Accelerator Driven Subcritical Reactors with thorium fuel Doctoral Training Course University of Huddersfield 11 April 2013 Accelerator Driven Subcritical Reactors with thorium fuel Bob Cywinski School of Applied Sciences International Institute for Accelerator Applications

The Global Energy Crisis

The Carbon Problem Energy source Grams of CO2 per KWh of electricity Nuclear 4 Wind 8 Hydro electric Energy crops 17 Geothermal 79 Solar 133 Gas 430 Diesel 772 Oil 828 Coal 955 source: Government Energy Technology Support Unit (confirmed by OECD)

Current nuclear supply Country No. Reactors GW capacity % Total Electricity France 58 63 75 Sweden 10 9 37 South Korea 21 19 31 Japan 55 47 29 Germany 17 20 26 United States 104 101 20 Russia 32 23 18 United Kingdom 19 11 17 Canada 18 13 15 India 20 5 3 21 Others 87 69 Totals: 441 380 14 But this represents only 5% of global energy consumption To increase this by x5 would reduce carbon emissions by 25%

Fission

Conventional Reactors

Uranium as nuclear fuel Natural uranium: 99.3% U-238, 0.7% U-235 Enriched uranium 97% U-238, 3% U-235

Uranium requirements Scenario 1 No new nuclear build Scenario 2 Maintain current nuclear capability (implies major increase in plant construction) Scenario 3 Nuclear renaissance: increase in nuclear power generation to 1500 GW capacity by 2050

Breeding nuclear fuel Natural uranium: 99.3% U-238, 0.7% U-235 Enriched uranium 97% U-238, 3% 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 5x103 tonnes of thorium An alternative fuel? 27x109 barrels of oil 2.5x1012 m3 natural gas 65x103 tonnes of uranium

Thorium resources

Breeding fuel from thorium Advantages Does not need processing Generates virtually no plutonium and less higher actinides 233U has superior fissile properties n 232Th 233Th 233Pa 233U b g 27 days 22 mins 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 1,000 10,000 100,000 1,000,000 10,000,000 10 100,000,000 1,000,000,000 100,000

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 n 232Th 233Th 233Pa 233U b g 27 days 22 mins Disadvantages Requires introduction of fissile seed (235U or Pu) The decay of parasitic 232U results in high gamma activity from 208Tl.

Spallation ISIS 200kW 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 Number of neutrons per unit energy of incident proton

The Accelerator Driven Subcritical Reactor

3. The Accelerator Driven Subcritical Reactor

Accelerator power The (thermal) power output of an ADSR is given by with N = number of spallation neutrons/sec Ef = 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 Given that a 1 Gev proton produces 24 neutrons (in lead) this corresponds to a proton current of

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

Accelerator power

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

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 600 MW Electrical Power 10MW Accelerator 20 MW electrical 1550MW Thermal 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 1b€ European project to build an ADSR for transmutation and waste management (2015) Abderrahim et al., Nuclear Physics News, Vol. 20, No. 1, 2010

ADSR Projects: Aker/Jacobs Keff 0.995 Accelerator 3MW ADSR 600MW

ADSR Projects: Aker/Jacobs

Towards an ADSR ??

Proton drivers? Cyclotron Synchrotron Linac High Current (<A) Low Energy (600MeV) Continuous beam Synchrotron Low Current (<mA) High Energy (TeV) Pulsed Beam Linac High Current, High Energy Pulsed or continuous beam Large and expensive

Why has no ADSR been built? ...because accelerators are relatively unreliable

Why has no ADSR been built? ...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 . Interest in thorium is now growing: eg Weinberg Foundation, All Party Parliamentary Group on Thorium, Annual International Conference (IThEC) http://thorea.hud.ac.uk/

IAEA support “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…” I A E A Alexander Stanculescu Nuclear Power Technology Development Section International 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

Thank you ! Thank You! http://thorea.hud.ac.uk/