The Path to Fusion PowerThe Path to Fusion Power

Chris Llewellyn SmithChris Llewellyn Smith

Director UKAEA CulhamDirector UKAEA CulhamChairman Consultative Committee for Euratom on FusionChairman Consultative Committee for Euratom on Fusion

Chair ITER CouncilChair ITER Council

ContextContext Huge increase in global energy use expected + needed to lift

billions out of poverty Meeting demand in an environmentally responsible manner will

be an enormous challenge

A ‘portfolio’ approach is needed (no silver bullet) (NB Electricity only = 1/3 of total primary energy demand)

– improved efficiency (encouraged by fiscal measures)– renewables* when appropriate,

* none can meet a large % of the world’s needs, except solar which could provide 100% in principle - but big breakthroughs in cost and storage needed

– must including large scale sources of base-load power, for which only options are: hydro (but potential limited), continue burning fossil fuels (so carbon capture and storage important), fission, and potentially fusion

FUSIONFUSIONpowers the sun and stars

and a controlled ‘magnetic confinement’ fusion experiment at the Joint European Torus (JET)(in the UK) has produced 16 MW of fusion power

so it worksworks

s

The big question is- when will it work reliably and economically, on the scale of a power station?

First: What is it? Why bother? Why is it taking so long?

WHAT IS FUSION ?WHAT IS FUSION ?

A “magnetic bottle” called a tokamak keeps the hot gas away from the wall

Challenges: make an effective “magnetic bottle” (now done ?)a robust container, and a reliable system

* ten million times more than in chemical reactions, e.g. in burning fossil fuels while a 1 GW coal power station would use 10,000 tonnes of coal a day, a fusion power station would only use 1 Kg of D + T

Most effective fusion process involves deuterium (heavy hydrogen) and tritium (super heavy hydrogen) heated to above 100 million °C :

Deuterium

Tritium Neutron

Helium

+ energy (17.6MeV)*

WHAT IS FUSION ?WHAT IS FUSION ?

A “magnetic bottle” called a tokamak keeps the hot gas away from the wall

Challenges: make an effective “magnetic bottle” (now done ?)a robust container, and a reliable system

* ten million times more than in chemical reactions, e.g. in burning fossil fuels while a 1 GW coal power station would use 10,000 tonnes of coal a day, a fusion power station would only use 1 Kg of D + T

Most effective fusion process involves deuterium (heavy hydrogen) and tritium (super heavy hydrogen) heated to above 100 million °C :

Deuterium

Tritium Neutron

Helium

+ energy (17.6MeV)*

A Fusion Power plantA Fusion Power plant would be like a conventional one, but with a different fuel and furnace

The blanket captures energetic neutrons produced in the fusion process, which:

- react with lithium in the blanket to produce Tritium ( fuel the reactor)

- deposit their energy heat which is extracted through a cooling circuit and used to boil water and produce steam to drive a generator

Why bother?Why bother?Lithium in one laptop battery ( tritium from the reaction:

neutron (from fusion) + lithium tritium + helium)

+ 40 litres of water (from which ‘heavy water’/deuterium can easily be extracted), used to fuel a fusion power station, would provide 200,000 kW-hours =

(EU electricity production for 30 years)/(population) in an intrinsically safe manner with no CO2

Unless/until we find a barrier, this is sufficient reason to develop fusion power

FUSION ADVANTAGESFUSION ADVANTAGES– unlimited fuel

– no CO2 or air pollution

– intrinsic safety

– no radioactive “ash” and no long-lived radioactive waste

– competitive* electricity generation cost, if reasonable availability (e.g 75%) can be achieved

*compared to most other carbon free electricity sources

FUSION DISADVANTAGESFUSION DISADVANTAGES The blankets will become radioactive

but can choose materials so that half lives ~ 10 years, and all components could be recycled new fusion power plant within 100 years (no waste for permanent repository disposal: no long-term burden on future generations)

More research and development needed

Fusion power stations will need plasma volumes of at least 1000 m3 (ten times JET), so small scale demonstration impossible (hence - relatively slow - step by step progress)

Why so long?Why so long? Cannot demonstrate on a small scale: (power out)/(power to operate) grows faster than (size of fusion device)2 – need GW scale to be viable

Not funded with any urgency – otherwise from agreement on basic geometry in 1969, could have reached today’s position 15 years ago (note that energy R&D boosted by oil crisis but then collapsed)

It is very challenging- need to heat ~ 2000 m3 of gas to over 100 M 0C, without it touching the walls- find robust materials with which to make the walls (able to withstand intense neutron bombardment and heat loads)- ensure reliability of very complex system

Nevertheless huge progress: from T3 to JET and from JET to ITER (later)

T3: Volume ~1 m3

Temperature ~ 3 M 0CEstablished tokamak as best configuration (1969)

Progress in FusionProgress in Fusionhas been enormous, but even JET (currently the world’s leading fusion research facility) is not large enough to be a (net) source of power

JET: Volume ~100 m3

Temperature ~ 150 M 0CWorld record (16 MW) for fusion power (1997)

JETJET

MAST

ProgressProgress• Huge strides in physics,

engineering, technology

• JET: 16 MW of fusion power ~ equal to heating power.

• Ready to build a Giga Watt-scale tokamak: ITER – expected to produce 10 x power needed to heat the plasma

[Pi =pressure in plasma;

τE = (energy in plasma)/(power supplied to keep it hot)]

NEXT STEPS FOR FUSIONNEXT STEPS FOR FUSION Construct ITER (International Tokamak Experimental

Reactor)

energy out = 10 energy in

“burning” plasma

During construction, further improve tokamak performance in experiments at JET, DIII-D, ASDEX-U, JT- 60…further develop technology, and continue work on alternative configurations [Spherical Tokamaks (pioneered in UK), Stellarators]

Intensified R&D on i) materials for plasma facing and

structural components and test of materials at the proposed International Fusion Materials Irradiation Facility (IFMIF), and ii) fusion technologies

JET (to scale)

ITER

• Aim - demonstrate integrated physics and engineering on the scale of a power station

• Key ITER technologies fabricated and tested by industry

• 5 Billion Euro construction cost (will be at Cadarache in southern France)

• Partners house over half the world’s population

ITERITER

Plasma Physics IssuesPlasma Physics IssuesMajor positive developments (1980s and 90s) ‘Bootstrap’ plasma current (predicted at Culham) much less external power needed than previously thought

High confinement mode (serendipitous discovery at Garching) higher pressure + more fusion power with given magnetic field

Potential Problems New instabilities in burning plasmas?

Steady state operation in power station conditions (looks possible with help of bootstrap current: if not, could pulsed machine, or stellarator)

Potential improvement Better control of potential instabilites to allow higher pressure

Transition to H mode at MAST (at Culham, UK)Transition to H mode at MAST (at Culham, UK)

After: The edge of the plasma is very sharp and energy containment improves so the plasma pressure you can maintain is bigger

Before: the edge of the plasma is fuzzy and energy containment is poor

Spherical TokamaksSpherical TokamaksBased on promising, more compact but less developed, configuration than JET and ITER - use magnetic field much more efficiently (but face other challenges):

STARTSTART (Culham, UK 1991-1998, first substantial Spherical Tokamak) raised world record for key figure of merit ( = ratio of plasma to magnetic pressure) from 13% to 40% !

Many STs built subsequently: world’s leading STs are

NSTX (Princeton) and MAST (Culham):

Spherical TokamaksSpherical Tokamaks Making important contributions to conventional tokamak physics

different shape → new perspective

Could play vital role as a “Component Test Facility” in the medium-term

A CTF, which would test whole components (blankets, welds, joints,…), is a highly desirable (perhaps essential) step between ITER and a prototype power station

Could, in long-run, be basis for (smaller and simpler) power stations

No superconducting magnets → cheaper and simpler

STELLARATORSSTELLARATORS(Originally pioneered at Princeton)(Originally pioneered at Princeton)

Helical field, needed to confine plasma, provided externally Avoid need to drive the Mega Amp currents that provide (part of the) helical fields in Tokamaks, and are a source of instabilities Intrinsically steady state devices. The price is greater complexity.

LHD in Japan: W7-X under construction in Germany:

Structural materials – subjected to bombardment of 2 MW/m2 from 14 MeV neutrons

Plasma facing materials subjected to an additional 500 kW/m2 from hot particles and electromagnetic radiation (much more on ‘divertor’)

Various materials have been considered, and there are good candidates that may survive in these conditions, BUT:

Further modelling + experiments essential:

Only a dedicated (€800M) accelerator-based test facility - the International Fusion Materials Irradiation Facility (IFMIF) - can reproduce reactor conditions: results from IFMIF will be needed before a prototype commercial reactor can be licensed and built

MATERIALSMATERIALS

Materials IssuesMaterials Issues

Major positive development (1990s) Body-centred cubic low activation steels seem able to withstand neutron damage

Potential problems Effect of helium generation in the materials

Heat on ‘divertor’ (can be reduced by compromising design)

Potential improvement Development of advanced materials (SiC ceramics,…) for much higher temperature operation

European Power Plant Conceptual StudyEuropean Power Plant Conceptual Study

Results Confirm good safety and environmental features of fusion Give encouraging range for the expected cost of fusion generated electricity (9 €-cents/kW-hour for early near-term [water cooled steel] model; 5 €-cents/kW-hour for early advanced [Li-Pb cooled Si-C composites] model)

Note Economics favours large fusion power plants major centres of population (complementary to renewables) Capital intensive; very low operating cost – lots of cheap off peak power hydrogen?

Results of this study used as input to Culham ‘Fast Track’ study

European Power Plant Conceptual StudyEuropean Power Plant Conceptual Study

Results Confirm good safety and environmental features of fusion Give encouraging range for the expected cost of fusion generated electricity (9 €-cents/kW-hour for early near-term [water cooled steel] model; 5 €-cents/kW-hour for early advanced [Li-Pb cooled Si-C composites] model)

Note Economics favours large fusion power plants major centres of population (complementary to renewables) Capital intensive; very low operating cost – lots of cheap off peak power hydrogen?

Results of this study used as input to Culham ‘Fast Track’ study

FUSION ‘FAST TRACK’FUSION ‘FAST TRACK’

• During ITER construction

– operate JET, DIII-D, JT60… speed up/improve ITER operation

• In parallel intensify materials work (approve and build IFMIF as soon as possible) and development of fusion technologies (magnets, remote handling, heating systems, fuel cycle, safety,…)

• Then, having assimilated results from ITER and IFMIF,

build a Prototype Power Plant (‘DEMO’)

Fusion a reality in our lifetimes

Fast Track - Pillars OnlyFast Track - Pillars Onlyyear 0

2005 2010 2015 2020 2025 2030 2035 2040 2045 2050

4525 30 35 405 10 15 20

conceptual design

operation: priority materials

conceptual design

construction

construction

upgrade,construct

operateTodays

expts.

licensing

H & D operation

low-duty D-T operation

high-duty D-T operation

TBM: checkout and characterisation

TBM performance tests & post-exposure tests

second D-T operation phaseITER

EVEDA (design)

other materials testingIFMIF

engineering designconstruction phase 1

blanket construction

phase 2blanket

construction &installation

operation phase 1operation phase 2

blanket design

phase 2 blanket design

licensing

DEMO(s)

engineering designconstruction operate

licensing

Commercial Power plants

blanket optimisation

plasma performance confirmation

design confirmation

technology issues (e.g. plasma-surface interactions)

plasma issues

single beam

licensing licensing

plasma confirmation

materials optimisation

plasma optimisation

mobilis-ation

materials characterisation

R & D on alternative concepts and advanced materials

impacts of advances impacts of advances impacts of advances impacts of advances impacts of advances

Role of Fusion in 2100?Role of Fusion in 2100? A 1998 study (using MARKAL) by the Netherlands Energy Research Foundation (ECN) looked at potential role of fusion in the European Energy market** a ‘world study’ is currently being made in the framework of the European Fusion Development Agreement

Some of the assumptions (e.g. 2100 cost of oil = $30/barrel!) no longer look reasonable, others still valid (e.g. expected cost of fusion energy)

– all such modelling is of course subject to enormous uncertainties (especially on discount rate and environmental targets)

modelling = exploration of what might happen, not prediction of what will happen

Outcome of ECN modellingOutcome of ECN modelling With no constraint on carbon, coal is dominant

Fusion plays an important role with atmospheric CO2 limited to ~ 600 ppm or less, or a carbon tax of €30/tonne or more

This conclusion is relatively insensitive to other assumptions

– it is very hard to meet expected demand with carbon constrained

e.g. changing assumptions to allow more fission reduces gas, not fusion*

* unless unlimited fission allowed at ~ current uranium price/without fast breeders – which seems unlikely

Conclusions on FusionConclusions on Fusion DEMO could be putting fusion power into the grid in under 30 years, given• Funding* to begin IFMIF in parallel with ITER, plus technology development and start of design of DEMO• No major adverse surprises

*world fusion funding ~ $1.5 billion pa [c/f electricity (energy) market ~ $1.5 trillion ($4.5 trillion) p.a.]

The cocktail of energy sources that are needed (plus improved efficiency) to meet the energy challenge must include large-scale sources of base load electricity – fusion is one of very few options