in the plasma particles following a helical path

deuterium

nucleus

tritium

nucleus

neutron

helium

nucleus

+ energy

(17.6 MeV)

fusion

9 R Pitts

et al.

2006.

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What is fusion? The basic physics

Figure 6: Schematic

of a tokamak.

Source:

EFDA JET.

round the torus (black). This helical motion is key to the
stability of a tokamak plasma.

At the start of a voltage sweep the plasma is cold

and viscous. Much of the applied electrical energy is
converted into plasma heat because of friction effects.
However, such resistive heating alone is insufficient. In
modern tokamaks, heat is also transferred to the plasma
in a range of other ways, including resonant radio fre-
quency energy (not unlike the operation of a domestic
microwave oven) and high-energy beams of neutral par-
ticles, such as hydrogen atoms (the motion of which is
unaffected by the magnetic fields of the tokamak, at least
prior to ionisation).

Tokamak plasma physics is benchmarked according

to a few key indicators; an important one is the pressure
ratio,

. This is the ratio of the pressure in the plasma

to the “magnetic pressure”, or energy density, which is
proportional to the square of the applied magnetic field.
Generally those considering fusion power concepts are
attracted to high-

designs because of their more effi-

cient use of the magnetic field.

Inductively driven tokamaks are pulsed machines.

Fundamentally this arises because the plasma cur-
rent is driven by transformer action, and the primary
circuit necessarily only has a limited voltage swing.
This transformer action provides the initial heating and
sets up the plasma current. Once the voltage sweep is
finished, the plasma current starts to decay because
of resistive losses. However, this plasma current can
be sustained via directed heating, and also as a result
of complex secondary effects, such as the so-called
“bootstrap current”. These additional sources may be
sufficient to allow a power station to operate in a near-
continuous, rather than pulsed, mode. At present, most
fusion proponents look to tokamak operations lasting
several hours in a long pulse mode, with only limited

time required to reset for the next pulse.

Tokamaks require several sets of magnetic coils.

Physically the largest coils are the toroidal field coils
– superconducting magnets (blue in

figure 6

). The mag-

netic fields required for a tokamak are very large, yet
space around and within the machine is at a premium.
These constraints lead to the need for superconducting
magnets in all future large-scale tokamaks. The Interna-
tional Thermonuclear Experimental Reactor (ITER) will
use some of the largest superconducting magnets in
the world.

Superconductors have the property of zero

electrical resistance at low temperatures, which allows
large currents to flow through ITER’s electromagnets
with very high efficiency.

transformer winding

(primary circuit)

iron transformer core

toroidal

field coils

toroidal

magnetic field

poloidal

magnetic field

resultant

helical field

(twist exaggerated)

plasma current

(secondary circuit)

10 See section 3.

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The quest for fusion: a history

The first fusion experiments were conducted at the Uni-
versity of Cambridge, UK, during the 1930s, but it wasn’t
until the following decade that fusion’s potential as an
energy source was realised. Fusion research for energy
generation has had a turbulent and complex history.

The 1950s saw misplaced optimism with the opera-

tion in the UK of the Harwell Laboratory’s Zero-Energy
Thermonuclear Assembly (ZETA)

– a stabilised toroidal

pinch machine. It had a toroidal shape but the region
of plasma physics interest was restricted to a particu-
lar toroidal segment – the “pinch”, where the plasma
was magnetically squeezed to increase its “magnetic
density”.

Throughout the early years of fusion research, plasma

stability in MCF systems presented an ongoing diffi-
culty. While some in Britain were calling for an end to
fusion-energy research, a breakthrough came in 1968
from the Kurchatov Institute in the Soviet Union. A new
approach known as the tokamak was found to work very
well in the form of the T3 machine, which was based on
a 1951 concept from Igor Tamm and Andrei Sakharov.

In the 1970s the construction of big fusion-research

machines was approved, including a European collabo-
ration to build the biggest machine to date – the Joint
European Torus (JET). In the 1980s, Soviet general
secretary Mikhael Gorbachev proposed to US president
Ronald Reagan that the superpowers might collaborate
to build ITER. In the 1990s, however, policy-makers’
enthusiasm for grand energy research projects wavered
against a background of sustained low oil prices. A key
step was taken in November 2006 when a much-revised
ITER plan was finally agreed as a seven-party interna-
tional collaboration.

3.1: Achievements of the large tokamaks

While much good research has been conducted on
small tokamaks, it is three large tokamaks that have
done the most to help to make fusion energy a viable
prospect. They are:

Japan Atomic Energy Research Institute Tokamak-60

●

(JT-60) in Naka, Japan, 1985 to present;
Tokamak Fusion Test Reactor in Princeton, New

●

Jersey, US, 1982–1997;
JET in Culham, Oxfordshire, UK, 1984 to present.

●

Together these three machines have demonstrated the

scientific fundamentals of fusion power production. For
instance, researchers at JT-60 demonstrated that even
once the initial driving transformer sweep has ended, it
should be possible to continue to operate the tokamak
by means of an external current drive – an important

step towards continuous electricity generation.

A greater challenge than maintained high plasma tem-

perature is plasma confinement. Much work has been
undertaken to understand the diffusion of plasmas in
tokamak fields. Key considerations are high-energy par-
ticle collisions and plasma turbulence. Another critical
topic specifically for the tokamak is continuous opera-
tion. Sustained plasma motion and confinement might
be maintainable as a consequence of the bootstrap cur-
rent – an important effect predicted theoretically in the
early 1970s and first observed by Michael Zarnstorff in
1984 at the University of Wisconsin-Madison.

The boot-

strap current was not anticipated when tokamaks were
first proposed, but it could be of great importance in
achieving continuous electricity generation. If the boot-
strap current is insufficient, plasma motion may also be
enhanced, for example via directed neutral beam injec-
tion or resonant frequency electromagnetic waves.

JET

has achieved the highest level of fusion energy produc-
tion (

figure 8

). In 1997, JET briefly produced 64% of the

amount of energy being fed into the plasma (denoted by
Q = 0.64). This refers to the total energy released by the
reaction, four-fifths of which is taken up by the emitted
neutrons, providing the heat for electricity generation.
Only when the plasma reactions release five times the
amount of energy that is put in (Q > 5) is the internal
heating power greater than the supplied power. Clearly a
power station needs to produce vastly more energy than
it consumes (e.g. Q ~ 50). Originally it was anticipated

that a fusion power station might operate without ongo-
ing supplied power, in ignition mode (Q = ∞). Increas-

The quest for fusion: a history

Figure 7: The JET tokamak. Source: EDFA-JET.

11 C M Braams and P E Stott

2002, section 4.2.

12 See section 2.1.

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The quest for fusion: a history

Figure 8 (left): Record-

breaking deuterium-

tritium fusion energy

production at the JET

facility. Source: EDFA-

JET.
Figure 9 (right): ITER

cryostat and tokamak.

Source: ITER.

ingly, however, this is recognised as neither essential
nor even desirable for reasons of plasma control.

3.2: The International Thermonuclear

Experimental Reactor

ITER (“the way” in Latin) is an experimental tokamak reac-
tor that is due to be built between 2009 and 2018. The
project is a collaboration between the EU, China, India,
Japan, Russia, South Korea and the US, although current
US participation is shaky, with only $10.7 m (£5.4 m)

having been appropriated for ITER in the 2008 federal
budget, rather than the expected $160 m (£81.0 m).

ITER is to be the next step on the main trajectory

towards a fusion power station, combining fusion sci-
ence and technology. ITER will cost at least €10 bn
(£7.9 bn) over its 30-year lifetime. Roughly half of this
will be used to build the machine and half to operate
and decommission it. Following intense international
competition, the global partners agreed to locate the
machine at Cadarache in southern France.

While the earliest plans imagined that ITER should

achieve ignition, this ambition has been scaled back
(from aiming to achieve an infinite Q value, ignition, to a
level of at least Q = 10), recognising that power stations
would be unlikely to operate in ignition mode.

The goal for ITER is to produce roughly 500 MW of

thermal energy

(a similar power rating to that of a

modular natural-gas-fuelled combined-cycle gas turbine
for power production) in long pulses of at least 400 sec-
onds. The reactor is experimental; there is no intention
of using ITER as a power station. Preparatory site works
began in 2007, and most of the design and negotiation
challenges have now been met.

fusion power (MW)

time (seconds)

JET

(1991)

Q = 0.2

JET

(1997)

JET

(1997)

Q = 0.64

13 Based on 2008 exchange

rates.

ibid.

15 C Llewelyn Smith and

D Ward 2005.

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Unconventional approaches to magnetic confinement

While there is a clear and coherent path from the early
Russian T3 machine, through the big tokamaks of the
1970s, towards ITER and an eventual fusion power sta-
tion, this sequence is not the only interesting and poten-
tially energy relevant tokamak research.

One research thread has been that of low-cost toka-

maks,  intended  primarily  for  scientific,  rather  than
energy,  purposes.  Perhaps  the  most  radical  of  such
proposals is the Ignitor concept from Bruno Coppi and
colleagues  at  Massachusetts  Institute  of  Technology
(MIT) and the Italian National Agency for New Technolo-
gies, Energy and the Environment (ENEA).

This design aims to achieve ignition as cheaply as pos-

sible. Perhaps most important is that the project avoids
some of the more complicated technology of other
fusion reactors by not employing a divertor to extract
the helium ash, because the machine is intended from
the outset only to perform pulsed experiments. Coppi
points to the high levels of inherent plasma cleanliness
in the Ignitor concept as being a key positive attribute
of that particular low-cost approach. At present, while
components of Ignitor have been manufactured, the
machine is far from complete.

4.1: Spherical tokamaks

Another radical and highly successful concept is Mar-
tin Peng’s spherical tokamak (ST), which was demon-
strated for the first time in the UK by the Spherical Tight
Aspect Ratio Tokamak (START). The Culham Science
Centre team built START in its spare time using sec-
ond-hand equipment, and in 1998 smashed the world
record with a high value for the key plasma-physics
benchmark – the pressure ratio

Since the success

of START, impressive achievements have been made
with second-generation STs, with Globus-M in Russia,
the National Spherical Torus Experiment at Princeton
in the US, and in the UK with the Mega Amp Spherical

Tokamak (MAST), which has been running since 1999.

The ST is topologically identical to the torus of the

conventional tokamaks because the sphere has a hole
running through it. The term spherical refers to the outer
shape only.

Princeton Plasma Physics Laboratory reports that ST

plasma configuration “may have several advantages, a
major one being the ability to confine a higher plasma
pressure for a given magnetic field strength. Since the
amount of fusion power produced is proportional to
the square of the plasma pressure, the use of spheri-
cally shaped plasmas could allow the development of
smaller, more economical fusion reactors.”

In addition to a very high pressure ratio, STs also have

the advantage of a very large bootstrap current com-
pared with conventional tori. This suggests the possibil-
ity that sustained operations would be achieved more
easily in an ST than in more conventional approaches.
Despite these opportunities, it must be emphasised
that STs are far less developed than conventional tori
such as ITER, which remain the technology on track for
the first commercial deployment of fusion.

4.2: Beyond tokamaks: the stellarator

Before the breakthrough that gave us the tokamak, there
was one other candidate expected to achieve a sustained
MCF plasma. This was known as the stellarator, and in the
1960s the US was a world leader in this area. In a stel-
larator, unlike in a tokamak, the field coils alone provide
an induced helicity to the plasma. There is no transformer
action with a sweeping driving current, so the machine
operates in a steady-state mode, with plasma confine-
ment arising solely from the geometry of the external
magnetic field. Studies done in Japan and Europe have
shown that stellarators achieve distinctly higher plasma
densities than tokamaks and do not suffer from current-
driven instabilities and plasma disruptions like the toka-

Unconventional approaches to

magnetic confinement

Figure 10 (left): Hot

plasma from the MAST

fusion experiment.

Source: UKAEA

Culham.
Figure 11 (right):

Schematic

arrangement of

a magnetic field

coil system for the

Wendelstein 7-X

stellarator under

construction in

Greifswald, Germany.

Source: Max Planck

Institute.

16 R Herman 1990.

17 www.pppl.gov/projects/

pages/nstx.html.

18 See section 2.1.

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Unconventional approaches to magnetic confinement

mak. The confinement is observed to be similar to that of
equal-sized tokamaks.

figure 11

illustrates, the stellarator requires field

coils of an extremely complex configuration. Despite
the benefits provided by computer-aided design, stel-

larators remain difficult machines to manufacture. The
most impressive attempt under way is in Greifswald,
Germany, where the 30 m

Wendelstein 7-X stellarator

is under development, with the first plasma operation
scheduled for 2014.

19 J-H Feist

et al.

2007.

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Why is fusion development so slow?

Figure 12: The goal

of fusion energy

recedes if research

is under-supported.

Source: DOE Princeton

University Plasma

Physics Laboratory.

In public policy terms, the greatest challenge facing
fusion is the pervasive perception that fusion as a power
source is an ever-receding goal. This view is not without
foundation. On 18 April 1967, then UK minister of tech-
nology Tony Benn noted in his diary that Soviet nuclear
scientist Lev Andreevich Artsimovich had said to him:
“Well, 10 years ago we said it would take us 20 years
to make fusion work and we still say that it will take 20
years to make fusion work, so we haven’t altered our
view in any way.”

Such insights might lead us to the

view that things have actually got worse, not better.

In the fusion research laboratories an alternative view

is presented. It is argued that the crucial measure is
not time but effort. If sufficient resources had been pro-
vided and sustained then some of the earlier promises
would have been fulfilled.

A 1976 report from the US Energy Research and

Development Administration presented a set of sce-
narios for the then future development of MCE. The
costs presented (US dollars in 1976) range from about
$15 bn to $20 bn

(£8.3 bn to £11.1 bn).

Research-

ers at Princeton Plasma Physics Laboratory have con-
sidered US support for fusion since 1980 (

figure 12

). If

all had gone well, the original 1980 estimate of $30 bn
(£12.9 bn)

might have been sufficient to achieve

demonstration fusion by the year 2000. In fact, federal
research funding was supplied at a far slower rate than
originally anticipated in the Magnetic Fusion Engineer-
ing Act of 1980. As a consequence the prospect of a

demonstration of commercial fusion power production
receded to the year 2035. The simple message from
the fusion research community is that if we work less
than half as hard, it will take us more than twice as long.
These voices assert that if fusion is to address press-
ing energy policy challenges, it will need resources that
constitute a significant proportion of the energy budget.
At present, Europe devotes less than 0.5% of its total
energy spend to related R&D, and fusion research is
merely a small part of that total. To make significant
adjustments to Europe’s energy system to address pol-
icy goals, much more R&D will be needed, not only in
fusion but also in other areas.

5.1: A strategy for the 21st century

Scientific fusion research has had many successes, and
it is often said that no fundamental scientific challenges
remain, only engineering ones. Such statements can,
however, give a false impression. While the fusion reac-
tion is well understood, many physics questions remain,
such as those regarding plasma-burn control and robust
fusion materials.

Various “fast-track” approaches are being pushed by

fusion laboratories to bring forward the time when fusion
energy will be a viable option. Central to the fast track is
a strong emphasis on materials testing. Originally ITER
was, in part, intended to provide a source of fast neu-
trons for materials testing.

The necessary materials

research would only start once ITER had demonstrated

Why is fusion development so slow?

funding for fusion research ($m – 2002)

35 000

year

1980

1985

1990

1995

2000

2005

2010

2015

2020

2025

2030

2035

30 000

25 000

20 000

15 000

10 000

5000

Magnetic fusion

Engineering Act

of 1980 intended

spend

actual spend

up to 2003

Fusion Energy Development

Plan, 2003 (MFE)

intended spend

ITER

demo

FED

2003 status

20 T Benn 1996.

21 The 1976 ERDA report is

most accessible as a reprint:

S O Dean, Fusion power by

magnetic confinement program

plan

Journal of Fusion Energy

17 4

263–287.

22 Based on the 1976

12 month average exchange

rate.

23 Based on the 1980

12 month average exchange

rate.

24 V Barabash 2004.

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Why is fusion development so slow?

the fundamental fusion physics. Now, however, it is
recognised that other experimental demands will mean
that ITER will not deliver the sustained high neutron
fluxes required. Furthermore, waiting until the sched-
uled start of ITER in 2018 would cause an unhelpful
delay in materials research. As a consequence, the fast
track includes the International Fusion Material Irradia-
tion Facility (IFMIF), which was conceived in 1996. The
Japanese are taking the lead on the engineering design
of IFMIF in Rokkasho, but no site has been proposed in
Japan, or elsewhere, for the facility. IFMIF would allow
rapid progress on important materials-science research
essential for fusion power stations, but at present the
IFMIF facility is yet to be funded.

In addition to IFMIF, the fast track envisages only one

step between the ITER experimental facility and a first
commercial power station. That intermediate step is the
Demonstration Power Plant (DEMO), which is intended
to produce 250% of the heat of ITER – a thermal output
consistent with the demands of an actual fusion power
station. It is conventional to speak in terms of a single
DEMO power station following the ITER research project,
although it is probable that there would be several in
different parts of the world such as in the US, Europe,
Japan, and perhaps China or India. In some countries the
DEMO stage is expected to be led by private corporations
with public subsidy or other forms of initial support.

Conventionally it has been intended that DEMO should

follow ITER and build on the research undertaken with
that machine. Increasingly, however, individuals such as
Chris Llewellyn Smith, director of the UK Atomic Energy
Authority (UKAEA) Culham Division, have been advo-
cating a prompt start to the construction of DEMO, in
advance of completion of the ITER machine.

5.2: Historical, current and future costs

Fusion research is controversial in science and technol-
ogy public-policy circles, not because of its technical
merits or otherwise but because of its cost. For some it
is the great white elephant of energy research budgets
with ever more good public money being sent to follow
investments gone bad. For others, the history of fusion
is one of consistent underfunding punctuated by rela-
tively short bursts of proper research support when oil
prices peak.

Fusion research is “big science”, but for most coun-

tries it is big science with a purpose – commercial energy
production. The fusion community’s ambition to yield
a sustainable energy source for the late 21st century
prompts one to consider the costs of fusion research
against those of other proposed energy technologies.

At the EU level the bulk of research support for fusion

is handled via the Framework Programmes. In the Sev-
enth Framework Programme (2007–2013), EURATOM
has a budget of approximately €2.7 bn, whereas Euro-
pean co-operation in (non-nuclear) energy matters
receives €2.35 bn.

Of the EURATOM budget, roughly

85% is for fusion research.

In these terms fusion can

appear to be expensive, taking the lion’s share of the
pie. The pie, however, is not static. For instance, the EU
budget for energy and transport networks has risen by
92.5% between 2007 and 2008.

It seems probable,

as has occurred before, that as public-policy concern
for energy rises, fusion budgets will recede in relative
importance while growing in absolute terms.

It is also important to stress that most fusion research

occurs at an international (e.g. European or global) scale.
As such, the costs specified for this kind of research can
appear to be very large when compared with more con-
ventional national research programmes in energy.

25 Council of the European

Union press release, 16887/06

(Presse 366), www.consilium.

europa.eu/ueDocs/cms_Data/

docs/pressData/en/

misc/92236.pdf.

26 Note that the EC also

supports the Joint Research

Centre, much of which relates to

non-nuclear energy.

27 EU Budget 2008

flier. Available at http://

ec.europa.eu/budget/library/

publications/budget_in_fig/

dep_eu_budg_2008_en.pdf.

proportion of total UK energy RD&D

197

year

renewables

fusion

0.5

0.4

0.3

0.2

0.1

197

1978 198

1982 198

1986 198

1990 1992 199

1996 199

2000 200

2004

0.0

Figure 13: Proportion of

UK public spending on

fusion in comparison

with renewables RD&D.

Source: International

Energy Agency (see

www.iea.org/textbase/

stats/rd.asp).

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Why is fusion development so slow?

28 K Kim

et al.

2005.

29 The subject of current

research at MIT.

Looking at energy research spending in the UK allows

a cross-comparison of fusion research support with
renewables (

figure 13

). Broadly, the funding levels are

similar, with fusion having secured greater support dur-
ing the 1990s when energy was inexpensive globally.
Now that energy prices have started to rise significantly
and climate change becomes a more pressing concern,
support for renewables research is rising fast, outstrip-
ping that available to fusion.

Tokamak research involves co-operation and negotia-

tion between some of the world’s leading high-technol-
ogy economies. Fusion research includes activity at the
Universidad Nacional Autónoma de México and at the
University of Malaya in Kuala Lumpur, Malaysia. China
has shown an impressive ability to develop its fusion
research  capacity,  starting  with  the  use  of  donated
second-hand fusion experiments such as the German
Asdex and the Russian T7 tokamaks. China currently
has  a  world-leading  position  with  its  impressive  and
operational  mega-ampere  superconducting  tokamak
EAST, formerly known as HT-7U, which started its experi-
mental programme in September 2006.

Another country rapidly accelerating its fusion

research base is South Korea. In September 2007,
South Korea finished construction of a new experimen-
tal tokamak known as KSTAR. This machine will be the
first in the world to make use of advanced superconduct-
ing magnet technology based on niobium-3-tin (Nb

Sn)

conductors. Similar technology is planned for ITER. The
KSTAR team encountered and successfully overcame
some difficulties testing the large superconducting
toroidal field coils.

Such technical difficulties are to

be expected in any large, complex, high-technology
project. Lessons learned from smaller machines, such
as KSTAR, can help to minimise the technical risks to be
faced by ITER, but they cannot be eliminated entirely.

5.3: Commercial fusion before fusion

electricity: faster than fast track?

While most fusion research is dedicated to electricity
generation through the orthodox approaches described
here,  there  is  also  a  separate  fusion  research  com-
munity that addresses the issue of nuclear weapons
reliability.  However,  these  two  relatively  well  funded
communities  are  not  the  entirety  of  energy-related

fusion research, and occasionally radical ideas emerge
from outside these large fusion laboratories. Frequently
these external proposals seek to make use of fusion
energy on timescales that are even shorter than the
fast track of MCE. Most of these ideas focus on a direct
use of the heat of fast neutrons produced by tokamak
fusion, rather than using it to make electricity.

There are also some, such as Wallace Manheimer

of the US Naval Research Laboratory, who seek to link
fusion to fission-based nuclear power. Manheimer has
advocated the construction of fission–fusion hybrids,
in which fast neutrons released through fusion prompt
fission reactions in the blanket for boosted energy
production. This technique might be used to produce
fissile uranium-233 fuels for conventional fission reac-
tors from abundant thorium;

or fusion’s fast neutrons

might be used to transmute existing fission wastes into
more benign and shorter-lived isotopes.

Leslie Bromberg and colleagues at the Plasma Sci-

ence and Fusion Center at MIT are interested in the role
of an MCF facility as a fuel source for a fleet of relatively
conventional fission power stations. Such a fusion facil-
ity would not produce commercial electricity, hydrogen
or process heat; it would instead produce nuclear fuel
for fission power stations. In the future, the commercial-
isation of fusion might involve much more than simply
the sale of clean electricity.

Researchers from General Atomics in San Diego

have long suggested that fusion-process heat might be
used to produce hydrogen via high-temperature cata-
lytic chemistry. This could be a highly efficient route
to hydrogen production that does not involve electricity
production or electrolysis. One possible supply-chain
for hydrogen would make use of liquid tanker shipments
rather than gas-pipeline networks. In collaboration with
Richard Clarke of Culham Science Centre and Bartek
Glowacki of the Department of Materials Science and
Metallurgy at the University of Cambridge, the author
of this report has proposed that a fusion reactor for
liquid-hydrogen production might make use of that
same liquid-hydrogen product to cool the magnets of
the fusion device. This approach seeks to free fusion
reactors from the cost of large amounts of helium as
a consumable for the cryogenics system. The idea is
known as Fusion Island.

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Fusion – another way?

Figure 14: Early

representation of the

EU’s HiPER. Source:

HiPER (see www.hiper-

laser.org).

6.1: Inertial confinement fusion energy

While the major current approaches to fusion are all
MCF based, ICF could also present opportunities for
fusion energy.

In a thermonuclear weapon, fusion materials are com-

pressed using radiation emitted by a first-stage fission
reaction. In ICF, similar but much smaller pulsed com-
pression is employed on a (relatively) tiny fuel pellet.
Inevitably, therefore, ICE would produce pulsed power.
In a potential power station this would involve releasing
energy in a series of millions of tiny controlled explo-
sions, not unlike the millions of explosions that occur in
an internal combustion car engine. Such an ICE power
station might pulse at around five times a second. The
major approach to ICF uses very-high-intensity converg-
ing laser beams to compress and heat a millimetre-sized
fusion fuel pellet. Significant experimental facilities,
dedicated partly to assessing nuclear weapons reli-
ability, are under construction in the US and France.
These are also likely to advance progress towards com-
mercial ICF energy production. It is expected that the
US Department of Energy installation will demonstrate
ignition in around 2020. Even with such developments
it remains probable that MCF will be the quicker route
to commercial usable fusion energy.

In September 2007, EU scientists recommended sup-

port for a British-led High Power Laser Energy Research
Facility (HiPER). This completely civilian enterprise will
build on military advances in ICF from the US and else-
where. A £500 m research programme is expected for
HiPER over seven years.

6.2: Plasma pinch

Another possibility, taking ideas from both MCF and ICF,
is the plasma pinch. The most developed concept is the
Z-pinch, which achieves fusion in a similar way to ICF. A
fuel pellet of cryogenically frozen deuterium and tritium
is compressed by a uniform radiation pressure, which is
achieved by rapidly creating, vaporising and pinching a
plasma of ionised metal atoms rather than by the direct
use of laser beams.

The heavy ionised metal plasma arises from the pas-

sage of an enormous current through a small high-preci-
sion wire cage known as a hohlraum. When the pinched
metal ions collide at high energy, X-rays are produced
that should in principle be sufficient to compress a
pellet of fuel into a fusing plasma. If Z-pinch machines
could be developed for electricity production, they
would have the following advantages over conventional

ICE systems: the pulse rate would be more manageable
at once every 10 seconds rather than several times a
second; the energy production process would be more
efficient; and the energy produced per pulse would be
larger. The drawbacks compared with more conven-
tional ICE approaches would be that each fuel pellet
assembly would be a more complex manufactured item
and that the hohlraum in Z-pinch would be far larger
than its ICE equivalent. Lastly, it is important to stress
that Z-pinch for energy production is farther from com-
mercialisation than conventional ICE and hence much
further from commercialisation than MCE approaches
based on ITER.

6.3: Cold fusion?

In 1989 two electrochemists, Stanley Pons and Mar-
tin Fleischmann, observed unusual phenomena that,
they reported, suggested fusion in a simple table-top
apparatus. Some researchers, including Peter Hagel-
stein of MIT, continue to search for fundamental new
physics in such experiments. If cold fusion releases
energy, as Hagelstein and others continue to report,
then it does so without the production of large num-
bers of high-energy neutrons or other emitted reaction
products. That would mean that the physics involved
must differ fundamentally from that observed in a con-
ventional “hot fusion” process. Any cold fusion reac-
tion would involve the emitted nuclear energy coupling
directly with the atomic lattice of the electrodes in
the table-top cell: such speculative new physics has
been termed condensed-matter nuclear science. The
orthodox view of cold fusion is that such phenomena
do not exist. In response the proponents continue to
suggest that such phenomena are merely difficult to
generate.

Fusion – another way?

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Six challenges for fusion

7.1: Planned availability

Large capital costs with a small marginal cost of elec-
tricity-generation force fusion power towards base-load
supply. D Ladra and co-workers have reported: “to be
competitive, fusion power stations should have high
availability, preferably exceeding 80%, with very few
unplanned shutdowns”.

The 80% target, now routinely

achieved by fission technology, will be a stretch for any
planned fusion power station.

The requirement for continuous power at high avail-

ability  is  particularly  demanding  for  the  tokamak’s
essentially pulsed output, albeit possibly operating in
very-long-pulse  mode.  Although  researchers  suggest
that plasma motion and stability can be maintained for
many hours after the initiating voltage sweep, there is
a significant availability difference between long-pulse
operations  and  a  truly  continuous  operation.  Much
consideration has been given to the challenge of con-
tinuous operation.

In extremis, multiple tokamaks in a

single power station would be a possibility. For instance,
two pulsed tokamaks operating out of phase with each
other might raise steam to drive a single turbogenerator
set for continuous electricity production.

7.2: Reliability

An even greater challenge than availability is the
need to achieve very high levels of reliability. That is,
unscheduled and unanticipated interruptions to power
generation must be avoided. A fusion-based electric-
ity company in a modern competitive electricity market
will need to enter into long-term bilateral contracts with
electricity suppliers to provide the necessary business
stability.

A rule of thumb for plasma stability in tokamaks is:

the bigger the machine, the better. Also, the engineer-
ing of a fusion power station is likely to face significant
economies of scale, further favouring large machines
of at least 1.5 GW electrical output. If such a machine
were to be forced to shut down unexpectedly then there
would be significant penalties in the electricity market.
In addition, intervention would be required to ensure
the supply-demand balance. This represents a potential
pressure on the system operator (i.e. the National Grid
in the UK). If a power station were to fail during a high-
demand period, even if the cause of the problem was
minor, the station might not be able to restart because
the system operator would not be able to spare the
large amounts of power required to restart the fusion
process. This issue is relatively easy to address, with
on-site generation and/or energy storage such as fly-
wheels, which can already deliver many hundreds of
megawatts on JET. Such items would provide the restart

power but would represent a significant capital cost for
the MCE power station and in a conventional concept
would only be used intermittently.

7.3: Structural integrity

As a consequence of its basis as a transformer driven
by a single sweep of the primary, a tokamak is inher-
ently a pulsed device. A power station will operate with
very long pulses, but during its life it will still be subject
to many tens of thousands of pulses. Given the very
large magnetic fields associated with plasma confine-
ment and drive, each pulse will place significant mag-
netic stresses on the structure of the power station.
The station must withstand repeated cycling of these
structural loads.

Much of a station’s structure, such as the blanket, will

be at high temperatures at which conventional steels
cease to have good tensile properties, and this will
make the structural strength of the machine an even
greater challenge.

Lastly, some of the structural components could be

exposed to significant neutron fluxes. Each fast neutron
impact can cause microstructural defects in engineer-
ing materials.

A tokamak power station is a major structural engi-

neering challenge, in terms not of whether it can be
built, but of whether it can survive years of reliable
operation.

7.4: Helium supply

While the fuels for fusion power are abundant and eas-
ily obtained, this does not mean that a fusion power
station would be free from energy security risks. Cen-
tral to such risks must be the long-term availability of
affordable helium used for tokamak pumping, purging
and, above all, cooling superconducting magnets. While
helium could in principle be obtained from the atmos-
phere at great cost, and while it is also possible that
economically viable helium gas wells could be devel-
oped, the reality today is that all commercial helium is
obtained as a by-product of the natural-gas industry.
That industry is expanding and, as it moves towards liq-
uefied production and supply, the economics of helium
production are favoured. While it is likely that abundant
helium will be available in the short term, the natural-
gas industry is a fundamentally unsustainable process
of resource depletion. These issues are considered by
a joint UKAEA, Linde-BOC and University of Cambridge
research project considering global helium resources.

Helium availability and cost are potentially serious
issues for the large-scale deployment of fusion energy
systems. A move to liquid hydrogen for superconductiv-

Six challenges for fusion

30 D Ladra

et al.

2001.

31 H S Bosch

et al.

1996.

32 Z Cai

et al.

2007.

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Six challenges for fusion

ity would eliminate the jeopardy, possibly extant, in an
over-reliance on helium.

7.5: High-temperature plasma-facing

materials – the divertor

Components directly facing the very hot fusion plasma
include the first wall of the blanket on the outer edge of
the torus and the divertor, which is usually placed round
the bottom of the torus. In all MCF the plasma must
at some point touch the vacuum vessel. This could be
using a device dedicated to that purpose (a limiter), but
more conventionally that role is played by the divertor.
As a result of contact with the vacuum vessel, the tiles
of the divertor will glow white hot. It is expected that
these tiles will need frequent replacement and, given
that the tokamak vessel will be a highly radioactive envi-
ronment, this will need to be done robotically. At JET,
much effort has gone into such remote handling. Never-
theless, divertor component reliability and replacement
represent key challenges for a fusion power station.

7.6: Problematic materials

It is often rightly stressed that, if properly developed,
a fusion power programme need not lead to a legacy
of long-lived radioactive waste. The waste of the fusion
process is harmless helium gas in small quantities. The
main issue of concern for waste is the radioactivation
of the tokamak. It is possible to manufacture the device
from materials known only to activate into short-lived
radioisotopes. As such we can be confident that a
fusion power station would leave a negligible radioac-
tive legacy 100 years after shutdown.

A more controversial matter is whether fusion energy

would represent a proliferation hazard. There is agree-
ment on the benefits of fusion making no use of fissile
isotopes such as uranium-235 or plutonium-239, which
are required for fission weapons, but beyond that opin-
ion is divided. The remaining issues fall into two broad
classes: tritium and fast neutrons.

7.6.1: Tritium

Tritium is an intensely radioactive gas with a half-life of
12.3 years, and it is an essential fuel for a fusion power
station. Despite its radioactive hazards it has numerous
conventional industrial applications. It is also a material

of interest to the nuclear weapons community, particu-
larly in the context of boosted fission weapons.

Even in a scenario of nuclear weapons proliferation

it is possible that tritium might remain as a material of
only modest concern because the spread of thermo-
nuclear  fusion-boosted  weapons  might  be  prevented
purely via the prevention of the spread of basic nuclear
weapons technology. Such long-standing proliferation
prevention  methods  rely  on  safeguards  against  the
spread of special nuclear materials – essentially plu-
tonium  and  highly  enriched  uranium.

Without such

materials, fission weapons and boosted fission weap-
ons cannot exist.

At present, tritium is not a material controlled by

strong international safeguards. It has numerous indus-
trial applications and is difficult to inventory because
it tends to be absorbed into metals and other struc-
tures. If nuclear proliferation grows as an international
concern then it seems likely that tritium controls would
increase in the coming years, possibly affecting the
fusion research community in all countries.

7.6.2: Fast neutrons

Deuterium-tritium fusion is a source of high-energy
neutrons. Some assert that these represent a prolifera-
tion risk because they can convert mundane materials
(benign fertile actinide elements), such as thorium and
depleted uranium (neither of which are subject to any
controls and both of which are difficult to detect), into the
special nuclear materials (fissile isotopes) of proliferation
concern. Such a breeder capacity would require special
engineering of the tokamak, including additional cooling,
shielding and a reprocessing capability. It would not be
possible to establish such infrastructures at a station
that was subject to rigorous international inspections.
The additional equipment required, and the fissile mate-
rials produced, would be easily detected and current
International Atomic Energy Agency (IAEA) safeguards
should be sufficient to prevent illicit production of any fis-
sile materials at a fusion facility. It is important to stress
that there are much easier ways for proliferators to seek
to make fissile isotopes than via the misuse of a future
fusion facility. Nevertheless, as a source of high-energy
fast neutrons, fusion energy applications will surely need
to be monitored.

33 Federation of American

Scientists

Special Weapons

Primer Tritium Production

, see

www.fas.org/nuke/intro/nuke/

tritium.htm.

34 After the first Gulf War in

the early 1990s, the IAEA

Safeguards were extended to

include fuel-cycle research

and specified manufacturing

activities, such as heavy-water

manufacture, see www.hse.

gov.uk/nuclear/safeguards/

what.htm.

n s t I t u t e

o f

h y s I c s

e P o R t

u s I o n

a s

a n

n e R g y

o u R c e

e P t e m b e R

2 0 0 8

8&9:

Conclusions and bibliography

In the last 10 years the pace of development for fusion
as an energy source has noticeably quickened. ITER has
been agreed, the fast track has been accepted, and
energy and climate sustainability have moved to centre
stage. As a consequence, the fusion community is start-
ing to look forward collectively to the day that fusion
energy becomes a commercial reality. The best years
for fusion physics are still to come.

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