Bob CywinskiSchool of Applied Sciences

International Institute for Accelerator Applications

Accelerator Driven Subcritical Reactors

with thorium fuel

Doctoral Training CourseUniversity of Huddersfield

11 April 2013

The Global Energy Crisis

The Carbon Problem

Energy Energy sourcesource

Grams of Grams of COCO22

per KWh of per KWh of electricityelectricity

NuclearNuclear 44

WindWind 88

Hydro electricHydro electric 88

Energy cropsEnergy crops 1717

GeothermalGeothermal 7979

SolarSolar 133133

GasGas 430430

DieselDiesel 772772

OilOil 828828

CoalCoal 955955

source: Government Energy Technology Support Unit (confirmed by OECD)

Current nuclear supply

Country No. Reactors GW capacity % Total Electricity

France 58 63 75Sweden 10 9 37South Korea 21 19 31Japan 55 47 29Germany 17 20 26United States 104 101 20Russia 32 23 18United Kingdom 19 11 17Canada 18 13 15India 20 5 321 Others 87 69

Totals: 441 380 14

But this represents only 5% of global energy consumptionTo increase this by x5 would reduce carbon emissions by 25%

Fission

Conventional Reactors

Uranium as nuclear fuel

Enriched uranium97% U-238, 3% U-235

Natural uranium: 99.3% U-238, 0.7% U-235

Uranium requirements

Scenario 1No new nuclear build

Scenario 2Maintain current nuclear capability (implies major increase in plant construction)

Scenario 3Nuclear renaissance: increase in nuclear power generation to 1500 GW capacity by 2050

Breeding nuclear fuel

Enriched uranium97% U-238, 3% U-235

Natural uranium: 99.3% U-238, 0.7% U-235

Retaining the nuclear option

...... the nuclear option should be retained precisely because it is an important carbon-free source of power….

....but there are four unresolved problems:

high relative costs

perceived adverse safety, environmental, and health effects

potential security risks stemming from proliferation

unresolved challenges in long-term management of nuclear wastes.

Annual global use of energy resources

5x109 tonnes of coal

27x109 barrels of oil

2.5x1012 m3 natural gas

65x103 tonnes of uranium

5x103 tonnes of thorium

An alternative fuel?

Thorium resources

Breeding fuel from thorium

Advantages

Does not need processing

Generates virtually no plutonium and less higher actinides

233U has superior fissile properties

Disadvantages

Requires introduction of fissile seed (235U or Pu)

The decay of parasitic 232U results in high gamma activity from 208Tl.

Advantages of thorium: waste

100,000100 1,000 10,000 100,000 1,000,000 10,000,00010

10

100100100

1,000

10,000

100,000

100,0001,000,000

10,000,000

100,000,000

1,000,000,000

Past experience with thorium:

Breeding fuel from thorium

Advantages

Does not need processing

Generates virtually no plutonium and less higher actinides

233U has superior fissile properties

Disadvantages

Requires introduction of fissile seed (235U or Pu)

The decay of parasitic 232U results in high gamma activity from 208Tl.

Spallation

ISIS200kW

SNS (1 MW)

J-PARC (1MW)

Spallation neutrons

The energy spectrum of proton induced spallation neutrons .The target is a lead cylinder of diameter 20 cm

At 1 Gev, approximately 24 neutrons per proton are produced

Spallation neutrons

Num

ber

of

neu

tro

ns p

er

uni

t en

erg

y o

f in

cide

nt

prot

on

The Accelerator Driven Subcritical Reactor

3. The Accelerator Driven Subcritical Reactor

Accelerator powerThe (thermal) power output of an ADSR is given by

eff

efffth k1

k.

ENP

with N = number of spallation neutrons/secEf = energy released/fission (~200MeV)ν = mean number of neutrons released per fission (~2)keff= criticality factor (<1 for ADSR)

So, for a thermal power of 1550MW we require

1

eff

eff19 s.neutronsk

k1106.9N

Given that a 1 Gev proton produces 24 neutrons (in lead) this corresponds to a proton current of

mAk

k1640amps

kk1

106.124

106.9i

eff

eff

eff

eff1919

Accelerator power

keff=0.95, i=33.7mA

keff=0.99i=6.5mA

To meet a constraint of a 10MW proton accelerator we need keff>0.985

Accelerator power

So, for a thermal power of 1550MW we require

1

eff

eff19 s.neutronsk

k1106.9N

Given that a 1 Gev proton produces 24 neutrons (in lead) this corresponds to a proton current of

mAk

k1640amps

kk1

106.124

106.9i

eff

eff

eff

eff1919

Accelerator power

H.M. Broeders, I. Broeders : Nuclear Engineering and Design 202 (2000) 209–218

1. Initial loss due to build-up of absorbing Pa233 and decrease of U233 enrichment by neutron absorption and fission

1 2

2. Increase due to increasing U233 enrichment from subsequent β-decay of Pa233

3

3. Long term decrease due to build up of neutron absorbing fission products

A Thorium Fuelled ADSR

Evolution of the criticality value, keff

Parks (Cambridge)

Evolution of power output

Coates, Parks (Cambridge)

Accelerator power

ADSR Shutdown

Parks (Cambridge)

The ADSR as an energy amplifier

10MW Accelerator

20 MWelectrical

1550MW Thermal Power

600 MW Electrical Power

“A reactor needs an accelerator like a fish needs a bicycle…”

http://sketchedout.files.wordpress.com/2011/04/fish-bike-4504.jpg

Waste management

The ADSR for waste management

Applications of Accelerator Driven Systems

Applications of Accelerator Driven Systems Technology Transmuting selected isotopes present in nuclear waste (e.g., actinides, fission products) to reduce the burden these isotopes place on geologic repositories. Generating electricity and/or process heat. Producing fissile materials for subsequent use in critical or sub-critical systems by irradiating fertile elements.

Transmuting selected isotopes present in nuclear waste (e.g., actinides, fission products) to mitigate the need for geologic repositories.

Generating electricity and/or process heat

Producing fissile materials for use in conventional critical or novel sub-critical reactors by irradiating fertile precursors.

Waste management

From: Hamid Aït Abderrahim (MYRRHA)

ADSR Projects: MYRRHA

The MYRRHA Project

Abderrahim et al., Nuclear Physics News, Vol. 20, No. 1, 2010

1b€ European project to build an ADSR for transmutation and waste management (2015)

ADSR Projects: Aker/Jacobs

Keff 0.995Accelerator 3MWADSR 600MW

ADSR Projects: Aker/Jacobs

Towards an ADSR

??

Proton drivers?

Cyclotron High Current (<A) Low Energy (600MeV)Continuous beam

SynchrotronLow Current (<mA) High Energy (TeV)Pulsed Beam

LinacHigh Current, High EnergyPulsed or continuous beamLarge and expensive

Why has no ADSR been built?

...because accelerators are relatively unreliable

Why has no ADSR been built?

o

...because accelerators are relatively unreliable, (largely because of ion source and RF issues )

From: Ali Ahmad

Technology readiness assessment (US)

EMMA – the world’s first ns-FFAG

EMMA – the world’s first ns-FFAG

Multiple FFAG proton injection

Multiple injection: - mitigates against proton beam trips and fluctuations - homogenises power distribution across ADSR core

Patent taken out on multiple injection

The way forward?

In 2009 Science Minister, Lord Drayson, asked ThorEA to prepare a report outlining what might be needed to deliver the technology to build the world’s first ADSR power station...........ThorEA delivered that report in October 2009.

http://thorea.hud.ac.uk/

Interest in thorium is now growing:eg Weinberg Foundation,All Party Parliamentary Group on Thorium, Annual International Conference (IThEC)

IAEA support

I A E AI A E A

“IAEA warmly welcomes the proposed accelerator driver development programme embodied in the ThorEA project as a positive contribution to the international effort to secure the eventual global deployment of sustainable thorium-fuelled ADSR power generation systems…”

Alexander StanculescuNuclear Power Technology Development SectionInternational Atomic Energy Agency (IAEA)Vienna

Conclusions

Thorium has been used in the past and could now be deployed in conventional, molten salt, ADS and even hybrid MS/ADS reactors providing an alternative, sustainable, safe, low waste and proliferation-resistant technology for nuclear power generation

780kg of thorium = 200 tonnes of uranium (as currently used)

No plutonium is used and very little is produced

After 70 years the radiotoxicity is 20,000 times less than an equivalent conventional nuclear power station

Thorium systems provide means of burning existing legacy waste

Waste can be mixed with thorium and burnt as fuel, reducing radiotoxity by orders of magnitude and turning a liability into an asset

But......Significant R&D has to be carried out on:

•Materials research (particularly for MSR systems)

•Improving accelerator reliability (for ADSR and hybrids)

•Beam, spallation target and blanket interfaces

ThankYou!

Thank you !

http://thorea.hud.ac.uk/